Titanium Salen Complexes with Appended Silver NHC Groups as Nucleophilic Carbene Reservoir for Cooperative Asymmetric Lewis Acid/NHC Catalysis

Article abstract of DOI:10.1002/ejoc.201700436

Lewis acid catalysis and nucleophilic carbene catalysis are complementary fundamental concepts to accelerate and control chemical reactions of aldehyde substrates. Their efficient merger has recently been achieved using two separate catalyst species. The

Full text of DOI:10.1002/ejoc.201700436

A Journal of
Accepted Article
Title: Titanium Salen Complexes with Appended Silver NHC Groups
as Nucleophilic Carbene Reservoir for Cooperative Asymmetric
Lewis Acid / NHC Catalysis
Authors: Katja Latendorf, Melanie Mechler, Irina Schamne, Daniel
Mack, Wolfgang Frey, and René Peters
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700436
Link to VoR: http://dx.doi.org/10.1002/ejoc.201700436
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
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Titanium Salen Complexes with Appended Silver NHC Groups as
Nucleophilic Carbene Reservoir for Cooperative Asymmetric
Lewis Acid / NHC Catalysis
Katja Latendorf,[a] Melanie Mechler,[a] Irina Schamne,[a] Daniel Mack,[a] Wolfgang Frey,[a] and
René Peters*[a]
Abstract: Lewis acid catalysis and nucleophilic carbene catalysis
are complementary fundamental concepts to accelerate and
control chemical reactions of aldehyde substrates. Their efficient
merger has recently been achieved using two separate catalyst
species. The present report describes our efforts to develop a
cooperative catalyst system which incorporates both features –
Lewis acid and nucleophilic NHC – within the same catalyst entity.
To generate free carbene moities under very mild conditions, Ag-
NHC complexes were formed releasing the nucleophilic carbene
upon treatment with PPh3. The result is the formation of an enol-δ-
lactone as new enal dimerization product. Silver is essential for the
reactivity mode thus suggesting that it plays a double role in the
catalytic event.
simultaneous activation of both substrates in quasi-
intramolecular bond formations. Thereby we were hoping to
increase both activity and stereocontrol in NHC catalyzed
reactions.
Results and Discussion
Ligand Synthesis
As dual activation catalyst precursors we synthesized Ti(IV)
salen complexes 5 with appended azolium moieties in the
ligand periphery. The azolium units were connected to the
C(6)-positions of both phenolates via benzylic methylene
linkers. The salen ligands 4 were prepared over 3 steps (Table
1) from the commercially available p-alkylated salicylic
aldehyde 1 in analogy to related onium salen ligands, which we
previously reported for asymmetric cooperative Lewis
acid/onium salt catalysis[6] and salen bis-NHC hybrid ligand
systems for bi- or polymetallic complexes.[7] Concretely,
halomethylation of 1 furnished benzylic halides 2 in high
yields.[8] Nucleophilic substitution of the leaving groups X= Br
or Cl proceeded with good to high yields for different N-
substituted imidazoles, benzimidazoles, as well as a chiral
enantiopure imidazoline as summarized in Table 1. In general,
the azolium salts 3 precipitated during their formation and were
thus readily separated from remaining starting materials.
Residual impurities could be conveniently removed by
trituration with diethylether and subsequent centrifugation.
The following diimine formation by condensation of various 1,2-
diamines with two equivalents of aldehydes 3 occurred
smoothly in most cases with yields usually ≥85%. Water was
removed from the reaction equilibrium by activated 4Å
molecular sieves in EtOH at room temperature.
Introduction
Inspired by the mode of action of vitamin B1 (thiamine) in
nature, N-heterocyclic carbenes (NHCs) have been intensively
studied as nucleophilic catalysts in order to invert the classical
carbonyl reactivity in aldehydes.[1] In addition, NHCs are
frequently used as ligands for transition metal catalyzed
reactions.[2] In contrast, for a long time the cooperation of
Lewis acids and nucleophilic NHCs in synergistic dual
activation catalysis approaches appeared very difficult,
because NHCs are known to form relatively stable complexes
with a large number of different metal centers[2] and self-
quenching of catalytic activity is thus the logical consequence.
However, in recent years especially Scheidt et al. described a
number of catalytic applications, in which nucleophilic NHCs
efficiently cooperate with hard, oxophilic Lewis acids.[3-5] In the
reported systems, the catalytically active NHC moieties
activating a pronucleophilic aldehyde and the Lewis acid co-
catalysts activating an electrophilic substrate were, in general,
two separate species. The objective of the here presented
investigation was to study bifunctional Lewis acid/nucleophilic
Synthesis and Structure of Titanium(IV)-Salen
Complexes with Appended Azolium Groups
For complexation, Ti(IV) was used as central metal. The
relatively rigid ligand structure in combination with the hard
acid character of Ti(IV) was expected to disfavor an
intramolecular coordination of in situ generated NHCs to the Ti
center.[7] Quantitative complexations were achieved in analogy
to a procedure by Belokon’, North et al. by treatment of ligands
4 with commercial Ti(OiPr)4 in CH2Cl2 at 30 °C (Table 1).[9]
Solubility of the ionic ligands 4 and Ti(IV) complexes 5 is
largely limited to chlorinated solvents like CH2Cl2, CHCl3, or
1,2-dichloroethane and alcohols.
NHC catalyst systems as cooperative catalysts for
a
[a]
Dr. Katja Latendorf, Dr. Melanie Mechler, Irina Schamne, M.Sc.
Daniel Mack, Dr. Wolfgang Frey, Prof. Dr. René Peters
Universität Stuttgart
Institut für Organische Chemie
Pfaffenwaldring 55, D-70569 Stuttgart, Germany
E-mail: rene.peters@oc.uni-stuttgart.de
www.peters.oc.uni-stuttgart.de
Supporting information for this article is given via a link at the end of
the document.
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10.1002/ejoc.201700436
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Table 1. Synthesis of the bisazolium functionalized salen ligands 4 and Ti-complexes 5.
yield 4 [%]a)
yield 5 [%]a)
dr 5
#
heterocycle
R
X
yield 3 [%]a)
diamine
4 / 5
1
CyHex
DiPh
a
b
c
d
e
f
99
98
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
5.0:1
5.0:1
Im
Me
Br
83
2
3
CyHex
DiPh
96
2.3:1
Im
Im
Im
Ph
Br
Br
Cl
64
4
94
2.0:1
5
CyHex
DiPh
98
10:1
6
98
3.3:1
7
Mes
79
DiPMP
DiCy
g
h
i
96
1.7:1
8
90
>50:1
7.2:1
9
N(CH2)2N
CyHex
DiPh
96
10
11
12
13
14
15
16
17
18
19
20
j
99 (ref. 7a)
98
6.5:1
Mes
73 (ref. 7a)
k
l
3.3:1
Im
Im
Im
2,6-Et-C6H3
2,6-i-Pr-C6H3
4-CF3-C6H4
Br
Br
Br
82
68
77
CyHex
CyHex
CyHex
CyHex
DiPh
95
>50:1
>50:1
1.6:1
m
n
o
p
q
r
>99
74
99
>50:1
3.8:1
BI
BI
BI
Me
Ph
Br
Br
Br
84
93
83
97
CyHex
DiPh
89
15:1
89
1.1:1
CyHex
DiPh
s
t
>99
90
48.7:8.5:1.7:1
1.3:1
Mes
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21
Im*
Mes
Br
79
CyHex
u
85
>99
>50:1
a) Yield of isolated product.
X-ray crystal structure analyses suggest the dimeric nature of
complexes 5 in the solid state. E.g., for complex 5c two species
with an isomeric ratio of 2.3:1 were detected by 1H-NMR
spectroscopy for a solution in CD2Cl2. Figure 1 shows the solid
state structure of one isomer of 5c.[10] In this dimer both Ti
centers adopt a distorted octahedral coordination geometry with
a Δ-cis-β configuration[11] resulting in a C2-symmetric isomer.
This symmetry is in agreement with the 1H-NMR spectra
showing two signal sets, whereas four signal sets were to be
expected for a C1-symmetric dimer. For all other complexes 5
based on a chiral cyclohexane-1,2-diyl (CyHex) backbone very
similar 1H-NMR spectra with two signal sets for the major isomer
were obtained.
Both ligands are twisted in 5c by an angle of ca 99° relative to
each other as Figure 2 visualizes, in which two planes
incorporating both Ti centers and a CHN stereocenter of the
chiral backbones are highlighted. A „head-to-head“ or „head-to-
tail“ assignment[12] is thus not useful in the present case.
The ratio of both isomers depended on the N-substituent R on
the imidazolium ring. It decreased from R = Me (5.0:1, entry 1) to
Ph (2.3:1, entry 3), and increased with the more bulky ortho-
disubstituted residue mesityl (10:1, entry 5). For 2,6-
diethylphenyl (>50:1, entry 12) and 2,6-diisopropylphenyl (>50:1,
entry 13) residues R, only one C2-symmetric isomer was
Figure 1. X-ray crystal structure analysis and simplified schematic
representation of 5c. H atoms, solvents molecules and counterions have been
omitted for clarity. Color code: C: gray, N: blue, O: red, Ti: greenish blue.
1
detected by H-NMR. In contrast, with a 4-trifluoromethylphenyl
residue R the ratio decreased to 1.6:1 in 5n (entry 14).[13]
A µ-oxo-bridged dimeric species of 5n crystallized from CD2Cl2
again showing a Δ-cis-β configuration for both Ti centers.[10]
Albeit the single crystal broke upon irradiation due to a large
amount of included volatile CD2Cl2 thus impeding a detailed
discussion of structural parameters, the analysis confirms both
the constitution and configuration and again shows that both
metal salen units within the dimer are tilted by ca. 99° towards
each other.
Figure 2. Visualization of the relative arrangement of both Ti salen units in the
C2-symmetric dimer 5c by two highlighted planes incorporating both Ti centers
and a CHN stereocenter of the chiral backbones.
Purification of the complexes, which was in general not
necessary, is possible by precipitation using, e.g., n-pentane. µ-
Oxo-bridged dimeric species were formed under the reaction
conditions, which is explained by hydrolysis of the TiOiPr bonds
by residual water.[9] In most cases, two isomers were detected
by NMR. For all complexes listed in Table 1, monomeric
titanium-oxo species were detected by ESI-HRMS probably due
to deaggregation under the experimental conditions, whereas
the heavier, tetracationic dimers were not detectable. However,
Figure 3. X-ray crystal structure analysis 5n. H atoms, solvents molecules and
counterions have been omitted for clarity. Color code: C: gray, N: blue, O: red,
Ti: greenish blue, F: lime green. Both ligands are shifted by an angle of ca 99°
relative to each other as visualized by two highlighted planes incorporating the
Ti centers and a CHN stereocenter of the chiral backbones.
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Additional complexes 5 based on the chiral CyHex backbone
were prepared containing benzimidazolium (entries 15, 17, 19)
and chiral imidazolinium (entry 21) moieties. In most cases the
isomeric ratios were significantly higher in these cases than for
the imidazolium containing complexes, the only exception being
the N-mesitylimidazolium substituted complex 5s, for which four
isomers were detected.
Moreover, a number of complexes based a 1,2-diphenylethane-
1,2-diyl (DiPh) backbone were prepared, carrying either N-
substituted imidazolium or benzimidazolium moieties. In general,
the isomeric ratios were in most cases lower than for complexes
based on a cyclohexane-1,2-diyl backbone, in particular for the
benzimidazolium derivatives (entries 16, 18, 20). In addition, an
N-mesityl imidazolium derivative was prepared based on a 1,2-
Furthermore, an achiral racemic reference complex was
prepared based on a 1,2-diaminoethane backbone (Table 1,
entry 9).
Investigation of the Ti-Complexes as Cooperative Lewis
Acid/NHC Catalysts
To probe a possible cooperative action of the Ti(IV) centers and
the in situ generated NHC moieties, the dimerization of
cinnamaldehyde 10 was studied using 10 mol% of precatalysts 5.
The dimerization of enals proceeding via vinylogous Breslow
intermediates has previously been intensively investigated by a
number of research groups.[14] Depending on the reaction
conditions and catalysts used, different major reaction products
like cyclopentenes and γ-lactones were reported in these
studies.[14]
di-para-methoxyphenylethane-1,2-diyl
displaying a low isomeric ratio (entry 7). In contrast, its
counterpart based on 1,2-dicyclohexylethane-1,2-diyl
(DiPMB)
backbone
To generate a nucleophilic NHC unit, the use of different anionic
and neutral bases (40 mol%) like LHMDS and DBU
a
backbone was a single isomer (DiCy, entry 8). For all major
species two rather than four signals sets were counted per dimer
indicating a C2-symmetry of the dimer.
In addition to the salen ligands 4, we also prepared a monoimine
ligand 6 by condensation of aldehyde 2 with enantiopure
aminoindanol. Despite a 1:1 stoichiometry of 6 and Ti(OiPr)4, a
complex 7 carrying two phenoxyiminoalcoholate ligands was
quantitatively formed with a diastereomeric ratio of 1.4:1
(Scheme 1). The formation of isomers is most likely explained by
configurational isomers regarding the octahedral Ti stereocenter.
(diazabicycloundec-7-ene)
was
investigated.
Table
3
summarizes the results obtained for several Ti complexes 5. In
each case γ-lactone 11 was found as a product,[15,16] but yields
were usually low despite good to high conversions in most
instances.
Table 2. Investigation of LHMDS and DBU as bases.
yield
11
[%]a)
ee
(cis)
[%]c)
ee
(trans)
[%]c)
base,
conv.
[%]a)
5
cis/transb)
#
solvent
1
2.2:1
0.6:1
1.2:1
1.3:1
1.1:1
0.9:1
3.7:1
0.5:1
1.5:1
0.5:1
2.4:1
0.9:1
-
a
a
c
c
e
e
o
o
q
q
s
s
u
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
LHMDS, THF
DBU, CH2Cl2
81
21
10
13
13
13
27
14
44
22
23
36
32
<2
11
24
2
67
14
4
9
0
15
7
2
87
83
37
96
50
87
50
80
58
>99
88
n.d.
3
2
Scheme 1. Synthesis of Ti(IV) bis(phenoxyiminoalcoholate) complex 7.
4
2
5
27
10
6
17
22
14
6
4
Moreover, titanium(IV) complex 9 was prepared from the C1-
symmetric salen ligand 8 equipped with a single imidazolium unit
(Scheme 2). Three µ-oxo-bridged dimeric diastereomers were
formed with a ratio of 10:3:1 in quantitative yield. The major
dimer is C1-symmetric as judged from 1H-NMR-spectroscopy.
6
7
8
9
30
2
4
7
10
11
12
17
-
-
Scheme 2. Synthesis of dimeric Ti(IV) complex 9 from C1-symmetric salen
ligand 8 equipped with a single imidazolium moiety.
a) Conversion and yield determined from the crude product by GC/FID. b)
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Diastereomeric ratio determined by 1H-NMR of the crude product. c)
Enantiomeric excess determined by HPLC. A negative sign indicates that the
other enantiomer than the one depicted was formed in excess.
Benzoin addition was identified as one of the common side
reactions preventing higher yields. Both diastereoselectivity and
enantioselectivity were also usually quite low. The best ee value
of 67% was obtained with the N-phenyl substituted catalyst 5c,
but the yield of 11 was poor in this case (entry 4). The best yield
was obtained in the reaction with N-methyl benzimidazolium
derivative 5o and LHMDS, which provided only low amounts of
side products in a quite clean transformation. However, the
product diastereomers were (nearly) racemic (entry 8).
Alternative anionic and neutral bases like KHMDS, KOtBu and
TBD did not improve the reaction outcomes. Experiments using
Cs2CO3 were also conducted, but resulted in no conversion of
the starting material.
A general problem appeared to be catalyst decomposition under
the basic reaction conditions and milder conditions seemed to
be necessary for better results. Since we previously described
the smooth formation of bi- and polymetallic salen-NHC-hybrid
complexes, in which reactive NHC-Ag complexes efficiently
underwent a carbene transfer to other metal centers, we were
curious to use the NHC-Ag units as sources for the nucleophilic
carbene moieties.
Hedrick reported in 2005 the use of Ag(I)-NHC complexes as
nucleophilic carbene delivery reagents for the organocatalyzed
ring opening polymerization of lactide and for transesterification
reactions.[17] The thermal lability of the Ag(I)-NHC complexes
allowed to release the free carbene by heat.
Since we were striving for very mild reaction conditions, NHC
release was investigated by addition of PPh3 instead as a
competing ligand to trap the Ag ions. The thermally and air labile,
light-sensitive Ag-NHC complexes 5-Ag were formed in situ in
quantitative yields, based on our previous protocol towards bi-
and polymetallic metal salen/NHC-Ag hybrid complexes, which
used modified reaction conditions originally reported by Lin as
‘Ag2O route’.[18,19] After complete conversion, any excess of the
silver reagent was removed by filtration.
Scheme 3. In-situ formation of hybrid Ti(IV) salen/Ag(I)-NHC complexes 5-Ag
(only two of several possible species are shown, see text).
Surprisingly, treating cinnamaldehyde with several Ti/Ag
complexes in situ prepared from the imidazolium precursors 5
(10 mol%) and PPh3 a new dimerization product was formed.
Rather than the expected, literature known γ-lactone 11 the
unknown δ-lactone 12 was obtained as the major product in a
number of cases (Table 3). Enol-δ-lactones like 12 are
structurally interesting products. However, the isolation of 12
proved very difficult, probably as a result of the unsubstituted
positions C(2) and C(3) which might cause a higher reactivity
towards hydrolysis. In contrast, various C(2) and/or C(3)
substituted enol-δ-lactones have previously been synthesized
via NHC catalysis by means of two different coupling partners,
one of them usually being an activated enone.[22] To report
accurate yields reflecting the efficiency of the new
transformation, we thus report yields determined from the crude
product by GC/FID (Table 3). Nevertheless, isolation of 12 was
achieved by preparative TLC for analytical purposes, but with a
massive loss of material.
In the catalytic experiments, the silver complexes were
preformed in 1,2-dichloroethane at 30 °C for 15 h using 20 mol%
Ag2O. It was found that addition of another 40 mol% of Ag2O
during the catalytic reaction was important for reproducibly high
conversions.[23] In control experiments no conversion of
cinnamaldehyde was noticed in the absence of PPh3. The
phosphine is thus necessary for generation of sufficient amounts
of free nucleophilic NHC moieties. Table 3 summarizes the
results of the different precatalysts used in the model reaction.
The 1H-NMR spectra of the mixed Ti/Ag complexes are very
complex. As described above complexes 5 are µ-oxo-bridged
dimeric complexes, which often consist of diastereomeric
mixtures. In complexes 5-Ag the situation is further complicated,
because in analogy to early studies by Nolan[20,21] and also our
own previous investigations[7] either Ag(I)X might be coordinated
by a single NHC ligand or two NHCs bind to a cationic silver
center (Scheme 3). This latter binding mode could be realized
with two NHCs connected to the same or different salen units
and dimers. The result is a complex equilibrium mixture.
Nevertheless, formation of the Ag-NHC bonds was clearly
supported by disappearance of the prominent NCHN-azolium
1
signals in the H-NMR spectra and by mass spectrometry (ESI-
HRMS). The latter detected the (more volatile) monomeric
fragments carrying one Ag(I) ion per two NHC donors.
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N-mesityl imidazolium substituted precatalysts 5e-5g (entries 5-
7), and the N-2,6-diethylphenyl imidazolium precatalyst 5l (entry
10). To prepare racemic reference samples, N-mesityl
imidazolium substituted precatalyst 5i (based on the achiral 1,2-
diaminoethane for diimine formation) was studied and also
showed a preference for formation of enol-δ-lactone 12 (entry 9).
The best yields of 12 were obtained with 5e (entry 5) and 5f
(entry 6).[24] In these examples the ee value of the major cis-
configured 12 was 65% (9% ee for the minor trans isomer) and
69% (70% ee for trans), respectively. Formally replacing the
DiPh ligand backbone (entry 6) by the aliphatic DiCy ligand
backbone in 5h (entry 8) led to a preference for the γ-lactone 11,
which was formed with good diastereoselectivity and low
Table 3. Investigation of in situ formed Ag-complexes in combination with
PPh3 to release nucleophilic NHC moieties.
yield
11
[%]a)
yield
12
[%]a)
ee
conv.
[%]a)
cis/transb)
cis/transb)
precat.
#
12 (cis)
[%]c)
11
12
enantioselectivity
(27%
ee
for
cis-11),
whereas
diastereoselectivity was poor for enol-δ-lactone 12. In addition,
the cyclohexyl groups in the chiral backbone had a detrimental
effect on the ee of 12, which was only 15% (compare to 69% for
entry 6 with a phenyl group instead in the backbone). We were
thus wondering, if π-interactions of the Ph groups were
beneficial for high enantiocontrol and studied the DiPMP
backbone containing the more electron-rich 4-MeO-substituted
phenyl rings. However, this change slightly reduced enantio-,
diastereoselectivity and yield of 12, although γ-lactone 11 was
not formed in that case (entry 7).
1
-
5a
5b
5c
5d
5e
5f
12
0
0
-
-
2
3
4
5
6
7
2.8:1
-
75
17
0
0
-
-
11
0
-
-
1.2:1
1.9:1
0.9:1
-
84
17
13
27
0
14
48
42
37
1.7:1
4.5:1
2.7:1
2.0:1
n.d.
65
69
64
100
100
100
Enol-δ-lactone 12 was also formed with complex 9 prepared
from the C1-symmetric ligand bearing a single N-Mes substituted
imidazolium unit (entry 20), whereas 11 was not detected.
However, in both cases stereoselectivity was poor.
5g
8
11.6:1
5h
5i
90
94
91
30
20
13
20
41
39
1.4:1
1.2:1
1.8:1
15
-
9
Investigation of an Achiral Catalyst Control System
Since the formation of enol-δ-lactone 12 by NHC catalysis is
unprecedented, control experiments were conducted with a
simple achiral NHC silver complex, which was prepared from
IMes-Cl and Ag2O in the absence of light in dichloromethane at
55 °C in a sealed reaction vial for 15 h (Scheme 4). 1H-NMR
spectroscopy confirmed that the known mono-NHC Ag complex
13 was almost exclusively formed.[20]
1.8:1
1.4:1
10
5l
n.d.
11
12
13
14
15
16
17
18
1.3:1
-
5m
5n
5o
5p
5q
5r
95
46
70
93
66
64
96
100
16
0
0
-
n.d.
0
-
-
-
-
-
-
2.0:1
1.9:1
1.1:1
1.2:1
1.3:1
22
30
16
18
10
0
0
-
0
-
0
-
0
-
5s
5t
10
0
6.6:1
-
Scheme 4. Preparation of IMesAgCl 13.
-
-
-
-
19
20
5u
9
0
0
0
0
-
-
In 2004, the groups of Glorius and Bode independently reported
that γ-lactones are formed from enals employing catalytic
amounts of IMes-HCl in the presence of DBU or KOtBu for NHC
generation.[15] Enol-δ-lactone 12 was not mentioned in these
studies. In our control experiments we used a combination of
Ti(OiPr)4 (20 mol%) and complex 13 (20 mol%) plus PPh3 for the
NHC release (Table 4). In the absence of PPh3, no conversion
was observed at 30 °C in CH2Cl2 (entry 1). In contrast, in the
presence of PPh3, γ-lactone 11 and enol-δ-lactone 12 were both
formed and their ratio depended on the amount of PPh3 and
88
50
1.1:1
17
a) Conversion and yield determined from the crude product by GC/FID. b)
Diastereomeric ratio determined by 1H-NMR of the crude product. c)
Enantiomeric excess determined by HPLC. Different signs indicate that
different enantiomers were formed in excess.
With the exception of entries 1 and 3 (use of the imidazolium
substituted catalysts 5a and 5c), always good to full conversion
was found. Formation of enol-δ-lactone 12 was preferred for the
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European Journal of Organic Chemistry
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additional Ag2O (entries 2 & 3). Increasing their quantities, enol-
δ-lactone 12 became the major product. Several other solvents
were screened, but with none of them an improvement of the
formation of 12 could be achieved compared to CH2Cl2. In
contrast, in several solvents the formation of γ-lactone 11
became considerably more efficient. Good yields of 11 were
achieved using polar aprotic solvents like acetone (entry 6) and
diglyme (entry 7). These results demonstrate that Ag-NHC
complexes can provide a synthetically efficient alternative to the
liberation of NHCs by conventional bases. Entry 6 was also
repeated in the absence of Ti(OiPr)4. This had a massive effect
on the reaction outcome, because enol-δ-lactone 12 became the
major product again (11: 30% (cis/trans = 3.8:1); 12: 40%
(cis/trans = 1.1:1)).
confirmed by X-ray crystal structure analysis (Figure 4).[25] Both
phenyl rings are located on the convex face of the bicyclic [3.2.0]
core. The other diastereomer possesses a trans-configuration of
both phenyl rings. A trans-isomer was previously reported by
Scheidt et al. as a product (15% yield) during the dimerization of
10 catalyzed by IMes using DBU as base.[26] It is remarkable
that IMes using the Ag-carbene route leads to
a
diastereodivergent reaction outcome.
Table 4. Investigation of the solvent effect in the dimerization of
cinnamaldehyde 10 using IMesAgCl 13 as precatalyst.
Scheme 5. Effect of 4Å molecular sieves on dimerization of cinnamaldehyde
10 using IMesAgCl 13 as precatalyst.
yield 11
[%]a)
(cis/transb))
yield 12
[%]a)
cis/transb))
equiv.
Ag2O
equiv.
PPh3
conv.
[%]a)
solvent
1
2
3
4
5
6
7
8
9
-
-
(CH2Cl)2
(CH2Cl)2
(CH2Cl)2
CH2Cl2
CHCl3
0
0
0
0.4
0.4
0.8
0.8
0.8
0.8
0.8
0.8
0.8
92
23 (0.8:1)
29 (0.8:1)
25 (0.7:1)
54 (3.6:1)
69 (3.3:1)
74 (5.8:1)
57 (5.1:1)
59 (4.2:1)
19 (1.9:1)
40 (0.3:1)
23 (2.6:1)
20 (2.1:1)
19 (4.2:1)
0 (-)
0.8
91
Figure 4. X-ray crystal structure analysis of bicyclic β-lactone 14. H atoms,
solvents molecules and counterions have been omitted for clarity. Color code:
C: gray, O: red, H: babyblue.
-
-
-
-
-
-
>99
>99
>99
>99
95
Mechanistic Considerations
acetone
diglyme
DMF
It has been suggested previously that the dimerization of enals
to give γ-lactones like 11 proceeds via vinylogous Breslow
intermediates I (for structure see Scheme 6).[15,14] The latter is a
d3-reagent and is likely to undergo a 1,2-addition to another enal
molecule followed by lactone formation to release the catalyst.
For the NHC catalyzed formations of δ-lactones it has been
0 (-)
DMSO
>99
18 (2.0:1)
suggested that the vinylogous Breslow intermediate
I is
protonated at the d3-position to form an enolate d2
intermediate.[14,22] The latter usually undergoes a 1,4-addition
with an α,β-unsaturated ketone followed by enolization.
a) Conversion and yield determined from the crude product by GC/FID. b)
Diastereomeric ratio determined by 1H-NMR of the crude product.
Interestingly, performing the dimerization again in 1,2-
dichloroethane, yet in the presence of activated 4Å molecular
sieves, only traces of enol-δ-lactone 12 were produced. Next to
γ-lactone 11 in that case bicyclic β-lactone 14 was isolated in
significant quantities as a mixture of two diastereomers (ratio
9.2:1), which are separable by chromatography. The constitution
and relative configuration of the major diastereomer were
For the here reported δ-lactone formation by enal dimerization
we assume a similar mechanism (Scheme 6). As mentioned
above, NHC catalyzed dimerization of enals did not result in
enol-δ-lactone formation in previous studies. In the present
study it was also only formed using the Ti-salen complexes with
appended NHC-Ag moieties[27] or from an Imes-Ag complex
when releasing the free NHC by a phosphine. We thus suggest
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
that Ag(I) might play an additional role than masking the carbene. chosen. These results point to a cooperative action of Lewis acid
It might be that the carbophilic Ag(I) also activates the C=C
double bond of the enal by complexation thereby favoring a 1,4-
addition mode, which was usually not found for enals.[15,14,28,29]
Ti(IV) might support the event by additional enal activation via
coordination of the carbonyl group and stabilization of the
enolate.
and NHC.
Our results indicate that residual water might play a role for the
synthesis of 12, because under very dry conditions 12 was not
formed (Scheme 5). Water might act as a proton source/shovel
in the step I -> II (Scheme 6).[30] In contrast, for the formation of
11 and 14, the homoenolate I must not be protonated and
should itself attack another enal.
Figure 5 shows our working model to illustrate how the
polyfunctional catalyst might e.g, work in a quasi-intramolecular
mode of action. However, competing intermolecular pathways
cannot be ruled out by our data.
Figure 5. Working model showing a possible tentative cooperative activation
mode.
The Ag ion activating the enal might also be part of an NHC
silver moiety connected to the same or a different salen entity.[23]
Conclusions
In conclusion, we have reported the first integration of a
nucleophilic NHC moiety and a Lewis acid within the same chiral
catalyst molecule. In order to generate the nucleophilic NHCs
under mild conditions, Ag-NHC complexes were formed as
masked nucleophilic carbenes which could be released upon
treatment with PPh3. This allowed for interesting new reactivity
providing an enol-δ-lactone as new enal dimerization product,
which proved to be rather unstable though. Control experiments
with an IMes-Ag complex showed that the presence of Ag is
essential to get this new product. However, depending on the
reaction conditions also a known γ-lactone could be formed in
good yields using this Ag-carbene route, which might thus be an
interesting alternative compared to the common imidazolium
salt/base approaches.
Scheme 6. Suggested simplified cooperative mechanism for the NHC/Ti/Ag
catalyzed synthesis of enol-δ-lactone 12.
For control experiments we also tried to form the corresponding
Ag-NHC complexes directly from ligand 4e, but unfortunately
these experiments were not successful. To learn more about the
role of the Ti(IV) centers, several other salen metal complexes
were thus prepared from ligand 4e using different metal sources
(see the Experimental Section). Using the conditions of Table 3,
20 mol% of these complexes were used, because they are
monomeric. With M = Ni(II) γ-lactone 11 was formed in a yield of
19% (cis/trans = 2.9:1), whereas the enol-δ-lactone 12 was not
found. With M = Al(III)-Me a similar result was obtained: 21% of
11 (cis/trans = 1.1:1) and 0% enol-δ-lactone 12. With M = Zn(II)
none of these products was detected. In contrast with M = Mg(II)
similar amounts of 11 and 12 were obtained (11: 19%, (cis/trans
= 0.7:1); 12: 20%, (cis/trans = 1.4:1), ee (cis-12): 45%). These
results show that the choice of the Lewis acid is important for the
reaction outcome. The type of the product, the reactivity as well
as the stereoselectivity strongly depend on the metal center
Experimental Section
General Methods: All syntheses of ligand precursors, ligands and metal
complexes were performed in oven-dried (150 °C) glassware under a
positive pressure of nitrogen (about 0.1 bar). Reaction mixtures were
stirred magnetically in these cases. All NHC catalyzed reactions were
performed in oven-dried (150 °C) glassware under a positive pressure of
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
nitrogen (about 0.2 bar) using
a
parallel synthesizer (Heidolph
referred in terms of ppm and J-coupling constants are given in Hz.
Abbreviations for multiplicities are as follows: s (singulet), d (doublet), t
(triplet), q (quartet), quint (quintet), sext (sextet), m (multiplet), b (broad
signal). Assignment of 13C-NMR-signals is based on maiQC-spectra
where possible. IR-spectra were recorded by the analytical service of the
Universität Stuttgart on a spectrometer with an ATR unit. IR-spectra of air
sensitive complexes were measured by Dr. Birgit Stadelmann (group of
Prof. D. Gudat, Institut Anorganische Chemie, Universität Stuttgart) in a
glovebox under inert gas atmosphere. The aggregation state of the
sample is stated in parentheses, signals are given by wavenumbers
(cm1). Mass spectra and were obtained from the analytical service of the
Universität Stuttgart. The ionization method is stated in parentheses.
Single crystal X-ray analyses were performed by Dr. Wolfgang Frey
(Universität Stuttgart). Single crystal X-ray analyses were performed by
Dr. Wolfgang Frey (Universität Stuttgart, Bruker Kappa APEXII Duo (Mo
and Cu-Kα radiation)). Enantiomeric excesses (ee’s) were determined by
high performance liquid chromatography (HPLC) at room temperature.
The γ- and δ-lactone products were eluted by n-hexane/isopropanol and
detected at λ = 210 nm.
Synthesis1). Reaction mixtures were permanently shaken in these cases.
For all reactions liquids and solutions were added via syringes and septa.
High pressure reactions were performed in ACE pressure tubes.
Solvents were removed at a heating bath temperature of 40 °C and 600 –
10 mbar pressure by rotary evaporation, if not mentioned otherwise. Non-
volatile compounds were dried under high vacuum at ca. 0.1 mbar
pressure. Dichloromethane, diethylether, n-pentane and tetrahydrofurane
were purified by distillation and subsequently by a solvent purification
system to remove water and oxygen (MBraun SPS 800). 1,2-
Dichloroethane (extra dry, 99.8%, crown-capped bottles by Sigma-
Aldrich) was additionally dried over CaCl2, distilled under N2 atmosphere
and stored in Young-flasks over 4Å molecular sieves at 2-7 °C under a
N2 atmosphere. Chloroform (>99%), ethanol (absolute), n-hexane (HPLC
quality), methanol (HPLC quality), methyl-tert-butylether (MTBE, GC
quality) and isopropanol (HPLC quality) were used as purchased.
Solvents for reaction workup and column chromatography
(dichloromethane, diethylether, ethyl acetate, petrolether) were of
technical quality and used after distillation. Ti(OiPr)4 and aldehyde 10
were distilled under N2 atmosphere using a Vigreux column and stored
under N2 atmosphere at 30 °C. All ligands were stored in a dessicator
over CaCl2 at 2-7 °C. The following ligand precursors and ligands were
prepared according to literature procedures: 1-mesityl-1H-imidazol,[31] 4-
mesityl-4H-1,2,4-triazole,[32] 4-phenyl-4H-1,2,4-triazole,[33] 1-phenyl-1H-
benzo[d]imidazol,[34] 1-mesityl-1H-benzo[d]imidazole,[35] (1R,2R)-N1-
General Procedures (GPs)
General Procedure for the Synthesis of Aldehydes 3 (GP1)[6,7]
5-(tert-Butyl)-3-(halomethyl)-2-hydroxybenzaldehyd 2[8] (1.0 equiv.) was
dissolved in acetonitrile (0.5 M) and the corresponding heterocycle (1.1
equiv.) was added. The mixture was stirred for 15 h at room temperature.
Subsequently diethylether was added to cause precipitation. The mixture
was centrifuged and the liquid was removed. The solid was thorougly
washed with diethylether. 3 was dried in vacuo and no further purification
was necessary.
mesityl-1,2-diphenylethan-1,2-diamine,[36]
5-tert-butyl-2-
5-(tert-butyl)-3-(halomethyl)-2-
hydroxybenzaldehyde
1,[37]
hydroxybenzaldehydes 2,[8] 3-(5-(tert-butyl)-3-formyl-2-hydroxybenzyl)-1-
methyl-1H-imidazol-3-ium-bromide (3-Im-Me),[6] 3-(5-(tert-butyl)-3-formyl-
2-hydroxybenzyl)-1-phenyl-1H-imidazol-3-ium-bromide
(1R,2R)-1,2-bis(4-methoxyphenyl)ethan-1,2-diamine,[38]
(3-Im-Ph),[7a]
(1R,2R)-1,2-
dicyclohexylethan-1,2-diamine,[39]
(R,R)-(–)-N,N’-bis(5-tert-butyl-3-((1-
methyl-1H-imidazol-3-ium)-1-ylmethyl)-salicyliden)-1,2-cyclohexan-
diamin-dibromide (4a)[6] and (R,R)-(–)-N,N’-bis(5-tert-butyl-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-salicyliden)-1,2-cyclohexan-diamin-
dichlorid (4j).[7a] All other laboratory chemicals were purchased from
commercial suppliers and were used without purification unless
otherwise indicated. Reactions for synthesizing ligand precursors and
ligands were monitorred by thin layer chromatography (TLC), for which
silica gel plates from Merck (silica gel 60 F254) were used. Visualization
occurred by fluorescence quenching under UV light (λ = 254 nm) and/or
by staining with a KMnO4 (1.5 g KMnO4, 10 g K2CO3, 5 mL 1M NaOH,
200 mL Wasser) or anisaldehyde (5 mL conz. H2SO4, 1.5 mL acetic acid,
3.7 mL p-anisaldehyde in 135 mL ethanol) solution. Purification by flash-
chromatography was performed on silica gel 0.040 – 0.063 mm provided
by Merck, using a forced flow of eluent at ca. 0.1 pressure. Preparative
TLC was performed on regular silica gel plates (silica gel 60 F254). Yields
usually refer to chromatographically purified compounds and are
calculated in mol% of the used starting material if not mentioned
otherwise. Conversions of NHC catalyzed reactions were determined by
1H-NMR-spectroscopy using an internal standard (DMF, >99 % or
acetophenone, >99 %) or alternatively by gas chromatography (GC) (HP
6890 Series II, injector and detector temperature: 350 °C, oven
temperature: 80/1‘/10°C*min-1→300/5‘, flow rate: 2.0 mL min1, columns:
Zebron Zb-5 30m x 0.32mm x 0.25µm and Restek RtX-5 30m x 0.53mm
x 1.50µm, solvent for all samples: ethyl acetate) using a calibration curve.
Melting points were measured in open glass capillaries and are
uncorrected. Optical rotation was measured on a polarimeter operating at
the sodium D line with a 100 mm path cell length. The solvent and
concentration in g mL1 are provided in brackets for the corresponding
compounds. NMR-spectra were recorded at 21 °C on spectrometers
operating at 500, 300 MHz or 250 MHz (1H), 125 MHz, 75 MHz or
63 MHz (13C) and 235 MHz (19F). Deuterated solvents were used as
purchased and are stated for the corresponding compound
characterizations after the corresponding frequency. Chemical shifts are
General Procedure for the Synthesis of Salen Ligands 4 (GP2)[6,7]
A solution of aldehyde 3 (2.0 equiv.) in ethanol (5 mL / g aldehyde X) was
added to the corresponding diamine (0.05 M in EtOH) and molecular
sieves (4Å). The mixture was stirred for 20 h at ambient temperature.
After filtration over celite, EtOH was evaporated. The solid was thorougly
washed with diethylether. 4 was dried in vacuo and no further purification
was necessary.
General Procedure for the Synthesis of Titanium(IV) Salen
Complexes 5 (GP3)
To a solution of salen ligand 4 in dichloromethane (0.2 M) a solution of
Ti(OiPr)4 (1.0 equiv.) in dichloromethane (1.0 M) was added. The
reaction mixture was stirred for 15 h at 30 °C. All volatiles were
evaporated and the titanium(IV) salen complexes 5 were dried for 2 h at
0,01 mbar. Complete conversion was verified by 1H-NMR analysis in all
cases.
Synthesis of Ligand Precursors
(4R,5R)-1-Mesityl-4,5-diphenyl-4,5-dihydro-1H-imidazole: A solution
of (1R,2R)-N1-mesityl-1,2-diphenylethan-1,2-diamine (512 mg, 1.6 mmol,
1.0 equiv.), trimethylorthoformate (170 µL, 1.6 mmol, 1.0 equiv.) and
conc. acetic acid (89 µL, 1.6 mmol, 1.0 equiv.) in acetonitrile was heated
to reflux for 15 h. After evaporation of solvent the remaining oil was
washed with diethylether providing (4R,5R)-1-Mesityl-4,5-diphenyl-4,5-
dihydro-1H-imidazole (439 mg, 1.3 mmol, 83%) as a colourless solid
after drying in vacuo. C24H24N2, MW: 340.46 g mol–1. M.p.: 98 - 100 °C.
1
[α]20D (c = 1.0 g·dL-1, CH2Cl2) = 78. H-NMR (500 MHz, CDCl3, 21 °C): δ
= 7.35 – 7.29 (m, 10H, CPh-H), 6.80 (s, 1H, CMes-H), 6.70 (s, 1H, CMes-H),
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
5.61 (d, J = 9.2, 1H, CHN), 4.71 (d, J = 9.2, 1H, CHN), 2.19 (s, 6H,
(CH3)Mes), 2.00 (s, 3H, (CH3)Mes). 13C-NMR (125 MHz, CDCl3, 21 °C): δ =
153.9 (1C, NCHN), 141.1 (1C, Cq), 137.6 (1C, Cq), 135.7 (1C, Cq), 135.6
(1C, Cq), 134.2 (1C, Cq), 130.9 (1C, Cq), 127.8 (1C, CMes-H), 127.6 (1C,
CMes-H), 126.8 (2C, CPh-H), 126.76 (3C, CPh-H), 126.71 (3C, CPh-H),
125.5 (1C, CPh-H), 124.3 (1C, CPh-H), 74.8 (1C, CHN), 72.4 (1C, CHN),
19.8 (2C, (CH3)Mes), 18.9 (1C, (CH3)Mes). IR (CDCl3): 3029, 2921, 1704,
1596, 1576, 1475, 1407, 1257, 1076, 911, 737, 699, 621. HRMS (ESI)
m/z: calculated for (C24H25N2)+: 341.2012, found: 341.2025.
(t, J = 1.5, 1H, (CH=CH)Im), 7.55 (d, J = 2.4, 1H, CAr-H), 7.46 (d, J = 7.7,
1H, CPh-H), 7.22 (d, J = 7.7, 1H, CPh-H), 7.09 (t, J = 1.5, 1H, (CH=CH)Im),
6.06 (s, 2H, CAr-CH2-NIm), 2.33 (sept, J = 6.7, 2H, (CH(CH3)2), 1.29 (s, 9
H C(CH3)3), 1.12 (d, J = 6.7, 2H, (CH(CH3)2), 1.05 (d, J = 6.7, 2H,
(CH(CH3)2). 13C-NMR (125 MHz, CDCl3, 21 °C): δ = 197.0 (1C, CHO),
157.4 (1C, CAr-OH), 145.4 (1C, Cq), 144.6 (1C, Cq), 138.2 (1C, NCHNIm),
137.8 (1C, CAr-H), 131.9 (1C, CPh-H), 131.3 (1C, CAr-H), 130.1 (12C, Cq),
124.7 (2C, CPh-H), 123.8 (1C, (CH=CH)Im), 123.7 (1C, (CH=CH)Im), 122.1
(1C, Cq), 120.2 (1C, Cq), 47.5 (1C, CAr-CH2-NIm), 34.6 (1C, C(CH3)3), 31.3
(3C, C(CH3)3), 28.7 (1C, CH(CH3)2), 24.5 (1C, CH(CH3)2), 24.0 (2C,
CH(CH3)2). IR (solid): 3161, 3088, 2962, 2870, 1637, 1539, 1458, 1390,
1181, 1012, 761, 669, 652. HRMS (ESI) m/z: calculated for
(C27H35BrN2O2)+: 419.2675; found: 419.2693.
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-mesityl-1H-imidazol-3-
ium-bromide (3-Im-Mes): A solution of (3-(bromomethyl)-5-(tert-butyl)-2-
hydroxybenzaldehyde (2) (1.95 g, 7.20 mmol, 1.0 equiv.) was treated
with 1-mesityl-1H-imidazole (1.41 g, 7.56 mmol, 1.1 equiv.) according to
GP1. 3-Im-Mes was obtained as a beige hygroscopic solid (2.59 g, 5.66
mmol, 79%) after washing for several times with diethylether.
C24H29BrN2O2. MW: 457.40 g mol–1. M.p.: decomp. > 210 °C. 1H-NMR
(300 MHz, CDCl3, 21 °C): δ = 11.46 (s, 1H, CAr-OH), 10.56 (t, J = 1.4, 1H,
NCHNIm), 9.92 (s, 1H, CHO), 8.65 (d, J = 2.4, 1H, CAr-H), 7.88 (t, J = 1.6,
1H, (CH=CH)Im), 7.60 (d, J = 2.4, 1H, CAr-H), 7.06 (t, J = 1.9, 1H,
(CH=CH)Im), 6.99 (s, 2H, CMes-H), 6.06 (s, 2H, CAr-CH2-NIm), 2.33 (s, 3H,
(CH3) Mes), 2.05 (s, 6H, (CH3) Mes), 1.37 (s, 9H, C(CH3)3). 13C-NMR (125
MHz, CDCl3, 21 °C): δ = 197.0 (1C, CHO), 157.5 (1C, CAr-OH), 144.7
(1C, Cq), 141.4 (1C, Cq), 138.3 (1C, NCHNIm), 138.1 (1C, CAr-H), 134.2
(2C, Cq), 131.4 (1C, CAr-H), 130.7 (1C, Cq), 129.9 (2C, CMes-H), 123.5
(1C, (CH=CH)Im), 122.5 (1C, (CH=CH)Im), 121.9 (1C, Cq), 120.2 (1C, Cq),
47.7 (1C, CAr-CH2-NIm), 34.6 (1C, C(CH3)3), 31.3 (3C, C(CH3)3), 21.1 (1C,
(CH3)Mes), 17.7 (2C, (CH3)Mes). IR (solid): 3152, 2954, 2869, 2212, 1965,
1620, 1201, 770. HRMS (ESI) m/z: calculated for (C24H29N2O2)+:
377.2222; found: 377.2224.
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-methyl-1H-
benzo[d]imidazol-3-ium-bromide (3-BI-Me):
A
solution of (3-
(bromomethyl)-5-(tert-butyl)-2-hydroxybenzaldehyde (2) (271.2 mg, 1.0
mmol, 1.0 equiv..) was treated with 1-methyl-1H-benzimidazole (138.8
mg, 1.05 mmol, 1.1 equiv.) according to GP1. 3-BI-Me was obtained as a
white hygroscopic solid (340 mg, 0.84 mmol, 84%) after washing for
several times with diethylether. C20H23BrN2O2. MW: 403.32 g mol–1. M.p.:
214 °C. 1H-NMR (300 MHz, CD2Cl2, 21 °C): δ = 11.73 (s, 1H, CAr-OH),
11.45 (s, 1H, NCHNBI), 9.90 (s, 1H, CHO), 8.39 (d, J = 2.2, 1H, CAr-H),
8.05 – 8.01 (m, 1H, CBI-H), 7.66 (m, 3H, CBI-H), 7.61 (d, J = 2.2, 1H, CAr-
H), 5.89 (s, 2H, CAr-CH2-NBI), 4.26 (s, 3H, (CH3) BI), 1.40 (s, 9H, C(CH3)3).
13C-NMR (125 MHz, CDCl3): δ = 196.8 (CHO), 157.2 (CArOH), 144.3,
143.5 (NCHNImid), 137.0, 131.8, 131.6, 131.3, 127.2, 127.2, 120.8, 120.3,
114.1, 112.6, 45.1 (CArCH2), 34.5 (C(CH3)3), 33.9 (NCH3), 31.4 (C(CH3)3).
IR (fest): 2955, 2871, 1666, 1605, 1562, 1453, 1417, 1364, 1258, 1201,
1023, 1004, 793, 758, 711. HRMS (ESI) m/z: calculated for
(C20H23N2O2)+: 323.1767; found: 323.1754.
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-(2,6-diethylphenyl)-1H-
imidazol-3-ium-bromide (3-Im-Et2Ph): A solution of (3-(bromomethyl)-
5-(tert-butyl)-2-hydroxybenzaldehyde (2) (575 mg, 2.1 mmol, 1.0 equiv..)
was treated with 1-(2,6-diethylphenyl)-1H-imidazole (426 mg, 2.1 mmol,
1.1 equiv.) according to GP1. 3-Im-Et2Ph was obtained as a white
hygroscopic solid (825 mg, 1.8 mmol, 82%) after washing for several
times with diethylether. C25H31BrN2O2. MW: 471,44 g mol–1. M.p.:
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-phenyl-1H-
benzo[d]imidazol-3-ium-bromide (3-BI-Ph):
A
solution of (3-
(bromomethyl)-5-(tert-butyl)-2-hydroxybenzaldehyde (2) (1.27 g, 4.68
mmol, 1.0 equiv..) was treated with 1-phenyl-1H-benzimidazole (0.95 g,
4.91 mmol, 1.1 equiv.) according to GP1. 3-BI-Ph was obtained as a
white hygroscopic solid (2.03 g, 4.36 mmol, 93%) after washing for
several times with diethylether. C25H25BrN2O2. MW: 465.38 g mol–1. M.p.:
186 – 188°C. 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 11.54 (s, 1H, CAr-
OH), 11.45 (s, 1H, NCHNBI), 9.89 (s, 1H, CHO), 8.66 (d, J = 2.1, 1H, CAr-
H), 8.16 (m, 1H, CBI-H), 7.89 (m, 2H, CBI-H), 7.75 – 7.61 (m, 6H, CPh-H,
CBI-H), 7.61 (d, J = 2.2, 1H, CAr-H), 6.19 (s, 2H, CAr-CH2-NBI), 1.41 (s, 9 H
C(CH3)3). 13C-NMR (125 MHz, CDCl3, 21 °C): δ = 196.9 (1C, CHO),
157.5 (1C, CAr-OH), 144.5 (1C, NCHNBI), 137.8 (1C, CAr-H), 133.0 (1C,
Cq), 131.9 (1C, Cq), 131.5 (1C, CAr-H), 131.0 (1C, Cq), 130.83 (3C, CPh-H
or CBI-H and Cq), 130.80 (1C, , CPh-H or CBI-H), 127.6 (1C, CPh-H or CBI-
H), 127.5 (1C, CPh-H or CBI-H), 124.8 (2C, CBI-H), 121.3 (1C, Cq), 120.2
(1C, Cq), 114.5 (1C, CBI-H), 113.3 (1C, CPh-H or CBI-H), 45.3 (1C, CAr-
CH2-NBI), 34.6 (1C, C(CH3)3), 31.4 (3C, C(CH3)3). IR (solid): 2931, 2866,
2804, 1853, 1649, 1562, 1436, 1217, 1004, 760. HRMS (ESI) m/z:
calculated for (C25H25N2O2)+: 385.1911, found: 385.1903.
1
decomp. > 200 °C. H-NMR (500 MHz, CDCl3, 21 °C): δ = 11.38 (s, 1H,
CAr-OH), 10.36 (t, J = 1.6, 1H, N=CHN), 9.86 (s, 1H, CHO), 8.54 (d, J =
2.5, 1H, CAr-H), 7.93 (t, J = 1.4, 1H, (CH=CH)Im), 7.55 (d, J = 2.4, 1H,
CAr-H), 7.38 (t, J = 7.8, 1H, CPh-H), 7.16 (d, J = 7.7, 1H, CPh-H), 7.13 (t, J
= 1.4, 1H, (CH=CH)Im), 6.02 (s, 2H, CAr-CH2-NIm), 2.22 (m, 4 H, (CH2)Et),
1.29 (s, 9 H C(CH3)3) 1.04 (t, J = 7.5, 6H, (CH3)Et). 13C-NMR (125 MHz,
CDCl3, 21 °C): δ = 196.9 (1C, CHO), 157.4 (1C, CAr-OH), 144.5 (1C, Cq),
140.5 (1C, Cq), 138.1 (1C, NCHNIm), 137.7 (1C, CAr-H), 131.9 (2C, Cq),
131.5 (1C, CPh-H), 131.3 (1C, CAr-H), 127.4 (2C, CPh-H), 123.6 (1C,
(CH=CH)Im), 123.5 (1C, (CH=CH)Im), 122.0 (1C, Cq), 120.2 (1C, Cq), 47.6
(1C, CAr-CH2-NIm), 34.6 (1C, C(CH3)3), 31.3 (3C, C(CH3)3), 24.2 (1C,
(CH2)Et), 14.9 (2C, (CH3)Et). IR (solid): 3067, 2965, 2917, 2848, 1647,
1544, 1463, 1368, 1275, 1222, 1198, 1178, 1071, 1011, 916, 804, 786,
756, 716, 641, 632, 555. HRMS (ESI) m/z: calculated for (C25H31N2O2)+:
391.2387; found 391.2380.
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-mesityl-1H-
3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-(2,6-
benzo[d]imidazol-3-ium-bromide (3-BI-Mes):
A
solution of (3-
diisopropylphenyl)-1H-imidazol-3-ium-bromide
(3-Im-iPr2Ph):
A
(bromomethyl)-5-(tert-butyl)-2-hydroxybenzaldehyde (2) (1.08 g, 4.00
mmol, 1.0 equiv..) was treated with 1-mesityl-1H-benzimidazole (0.99 g,
4.20 mmol, 1.1 equiv.) according to GP1. 3-BI-Mes was obtained as a
white hygroscopic solid (1.69 g, 3.33 mmol, 83%) after washing for
several times with diethylether. C28H31BrN2O2. MW: 507.46 g mol–1. M.p.:
decomp. T > 200 °C. 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 11.50(s, 1H,
CAr-OH), 11.40 (s, 1H, NCHNBI), 9.91 (s, 1H, CHO), 8.55 (d, J = 2.4, 1H,
CAr-H), 8.10 (td, J = 8.2, J = 0.9, 1H, CBI-H), 7.63 (td, J = 7.9, J = 1.4, 1H,
CBI-H), 7.57 (d, J = 2.5, 1H, CAr-H), 7.55 (td, J = 7.9, J = 1.4, 1H, CBI-H),
solution of (3-(bromomethyl)-5-(tert-butyl)-2-hydroxybenzaldehyde (X)
(679 mg, 2.5 mmol, 1.0 equiv..) was treated with 1-(2,6-
diisopropylphenyl)-1H-imidazole (574 mg, 2.5 mmol, 1.1 equiv.)
according to GP1. 3-Im-iPr2Ph was obtained as a white hygroscopic
solid (847 mg, 1.7 mmol, 68%) after washing for several times with
diethylether. C27H35BrN2O2. MW: 499.49 g mol–1. M.p.: decomp. > 200 °C.
1H-NMR (500 MHz, CDCl3, 21 °C): δ = 11.39 (s, 1H, CAr-OH), 10.30 (t, J
= 1.42, 1H, N=CHN), 9.86 (s, 1H, CHO), 8.60 (d, J = 2.2, 1H, CAr-H), 8.02
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
7.21 (dt, J = 8.2, J = 0.9, CBI-H), 7.08 (s, 2H, CMes-H), 6.31 (s, 2H, CAr-
CH2-NBI), 2.39 (s, 3H, (CH3)Mes), 2.00 (s, 6H, (CH3)Mes), 1.35 (s, 9H,
C(CH3)3). 13C-NMR (125 MHz, CDCl3, 21 °C): δ = 196.9 (1C, CHO),
157.3 (1C, CAr-OH), 144.3 (1C, Cq), 143.7 (1C, NCHNBI), 143.5 (1C, Cq),
141.7 (1C, Cq), 137.2 (1C, CAr-H), 135.3 (1C, Cq), 135.3 (1C, Cq), 131.6
(1C, CAr-H), 132.3 (1C), 131.2 (1C), 130.2 (2C, CMes-H), 128.0 (2C, Cq),
127.7 (1C, CBI-H), 127.5 (1C, CBI-H), 121.4 (1C, Cq), 120.2 (1C, Cq),
114.4 (1C, CBI-H), 113.0 (1C, CBI-H), 45.1 (1C, CAr-CH2-NBI), 34.6 (1C,
C(CH3)3), 31.3 (3C, C(CH3)3), 21.1 (1C, (CH3)Mes), 17.7 (2C, CH3) Mes). IR
(CD2Cl2): 2955, 1751, 1650, 1446, 1274, 1201, 732. HRMS (ESI) m/z:
calculated for (C28H31N2O2)+: 427.2380, found: 427.2385.
(d, J = 13.5, 1H, CAr-CH2NIm), 2.45 (s, 3H, (CH3)Mes), 2.20 (s, 3H,
(CH3)Mes), 1.83 (s, 3H, (CH3)Mes), 1.30 (s, 9H, (CH3)3). 13C-NMR (125
MHz, CDCl3, 21 °C): δ = 197.0 (1C, CHO), 158.8 (1C, NCHN), 157.9 (1C,
CAr-OH), 144.0 (1C, Cq), 140.0 (1C, Cq), 137.7 (1C, CAr-H), 136.1 (1C,
Cq), 135.1 (1C, Cq), 134.9 (1C, Cq), 133.5 (1C, Cq), 130.9 (1C, CAr-H),
130.30 (1C, CMes-H), 130.29 (1C, CPh-H), 130.1 (1C, CMes-H), 130.05 (1C,
CPh-H), 129.9 (2C, CPh-H), 129.2 (2C, CPh-H), 129.0 (1C, Cq), 128.7 (2C,
CPh-H), 127.5 (2C, CPh-H), 121.0 (1C, Cq), 120.1 (1C, Cq), 75.4 (1H,
CHNIm), 70.9 (1H, CHNIm), 46.8 (1C, CAr-CH2NIm), 34.4 (1C, C(CH3)3),
31.2 (3C, (CH3)3), 20.9 (1C, (CH3)Mes), 19.2 (1C, (CH3)Mes), 18.3 (1C,
(CH3)Mes). IR (CDCl3): 2957, 1650, 1601, 1410, 1214, 1091, 401, 622.
HRMS (ESI) m/z: calculated for (C36H39N2O2)+: 531.3006, found:
531.3001.
1-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-4-phenyl-4H-1,2,4-triazol-
1-ium-bromide (3-Tr-Ph): A solution of (3-(bromomethyl)-5-(tert-butyl)-2-
hydroxybenzaldehyde (2) (677.9 mg, 2.50 mmol, 1.0 equiv..) was treated
with 4-phenyl-4H-1,2,4-triazole (381.0 mg, 2.65 mmol, 1.1 equiv.)
according to GP1. 3-Tr-Ph was obtained as a white hygroscopic solid
(801.0 mg, 1.92 mmol, 77%) after washing for several times with
diethylether. C20H22BrN3O2, MW: 416.31 g mol–1. M.p.: decomp. > 200 °C.
1H-NMR (300 MHz, CD3OD, 21 °C): δ = 9.99 (s, 1H, CAr-OH), 9.45 (s, 1H,
CHO), 8.01 (d, J = 2.1, 1H, CAr-H), 7.91 (d, J = 2.1, 1H, CAr-H), 7.88 –
7.68 (m, 5H, CPh-H), 5.79 (s, 2H, CAr-CH2-NT), 1.41 (s, 9H, C(CH3)3). 13C-
NMR (500 MHz, CD3OD, 21 °C): δ = 198.9 (1C, CHO), 158.7 (1C, CAr-
OH), 144.8 (1C, Cq) 144.6 (2C, NCHN), 137.5 (1C, CAr-H), 133.5 (1C,
CAr-H), 132.2 (1C, Cq), 131.6 (2C, CPh-H), 124.01 (2C, CPh-H), 123.99
(1C, CPh-H), 122.1 (1C, Cq), 120.9 (1C, Cq), 52.6 (1C, CAr-CH2-NT), 35.3
(1C, C(CH3)3), 31.6 (1C, C(CH3)3). IR (solid): 3400 (b), 2954 (b), 1651,
1565, 1491, 1365, 1219, 1098, 1050, 761, 688. HRMS (ESI) m/z:
calculated for (C20H22N3O2)+: 336.1707, found: 336.1707.
Synthesis of the Ligands
Synthesis of Salen Ligands with a (1R,2R)-Cyclohexane Backbone
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-phenyl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4c):
(1R,2R)-Cyclohexane-1,2-diamine (75.4 mg, 0.66 mmol, 1.0 equiv.) was
treated with aldehyde 3-Im-Ph (548 mg, 1.32 mmol, 2.0 equiv.) according
to GP2. 4c was obtained as a yellow hygroscopic solid (578 mg, 0.640
mmol, 96%) after washing with diethylether. C48H56Br2N6O2. MW: 908.81
g mol–1. M.p.: decomp. T > 190 °C. [α]20D (c = 0.1 g·dL-1 CH2Cl2): –224.
1H-NMR (300 MHz, CD2Cl2, 21 °C): δ = 14.05 (s, 2H, CAr-OH), 11.35 (t, J
= 1.4, 2H, NCHN), 8.40 (s, 2H, N=CH), 8.16 (d, J = 2.5, 2H, CAr-H), 7.71 -
7.68 (m, 4H, CPh-H), 7.58 - 7.44 (m, 10H, CAr-H, (CH=CH)Im), 7.29 (d,
J = 2.3, 2H, CAr-H), 5.80 (d, J = 13.9, 2H, CAr-CH2-NIm), 5.69 (d, J = 13.9,
2H, CAr-CH2-NIm), 3.45 (m, 2H, CCyHN), 1.99 - 1.88 (m, 4H, (CH2)Cy), 1.77
- 1.65 (m, 2H, (CH2)Cy), 1.52 - 1.43 (m, 2H, (CH2)Cy), 1.26 (s, 18H,
C(CH3)3). 13C-NMR (125 MHz, CDCl3): δ = 164.7 (N=C), 158.1 (CArOH),
142.2, 165.6 (NCHNImid), 134.4, 132.6, 130.5 (2 x CAr), 130.0, 129.7,
123.7, 121.6 (2 x CAr), 120.8, 120.2, 119.1, 71.7 (N(CH)ring), 48.4
(CArCH2), 34.3 (C(CH3)3), 33.0 ((CH2)Ring), 31.5 (C(CH3)3), 24.2
((CH2)Ring). IR (solid): 3377, 2949, 2862, 1627, 1547, 1479, 1463, 1446,
1218, 1069, 758, 686, 632. HRMS (ESI) m/z: calculated for
(C48H56BrN6O2)+: 827.3642, found: 827.3643.
1-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-4-mesityl-4H-1,2,4-
triazol-1-ium-bromide (3-Tr-Mes): A solution of (3-(bromomethyl)-5-
(tert-butyl)-2-hydroxybenzaldehyde (2) (135.6 mg, 0.50 mmol, 1.0
equiv..) was treated with 4-mesityl-4H-1,2,4-triazole (98.3 mg, 0.53 mmol,
1.1 equiv.) according to GP1. 3-Tr-Mes was obtained as a beige
hygroscopic solid (191.0 mg, 0.42 mmol, 83%) after washing for several
times with diethylether. C23H28BrN3O2. MW: 458.39 g mol–1. M.p.:
1
decomp. > 140 °C. H-NMR (300 MHz, CD3OD, 21 °C): δ = 9,98 (s, 1H,
CAr-OH), 9,19 (s, 1H, CHO), 8.65 (s, 1H, NCHN), 7.99 (d, J = 2.3, 1H,
CAr-H), 7.91 (d, J = 2.5, 1H, CAr-H), 7.17 (s, 2H, CMes-H), 7.10 (s, 1H,
NCHN), 5.82 (s, 2H, CAr-CH2-NT), 2.39 (s, 3H, (CH3)Mes), 2.10 (s, 6 H,
(CH3)Mes), 1.42 (s, 9 H C(CH3)3). 13C-NMR (125 MHz, CD3OD, 21 °C): δ =
163.4 (1C, CHO), 156.5 (1C, CAr-OH), 146.9 (1C, Cq), 145.7 (2C, NCHN),
145.2 (1C, Cq), 143.5 (1C, Cq), 136.0 (1C, Cq), 135.2 (1C, CAr-H), 133.1
(1C, CAr-H), 131.1 (2C, CMes-H), 129.3 (1C, Cq), 121.3 (1C, Cq), 117.9
(1C, Cq), 53.7 (1C, CAr-CH2-NT), 35.3 (1C, C(CH3)3), 31.7 (1C, C(CH3)3),
21.2 (2C, (CH3)Mes), 17.7 (1C, (CH3)Mes). IR (solid): 3500 (b), 3200 (b),
3100 (b), 2955, 1621, 1483, 1229, 1059, 1034, 855, 618. HRMS (ESI)
m/z: calculated for (C23H28N3O2)+: 378.2176, found: 378.2183.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4e):
(1R,2R)-Cyclohexane-1,2-diamine (90.2 mg, 0.79 mmol, 1.0 equiv.) was
treated with aldehyde 3-Im-Mes (723 mg, 1.58 mmol, 2.0 equiv.)
according to GP2. 4e was obtained as a brown-yellow hygroscopic solid
(770 mg, 0.77 mmol, 98%) after washing with diethylether.
C54H68Br2N6O2. MW: 992.96 g mol–1. M.p.: decomp. T > 200 °C. [α]20
D
(c = 0.1 g·dL-1 CH2Cl2): –218. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ =
14.01 (b, 2H, CAr-OH), 10.45 (t, J = 1.5, 2H, NCHN), 8.37 (s, 2H, N=CH),
8.00 (d, J = 2.3, 2H, CAr-H), 7.72 (t, J = 1.7, 2H, (CH=CH)Im), 7.27 (d, J =
2.4, 2H, CAr-H), 7.13 (t, J = 1.7, 2H, (CH=CH)Im), 7.02 (s, 4H, CMes-H),
5.83 (d, J = 13.9, 2H, CAr-CH2-NIm), 5.79 (d, J = 13.9, 2H, CAr-CH2-NIm),
3.42 (m, 2H, CCyHN), 2.34 (s, 6H, (CH3)Mes), 2.04 (s, 6H, (CH3)Mes), 2.02
(s, 6H, (CH3)Mes), 1.91 (m, 4H, (CH2)Cy), 1.69 (m, 2H, (CH2)Cy), 1.50 (m,
2H, (CH2)Cy), 1.25 (s, 18H, (CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C):
δ = 165.2 (2C, N=CH), 158.3 (2C, CAr-OH), 142.5 (2C, Cq), 141.7 (2C,
Cq), 138.7 (2C, NCHN), 134.8 (4C, Cq), 132.5 (2C, CAr-H), 131.2 (2C, Cq),
130.1 (4C, CMes-H), 129.8 (2C, CAr-H), 123.5 (2C, (CH=CH)Im), 123.3 (2C,
(CH=CH)Im), 121.5 (2C, Cq), 118.5 (2C, Cq), 72.2 (2C, CCyHN), 48.8 (2C,
CAr-CH2-NIm), 34.6 (2C, C(CH3)3), 33.4 (2C, (CH2)Cy), 31.5 (6C, C(CH3)3),
24.5 (2C, CH2)Cy), 21.3 (2C, (CH3)Mes), 17.8 (2C, (CH3)Mes), 17.8 (2C,
(CH3)Mes). IR (solid): 3924, 3908, 3842, 3754, 3606, 3328, 2924, 2861,
2571, 2373, 2346, 2324, 2187, 2164, 2112, 1967, 1841, 1715, 1628,
1480, 1179, 1037, 788. HRMS (ESI) m/z: calculated for (C54H68BrN6O2)+:
911.4582, found: 911.4585.
(4R,5R)-3-(5-(tert-Butyl)-3-formyl-2-hydroxybenzyl)-1-mesityl-4,5-
diphenyl-4,5-dihydro-1H-imidazol-3-ium-bromide (3-Im*): A solution
of (3-(bromomethyl)-5-(tert-butyl)-2-hydroxybenzaldehyde (2) (135.6 mg,
0.50 mmol, 1.0 equiv.) was treated with (4R,5R)-1-mesityl-4,5-diphenyl-
4,5-dihydro-1H-imidazole (178.7 mg, 0.53 mmol, 1.1 equiv.) according to
GP1. 3-Im* was obtained as a white hygroscopic solid (241.9 mg, 0.40
mmol, 79%) after washing for several times with diethylether.
C36H39BrN2O2, MW: 611.62 g mol–1. M.p.: decomp. > 130 °C. [α]20
D
(c = 1.0 g·dL-1, CH2Cl2) = 138. 1H-NMR (500 MHz, CDCl3, 21 °C): δ =
11.42 (s, 1H, CAr-OH), 9.99 (s, 1H, CHO), 9.87 (b, 1H, NCHN), 7.79 (d, J
= 3.8, 1H, CAr-H), 7.61 (d, J = 3.8, 1H, CAr-H), 7.45 (m, 5H, CPh-H), 7.33 (t,
J = 7.3, 1H, CPh-H), 7.24 (t, J = 7.3, 2H, CPh-H), 7.07 (d, J = 7.5, 2H, CPh
-
H), 6.86 (s, 1H, CMes-H), 6.68 (s, 1H, CMes-H), 5.84 (d, J = 13.5, 1H, CAr-
CH2-NIm), 5.48 (d, J = 8.3, 1H, CHNIm), 5.19 (d, J = 8.3, 1H, CHNIm), 4.69
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((2,6-diethylphenyl)-1H-imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4l): (1R,2R)-Cyclohexane-1,2-diamine (18 mg, 0.16 mmol, 1.0 equiv.)
was treated with aldehyde 3-Im-Et2Ph (151 mg, 0.32 mmol, 2.0 equiv.)
according to GP2. 4l was obtained as a brown-yellow hygroscopic solid
(156 mg, 0.15 mmol, 95%) after washing with diethylether.
(m, 6H, (CH2)Cy), 1.27 (s, 18H, (CH3)3). 13C-NMR(125 MHz, CD2Cl2,
21 °C) δ = 165.1, 158.6, 142.5, 137.5, 137.1, 133.1, 132.3, 132.0, 128.3,
124.9, 124.0, 122.7, 122.5, 121.0, 120.0, 118.7, 72.0, 48.9, 34.7, 33.2,
31.6 ((CH3)3), 24.7. IR: 3371, 2949, 1631, 1323, 1170, 1121, 1062, 846.
HRMS (ESI): calculated for (C50H54F6N6O2)2+: 442.2101, found: 442.2073.
C56H72Br2N6O2, MW: 1021.04 g mol–1. M.p.: decomp. > 140 °C. [α]20
D
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-methyl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4o): (1R,2R)-Cyclohexane-1,2-diamine (73.1 mg, 0.64 mmol, 1.0 equiv.)
was treated with aldehyde 3-BI-Me (516 mg, 1.28 mmol, 2.0 equiv.)
according to GP2. 4o was obtained as a yellow hygroscopic solid
(565 mg, 0.64 mmol, 99%) after washing with diethylether.
C46H56Br2N6O2. MW: 884.78 g mol–1. M.p.: decomp. T > 195 °C. [α]20D (c
= 0.1 g·dL-1, CH2Cl2) = –250.5. 1H-NMR (300 MHz, CDCl3, 21 °C):
δ = 13.96 (s, 2H, CAr-OH), 11.08 (s, 2H, NCHN), 8.39 (s, 2H, N=CH),
7.81 (d, J = 8.5, 2H, CBI-H), 7.70 (d, J = 2.5, 2H, CAr-H), 7.65 (d, J = 8.5,
2H, CBI-H), 7.54 - 7.37 (m, 4H, CBI-H), 7.26 (d, J = 2.5, 2H, CAr-H), 5.75
(d, J = 14.5, 2H, CAr-CH2-NBI), 5.57 (d, J = 14.5, 2H, CAr-CH2-NBI), 4.27 (s,
6H, (CH3)BI), 3.48 - 3.45 (m, 2H, CCyHN), 1.88 - 1.83 (m, 4H, (CH2)Cy),
1.74 - 1.64 (m, 2H, (CH2)Cy), 1.49 - 1.42 (m, 2H, (CH2)Cy), 1.24 (s, 18H,
C(CH3)3). 13C-NMR (125 MHz, CDCl3): δ = 164.8 (N=C), 158.3 (CArOH),
143.5 (NCHNImid), 141.6, 132.0, 131.2, 131.1, 129.8, 126.9, 119.6, 118.2,
113.7, 112.7, 71.7 (N(CH)Ring), 46.6 (CArCH2), 34.2 (C(CH3)3), 34.0
((CH2)ring), 33.3 (NCH3), 31.5 ((CH2)Ring), 24.1 (C(CH3)3). IR (solid): 2948,
2861, 1971, 1628, 1566, 1446, 1363, 1278, 1225, 1199, 1141, 1092,
(c = 0.5 g·dL-1, CH2Cl2) = –190. 1H-NMR (300 MHz, CD2Cl2, 21 °C): δ =
13.99 (b, 2H, CAr-OH), 10.32 (t, J = 1.6, 2H, NCHN), 8.37 (s, 2H, N=CH),
8.02 (d, J = 2.4, 2H, CAr-H), 7.85 (t, J = 1.6, 2H, (CH=CH)Im), 7.49 (t, J =
7.8, CPh-H) 7.27 (m, 6H, CAr-H and CPh-H), 7.13 (t, J = 1.6, 2H,
(CH=CH)Im), 5.91 (d, J = 14.1, 2H, CAr-CH2-NIm), 5.84 (d, J = 13.9, 2H,
CAr-CH2-NIm), 3.41 (m, 2H, CCyHN), 2.29 (m, 8H, (CH2)Et), 1.92 (m, 4H,
(CH2)Cy), 1.70 (m, 2H, (CH2)Cy), 1.49 (m, 2H, (CH2)Cy), 1.26 (s, 18H,
(CH3)3), 1.07 (m, 12H, (CH3)Et). 13C-NMR (125 MHz, CDCl3, 21 °C): δ =
164.2 (2C, N=CH), 157.2 (2C, CAr-OH), 141.3 (2C, Cq), 139.94 (2C, Cq),
139.92 (2C, Cq), 137.4 (2C, NCHN), 131.4 (2C, CAr-H), 131.3 (2C, Cq),
130.6 (2C, CPh-H), 128.6 (2C, CAr-H), 126.6 (4C, CPh-H), 122.8 (2C,
(CH=CH)Im), 122.6 (2C, (CH=CH)Im), 120.4 (2C, Cq), 117.3 (2C, Cq), 71.1
(2C, CCyHN), 47.6 (2C, CAr-CH2-NIm), 33.4 (2C, C(CH3)3), 32.3 (2C,
(CH2)Cy), 30.4 (6C, C(CH3)3), 23.4 (2C, CH2)Cy), 23.3 (4C, (CH2)Et), 14.1
(2C, (CH3)Et), 14.0 (2C, (CH3)Et). IR (solid): 3348, 2929, 2856, 1628, 1461,
1180, 1062, 760, 721, 644. HRMS (ESI): calculated for (C56H72N6O2)2+
430.2853, found: 430.2870.
:
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((2,6-diisopropylphenyl)-1H-
imidazol-3-ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-
1014,
827,
746,
571.
HRMS
(ESI):
calculated
for
(C46H56BrN6O2)2+:803.3649, found: 803.3643.
dibromide (4m): (1R,2R)-Cyclohexane-1,2-diamine (14.0 mg, 0.12 mmol,
1.0 equiv.) was treated with aldehyde 3-Im-iPr2Ph (116 mg, 0.24 mmol,
2.0 equiv.) according to GP2. 4m was obtained as a brown-yellow
hygroscopic solid (134 mg, 0.12 mmol, >99%) after washing with
diethylether. C60H80Br2N6O2, MW: 1077,15 g mol–1. M.p.: decomp. >
140 °C. [α]20D (c = 0.5 g·dL-1, CH2Cl2) = –164. 1H-NMR (500 MHz, CD2Cl2,
21 °C): δ = 13.96 (b, 2H, CAr-OH), 10.24 (t, J = 1.6, 2H, NCHN), 8.37 (s,
2H, N=CH), 8.07 (d, J = 2.0, 2H, CAr-H), 8.01 (s, 2H, (CH=CH)Im), 7.55 (t,
J = 7.7, CPh-H) 7.31 (d, J = 7.8, 4H, CPh-H), 7.28 (d, J = 2.0, 2H, CAr-H),
7.17 (s, 2H, (CH=CH)Im), 5.88 (b, 4H, CAr-CH2-NIm), 3.40 (m, 2H, CCyHN),
2.25 (sept, J = 6.5, 4H, (CH(CH3)2), 1.91 (m, 4H, (CH2)Cy), 1.69 (m, 2H,
(CH2)Cy), 1.48 (m, 2H, (CH2)Cy), 1.25 (s, 18H, (CH3)3), 1.15 (d, J = 6.8,
12H, (CH(CH3)2), 1.10 (d, J = 6.8, 12H, (CH(CH3)2). 13C-NMR (125 MHz,
CD2Cl2, 21 °C): δ = 164.3 (2C, N=CH), 157.1 (2C, CAr-OH), 144.71 (2C,
Cq), 144.70 (2C, Cq), 141.3 (2C, Cq), 137.5 (2C, NCHN), 131.5 (2C, CAr-
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-phenyl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4q): (1R,2R)-Cyclohexane-1,2-diamine (57.1 mg, 0.50 mmol, 1.0 equiv.)
was treated with aldehyde 3-BI-Ph (465 mg, 1.00 mmol, 2.0 equiv.)
according to GP2. 4q was obtained as a yellow hygroscopic solid
(448 mg, 0.44 mmol, 89%) after washing with diethylether.
C56H60Br2N6O2. MW: 1008.94 g mol–1. M.p.: decomp. T > 173 °C. [α]20D (c
= 0.6 g·dL-1, CH2Cl2) = –142. 1H-NMR (500 MHz, CD2Cl2, 21 °C):
δ = 14.04 (s, 1H, CAr-OH), 11.41 (s, 2H, NCHN), 8.34 (s, 2H, N=CH),
8.03 (d, J = 2.5, 2H, CAr-H), 8.01 (d, J = 8.6, 2H, CBI-H), 7.84 (d, J = 7.9,
4H, CPh-H), 7.71 – 7.63 (m, 9H, CBI-H and CPh-H), 7.56 (t, J = 7.6, 2H,
CBI-H), 7.41 (t, J = 7.6, 2H, CBI-H), 7.23 (d, J = 2.5, 2H, CAr-H), 6.01 (d, J
= 14.2, 2H, CAr-CH2-NBI), 5.91 (d, J = 14.2, 2H, CAr-CH2-NBI), 3.44 (m, 2H,
CCyHN), 1.91 (m, 4H, (CH2)Cy), 1.71 (m, 2H, (CH2)Cy), 1.48 (m, 2H,
(CH2)Cy), 1.25 (s, 18H, (CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ =
165.3 (2C, N=CH), 158.4 (2C, CAr-OH), 142.3 (2C, NCHN), 133.7 (2C,
Cq), 132.4 (2C, CAr-H), 132.0 (2C, Cq), 131.5 (2C, Cq), 131.0 (4C, CPh-H),
129.9 (2C, CAr-H), 127.8 (2C, CBI-H), 127.5 (2C, CBI-H), 125.2 (4C, CBI-H),
120.5 (2C, Cq), 118.6 (2C, Cq), 114.7 (2C, CBI-H), 113.7 (2C, CBI-H), 72.3
(2C, CCyHN), 46.6 (2C, CAr-CH2-NBI), 34.5 (1C, C(CH3)3), 33.5 (2C,
(CH2)Cy), 31.6 (6C, C(CH3)3), 24.6 (2C, CH2)Cy). IR (solid): 3102, 3059,
2963, 2931, 2860, 1630, 1554, 1476, 1412, 1200, 1017, 746, 693, 575,
542. HRMS (ESI) m/z: calculated for (C56H60BrN6O2)+: 927.3956, found:
927.3941.
H), 131.0 (2C, CPh-H), 129.5 (2C, Cq), 128.7 (2C, CAr-H), 123.9 (4C, CPh
-
H), 122.9 (2C, (CH=CH)Im), 122.7 (2C, (CH=CH)Im), 120.4 (2C, Cq), 117.3
(2C, Cq), 71.2 (2C, CCyHN), 47.6 (2C, CAr-CH2-NIm), 33.4 (2C, C(CH3)3),
32.4 (2C, (CH2)Cy), 30.4 (6C, C(CH3)3), 27.9 (2C, (CH(CH3)2)iPr), 27.8 (2C,
(CH(CH3)2)iPr), 23.6 (2C, (CH(CH3)2), 23.5 (2C, (CH(CH3)2), 23.4 (2C,
CH2)Cy), 23.0 (2C, (CH(CH3)2)iPr), 22.9 (2C, (CH(CH3)2). IR (solid): 2959,
2923, 2853, 1628, 1467, 1226, 804, 753, 633. HRMS (ESI): calculated
for (C60H80N6O2)2+: 458.3166, found: 458.3147.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((4-(trifluoromethyl)phenyl)-1H-
imidazol-3-ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-
dibromide (4n): (1R,2R)-Cyclohexane-1,2-diamine (30.8 mg, 0.64 mmol,
1.0 equiv.) was treated with aldehyde 3-Im-F3CPh (264 mg, 0.54 mmol,
2.0 equiv.) according to GP2. 4n was obtained as a yellow hygroscopic
solid (211 mg, 0.20 mmol, 74%) after washing with diethylether.
C50H54Br2F6N6O2, MW: 1044.80 g mol–1. M.p.: 193 °C. [α]20D (c = 0.068
g·dL-1, DCM) = 126.5. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ = 14.13 (s,
2H, OH), 11.61 (s, 2H, NCHN), 8.43 (s, 2H, N=CH), 8.15 (d, 2H, J = 2.3
Hz, CAr-H), 8.03 (d, 4H, J = 8.6 Hz, CAr-H), 7.83 (d, 4H, J = 8.6 Hz, CAr-H),
7.69 (t, 2H, J = 1.6 Hz, Imidazol H), 7.46 (t, 2H, J = 1.6 Hz, Imidazol H),
7.33 (d, 2H, J = 2.3 Hz, CAr-H), 5.77 (d, 2H, J = 13.7 Hz, CAr-CH2-NIm),
5.68 (d, 2H, J = 13.7 Hz, CAr-CH2-NIm), 3.48 (m, 2H, CCyHN), 1.66-1.85
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4s): (1R,2R)-Cyclohexane-1,2-diamine (52.5 mg, 0.46 mmol, 1.0 equiv.)
was treated with aldehyde 3-BI-Mes (467 mg, 0.92 mmol, 2.0 equiv.)
according to GP2. 4s was obtained as a yellow hygroscopic solid
(502 mg, 0.46 mmol, 100%) after washing with diethylether.
C62H72Br2N6O2. MW: 1093.08 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c
= 0.6 g·dL-1, CH2Cl2) = –140. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ =
14.12 (b, 1H, Ar-OH), 11.19 (s, 2H, NCHN), 8.33 (s, 2H, N=CH), 7.97 (d,
J = 8.2, 2H, CBI-H), 7.94 (d, J = 2.3, 2H, CAr-H), 7.50 (t, J = 8.2, 2H, CBI-
H), 7.41 (t, J = 8.2, 2H, CBI-H), 7.21 (d, J = 2.4, 2H, CAr-H), 7.15 (d, J =
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
8.2, 2H, CBI-H), 7.10 (s, 4H, CMes-H), 6.16 (d, J = 14.2, 4H, CAr-CH2-NBI),
5.96 (d, J = 14.8, 4H, CAr-CH2-NBI), 3.41 (m, 2H, CCyHN), 2.39 (s, 6H,
(CH3) Mes), 1.97 (s, 6H, (CH3) Mes), 1.96 (s, 6H, (CH3) Mes), 1.89 (m, 4H,
(CH2)Cy), 1.68 (m, 2H, (CH2)Cy), 1.49 (m, 2H, (CH2)Cy), 1.20 (s, 18H,
(CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 165.3 (2C, N=CH),
158.2 (2C, CAr-OH), 144.6 (2C, NCHN), 142.3 (2C, Cq), 142.1 (2C, Cq),
135.9 (2C, Cq), 135.8 (2C, Cq), 132.0 (2C, Cq), 131.8 (2C, CAr-H), 131.4
(2C, Cq), 130.39 (2C, CMes-H), 130.37 (2C, CMes-H), 129.6 (2C, Cq), 128.2
(2C, CAr-H), 127.9 (2C, CBI-H), 127.4 (2C, CBI-H), 120.6 (2C, Cq), 118.5
(2C, Cq), 114.6 (2C, CBI-H), 113.4 (2C, CBI-H), 72.3 (2C, CCyHN), 46.7
(2C, CAr-CH2-NBI), 34.5 (2C, C(CH3)3), 33.5 (2C, (CH2)Cy), 31.5 (6C,
C(CH3)3), 24.5 (2C, CH2)Cy), 21.4 (2C, (CH3) Mes), 17.8 (2C, (CH3) Mes),
17.7 (2C, (CH3) Mes). IR (solid): 3646, 3365, 3948, 2862, 2165, 1706,
1627, 1444, 1227, 748. HRMS (ESI) m/z: calculated for (C62H72BrN6O2)+:
1011.4895, found:1011.4879.
21 °C): δ = 14.39 (b, 1H, CAr-OH), 10.13 (s, 2H, NCHN), 8.48 (s, 2H,
N=CH), 7.45 (m, 7H, CPh-H), 7.37 – 7.28 (m, 12H, CPh-H and CAr-H), 7.17
(m, 5H, CPh-H), 6.96 (s, 2H, CMes-H), 6.95 (s, 4H, CPh-H), 6.92 (s, J = 2.5,
2H, CAr-H), 6.76 (s, 2H, CMes-H), 5.81 (d, J = 13.9, 2H, CAr-CH2-NIm), 5.20
(d, J = 8.9, 2H, CIm-H), 5.08 (d, J = 8.9, 2H, CIm-H), 4.18 (d, J = 14.6, 2H,
CAr-CH2-NIm), 3.49 (m, 2H, CCyHN), 2.48 (s, 6H, (CH3)Mes), 2.23 (s, 6H,
(CH3)Mes), 2.07 (m, 2H, (CH2)Cy), 1.95 (m, 2H, (CH2)Cy), 1.91 (s, 6H,
(CH3)Mes), 1.75 (m, 2H, (CH2)Cy), 1.58 (m, 2H, (CH2)Cy), 1.13 (s, 18H,
(CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 165.9 (2C, N=CH),
159.9 (2C, NCHN), 158.9 (2C, CAr-OH), 141.9 (2C, Cq), 140.5 (2C, Cq),
136.6 (2C, Cq), 135.7 (4C, Cq), 135.3 (2C, Cq), 134.1 (2C, Cq), 132.3 (2C,
CAr-H), 130.6 (2C, CPh-H), 130.55 (2C, CPh-H), 130.4 (2C, CPh-H), 130.2
(4C, CMes-H), 129.9 (2C, CAr-H), 129.5 (2C, CPh-H), 129.4 (4C, CPh-H),
129.0 (4C, CPh-H), 127.9 (4C, CPh-H), 119.0 (2C, Cq), 118.4 (2C, Cq),
75.2 (2C, CIm-H), 72.3 (2C, CCyHN), 69.9 (2C, CIm-H), 48.3 (2C, CAr-CH2-
NIm), 34.3 (2C, C(CH3)3), 33.4 (2C, (CH2)Cy), 31.4 (6C, C(CH3)3), 24.5 (2C,
(CH2)Cy), 21.1 (2C, (CH3)Mes), 19.4 (2C, (CH3)Mes), 18.4 (2C, (CH3)Mes). IR
(CH2Cl2): 3840 (b), 2963, 2929, 2860, 1629, 1479, 1455, 1227, 1034,
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((4-phenyl-4H-1,2,4-triazolium)-1-
ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4v):
853, 757, 700, 629. HRMS (ESI) m/z: calculated for (C78H88N6O2)2+
:
(1R,2R)-Cyclohexane-1,2-diamine (106 mg, 0.92 mmol, 1.0 equiv.) was
treated with aldehyde 3-Tr-Ph (769 mg, 1.85 mmol, 2.0 equiv.) according
to GP2. 4v was obtained as a yellow hygroscopic solid (840 mg, 0.92
mmol, 100%) after washing with diethylether. C46H54Br2N8O2. MW:
910.78 g mol–1. M.p.: decomp. > 120 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) =
–50. 1H-NMR (300 MHz, CD2Cl2, 21 °C): δ = 13.88 (s, 2H, CAr-OH), 12.07
(s, 2H, NCHNT), 9.07 (s, 2H, NCHNT), 8.34 (s, 2H, N=CH), 7.92 - 7.89 (m,
4H, CPh-H), 7.67 (d, J = 2.5, 2H, CAr-H), 7.62-7.53 (m, 4H, CPh-H), 7.30 (d,
J = 2.5, 2H, CAr-H), 5.87 (d, J = 14.1, 2H, CAr-CH2-NT), 5.68 (d, J = 14.1,
2H, CAr-CH2-NT), 3.41 (m, 2H, CCyHN), 1.89 - 1.82 (m, 4H, (CH2)Cy), 1.71-
1.62 (m, 2H, (CH2)Cy), 1.53-1.36 (m, 2H, (CH2)Cy), 1.24 (s, 18H, (CH3)3).
13C-NMR (62 MHz, CD2Cl2, 21 °C): δ = 165.1 (2C, N=CH), 158.9 (2C,
CAr-OH), 142.8 (2C, Cq), 141.9 (2C, NCHNT), 141.4 (2C, NCHNT), 132.4
(2C, Cq), 132.1 (2C, CPh-H), 131.5 (2C, CAr-H), 131.1 (4C, CPh-H), 130.5
(2C, CAr-H), 122.9 (4C, CPh-H), 119.2 (2C, Cq), 118.5 (2C, Cq), 72.0 (2C,
CCyHN), 52.7 (2C, CAr-CH2-NIm), 34.4 (1C, C(CH3)3), 33.3 (2C, (CH2)Cy),
31.5 (6C, C(CH3)3), 24.6 (2C, CH2)Cy). IR (solid): 3632, 3401, 2949, 2863,
1747, 1628, 1628, 1225, 1002, 758. HRMS (ESI) m/z: calculated for
(C46H54BrN8O2)+: 829.3548, found: 829.3532.
570.3479, found: 570.3459.
Synthesis of Salen Ligands with
Backbone
a (1R,2R)-1,2-Diphenylethane
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-methyl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-dibromide
(4b): (1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50 mmol, 1.0
equiv.) was treated with aldehyde 3-Im-Me (353 mg, 1.00 mmol, 2.0
equiv.) according to GP2. 4b was obtained as a yellow hygroscopic solid
(433 mg, 0.49 mmol, 98%) after washing with diethylether.
C46H54Br2N6O2, MW: 882.79 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c
= 0.5 g·dL-1, CH2Cl2) = –34. 1H-NMR (250 MHz, CDCl3, 21 °C): δ = 14.04
(b, 1H, CAr-OH), 10.51 (s, 2H, NCHN), 8.33 (s, 2H, N=CH), 8.00 (d, J =
2.3, 2H, CAr-H), 7.87 (d, J = 2.3, 2H, CAr-H), 7.47 (t, J = 1.6, 2H,
(CH=CH)Im), 7.48 - 7.22 (m, 10H, CPh-H and CAr-H) 7.14 (t, J = 1.6, 2H,
(CH=CH)Im), 5.63 (d, J = 14.2, 2H, CAr-CH2-NIm), 5.52 (d, J = 13.9, 2H,
CAr-CH2-NIm), 4.90 (s, 2H, CEtHN), 4.08 (s, 6H, (CH3)Im), 1.27 (s, 18H,
(CH3)3). 13C-NMR (62 MHz, CDCl3, 21 °C): δ = 166.5 (2C, N=CH), 157.4
(2C, CAr-OH), 142.6 (2C, Cq), 139.2 (2C, NCHN), 137.7 (2C) 132.4 (2C,
CAr-H), 130.0 (2C), 128.8 (4C), 128.1 (2C), 127.7 (4C), 123.2 (2C,
(CH=CH)Im), 121.8 (2C, (CH=CH)Im), 120.5 (2C), 118.3 (2C, Cq), 79.1
(2C, CEtHN), 48.1 (2C, CAr-CH2-NIm), 36.7 (2C, (CH3)Im), 34.3 (2C,
C(CH3)3), 31.5 (6C, C(CH3)3). IR (solid): 3028, 2963, 2951, 2862, 2165,
1983, 1626, 1451, 1156, 699, 513. HRMS (ESI) m/z: calculated for
(C46H54BrN6O2)+: 803.3476, found: 803.3486.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((4-mesityl-4H-1,2,4-triazolium)-1-
ylmethyl)-salicylidene)-1,2-cyclohexane-diamine-dibromide
(4w):
(1R,2R)-Cyclohexane-1,2-diamine (14.8 mg, 0.13 mmol, 1.0 equiv.) was
treated with aldehyde 3-Tr-Mes (119 mg, 0.26 mmol, 2.0 equiv.)
according to GP2. 4w was obtained as a yellow hygroscopic solid
(126 mg, 0.13 mmol, 97%) after washing with diethylether.
C52H66Br2N8O2. MW: 994.94 g mol–1. M.p.: decomp. > 160 °C. [α]20D (c =
1
0.1 g·dL-1, CH2Cl2) = –92. H-NMR (300 MHz, CD2Cl2, 21 °C): δ = 13.86
(s, 2H, CAr-OH), 11.87 (s, 2H, NCHN), 8.33 (s, 2H, NCHN), 8.25 (s, 2H,
N=CH), 7.54 (d, J = 2.2, 2H, CAr-H), 7.23 (d, J = 2.2, 2H, CAr-H), 6.98 (s,
4H, CMes-H), 5.99 (d, J= 14.6, 2H, CAr-CH2-NT), 5.66 (d, J= 14.1, 2H, CAr-
CH2-NT), 3.30 (m, 2H, CCyHN), 2.29 (s, 6H, CH3), 2.04 (s, 6H, CH3), 1.82
(m, 4H, (CH2)Cy), 1.58 (m, 2H, (CH2)Cy), 1.40 (m, 2H, (CH2)Cy), 1.19 (s,
18H, (CH3)3). 13C-NMR (75 MHz, CD2Cl2, 21 °C): for solubility problems a
spectrum of sufficient quality could not be obtained. IR (DCM): 2953,
1631, 1558, 1264, 731. HRMS (ESI) m/z: calculated for (C52H66BrN8O2)+:
913.4487, found: 913.4483.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-phenyl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-dibromide
(4d): (1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50 mmol, 1.0
equiv.) was treated with aldehyde 3-Im-Ph (415 mg, 1.00 mmol, 2.0
equiv.) according to GP2. 4d was obtained as a yellow hygroscopic solid
(475 mg, 0.47 mmol, 94%) after washing with diethylether.
C56H58Br2N6O2. MW: 1006.93 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c
= 0.5 g·dL-1, CH2Cl2) = 84. 1H-NMR (250 MHz, CDCl3, 21 °C): δ = 14.09
(b, 1H, CAr-OH), 11.43 (s, 2H, NCHN), 8.36 (s, 2H, N=CH), 8.23 (d, J =
2.5, 2H, CAr-H), 7.74 – 7.71 (m, 4H), 7.64 (m, 2H), 7.53 – 7.18 (m, 20H),
5.98 (d, J = 14.3, 2H, CAr-CH2-NIm), 5.69 (d, J = 13.7, 2H, CAr-CH2-NIm),
4.90 (s, 2H, CEtHN), 1.27 (s, 18H, (CH3)3). 13C-NMR (62 MHz, CDCl3,
21 °C): δ = 166.5 (2C, N=CH), 157.5 (2C, CAr-OH), 142.8 (2C, Cq), 139.2
(2C, NCHN), 136.0 (2C) 134.0 (2C), 133.0 (2C, CAr-H), 130.7 (4C), 130.2
(2C), 129.9 (2C), 128.8 (4C), 128.1 (2C), 127.7 (4C), 122.8 (2C), 121.3
(4C), 120.8 (2C), 119.9 (2C), 118.3 (2C), 79.0 (2C, CEtHN), 48.1 (2C,
CAr-CH2-NIm), 34.3 (2C, C(CH3)3), 31.5 (6C, C(CH3)3). IR (solid): 2951,
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-(((4R,5R)-1-mesityl-4,5-diphenyl-4,5-
dihydro-1H-imidazolium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-
diamine-dibromide (4u): (1R,2R)-Cyclohexane-1,2-diamine (17.4 mg,
0.15 mmol, 1.0 equiv.) was treated with aldehyde 3-Im* (187 mg, 0.31
mmol, 2.0 equiv.) according to GP2. 4u was obtained as a yellow
hygroscopic solid (169 mg, 0.13 mmol, 85%) after washing with
diethylether. C78H88Br2N6O2, MW: 1301,41 g mol–1. M.p.: decomp. >
1
170 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) = –79. H-NMR (300 MHz, CD2Cl2,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
2863, 1627, 1598, 1450, 1202, 1042, 685, 571. HRMS (ESI) m/z:
(CH=CH)Im), 6.09 (d, J = 14.0, 2H, CAr-CH2-NIm), 5.79 (d, J = 14.0, 2H,
CAr-CH2-NIm), 4.88 (m, 2H, CEtHN), 2.25 (sept, J = 7.0, 4H, (CH(CH3)2),
1.26 (s, 18H, (CH3)3), 1.15 – 1.07 (m, 24, (CH(CH3)2). 13C-NMR (125
MHz, CD2Cl2, 21 °C): δ = 166.0 (2C, N=CH), 156.6 (2C, CAr-OH), 144.7
(2C, Cq), 144.66 (2C, Cq), 141.7 (2C, Cq), 138.5 (2C, Cq), 137.6 (2C,
NCHN), 131.6 (2C, CAr-H), 131.0 (2C, CPh-H), 129.5 (2C, Cq), 129.0 (2C,
CAr-H), 127.8 (4C, CPh-H), 127.2 (4C, CPh-H), 123.9 (2C, CPh-H), 123.8
(2C, CPh-H), 123.4 (2C, CPh-H), 122.9 (2C, (CH=CH)Im), 122.4 (2C,
(CH=CH)Im), 120.4 (2C, Cq), 117.5 (2C, Cq), 78.4 (2C, CEtHN), 47.4 (2C,
CAr-CH2-NIm), 33.4 (2C, C(CH3)3), 30.4 (6C, C(CH3)3), 27.9 (2C,
(CH(CH3)2), 27.86 (2C, (CH(CH3)2), 23.5 (2C, (CH(CH3)2), 23.4 (2C,
(CH(CH3)2), 22.9 (2C, (CH(CH3)2), 22.8 (2C, (CH(CH3)2). IR (solid): 3337,
2959, 2923, 2867, 1626, 1457, 1180, 1059, 804, 757, 699, 644. HRMS
(ESI): calculated for (C68H82N6O2)2+: 507.3244, found: 507.3235.
calculated for (C56H58BrN6O2)+: 927.3793, found: 927.3785.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-dibromide
(4f): (1R,2R)-1,2-Diphenylethane-1,2-diamine (215.2 mg, 1.01 mmol, 1.0
equiv.) was treated with aldehyde 3-Im-Mes (928 mg, 2.03 mmol, 2.0
equiv.) according to GP2. 4f was obtained as a yellow hygroscopic solid
(1.08 g, 0.99 mmol, 98%) after washing with diethylether. C62H70Br2N6O2.
MW: 1091.07 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c = 0.5 g·dL-1,
CH2Cl2) = –7. 1H-NMR (500 MHz, CDCl3, 21 °C): δ = 13.90 (s, 2H, CAr-
OH), 10.48 (s, 2H, NCHN), 8.19 (s, 2H, N=CH), 7.85 (d, J = 2.0, 2H, CAr-
H), 7.66 (s, 2H, (CH=CH)Im), 7.27 – 7.19 (m, 12H, (CH=CH)Im and CPh-H),
7.17 (d, J = 2.5, 2H, CAr-H), 6.93 (s, 2H, CMes-H), 6.86 (s, 2H, CMes-H),
5.94 (d, J = 13.5, 2H, CAr-CH2-NIm), 5.63 (d, J = 14.0, 2H, CAr-CH2-NIm),
4.84 (s, 2H, CEtHN), 2.31 (s, 6H, (CH3)Mes), 2.04 (s, 6H, (CH3)Mes), 1.93 (s,
6H, (CH3)Mes), 1.24 (s, 18H, (CH3)3). 13C-NMR (125 MHz, CDCl3, 21 °C):
δ = 166.8 (2C, N=CH), 157.5 (2C, CAr-OH), 142.4 (2C, Cq), 141.1 (2C,
Cq), 139.4 (2C, Cq), 138.6 (2C, NCHN), 134.4 (2C, Cq), 134.2 (2C, Cq),
131.9 (2C, CAr-H), 130.8 (2C, Cq), 129.9 (2C, CAr-H), 129.7 (4C, CMes-H),
128.7 (4C, CPh-H), 127.9 (2C, CPh-H), 127.6 (4C, CPh-H), 123.3 (2C,
(CH=CH)Im), 123.0 (2C, (CH=CH)Im), 121.1 (2C, Cq), 118.1 (2C, Cq), 79.3
(2C, CEtHN), 48.8 (2C, CAr-CH2-NIm), 34.3 (1C, C(CH3)3), 31.4 (6C,
C(CH3)3), 21.2 (2C, (CH3)Mes), 17.8 (2C, (CH3)Mes), 17.5 (2C, (CH3)Mes).
IR (solid): 3850, 3347 (b), 3086, 2953, 2867, 2323, 1981, 1625, 1195,
1041, 702. HRMS (ESI) m/z: calculated for (C62H70BrN6O2)+: 1009.4738,
found: 1009.4714.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-methyl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-
dibromide (4p): (1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50
mmol, 1.0 equiv.) was treated with aldehyde 3-BI-Me (403 mg, 1.00
mmol, 2.0 equiv.) according to GP2. 4p was obtained as a yellow
hygroscopic solid (478 mg, 0.49 mmol, 97%) after washing with
diethylether. C54H58Br2N6O2. MW: 1107.05 g mol–1. M.p.: decomp. T >
150 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) = 22. 1H-NMR (250 MHz, CDCl3,
21 °C): δ = 14.12 (b, 1H, CAr-OH), 11.38 (s, 2H, NCHN), 8.41 (s, 2H,
N=CH), 7.91 (d, J = 8.6, 2H, CBI-H), 7.70 (d, J = 2.4, 2H, CAr-H), 7.67 -
7.45 (m, 6H, CBI-H), 7.24 – 7.16 (m, 10H, CPh-H), 5.87 (d, J = 14.5, 2H,
CAr-CH2-NBI), 5.71 (d, J = 14.5, 2H, CAr-CH2-NBI), 4.94 (s, 2H, CEtHN),
4.31 (s, 6H, (CH3)BI), 1.24 (s, 18H, (CH3)3). 13C-NMR (62 MHz, CDCl3,
21 °C): δ = 166.6 (2C, N=CH), 157.5 (2C, CAr-OH), 143.8 (2C, Cq), 142.2
(2C, NCHN), 139.3 (2C), 132.0 (2C), 131.3 (2C), 130.1 (2C), 128.6 (4C),
127.8 (4C), 127.0 (2C), 119.5 (2C), 118.4 (2C), 113.8 (2C), 112.6 (2C),
79.2 (2C, CEtHN), 46.5 (2C, CAr-CH2-NBI), 34.2 (2C, C(CH3)3), 33.9 (2C,
(CH3)BI), 31.4 (6C, C(CH3)3). IR (solid): 2965, 2951, 2864, 1627, 1598,
1450, 1198, 1012, 888, 747, 569, 514. HRMS (ESI) m/z: calculated for
(C54H58BrN6O2)+: 903.3792, found: 903.3788.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene-1,2-diphenylethane-1,2-diamine-dichloride
(4k): 1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50 mmol, 1.0
equiv.) was treated with aldehyde 3-Im-Mes (413 mg, 1.00 mmol, 2.0
equiv.) according to GP2. 4k was obtained as a yellow hygroscopic solid
(492 mg, 0.49 mmol, 98%) after washing with diethylether.
C62H70Cl2N6O2, MW: 1002.18 g mol–1. M.p.: decomp. >200 °C. [α]20
D
(c = 0.5 g·dL-1, CH2Cl2) = 3. 1H-NMR (500 MHz, CDCl3, 21 °C): δ = 13.90
(s, 2H, CAr-OH), 10.85 (s, 2H, NCHN), 8.07 (s, 2H, N=CH), 7.70 (d, J =
2.1, 2H, CAr-H), 7.43 (s, 2H, (CH=CH)Im), 7.21 – 7.15 (m, 12H,
(CH=CH)Im und CPh-H), 7.13 (d, J = 2.4, 2H, CAr-H), 6.93 (s, 2H, (CH)Mes),
6.82 (s, 2H, (CH)Mes), 5.80 (d, J = 14.4, 2H, CAr-CH2-NIm), 5.35 (d, J =
14.4, 2H, CAr-CH2-NIm), 4.81 (s, 2H, CEtHN), 2.28 (s, 6H, (CH3)Mes), 2.01
(s, 6H, (CH3)Mes), 1.85 (s, 6H, (CH3)Mes), 1.21 (s, 18H, (CH3)3). 13C-NMR
(125 MHz, CDCl3, 21 °C): δ = 166.1 (2C, N=CH), 156.9 (2C, CAr-OH),
141.4 (2C, Cq), 140.3 (2C, Cq), 139.1 (2C, Cq), 138.9 (2C, NCHN), 133.9
(2C, Cq), 133.7 (2C, Cq), 131.0 (2C, CAr-H), 130.2 (2C, Cq), 129.0 (2C,
CAr-H), 128.9 (4C, CMes-H), 128.8 (4C, CPh-H), 127.8 (2C, CPh-H), 127.1
(2C, CPh-H), 126.8 (2C, CPh-H), 122.2 (2C, (CH=CH)Im), 121.5 (2C,
(CH=CH)Im), 120.3 (2C, Cq), 117.5 (2C, Cq), 78.4 (2C, CEtHN), 48.3 (2C,
CAr-CH2-NIm), 33.3 (1C, C(CH3)3), 30.4 (6C, C(CH3)3), 20.2 (2C, (CH3)Mes),
16.7 (2C, (CH3)Mes), 16.4 (2C, (CH3)Mes). IR (solid): 3400 (b), 3149, 3059,
2966, 2867, 1629, 1452, 1201, 1037, 823, 708, 579. HRMS (ESI):
calculated for (C62H70ClN6O2)+: 965.5243, found: 965.5222.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-phenyl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-
dibromide (4r): (1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50
mmol, 1.0 equiv.) was treated with aldehyde 3-BI-Ph (465 mg, 1.00 mmol,
2.0 equiv.) according to GP2. 4r was obtained as a yellow hygroscopic
solid (494 mg, 0.45 mmol, 89%) after washing with diethylether.
C64H62Br2N6O2. MW: 1107.05 g mol–1. M.p.: decomp. >170 °C. [α]20
D
(c = 0.5 g·dL-1 CH2Cl2) = 62. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ =
14.43 (s, 2H, CAr-OH), 11.63 (s, 2H, NCHN), 8.11 (s, 2H, N=CH), 7.98 (d,
J = 8.0, 2H, CBI-H), 7.94 (d, J = 2.2, 2H, CAr-H), 7.81 (m, 4H, CPh-H), 7.68
(d, J = 8.3, 2H, CBI-H), 7.61 (t, J = 8.3, 2H, CBI-H), 7.56 (d, J = 7.9, 2H,
CBI-H), 7.53 (m, 6H, CPh-H), 7.15 (m, 6H, CPh-H and CAr-H), 7.09 (t, J =
7.3, 2H, CPh-H), 6.97 (t, J = 7.6, 2H, CPh-H), 6.15 (d, J = 14.9, 4H, CAr-
CH2-NBI), 6.05 (d, J = 14.3, 4H, CAr-CH2-NBI), 4.84 (s, 2H, CEtHN), 1.29 (s,
18H, (CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 167.2 (2C, N=CH),
158.6 (2C, CAr-OH), 144.1 (2C, NCHN), 142.5 (2C, Cq), 139.8 (2C,
Cq),133.6 (2C, Cq), 132.6 (2C, CAr-H), 131.8 (2C, Cq), 131.5 (2C, Cq),
130.9 (6C, CPh-H), 130.0 (2C, CAr-H), 128.8 (4C, CPh-H) 128.1 (2C, CBI-
H), 127.9 (2C, CBI-H), 127.7 (2C CPh-H), 127.6 (4C CPh-H), 125.1 (4C,
CPh-H), 120.6 (2C, Cq), 118.5 (2C, Cq), 114.5 (2C, CBI-H), 113.8 (2C, CBI-
H), 79.0 (2C, CEtHN), 47.7 (2C, CAr-CH2-NBI), 34.5 (2C, C(CH3)3), 31.5
(6C, C(CH3)3). IR (solid): 2951, 2863, 1628, 1599, 1442, 1228, 1037, 923,
725, 699, 593, 550. HRMS (ESI) m/z: calculated for (C64H62BrN6O2)+:
1027.4109, found: 1027.4100.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-(((2,6-diisopropylphenyl)-1H-
imidazol-3-ium)-1-ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-
diamine-dibromide (4n): (1R,2R)-1,2-Diphenylethane-1,2-diamine (21
mg, 0.1 mmol, 1.0 equiv.) was treated with aldehyde 3-Im-iPr2Ph (97 mg,
0.2 mmol, 2.0 equiv.) according to GP2. 4n was obtained as a yellow
hygroscopic solid (91 mg, 0.08 mmol, 77%) after washing with
diethylether. C68H82Br2N6O2, MW: 1175.25 g mol–1. M.p.: decomp. >
1
140 °C. [α]20D (c = 0.5 g·dL-1, CH2Cl2) = –59. H-NMR (300 MHz, CD2Cl2,
21 °C): δ = 13.84 (b, 2H, CAr-OH), 10.51 (s, 2H, NCHN), 8.28 (s, 2H,
N=CH), 8.01 (d, J = 2.4, 2H, CAr-H), 7.77 (t, J = 1.6, 2H, (CH=CH)Im),
7.55 (t, J = 7.9, CPh-H) 7.32 – 7.21 (m, 18H, CPh-H and CAr-H and
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-benzo[d]imidazol-3-
ium)-1-ylmethyl)-salicylidene)-1,2-diphenylethane-1,2-diamine-
dibromide (4t): (1R,2R)-1,2-Diphenylethane-1,2-diamine (106 mg, 0.50
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
mmol, 1.0 equiv.) was treated with aldehyde 3-BI-Mes (508 mg, 1.00
mmol, 2.0 equiv.) according to GP2. 4t was obtained as a yellow
hygroscopic solid (534 mg, 0.45 mmol, 90%) after washing with
diethylether. C70H74Br2N6O2. MW: 1191.21. M.p.: decomp. > 180 °C.
2.03 (s, 6H, (CH3)Mes), 1.97 (s, 6H, (CH3)Mes), 1.97 (m, 2H, (CH2)Cy), 1.82
(m, 2H, (CH2)Cy), 1.43 (m, 4H, (CH2)Cy and (CH)Cy), 1.36 (s, 18H, (CH3)3),
1.28 – 1.02 (s, 8H, (CH2)Cy), 0.95 (m, 2H, (CH2)Cy), 0.83 (m, 2H, (CH2)Cy).
13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 165.9 (2C, N=CH), 159.4 (2C,
CAr-OH), 141.8 (2C, Cq), 141.5 (2C, Cq), 140.3 (2C, NCHN), 135.1 (2C,
Cq), 135.0 (2C, Cq), 131.6 (2C, CAr-H), 131.3 (2C, Cq), 130.0 (2C, CMes-H),
129.91 (2C, CMes-H), 129.86 (2C, CAr-H), 123.0 (2C, (CH=CH)Im), 122.8
(2C, (CH=CH)Im), 121.7 (2C, Cq), 118.1 (2C, Cq), 74.1 (2C, CCyHN), 49.9
(2C, CAr-CH2-NIm), 38.7 (2C, (CH)Cy), 34.5 (2C, C(CH3)3), 31.6 (6C,
C(CH3)3), 30.8 (2C, (CH2)Cy), 29.7 (2C, (CH2)Cy), 26.6 (2C, (CH2)Cy), 26.3
(2C, (CH2)Cy), 26.2 (2C, (CH2)Cy), 21.4 (2C, (CH3)Mes), 17.9 (2C,
(CH3)Mes), 17.7 (2C, (CH3)Mes). IR (CH2Cl2): 3480 (b), 2923, 2851, 1628,
1482, 1447, 1202, 1036, 852, 707, 649, 577. HRMS (ESI) m/z: calculated
for (C62H82N6O2)2+: 471.3244, found: 471.3246.
1
[α]20D (c = 0.5 g·dL-1 CH2Cl2) = –75. H-NMR (250 MHz, CDCl3, 21 °C): δ
= 14.16 (s, 2H, CAr-OH), 11.45 (s, 2H, NCHN), 8.00 (s, 2H, N=CH), 7.79
(m, 2H, CBI-H), 7.74 (d, J = 2.3, 2H, CAr-H), 7.53 (m, 4H, CBI-H), 7.25 –
7.14 (m, 16H, CPh-H, CAr-H, CMes-H and CBI-H), 6.91 (s, 2H, CMes-H), 6.23
(d, J = 14.6, 2H, CAr-CH2-NBI), 5.51 (d, J = 14.6, 2H, CAr-CH2-NBI), 4.84 (s,
2H, CEtHN), 2.44 (s, 6H, (CH3)Mes), 2.08 (s, 6H, (CH3)Mes), 1.78 (s, 6H,
(CH3)Mes), 1.30 (s, 18H, (CH3)3). 13C-NMR (125 MHz, CDCl3, 21 °C): δ =
167.4 (2C, N=CH), 158.4 (2C, CAr-OH), 145.5 (2C, NCHN), 142.5 (2C,
Cq), 141.9 (2C, Cq), 140.1 (2C, Cq), 136.4 (2C, Cq), 135.8 (2C, Cq), 132.0
(2C, Cq), 131.8 (2C, CAr-H), 131.2 (2C, Cq), 130.5 (2C, CAr-H), 130.2 (2C,
CMes-H), 130.1 (2C, CMes-H), 129.0 (4C, CPh-H), 128.6 (2C, CPh-H or CBI-
H), 128.2 (2C, Cq), 127.9 (2C, CPh-H or CBI-H), 127.7 (4C, CPh-H), 127.5
(2C, CBI-H), 120.3 (2C, Cq), 118.7 (2C, Cq), 114.2 (2C, CBI-H), 113.5 (2C,
CBI-H), 79.7 (2C, CEtHN), 48.3 (2C, CAr-CH2-NBI), 34.5 (2C, C(CH3)3),
31.5 (6C, C(CH3)3), 21.5 (2C, (CH3)Mes), 18.1 (2C, (CH3)Mes), 17.5 (2C,
(CH3)Mes). IR (solid): 2951, 2863, 1628, 1554, 1475, 1200, 1026, 888,
748, 693, 573, 509. HRMS (ESI) m/z: calculated for (C70H74BrN6O2)+:
1111.5051, found: 1111.5056.
N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-ylmethyl)-
salicylidene)-ethane-1,2-diamine-dibromide (4i): Ethane-1,2-diamine
(26.8 µL, 0.40 mmol, 1.0 equiv.) was treated with aldehyde 3-Im-Mes
(367 mg, 0.80, 2.0 equiv.) according to GP2. 4i was obtained as a yellow
hygroscopic solid (362 mg, 0.08 mmol, 96%) after washing with
diethylether. C50H62Br2N6O2, MW: 938.87 g mol–1. M.p.: decomp. T >
200 °C. 1H NMR (300 MHz, CDCl3, 21 °C): δ = 13.86 (b, 2H, CAr-OH),
10.50 (s, 2H, NCHN), 8.45 (s, 2H, N=CH), 7.99 (d, J = 2.5, 2H, CAr-H),
7.72 (s, 2H, (CH=CH)Im), 7.33 (d, J = 2.1, 2H, CAr-H), 7.15 (s, 2H,
(CH=CH)Im), 6.93 (s, 4H, CMes-H), 5.88 (s, 4H, CAr-CH2-NIm), 3.96 (s, 4H,
(CH2)Et), 2.31 (s, 6H, (CH3)Mes), 2.02 (s, 12H, (CH3)Mes), 1.30 (s, 18H,
(CH3)3). 13C NMR (125 MHz, CDCl3, 21 °C): δ = 166.7 (2C, N=CH), 157.9
(2C, CAr-OH), 142.4 (2C, Cq), 141.2 (2C, Cq), 138.4 (2C, NCHN), 134.3
(4C, Cq), 132.3 (2C, CAr-H), 130.8 (2C, Cq), 129.8 (4C, CMes-H), 129.5
(2C, CAr-H), 123.1 (2C, (CH=CH)Im), 122.9 (2C, (CH=CHN)Im, 121.2 (2C,
Cq), 118.0 (2C, Cq), 59.3 (2C, (CH2)Et), 48.7 (2C, CAr-CH2-NIm), 34.3 (1C,
C(CH3)3), 31.5 (6C, C(CH3)3), 21.1 (2C, (CH3)Mes), 17.7 (4C, (CH3)Mes). IR
(solid): 3850, 3741, 3373 (b), 2953, 2865, 2323, 2168, 2051, 1981, 1769,
1631, 1480, 1198, 1033, 853, 648. HRMS (ESI) m/z: calculated for
(C50H62Br2N6O2)2+: 389.2462, found: 389.2445
Synthesis of Salen Ligands with Alternative Backbones
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-bis(4-methoxyphenyl)ethane-1,2-
diamine-dibromide (4g): (1R,2R)-1,2-Bis(4-methoxyphenyl)ethan-1,2-
diamine (27.2 mg, 0.10 mmol, 1.0 equiv.) was treated with aldehyde 3-
Im-Mes (91.5 mg, 0.20 mmol, 2.0 equiv.) according to GP2. 4g was
obtained as a yellow hygroscopic solid (111 mg, 0.09 mmol, 96%) after
washing with diethylether. C64H74Br2N6O4, MW: 1151.14 g mol–1. M.p.:
decomp. T > 200 °C. [α]20D (c = 0.5 g·dL-1, CH2Cl2) = –5. 1H-NMR (500
MHz, CD2Cl2, 21 °C): δ = 14.06 (s, 2H, CAr-OH), 10.53 (s, 2H, NCHN),
8.16 (s, 2H, N=CH), 7.78 (d, J = 2.2, 2H, CAr-H), 7.54 (s, 2H, (CH=CH)Im),
7.23 (d, J = 2.4, 2H, CAr-H), 7.19 (s, 2H, (CH=CH)Im), 7.15 (d, J = 8.7, 4H,
CPh-H), 7.01 (s, 2H, CMes-H), 6.90 (s, 2H, CMes-H), 6.79 (d, J = 8.7, 4H,
CPh-H), 5.87 (d, J = 14.1, 2H, CAr-CH2-NIm), 5.45 (d, J = 14.1, 2H, CAr-
CH2-NIm), 4.80 (s, 2H, CEtHN), 3.74 (s, 6H, OCH3), 2.35 (s, 6H, (CH3)Mes),
2.09 (s, 6H, (CH3)Mes), 1.92 (s, 6H, (CH3)Mes), 1.28 (s, 18H, (CH3)3). 13C-
NMR (125 MHz, CD2Cl2, 21 °C): δ = 165.8 (2C, N=CH), 158.4 (2C, CAr-
OH), 141.4 (2C, Cq), 140.4 (2C, Cq), 138.4 (2C, NCHN), 133.9 (2C, Cq),
133.7 (2C, Cq), 130.9 (2C, CAr-H), 130.87 (2C, Cq), 130.1 (2C, Cq), 129.0
(4C, CAr-H and CMes-H), 128.8 (2C, CMes-H), 127.9 (4C, CPh-H), 122.2 (2C,
(CH=CH)Im), 121.7 (2C, (CH=CH)Im), 120.1 (2C, Cq), 117.5 (2C, Cq),
113.1 (4C, CPh-H), 77.8 (2C, CEtHN), 54.5 (2C, OCH3), 48.3 (2C, CAr-
CH2-NIm), 33.4 (1C, C(CH3)3), 30.4 (6C, C(CH3)3), 20.2 (2C, (CH3)Mes),
16.8 (2C, (CH3)Mes), 16.5 (2C, (CH3)Mes). IR (solid): 3386, 2956, 2867,
1679, 1628, 1512, 1249, 1201, 1067, 834, 648, 553. HRMS (ESI) m/z:
calculated for (C64H74BrN6O4)+: 1069.4949, found: 1069.4964.
Synthesis of C1-Symmetric Ligands
3-(5-(tert-Butyl)-2-hydroxy-3-(((1S,2R)-2-hydroxy-2,3-dihydro-1H-
inden-1-yl)imino)methyl)benzyl)-1-mesityl-1H-imidazol-3-ium
bromide (6): (1S,2R)-1-Amino-2,3-dihydro-1H-inden-2-ol (149 mg, 1.00
mmol, 1.0 equiv.) was treated with aldehyde 3-Im-Mes (457 mg, 1.00
mmol, 2.0 equiv.) according to GP2. 6 was obtained as a yellow
hygroscopic solid (567 mg, 0.96 mmol, 96%) after washing with
diethylether. C33H38BrN3O2, MW: 588.59, M.p.: decomp. >130 °C. [α]20
D
(c = 1.0 g·dL-1, CH2Cl2) = –39. 1H-NMR (250 MHz, CDCl3, 21 °C): δ =
14.21 (b, 1H, CAr-OH), 9.82 (s, 1H, NCHN), 8.52 (s, 1H, N=CH), 7.97 (d,
J = 2.3, 1H, CAr-H), 7.86 (s, 1H, (CH=CH)Im), 7.32 (d, J = 2.3, 1H, CAr-H),
7.31 – 7.16 (m, 4H, CPh-H), 7.04 (s, 1H, (CH=CH)Im), 6.98 (s, 2H, CMes-H),
5.71 (d, J = 16.7, 1H, CAr-CH2-NIm), 5.67 (d, J = 16.6, 1H, CAr-CH2-NIm),
4.88 (d, J = 5.2, 1H, CIndHN), 4.88 (dd, J = 10.8, J = 5.5, 1H, CIndHOH),
3.21 (dd, J = 16.1, J = 5.6, 1H, (CH2)Ind), 3.06 (dd, J = 16.0, J = 5.2, 1H,
(CH2)Ind), 2.32 (s, 3H, (CH3)Mes), 1.98 (s, 3H, (CH3)Mes), 1.94 (s, 3H,
(CH3)Mes), 1.30 (s, 9H, (CH3)3). 13C-NMR (125 MHz, CDCl3, 21 °C): δ =
166.4 (1C, N=CH), 161.6 (1C, CAr-OH), 141.8 (1C, Cq), 141.6 (1C, Cq),
141.1 (1C, Cq), 141.0 (1C, Cq), 138.2 (1C, NCHN), 134.8 (1C, Cq), 133.5
(1C, CAr-H), 131.2 (1C, Cq), 130.2 (1C, CAr-H), 130.1 (2C, CMes-H), 129.1
(1C, CPh-H), 127.3 (1C, CPh-H), 125.9 (1C, CPh-H), 125.2 (1C, CPh-H),
123.9 (1C, (CH=CH)Im), 123.1 (1C, (CH=CH)Im), 122.3 (1C, Cq), 117.8
(1C, Cq), 74.9 (1C, CIndHOH), 73.7 (1C, CIndHN), 49.5 (1C, CAr-CH2-NIm),
39.8 (1C, (CH2)Ind), 34.5 (1C, C(CH3)3), 31.5 (3C, C(CH3)3), 21.2 (1C,
(CH3)Mes), 17.72 (1C, (CH3)Mes), 17.65 (1C, (CH3)Mes). IR (solid): 3154,
1950, 1863, 1631, 1460, 1194, 1040, 853, 756, 555. HRMS (ESI) m/z:
calculated for (C33H38N3O2)+: 508.2959, found: 508.2969.
(R,R)-(–)-N,N’-Bis(5-tert-butyl-3-((1-mesityl-1H-imidazol-3-ium)-1-
ylmethyl)-salicylidene)-1,2-dicyclohexylethane-1,2-diamine-
dibromide (4h): (1R,2R)-1,2-Dicyclohexylethane-1,2-diamine (57.9 mg,
0.26 mmol, 1.0 equiv.) was treated with aldehyde 3-Im-Mes (236 mg,
0.52 mmol, 2.0 equiv.) according to GP2. 4h was obtained as a yellow
hygroscopic solid (257 mg, 0.23 mmol, 90%) after washing with
diethylether. C62H82Br2N6O2, MW: 1103.19 g mol–1. M.p.: decomp. >
180 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) = 85. 1H-NMR (500 MHz, CD2Cl2,
21 °C): δ = 14.21 (b, 1H, CAr-OH), 10.45 (t, J = 1.7, 2H, NCHN), 8.32 (s,
2H, N=CH), 7.66 (d, J = 2.3, 2H, CAr-H), 7.56 (t, J = 1.7, 2H, (CH=CH)Im),
7.38 (d, J = 2.6, 2H, CAr-H), 7.14 (t, J = 1.7, 2H, (CH=CH)Im), 6.89 (s, 2H,
CMes-H), 6.86 (s, 2H, CMes-H), 5.55 (d, J = 14.4, 2H, CAr-CH2-NIm), 5.41 (d,
J = 14.4, 2H, CAr-CH2-NIm), 3.28 (m, 2H, CCyHN), 2.30 (s, 6H, (CH3)Mes),
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
(R,R)-(–)-N-(3,5-Di-tert-butyl-1-ylmethyl)-N’-(5-tert-butyl-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-salicylidene)-1,2-cyclohexane-
diamine-bomide (8): To a solution of (1R,2R)-cyclohexane-1,2-diamine
(111 mg, 0.97 mmol, 1.0 equiv.) in a 1:1 dichlormethane/diethylether-
mixture (20 mL) was added dropwise aqueous HCl (1.0 M, 0.25 mL, 0.97
mmol, 1.0 equiv.) in dichlormethane and the suspension was stirred for
15 h at room temperature. The precipitate was taken up in ethanol and
H)mai, 7.67 (s, 1H)mii, 7.59 (s, 1H, CAr-H or (CH=CH)Im)mai, 7.54 (s, 1H,
CAr-H or (CH=CH)Im)mai, 7.49 (s, 1H, CAr-H or (CH=CH)Im)mai, 7.29 (s,
1H)mii, 7.10 (s, 1H)mii, 7.01 (s, 1H, (CH=CH)Im
CAr-CH2-NIm mai, 5.63 (b, 2H CAr-CH2-NIm mii, 5.39 (d, J = 14.4, 3H CAr-
CH2-NIm mai, 5.15 (b, 3H CAr-CH2-NIm mii, 4.08 (s, 3H, (CH3)Im mai+mii, 3.87
(m, 1H, CCyHN)mai+mii 3.59 (s, 3H, (CH3)Im)mai+mii 2.99 (m, 1H,
CCyHN)mai+mii, 2.46 (m, 1H, (CH2)Cy mai+mii, 2.20 (m, 1H, (CH2)Cy mai+mii
1.97 (m, 1H, (CH2)Cy mai+mii, 1.83 (m, 2H, (CH2)Cy mai+mii, 1.61 (m, 2H,
(CH2)Cy mai+mii, 1.38 (s, 9H, (CH3)3)mai+mii, 1.30 (s, 9H, (CH3)3)mai+mii, 1.03
(m, 1H, (CH2)Cy mai+mii
13C-NMR (125 MHz, CD2Cl2, 21 °C, nur Signale
)mai, 5.73 (d, J = 14.4, 1H
)
)
)
)
)
,
,
)
)
,
dichloromethane
(20
mL,
1:1)
and
3,5-di-tert-butyl-2-
)
)
hydroxybenzaldehyde (230 mg, 0.98 mmol, 1.0 equiv.) and 4Å molecular
sieves was added. After stirring for 5 h at room temperature the mixture
was filtered over celite. The filtrate was evaporated and the residue was
dissolved in ethanol (10 mL). Triethylamine (134 µL, 0.97 mmol, 1.0
equiv.) was added and the mixture was stirred for 30 min at room
temperature. After evaporation the residue was taken up in toluene.
Triethylammonium chloride was removed by centrifugation. The solvent
was again evaporated and the residue was dissolved in
dichlormethane/ethanol (1:1, 20 mL). Aldehyde 3-Im-Mes (444 mg, 0.97
mmol, 1.0 equiv) and 4Å molecular sieves was added and the mixture
was stirred for 15 h at room temperature. After filtration over celite all
volatiles were removed by evaporation. 8 was obtained as a yellow
hygroscopic solid (607 mg, 0.79 mmol, 81%) after washing with
diethylether and toluene. C45H61BrN4O2. MW: 769.91 g mol–1. M.p.:
decomp. T > 170 °C. [α]20D (c = 0.1 g·dL-1 CH2Cl2): –196. 1H-NMR (300
MHz, CD2Cl2, 21 °C): δ = 14.08 (b, 1H, CAr-OH), 13.64 (b, 1H, CAr-OH),
10.42 (t, J = 1.5, 1H, NCHN), 8.36 (s, 1H, N=CH), 8.29 (s, 1H, N=CH),
7.97 (d, J = 2.5, 2H, CAr-H), 7.80 (t, J = 1.6, 1H, (CH=CH)Im), 7.30 (d, J =
2.5, 2H, CAr-H), 7.23 (d, J = 2.5, 2H, CAr-H), 7.05 (t, J = 1.6, 1H,
(CH=CH)Im) 7.01 (m, 3H, CAr-H and (CH)Mes), 5.82 (d, J = 13.9, 1H, CAr-
CH2-NIm), 5.74 (d, J = 13.8, 1H, CAr-CH2-NIm), 3.42 (m, 1H, CCyHN), 3.31
(m, 1H, CCyHN), 2.33 (s, 3H, (CH3)Mes), 2.03 (s, 3H, (CH3)Mes), 2.01 (s, 3H,
(CH3)Mes), 1.91 (m, 4H, (CH2)Cy), 1.72 (m, 2H, (CH2)Cy), 1.49 (m, 2H,
(CH2)Cy), 1.37 (s, 9H, (CH3)3), 1.23 (s, 9H, (CH3)3), 1.21 (s, 9H, (CH3)3).
13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 165.0 (1C, N=CH), 164.2 (1C,
N=CH), 157.5 (1C, CAr-OH), 157.1 (1C, CAr-OH), 141.1 (1C, Cq), 140.4
(1C, Cq), 139.4 (1C, Cq), 137.6 (1C, NCHN), 135.6 (1C, Cq), 133.7 (1C,
Cq), 133.6 (1C, Cq), 131.4 (1C, CAr-H), 130.1 (1C, Cq), 128.9 (2C, CMes-H),
128.5 (1C, CAr-H), 126.1 (1C, CAr-H), 125.2 (1C, CAr-H), 122.5 (1C,
(CH=CH)Im), 121.9 (1C, (CH=CH)Im), 120.3 (1C, Cq), 117.2 (1C, Cq),
117.1 (1C, Cq), 71.6 (1C, CCyHN), 71.1 (1C, CCyHN), 47.8 (1C, CAr-CH2-
NIm), 34.1 (1C, C(CH3)3), 33.3 (1C, C(CH3)3), 33.2 (1C, C(CH3)3), 32.5
(1C, (CH2)Cy), 32.0 (1C, (CH2)Cy), 30.4 (3C, C(CH3)3), 30.3 (3C, C(CH3)3),
28.3 (3C, C(CH3)3), 23.5 (1C, CH2)Cy), 23.4 (1C, CH2)Cy), 20.1 (1C,
(CH3)Mes), 16.6 (2C, (CH3)Mes). IR (solid): 2950, 2861, 1626, 1440, 1390,
1173, 827, 710, 646, 578. HRMS (ESI) m/z: calculated for (C45H61N4O2)+:
689.4789, found: 689.4796.
)
)
.
der Hausptspezies): δ = 162.9 (1C, N=CH), 160.8 (1C, N=CH), 158.1 (1C,
CAr-OTi), 157.2 (1C, CAr-OTi), 142.4 (1C, Cq), 140.3 (1C, Cq), 136.5 (1C,
NCHN), 136.3 (1C, NCHN), 134.7 (1C, CAr-H), 132.9 (1C, CAr-H), 132.1
(1C, CAr-H or (CH=CH)Im), 132.1 (1C, Cq), 130.2 (1C, CAr-H or
(CH=CH)Im), 123.6 (1C, CAr-H or (CH=CH)Im), 122.2 (1C, CAr-H or
(CH=CH)Im), 122.0 (1C, Cq), 121.7 (1C, Cq), 121.2 (1C, (CH=CH)Im),
120.3 (1C, Cq), 120.25 (1C, CAr-H or (CH=CH)Im), 69.8 (1C, CCyHN), 67.3
(1C, CCyHN), 48.8 (1C, CAr-CH2-NIm), 46.9 (1C, CAr-CH2-NIm), 35.8 (1C,
C(CH3)3), 35.1 (1C, C(CH3)3), 33.6 (1C, (CH3)Im), 33.4 (1C, (CH3)Im), 30.5
(1C, (CH2)Cy), 30.4 (6C, C(CH3)3), 27.8 (1C, (CH2)Cy), 24.0 (1C, (CH2)Cy),
23.6 (1C, (CH2)Cy). IR (solid): 3450 (b), 2962, 2949, 2859, 2359, 2036,
1621, 1555, 1443, 1277, 1157, 833, 559, 533, 523. HRMS (ESI) m/z:
calculated for (C38H50N6O3Ti)2+: 373.1708, found: 343.1694.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-phenyl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl-
titanium(IV))tetrabromide (5c): Salen ligand 4c (9.1 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 5c was formed as a mixture of two
isomers (2.3:1, quantitative conversion, yellow solid). C96H108Br4N12O6Ti2.
MW: 1941.35 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c = 0.1 g·dL-1,
CH2Cl2) = 95. 1H-NMR (500 MHz, CDCl3, 21 °C, mai = major isomer, mii
= minor isomer): δ = 11.00 (s, 1H, NCHN)mai, 10.94 (s, 1H, NCHN)mii
10.56 (s, 1H, NCHN)mai, 10.33 (s, 1H, NCHN)mii, 9.38 (s, 1H, N=CH)mai
,
,
8.93 (d, J = 2.4, 1H, CAr-H)mai, 8.72 (s, 1H, N=CH)mii, 8.64 (s, 1H,
N=CH)mii, 8.64 (s, 1H, N=CH)mai, 8.33 (d, J = 1.7, 1H, CAr-H)mai, 8.22 (b,
2H)mai+Us, 7.82 (d, J = 2.2, 1H, CAr-H)mii, 7.71 (d, J = 2.0, 1H, CAr-H)mii
7.64 (d, J = 2.2, 1H, CAr-H)mii, 7.58 (m, 2H, CPh-H)mai+mii, 7.55 (d, J = 7.5,
2H, CPh-H)mai, 7.52 (d, J = 2.4, 1H, CAr-H)mai, 7.47 (m, 3H, CPh-H)mai+mii
7.40 (m, 3H, CPh-H)mai+mii, 7.36 (d, J = 7.5, 1H, CPh-H)mii, 7.32 (t, J = 7.5,
2H, CPh-H)mai+mii, 7.27 (m, 5H, CPh-H)mai+mii, 7.15 (t, J = 7.5, 1H, CPh-H)mii
7.11 (t, J = 1.6, 1H, (CH=CH)Im mai, 7.05 (t, J = 7.5, 1H, CPh-H)mai, 6.56 (t,
J = 1.6, 1H, (CH=CH)Im)mii, 6.43 (t, J = 1.6, 1H, (CH=CH)Im)mai, 6.34 (d, J
= 13.1, 1H, CAr-CH2-NIm mii, 6.16 (d, J = 14.3, 1H, CAr-CH2-NIm)mai, 5.66 (d,
J = 14.2, 1H, CAr-CH2-NIm
5.42 (d, J = 14.3, 1H, CAr-CH2-NIm
NIm mai, 5.35 (d, J = 13.4, 1H, CAr-CH2-NIm
,
,
,
)
)
)
mii, 5.58 (d, J = 13.8, 2H, CAr-CH2-NIm
)
,
,
mai+mii
)mai, 5.41 (d, J = 14.0, 1H, CAr-CH2-
Synthesis of the Ti(IV) Complexes
)
)mai, 3.73 (m, 1H, CCyHN)mii
3.63 (m, 1H, CCyHN)mai, 2.94 (m, 2H, CCyHN)mai+mii, 2.50 (m, 1H,
(CH2)Cy
(CH2)Cy
)
)
mii, 2.65 (m, 1H, (CH2)Cy mai
mai, 1.98 (m, 1H, (CH2)Cy mai
1.29 (s, 9H, (CH3)3)mii
(CH3)3)mai, , 1.03 (s, 9H, (CH3)3)mii, 0.95 (s, 9H, (CH3)3)mai, 0.79 (m, 2H,
(CH2)Cy mai+mii, 0.65 (m, 2H, (CH2)Cy
13C-NMR (125 MHz, CDCl3,
)
, 2.37 (m, 1H, (CH2)Cy mii
, 1.84 - 1.59 (m, 6H, (CH2)Cy mai+mii
1.26 (s, 9H,
) , 2.28 (m, 1H,
Synthesis of Salen Complexes with
Backbone
a
(1R,2R)-Cyclohexane
)
)
,
1.38 (m, 2H, (CH2)Cy mai+mii
)
,
,
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-methyl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl-
titanium(IV))tetrabromid (5a): Salen ligand 4a (7.8 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 5a was formed as a mixture of two
isomers (5.0:1, quantitative conversion, yellow solid). C76H100Br4N12O6Ti2.
)
)
.
mai+mii
21 °C): δ = 163.0 (1C, N=CH)mai, 162.2 (1C, N=CH)mii, 162.0 (1C,
N=CH)mai, 161.9 (1C, CAr-OTi)mai, 161.7 (1C, N=CH)mii, 159.5 (1C, CAr-
OTi)mai, 159.1 (1C, CAr-OTi)mii, 143.1 (1C, Cq)mii, 142.6 (1C, Cq)mai, 141.6
(1C, Cq)mai, 141.3 (1C, Cq)mii, 135.8 (1C, CAr-H)mai, 135.3 (1C, NCHN)mai
,
135.2 (1C, NCHN)mai, 134.4 (1C, CAr-H)mai, 134.1 (1C, NCHN)mii, 134.06
(1C, NCHN)mii, 133.76 (1C), 133.75 (1C), 133.5 (1C), 133.22 (1C),
133.20 (1C), 133.1 (1C), 132.8 (1C), 131.3 (1C), 130.8 (2C), 130.7 (1C),
130.4 (1C), 130.2 (2C), 130.0 (1C), 129.9 (1C), 129.8 (1C), 129.6 (1C),
120.4 (2C, CPh-H), 120.1 (1C, Cq)mii, 119. (1C, Cq)mai, 118.9 (1C,
MW: 1693.06 g mol–1. M.p.: decomp. T > 200 °C. [α]D (c = 0.1 g·dL-1,
25
CH2Cl2): 47. 1H-NMR (500 MHz, CD2Cl2, 21 °C, mai = major isomer , mii
= minor isomer): δ = 10.53 (s, 1H, NCHN)mii, 10.10 (s, 1H, NCHN)mai
,
9.88 (s, 1H, NCHN)mai, 9.43 (s, 1H, NCHN)mii, 9.20 (s, 1H)mii, 8.90 (s,
1H)mii, 8.55 (s, 1H, N=CH)mai, 8.53 (s, 1H, N=CH)mai, 8.32 (s, 1H)mii, 8.15
(s, 1H, CAr-H or (CH=CH)Im)mai, 8.11 (s, 1H)mii, 8.05 (s, 1H, CAr-H or
(CH=CH)Im
)mii, 118.6 (1C, (CH=CH)Im)mai, 71.4 (1C, CCyHN)mai, 70.7 (1C,
CCyHN)mii, 68.5 (1C, CCyHN)mai, 67.8 (1C, CCyHN)mii, 50.7 (1C, CAr-CH2-
(CH=CH)Im)mai, 7.76 (d, J = 2.0, 1H, CAr-H)mai, 7.71 (s, 1H, J = 2.0, CAr-
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
NIm
CAr-CH2-NIm
)
mai, 50.2 (1C, CAr-CH2-NIm)mii, 50.0 (1C, CAr-CH2-NIm)mai, 47.3 (1C,
10.51 (s, 1H, NCHNIm
(s, 1H)mii, 8.46 (s, 1H, N=CH)mai, 8.31 (s, 1H, (CH=CH)Im)mai, 8.27 (s, 1H,
N=CH)mai, 7.99 (s, 1H, (CH=CH)Im mai, 7.98 (s, 1H, (CH=CH)Im mai, 7.92 (s,
1H)mii, 7.82 (s, 1H)mii, 7.74 (d, J = 2.1, 1H, CAr-H)mai, 7.71 (d, J = 2.3, 1H,
CAr-H)mai, 7.66 (s, 1H)mii, 7.63 (s, 1H)mii, 7.47 (s, 1H, (CH=CH)Im mai, 7.40
(s, 1H)mii, 7.36 (d, J = 2.1, 2H, CAr-H)mai, 6.96 (s, 1H)mii, 6.92 (s, 2H, CMes
)mii, 10.05 (s, 1H, NCHNIm)mai, 9.02 (s, 1H)mii, 8.55
)mii, 34.5 (1C, C(CH3)3)mai, 34.35 (1C, C(CH3)3)mii, 34.33 (1C,
C(CH3)3)mai, 34.28 (1C, C(CH3)3)mii, 31.5 (3C, C(CH3)3)mii, 31.47 (3C,
C(CH3)3)mai, 31.4 (3C, C(CH3)3)mai, 31.3 (3C, C(CH3)3)mii, 30.2 (1C,
(CH2)Cy
(CH2)Cy
(CH2)Cy
)
)
)
)
)
,
29.7 (1C, (CH2)Cy mai
mai, 24.5 (1C, (CH2)Cy mii, 24.46 (1C, (CH2)Cy mai
mii, 24.0 (1C, (CH2)Cy mii
)
)
,
29.0 (1C, (CH2)Cy mii
)
,
28.9 (1C,
)
mai
)
, 24.3 (1C,
-
)
. IR (solid): 3380, 3140, 3054, 2923, 2853,
H)mai, 6.89 (s, 1H)mii, 6.86 (s, 1H)mii, 6.83 (s, 1H, CMes-H)mai, 6.68 (s, 1H,
CMes-H)mai, 6.66 (s, 1H, (CH=CH)Im)mai, 6.34 (d, J = 13.8, 1H, CAr-CH2-
1623, 1547, 1461, 1279, 1228, 1029, 760, 689, 528. HRMS (ESI) m/z:
calculated for (C48H54BrN6O3Ti)+: 889.2922, found: 889.2907.
NIm
CH2-NIm
CAr-CH2-NIm
CCyHN)mai, 3.75 (m, 1H, CCyHN)mii, 2.89 (m, 1H, CCyHN)mii, 2.76 (m, 1H,
)
mii, 5.97 (d, J = 14.5, 1H, CAr-CH2-NIm mai
mai, 5.67 (d, J = 14.3, 1H, CAr-CH2-NIm
mai, 5.53 (d, J = 13.8, 1H, CAr-CH2-NIm)mii, 3.81 (m, 1H,
)
, 5.77 (d, J = 14.0, 1H, CAr-
)
)mai, 5.62 (d, J = 14.0, 1H,
)
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl-
titanium(IV))tetrabromide (5e): Salen ligand 4e (9.9 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 5e was formed as a mixture of two
CCyHN)mai, 2.26 (s, 3H, (CH3)Mes mai
(CH2)Cy mai, 2.09 (m, 2H, (CH2)Cy mai
(CH3)Mes mai, 1.79 (s, 3H, (CH3)Mes mai
1H, (CH2)Cy mai, 1.47 (m, 2H, (CH2)Cy mai
9H, (CH3)3)mii, 1.18 (m, 1H, (CH2)Cy mai
9H, (CH3)3)mii, 0.67 (m, 1H, (CH2)Cy mai.
13C-NMR (125 MHz, CD2Cl2,
)
, 2.21 (s, 3H, (CH3)Mes mai
)
, 2.17 (m, 1H,
)
)
, 1.94 (s, 3H, (CH3)Mes)mai, 1.91 (s, 3H,
)
)
, 1.70 (s, 3H, (CH3)Mes)mai, 1.68 (m,
)
)
, 1.28 (s, 9H, (CH3)3)mai, 1.24 (s,
, 1.09 (s, 9H, (CH3)3)mai, 0.83 (s,
isomers
(10.0:1,
quantitative
conversion,
yellow
solid).
C108H132Br4N12O6Ti2. MW: 2109.67 g mol–1. M.p.: decomp. > 200 °C.
)
[α]20D (c = 0.1 g·dL-1, CH2Cl2) = 26. 1H-NMR (500 MHz, CD2Cl2, 21 °C,
)
21 °C, only signals of the major isomer): δ = 163.9 (1C, N=CH), 161.3
(1C, N=CH), 159.0 (1C, CAr-OTi), 158.1 (1C, CAr-OTi), 143.0 (1C, Cq),
141.4 (2C, Cq), 141.35 (1C, Cq), 138.9 (1C, Cq), 138. 8 (1C, NCHN),
138.79 (1C, Cq), 138.2 (1C, NCHN), 134.8 (1C, CAr-H), 134.6 (1C, Cq),
134.5 (2C, Cq), 132.2 (1C, CAr-H), 131.5 (1C, Cq), 131.4 (1C, CAr-H),
131.2 (1C, CAr-H), 130.1 (4C, CMes-H), 130.0 (1C, Cq), 125.7 (1C,
(CH=CH)Im), 124.0 (1C, (CH=CH)Im), 123.4 (1C, Cq), 123.1 (1C,
(CH=CH)Im), 123.0 (1C, (CH=CH)Im), 122.9 (1C, Cq), 122.8 (1C,
(CH=CH)Im), 122.3 (1C, Cq), 70.9 (1C, CCyHN), 68.4 (1C, CCyHN), 50.0
(1C, CAr-CH2-NIm), 48.1 (1C, CAr-CH2-NIm), 34.6 (1C, C(CH3)3), 34.5 (1C,
C(CH3)3), 31.5 (3C, C(CH3)3), 31.4 (3C, C(CH3)3), 28.8 (1C, (CH2)Cy),
25.2 (1C, (CH2)Cy), 24.9 (1C, (CH2)Cy), 21.3 (1C, (CH3)Mes), 21.2 (1C,
(CH3)Mes), 18.1 (1C, (CH3)Mes), 17.8 (1C, (CH3)Mes), 17.6 (1C, (CH3)Mes),
17.5 (1C, (CH3)Mes). IR (solid): 3450 (b), 3029, 2960, 2922, 2852, 1622,
1544, 1442, 1306, 1014, 833, 731, 671, 598, 529. HRMS (ESI) m/z:
calculated for (C54H66ClN6O3Ti)+: 929.4365, found: 929.4356.
mai = major isomer, mii = minor isomer): δ = 10.96 (s, 1H, NCHN)mii
10.37 (s, 1H, NCHN)mai, 10.20 (s, 1H, NCHN)mii, 9.81 (s, 1H, NCHN)mai
,
,
8.64 (s, 1H, N=CH)mai, 9.14 (s, 1H)mii, 8.64 (s, 1H, N=CH)mai, 8.60 (s,
1H)mii, 8.43 (b, 1H)mii, 8.41 (s, 1H, (CH=CH)Im mai, 8.35 (s, 1H, N=CH)mai
8.07 (s, 1H, (CH=CH)Im mai, 7.93 (d, J = 2.0, 1H, CAr-H)mai, 7.91 (s, 1H,
(CH=CH)Im mai, 7.89 (b, 1H)mii, 7.81 (b, 1H)mii, 7.78 (d, J = 2.0, 2H, CAr-
H)mai, 7.74 (b, 1H)mii, 7.56 (d, J = 1.6, 1H, CAr-H)mai, 7.48 (b, 1H)mii, 7.45
(d, J = 2.0, 1H, CAr-H)mai, 6.99 (s, 2H, CMes-H)mai, 6.91 (s, 1H, CMes-H)mai
6.77 (s, 1H, (CH=CH)Im)mai, 6.74 (s, 1H, CMes-H)mai, 6.39 (d, J = 14.4, 1H,
CAr-CH2-NIm mii, 6.07 (d, J = 15.0, 1H, CAr-CH2-NIm mai, 5.78 (d, J = 14.1,
1H, CAr-CH2-NIm)mai, 5.74 (d, J = 14.6, 1H, CAr-CH2-NIm)mai, 5.70 (d, J =
14.1, 1H, CAr-CH2-NIm mai, 5.62 (d, J = 14.6, 1H, CAr-CH2-NIm mii, 5.38 (d,
J = 14.6, 1H, CAr-CH2-NIm mii, 3.86 (m, 1H, CCyHN)mai, 3.80 (m, 1H,
CCyHN)mii, 2.95 (m, 1H, CCyHN)mii, 2.82 (m, 1H, CCyHN)mai, 2.33 (s, 3H,
(CH3)Mes mai, 2.28 (s, 3H, (CH3)Mes mai, 2.23 (m, 1H, (CH2)Cy mai, 2.13 (m,
2H, (CH2)Cy mai, 2.22 (s, 3H, (CH3)Mes mai, 1.98 (s, 3H, (CH3)Mes mai, 1.87 (s,
3H, (CH3)Mes mai, 1.79 (s, 3H, (CH3)Mes mai, 1.72 (m, 1H, (CH2)Cy mai, 1.52
(m, 2H, (CH2)Cy mai, 1.34 (s, 9H, (CH3)3)mai, 1.31 (s, 9H, (CH3)3)mii, 1.25 (s,
9H, (CH3)3)mii, 1.17 (s, 9H, (CH3)3)mai, 0.88 (m, 1H, (CH2)Cy mai, 0.77 (m,
1H, (CH2)Cy mai
13C-NMR (125 MHz, CD2Cl2, 21 °C, only signals of the
)
,
)
)
,
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-(2,6-
diethylphenyl)-1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}cyclohexyl-titanium(IV))tetrabromide (5l): Salen ligand 4l (10.2 mg,
)
)
.
major isomer): δ = 163.9 (1C, N=CH), 161.4 (1C, N=CH), 159.2 (1C, CAr-
OTi), 158.1 (1C, CAr-OTi), 143.0 (1C, Cq), 141.6 (1C, Cq), 141.5 (1C, Cq),
141.4 (1C, Cq), 138.18 (1C, NCHN), 138.16 (1C, Cq), 138.1 (1C, Cq),
137.6 (1C, NCHN), 134.60 (1C, CAr-H), 134.56 (1C, Cq), 134.4 (2C, Cq),
132.4 (1C, CAr-H), 131.64 (1C, CAr-H), 131.57 (1C, CAr-H), 131.2 (1C, Cq),
131.1 (1C, Cq), 130.13 (2C, CMes-H), 130.05 (1C, Cq), 126.1 (1C,
(CH=CH)Im), 124.3 (1C, (CH=CH)Im), 123.4 (1C, Cq), 123.2 (1C,
(CH=CH)Im), 123.1 (1C, (CH=CH)Im), 122.8 (1C, Cq), 122.4 (2C, CMes-H),
70.9 (1C, CCyHN), 68.6 (1C, CCyHN), 50.2 (1C, CAr-CH2-NIm), 48.1 (1C,
CAr-CH2-NIm), 34.6 (1C, C(CH3)3), 34.5 (1C, C(CH3)3), 31.6 (1C, (CH2)Cy),
31.58 (3C, C(CH3)3), 31.4 (3C, C(CH3)3), 28.8 (1C, (CH2)Cy), 25.3 (1C,
(CH2)Cy), 24.8 (1C, (CH2)Cy), 21.34 (1C, (CH3)Mes), 21.25 (1C, (CH3)Mes),
18.2 (1C, (CH3)Mes), 17.9 (1C, (CH3)Mes), 17.8 (1C, (CH3)Mes), 17.6 (1C,
(CH3)Mes). IR (solid): 3400 (b), 1350, 1923, 1621, 1441, 1194, 1031, 834,
670, 652, 577. HRMS (ESI) m/z: calculated for (C54H66BrN6O3Ti)+:
973.3862, found: 973.3878.
0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5l was
formed in almost isomerically pure form (>50:1, quantitative conversion,
yellow solid). C112H140Br4N12O6Ti2, MW: 2165.78 g mol–1. M.p.: decomp.
T > 180°C. [α]20 (c = 0.1 g·dL-1, CH2Cl2) = –21. 1H-NMR (500 MHz,
D
CD2Cl2, 21 °C): δ = 10.55 (s, 1H, NCHN), 9.76 (s, 1H, NCHN), 8.67 (s,
1H, N=CH), 8.46 (s, 1H, (CH=CH)Im), 8.36 (s, 1H, N=CH), 8.01 (s, 1H,
(CH=CH)Im), 7.98 (s, 1H, (CH=CH)Im), 7.96 (d, J = 2.6, 1H, CAr-H), 7.77
(d, J = 2.4, 2H, CAr-H), 7.54 (d, J = 2.2, 1H, CAr-H), 7.47 (t, J = 7.7, 1H,
CPh-H), 7.46 (d, J = 2.2, 1H, CAr-H), 7.40 (t, J = 7.7, 1H, CPh-H), 7.26 (d, J
= 7.3, 1H, CPh-H), 7.24 (d, J = 7.3, 1H, CPh-H), 7.17 (d, J = 7.6, 1H, CPh
-
H), 7.01 (d, J = 7.4, 1H, CPh-H), 6.94 (s, 1H, (CH=CH)Im), 6.18 (d, J =
14.7, 1H, CAr-CH2-NIm), 5.94 (d, J = 14.1, 1H, CAr-CH2-NIm), 5.86 (d, J =
14.9, 1H, CAr-CH2-NIm), 5.74 (d, J = 13.8, 1H, CAr-CH2-NIm), 3.86 (m, 1H,
CCyHN), 2.80 (m, 1H, CCyHN), 2.32 – 2.09 (m, 8H, (CH2)Et), 1.87 (m, 2H,
(CH2)Cy), 1.72 (m, 2H, (CH2)Cy), 1.45 (m, 2H, (CH2)Cy), 1.34 (s, 9H,
(CH3)3), 1.21 (s, 9H, (CH3)3), 1.08 (m, 6H, (CH3)Et), 0.89 (m, 6H, (CH3)Et),
0.69 (m, 2H, (CH2)Cy). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 162.6 (1C,
N=CH), 160.1 (1C, N=CH), 158.0 (1C, CAr-OTi), 156.8 (1C, CAr-OTi),
141.7 (1C, Cq), 140.2 (1C, Cq), 139.8 (1C, Cq), 139.7 (1C, Cq), 139.5 (1C,
Cq), 137.3 (1C, NCHN), 137.2 (1C, NCHN), 136.9 (1C, Cq), 133.0 (1C,
CAr-H), 131.3 (1C, (CH=CH)Im), 131.2 (2C), 130.5 (1C,) 130.3 (1C), 129.7
(1C, CPh-H), 126.6 (1C), 126.5 (1C), 126.4 (1C), 126.3 (1C), 125.8 (1C),
125.3 (1C, (CH=CH)Im), 123.2 (1C), 122.7 (1C), 122.4 (1C), 122.0 (1C,
Cq), 121.9 (1C, Cq), 121.4 (1C, Cq), 121.2 (1C, Cq), 69.8 (1C, CCyHN),
67.3 (1C, CCyHN), 49.0 (1C, CAr-CH2-NIm), 46.7 (1C, CAr-CH2-NIm), 33.5
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl-
titanium(IV))tetrachloride (5j): Salen ligand 4j (9.0 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 5j was formed as a mixture of two
isomers (6.5:1, quantitative conversion, yellow solid). C108H132Cl4N12O6Ti2.
MW: 1931.86 g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c = 1.0 g·dL-1,
CH2Cl2) = 31. 1H-NMR (500 MHz, CD2Cl2, 21 °C, mai = major isomer, mii
= minor isomer): δ = 11.32 (s, 1H, NCHNIm
)mii, 10.57 (s, 1H, NCHNIm
)
mai
,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
(1C, C(CH3)3), 33.4 (1C, C(CH3)3), 30.44 (3C, C(CH3)3), 30.4 (1C,
(CH2)Cy), 30.3 (3C, C(CH3)3), 28.9 (1C, (CH2)Cy), 27.7 (1C, (CH2)Cy), 24.4
(1C, (CH2)Cy), 23.4 (1C, (CH2)Et), 23.31 (1C, (CH2)Et), 23.3 (1C, (CH2)Et),
23.2 (1C, (CH2)Et), 14.6 (1C, (CH2)Cy), 14.0 (1C, (CH3)Et), 13.8 (1C,
(CH3)Et), 13.7 (2C, (CH3)Et). IR (solid): 3480, 2966, 2926, 2855, 1623,
1558, 1460, 1305, 1180, 1026, 803, 669, 545. HRMS (ESI): calculated
for (C56H70N6O3Ti)2+: 461.2492, found: 461.2483.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-methyl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}cyclohexyl-titanium(IV))tetrabromide (5o): Salen ligand 4o (8.8 mg,
0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0
M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5o
was formed in almost isomerically pure form (>50:1, quantitative
conversion, yellow solid). C92H108Br4N12O6Ti2, MW: 1893.30 g mol–1,
M.p.: decomp. > 200 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) = 5. 1H-NMR (500
MHz, CD2Cl2, 21 °C): δ = 11.08 (s, 1H, NCHN), 10.07 (s, 1H, NCHN),
8.78 (s, 1H, N=CH), 8.47 (s, 1H, N=CH), 8.00 (d, J = 2.1, 1H, CAr-H),
7.92 (d, J = 1.9, 1H, CAr-H), 7.72 (d, J = 8.4, 1H, CBI-H), 7.62 (d, J = 8.5,
2H, CBI-H), 7.52 (d, J = 8.5, 1H, CBI-H), 7.42 (t, J = 7.7, 2H, CBI-H), 7.37
(s, 1H, CAr-H), 7.14 (s, 1H, CAr-H), 7.12 (t, J = 7.7, 1H, CBI-H), 6.92 (t, J =
7.7, 1H, CBI-H), 6.87 (t, J = 7.6, 1H, CBI-H), 6.60 (d, J = 8.3, 1H, CBI-H),
6.18 (d, J = 15.9, 1H, CAr-CH2-NBI), 5.39 (d, J = 13.6, 1H, CAr-CH2-NBI),
5.32 (d, J = 13.7, 1H, CAr-CH2-NBI), 5.01 (d, J = 15.6, 1H, CAr-CH2-NBI),
4.11 (s, 3H, (CH3)BI), 3.90 (m, 1H, CCyHN), 3.63 (s, 3H, (CH3)BI), 2.91 (m,
1H, CCyHN), 2.44 (m, 1H, (CH2)Cy), 2.36 (m, 1H, (CH2)Cy), 1.98 (m, 1H,
(CH2)Cy), 1.73 (m, 1H, (CH2)Cy), 1.64 (m, 1H, (CH2)Cy), 1.32 (s, 9H,
(CH3)3), 1.00 (s, 9H, (CH3)3), 0.98 (m, 2H, (CH2)Cy). 13C-NMR (125 MHz,
CD2Cl2, 21 °C): δ = 164.8 (1C, N=CH), 161.9 (1C, N=CH), 159.8 (1C,
CAr-OTi), 157.4 (1C, CAr-OTi), 145.4 (1C, NCHN), 143.4 (1C, Cq), 143.2
(1C, NCHN), 141.8 (1C, Cq), 136.5 (1C, CAr-H), 132.9 (1C, CAr-H), 132.3
(1C, CAr-H), 132.1 (1C, CAr-H), 132.0 (1C, Cq), 131.8 (1C, Cq), 131.1 (1C,
Cq), 130.4 (1C, Cq), 127.2 (1C, CBI-H), 127.1 (1C, CBI-H), 126.9 (1C, CBI-
H), 126.4 (1C, CBI-H), 123.4 (1C, Cq), 121.9 (1C, Cq), 120.6 (1C, Cq),
120.4 (1C, Cq), 113.8 (1C, CBI-H), 113.5 (1C, CBI-H), 113.3 (1C, CBI-H),
113.1 (1C, CBI-H), 71.1 (1C, CCyHN), 69.1 (1C, CCyHN), 48.3 (1C, CAr-
CH2-NIm), 45.9 (1C, CAr-CH2-NIm), 34.7 (1C, C(CH3)3), 34.5 (1C, C(CH3)3),
34.2 (1C, (CH3)BI), 33.9 (1C, (CH3)BI), 32.1 (1C, (CH2)Cy), 31.6 (3C,
C(CH3)3), 31.3 (3C, C(CH3)3), 29.2 (1C, (CH2)Cy), 25.3 (1C, (CH2)Cy), 24.8
(1C, (CH2)Cy). IR (solid): 3480, 3139, 3022, 2950, 2860, 1621, 1564,
1442, 1226, 1131, 835, 745, 589. HRMS (ESI) m/z: calculated for
(C46H54BrN6O3Ti)+: 865.2923, found: 865.2922.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-(2,6-di-
iso-propylphenyl)-1H-imidazol-3-ium)-1-ylmethyl)-
phenyl]methyl]imino-κN}cyclohexyl-titanium(IV))tetrabromide (5m):
Salen ligand 4m (10.8 mg, 0.01 mmol, 1.0 equiv.) was treated with
Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.)
according to GP3. 5m was formed in almost isomerically pure form
(>50:1, quantitative conversion, yellow solid). C120H156Br4N12O6Ti2, MW:
2278.00 g mol–1. M.p.: decomp. T > 180°C. [α]20 (c = 0.1 g·dL-1,
D
CH2Cl2) = –60. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ = 10.70 (s, 1H,
NCHN), 10.10 (s, 1H, NCHN), 8.65 (s, 1H, N=CH), 8.43 (s, 1H, N=CH),
8.08 (s, 2H, (CH=CH)Im), 7.95 (d, J = 2.4, 1H, CAr-H), 7.87 (s, 1H,
(CH=CH)Im), 7.73 (d, J = 2.4, 1H, CAr-H), 7.05 (s, 1H, (CH=CH)Im), 7.58
(b, 1H, CAr-H), 7.53 (t, J = 7.7, 1H, CPh-H), 7.49 (t, J = 7.7, 1H, CPh-H),
7.46 (d, J = 2.3, 2H, CAr-H), 7.32 – 7.22 (m, 4H, CPh-H), 6.01 (d, J = 14.7,
1H, CAr-CH2-NIm), 6.00 (d, J = 14.0, 1H, CAr-CH2-NIm), 5.91 (d, J = 14.7,
1H, CAr-CH2-NIm), 5.78 (d, J = 14.1, 1H, CAr-CH2-NIm), 3.88 (m, 1H,
CCyHN), 2.83 (m, 1H, CCyHN), 2.37 – 2.11 (m, 6H, CH(CH3)2 and
(CH2)Cy), 1.82 (m, 2H, (CH2)Cy), 1.48 (m, 2H, (CH2)Cy), 1.36 (s, 9H,
(CH3)3), 1.23 (s, 9H, (CH3)3), 1.17 – 0.99 (m, 24H, CH(CH3)2), 0.72 (m,
2H, (CH2)Cy). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 162.3 (1C, N=CH),
160.0 (1C, N=CH), 157.8 (1C, CAr-OTi), 156.9 (1C, CAr-OTi), 144.7 (1C,
Cq), 144.6 (1C, Cq), 144.5 (1C, Cq), 144.4 (1C, Cq), 141.6 (1C, Cq), 140.0
(1C, Cq), 137.6 (1C, NCHN), 137.5 (1C, NCHN), 132.4 (1C, CAr-H), 131.0
(1C, CAr-H), 130.9 (2C, CPh-H), 130.1 (1C, CAr-H), 125.4 (1C), 123.9 (1C),
123.85 (1C), 123.8 (1C), 123.7 (1C), 123.3 (1C), 123.1 (1C), 122.9 (1C),
122.5 (1C), 122.2 (1C, Cq), 122.0 (1C, Cq), 121.6 (1C, Cq), 121.2 (1C, Cq),
69.8 (1C, CCyHN), 66.8 (1C, CCyHN), 48.5 (1C, CAr-CH2-NIm), 46.8 (1C,
CAr-CH2-NIm), 33.43 (1C, C(CH3)3), 33.4 (1C, C(CH3)3), 30.5 (3C,
C(CH3)3), 30.4 (1C, (CH2)Cy), 30.3 (3C, C(CH3)3), 28.0 (1C, (CH(CH3)2),
27.9 (1C, (CH(CH3)2), 27.7 (1C, (CH(CH3)2), 27.4(1C, (CH(CH3)2), 27.8
(1C, (CH2)Cy), 24.4 (1C, (CH(CH3)2), 23.9 (1C, (CH2)Cy), 23.8 (1C,
(CH2)Cy), 23.6 (1C, (CH(CH3)2), 23.5 (1C, (CH(CH3)2), 23.4 (1C,
(CH(CH3)2), 23.3 (1C, (CH(CH3)2), 23.2 (1C, (CH(CH3)2), 23.1 (1C,
(CH(CH3)2), 22.9 (1C, (CH(CH3)2). IR (solid): 3480, 2964, 2927, 2868,
1622, 1557, 1458, 1314, 1255, 1099, 804, 731, 529. HRMS (ESI):
calculated for (C60H78N6O3Ti)2+: 489.2805, found: 489.2799.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-phenyl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}cyclohexyl-titanium(IV))tetrabromide (5q): Salen ligand 4q (10.1
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5q
was formed as a mixture of two isomers (15.0:1, quantitative conversion,
yellow solid). C112H116Br4N12O6Ti2. MW: 2141.59 g mol–1. M.p.: decomp.
> 180 °C. [α]20 (c = 1.0 g·dL-1, CH2Cl2) = –216. 1H-NMR (300 MHz,
D
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.38 (s, 1H,
NCHN)mii, 11.12 (s, 1H, NCHN)mii, 11.03 (s, 1H, NCHN)mai, 10.89 (s, 1H,
NCHN)mai, 8.84 (s, 1H)mii, 8.61 (s, 1H, N=CH)mai, 8.41 (s, 1H)mii, 8.29 (s,
1H, N=CH)mai, 8.06 (m, 1H)mai, 8.05 (d, J = 2.2, 1H, CAr-H)mai, 8.00 (d, J =
2.1, 1H, CAr-H)mai, 7.96 (d, J = 8.4, 1H, CBI-H)mai, 7.79 (d, J = 8.6, 1H, CBI-
H)mai, 7.61 (m, 4H, CPh-H or CBI-H)mai, 7.47 (m, 3H)mai, 7.46 (d, J = 2.1,
1H, CAr-H)mai, 7.42 (d, J = 8.7, 1H, CBI-H)mai, 7.35 (d, J = 2.1, 1H, CAr-
H)mai, 7.32 (d, J = 8.7, 1H, CBI-H)mai, 7.26 (m, 4H)mai, 7.16 (t, J = 7.7, 1H,
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-(4-
trifluoromethylphenyl)-1H-imidazol-3-ium)-1-ylmethyl)-
phenyl]methyl]imino-κN}cyclohexyl-titanium(IV))tetrabromide (5n):
Salen ligand 4n (10.4 mg, 0.01 mmol, 1.0 equiv.) was treated with
Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.)
according to GP3. 5n was formed as a mixture of two isomers (1.6:1,
quantitative conversion, yellow solid). C100H104Br4F12N12O6Ti2, MW:
2213,34 g/mol. Smp: decomp. >200 °C. [훼]2퐷0 (c = 0.71 mg/mL, DCM)=
+76,2. 1H-NMR (500 MHz, CD2Cl2, 21 °C) δ =11.71 (d, J = 8.5, 1H),
11.40 (s, 5H), 10.88 (s, 2H), 10.58 (d, J = 8.5, 3H), 9.52 (s, 3H), 9.29 (s,
1H), 9.06 (s, 3H), 8.85 (s, 3H), 8.49 (m, 7H), 8.43 (m, 5H), 7.17 - 8.22 (m,
12H), 6.47 (d, J = 12.9, 2H), 5.99 (d, J = 14.2, 3H), 5.78 (m, 3H), 5.61 (d,
J = 13.9, 7H), 5.39 (s, 2H), 3.97 (q, J = 6.3 Hz, 5H, O-iPr), 3.80 (t, J =
11.0, 2H), 3.67 (t, J = 10.8, 3H), 3.49 (m, 1H), 2.50 (m, 8H), 1.97 - 2.11
(m, 9H), 1.17 (s, 18H, (CH3)3), 1.15 (s, 18H, (CH3)3). 13C-NMR (125 MHz,
CD2Cl2, 21 °C): A spectrum of sufficient quality was not available due to
rapid crystallization. IR: 3383, 2964, 2861, 1619, 1547, 1324, 1169, 1118,
1062. HRMS (ESI): A spectrum of sufficient quality was not available.
CBI-H)mai, 6.94 (b, 1H)mii, 6.75 (b, 1H)mii, 6.49 (t, J = 7.7, 1H, CBI-H)mai
,
6.19 (d, J = 13.6, 1H, CAr-CH2-NBI)mai, 5.88 (d, J = 13.8, 1H, CAr-CH2-
NBI)mii, 5.76 (d, J = 14.5, 1H, CAr-CH2-NBI)mai, 5.56 (d, J = 13.6, 1H, CAr-
CH2-NBI)mai, 5.49 (d, J = 14.1, 1H, CAr-CH2-NBI)mii, 5.37 (d, J = 14.1, 1H,
CAr-CH2-NBI)mii, 4.88 (d, J = 13.6, 1H, CAr-CH2-NBI)mai, 4.51 (d, J = 14.0,
1H, CAr-CH2-NBI)mai, 3.83 (m, 1H, CCyHN)mai, 3.69 (m, 1H, CCyHN)mii, 2.81
(m, 1H, CCyHN)mai, 2.62 (m, 1H, CCyHN)mai, 2.13 (m, 2H, (CH2)Cy mai
(m, 1H, (CH2)Cy mai, 1.63 (m, 1H, (CH2)Cy mai, 1.32 (s, 9H, (CH3)3)mai, 1.26
(m, 1H, (CH2)Cy mai, 1.17 (s, 9H, (CH3)3)mai, 0.80 (m, 2H, (CH2)Cy mai, 0.56
(m, 1H, (CH2)Cy mai
13C-NMR (125 MHz, CD2Cl2, 21 °C, only signals of
)
, 1.72
)
)
)
)
)
.
the major isomer): δ = 162.5 (1C, N=CH), 159.7 (1C, N=CH), 158.3 (1C,
CAr-O), 157.8 (1C, CAr-O), 142.2 (1C, Cq), 141.9 (1C, NCHN), 141.4 (1C,
NCHN), 140.4 (1C, Cq), 134.0 (1C, CAr-H), 132.8 (1C, CBI-H), 132.40 (1C,
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
Cq), 132.3 (1C, CAr-H), 131.8 (1C, CAr-H), 130.91 (1C, CAr-H), 130.88 (1C,
CBI-H), 130.3 (1C, Cq), 130.0 (1C, Cq), 129.9 (2 C, CPh-H), 129.7 (1C,
CAr-H), 129.6 (2 C, CPh-H), 129.5 (1C, Cq), 127.6 (1C, CPh-H), 127.4 (1C,
CPh-H), 126.2 (1C, CBI-H), 125.7 (1C, CBI-H), 124.0 (2C, CPh-H), 123.5
(2C, CPh-H), 123.2 (1C, Cq), 121.9 (1C, Cq), 121.3 (1C, Cq), 120.9 (1C,
Cq), 120.3 (1C, Cq), 113.8 (1C, CBI-H), 113.3 (1C, CBI-H), 112.9 (1C, CBI-
H), 112.1 (1C, CBI-H), 70.0 (1C, CCyHN), 67.3 (1C, CCyHN), 45.9 (1C, CAr-
CH2-NBI), 45.7 (1C, CAr-CH2-NBI), 43.2 (1C, Cq), 33.6 (1C, C(CH3)3), 33.5
(1C, C(CH3)3), 30.6 (3C, (CH3)3), 30.44 (1C, (CH2)Cy), 30.38 (3C, (CH3)3),
27.6 (1C, (CH2)Cy), 23.8 (1C, (CH2)Cy), 23.7 (1C, (CH2)Cy). IR (solid):
3450, 2949, 2860, 1621, 1552, 1456, 1199, 1027, 748, 693, 587, 528.
HRMS (ESI) m/z: calculated for (C56H58BrN6O3Ti)+: 989.3236, found:
989.3240.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
4,5-diphenyl-4,5-dihydro-1H-imidazol-3-ium)-1-ylmethyl)-
phenyl]methyl]imino-κN}cyclohexyl-titanium(IV))tetrabromide (5u):
Salen ligand 4u (13.0 mg, 0.01 mmol, 1.0 equiv.) was treated with
Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.)
according to GP3. 5u was formed in almost isomerically pure form (>50:1,
quantitative conversion, yellow solid). C156H172Br4N12O6Ti2. MW: 1465.44
g mol–1. M.p.: decomp. T > 200 °C. [α]20D (c = 0.1 g·dL-1, CH2Cl2) = –179.
1H-NMR (500 MHz, CD2Cl2, 21 °C): δ = 10.72 (s, 1H, NCHNIm), 9.71 (s,
1H, NCHNIm), 9.02 (d, J = 1.5, 1H, N=CH), 8.69 (d, J = 1.3, 1H, N=CH),
7.80 (d, J = 2.5, 1H, CAr-H), 7.75 (d, J = 2.5, 1H, CAr-H), 7.55 – 7.00 (m,
21H, CPh-H and CAr-H), 6.67 (d, J = 2.5, 1H, CAr-H), 6.69 (s, 1H, CMes-H),
6.83 (s, 1H, CAr-H), 6.52 (s, 1H, CAr-H), 5.99 (d, J = 14.3, 1H, CAr-CH2-
NIm), 5.88 (s, 1H, CAr-H), 5.38 (d, J = 14.3, 1H, CAr-CH2-NIm), 5.21 (d, J =
10.9, 1H, CImHPh), 5.19 (d, J = 9.6, 1H, CImHPh), 5.14 (d, J = 7.3, 1H,
CImHPh), 5.11 (d, J = 6.4, 1H, CImHPh), 4.62 (m, 1H, CCyHN), 3.90 (d, J =
14.3, 1H, CAr-CH2-NIm), 3.95 (sept., J = 6.1, 1H, Ti-O-CH(CH3)2), 3.65 (m,
1H, CCyHN), 3.42 (d, J = 14.3, 1H, CAr-CH2-NIm), 2.99 (m, 1H, (CH2)Cy),
2.68 (m, 1H, (CH2)Cy), 2.64 (s, 3H, (CH3)Mes), 2.49 (s, 3H, (CH3)Mes), 2.20
(m, 2H, (CH2)Cy), 2.11 (s, 3H, (CH3)Mes), 1.87 (s, 3H, (CH3)Mes), 1.70 (s,
3H, (CH3)Mes), 1.65 (m, 4H, (CH2)Cy), 1.32 (s, 9H, (CH3)3), 1.25 (s, 9H,
(CH3)3), 1.14 (d, J = 6.2, 6H, Ti-O-CH(CH3)2), 0.82 (s, 3H, (CH3)Mes). 13C-
NMR (125 MHz, CD2Cl2, 21 °C): δ = 163.1 (1C, N=CH), 161.9 (1C,
N=CH), 161.2 (1C, CAr-OTi), 160.0 (1C, CAr-OTi), 141.6 (1C, Cq), 140.9
(1C, Cq), 140.2 (1C, Cq), 139.9 (1C, Cq), 137.0 (2C, NCHN), 136.6 (1C,
Cq), 136.5 (2C, Cq), 135.6 (1C, CAr-H), 135.5 (1C, Cq), 135.4 (1C, Cq),
135.1 (1C, CAr-H), 134.8 (1C, Cq), 134.2 (1C, CAr-H), 133.7 (1C, Cq),
133.1 (1C, CAr-H), 132.8 (1C, Cq), 130.6 (1C), 130.5 (1C), 130.4 (2C),
130.3 (2C), 130.2 (2C), 130.2 (1C), 130.1 (1C), 129.7 (1C), 129.5 (1C),
129.43 (1C), 129.4 (1C), 129.3 (1C), 129.0 (2C), 128.4 (2C), 127.9 (2C),
123.1 (1C, (CH=CH)Im), 123.1 (1C, Cq), 122.5 (1C, Cq), 121.7 (1C, Cq),
121.0 (1C, Cq), 71.9 (1C, CCyHN), 75.9 (1C, CImHPh), 75.6 (1C, CImHPh),
70.7 (1C, CImHPh), 69.6 (1C, CImHPh), 68.7 (1C, CCyHN), 64.5 (1C, Ti-O-
CH(CH3)2), 47.5 (1C, CAr-CH2-NIm), 46.3 (1C, CAr-CH2-NIm), 34.4 (1C,
C(CH3)3), 34.2 (1C, C(CH3)3), 31.9 (1C, (CH2)Cy), 31.5 (3C, C(CH3)3),
31.46 (3C, C(CH3)3), 28.7 (1C, (CH2)Cy), 25.6 (1C, Ti-O-CH(CH3)2), 25.0
(1C, (CH2)Cy), 24.7 (1C, (CH2)Cy), 21.1 (1C, (CH3)Mes), 21.0 (1C, (CH3)Mes),
19.7 (1C, (CH3)Mes), 19.5 (1C, (CH3)Mes), 18.6 (1C, (CH3)Mes), 17.6 (1C,
(CH3)Mes). IR (solid): 3342, 2923, 2854, 1620, 1454, 1361, 1251, 1202,
1128, 1029, 850, 755, 732, 698, 627, 538. HRMS (ESI) m/z: calculated
for (C78H86N6O3Ti)2+: 601.3120, found: 610.3118.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}cyclohexyl-titanium(IV))tetrabromide (5s): Salen ligand 4s (10.9
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5s
was formed as a mixture of four isomers (48.7:8.5:1.7:1, quantitative
conversion, yellow solid). C124H140Br4N12O6Ti2, MW: 2309.91 g mol–1,
M.p.: decomp. > 200 °C. [α]20D (c = 1.0 g·dL-1, CH2Cl2) = –31. 1H-NMR
(500 MHz, CD2Cl2, 21 °C, mai = major isomer, mii1 = minor isomer 1,
mii2 = minor isomer 2, mii3 = minor isomer 3): δ = 12.02 (s, 1H,
NCHN)mii2, 11.93 (s, 1H, NCHN)mii3, 11.86 (s, 1H, NCHN)mii2, 11.53 (s, 1H,
NCHN)mai, 11.66 (s, 1H, NCHN)mii1, 11.64 (s, 1H, NCHN)mii1, 10.93 (s, 1H,
NCHN)mai, 9.04 (s, 1H)mii1, 8.76 (s, 1H)mii3, 8.74 (s, 1H)mii2, 8.72 (s, 1H)mii2
,
8.59 (m, 2H)mii2, 8.56 (s, 1H, N=CH)mai, 8.50 (s, 1H, N=CH)mai, 8.48 (s,
1H)mii1, 8.44 (s, 1H)mii1, 8.36 (s, 1H)mii1, 8.24 (d, J = 2.2, 1H, CAr-H)mai
,
8.16 (s, 1H)mii1, 8.09 (d, J = 8.3, 1H, CBI-H)mai, 8.01 (d, J = 8.7, 1H, CBI-
H)mai, 7.95 (s, 1H, CAr-H)mai, 7.79 (d, J = 2.3, 1H, CAr-H)mai, 7.59 (t, J = 7.7,
1H, CBI-H)mai, 7.55 (d, J = 2.3, 1H, CAr-H)mai, 7.49 (t, J = 8.0, 1H, CBI-H)mii1
,
7.39 (t, J = 8.1, 1H, CBI-H)mai, 7.35 (t, J = 7.0, 1H, CBI-H)mai, 7.25 (t, J =
7.6, 1H, CBI-H)mai, 7.19 (d, J = 8.6, 1H, CBI-H)mai, 7.09 (s, 1H, CMes-H)mai
7.02 (d, J = 7.9, 1H, CBI-H)mai, 7.01 (s, 1H, CMes-H)mai, 6.98 (s, 2H, CMes
H)mai, 6.75 (t, J = 7.9, 1H, CBI-H)mai, 6.51 (d, J = 15.5, 1H, CAr-CH2-NBI)mai
,
-
,
6.19 (d, J = 14.6, 1H, CAr-CH2-NBI)mai, 6.02 (d, J = 14.2, 1H, CAr-CH2-
NBI)mai, 5.94 (m, 2H, CAr-CH2-NBI)mii1, 5.47 (d, J = 14.2, 1H, CAr-CH2-
NBI)mai, 4.28 (m, 1H, CCyHN)mii1, 3.97 (m, 1H, CCyHN)mai, 3.00 (m, 1H,
CCyHN)mii1, 2.86 (m, 1H, CCyHN)mai, 2.37 (s, 3H, (CH3)Mes mai
(CH3)Mes mai, 2.22 (m, 1H, (CH2)Cy mai, 1.97 (s, 3H, (CH3)Mes mai
3H, (CH3)Mes mai, 1.78 (m, 1H, (CH2)Cy mai, 1.72 (s, 3H, (CH3)Mes mai
(s, 3H, (CH3)Mes mai, 1.49 (m, 2H, (CH2)Cy mai, 1.36 (s, 9H, (CH3)3)mii1, 1.33
(s, 9H, (CH3)3)mai, 1.16 (s, 9H, (CH3)3)mai, 1.09 (s, 9H, (CH3)3)mii1, 1.03 (m,
2H, (CH2)Cy mai, 0.78 (m, 1H, (CH2)Cy mai
13C-NMR (125 MHz, CD2Cl2,
)
, 2.36 (s, 3H,
, 1.93 (s,
, 1.62
)
)
)
)
)
)
)
)
Synthesis of Salen Complexes with a (1R,2R)-1,2-Diphenylethane
Backbone
)
)
.
21 °C, only signals of major isomer): δ = 163.7 (1C, N=CH), 160.9 (1C,
N=CH), 159.0 (1C, CAr-OTi), 158.5 (1C, CAr-OTi), 143.8 (1C, NCHN),
143.7 (1C, Cq), 143.2 (1C, Cq), 143.1 (1C, NCHN), 142.2 (1C, Cq), 142.1
(1C, Cq), 141.6 (1C, Cq), 135.7 (1C, Cq), 135.49 (1C, Cq), 135.46 (1C, Cq),
135.3 (1C, Cq), 135.1 (1C, CAr-H), 133.0 (1C, Cq), 132.9 (1C, Cq), 131.8
(1C, Cq), 131.6 (1C, Cq), 131.3 (1C, CAr-H), 131.2 (1C, CAr-H), 131.0 (1C,
CAr-H), 130.5 (1C, CMes-H), 130.4 (1C, CMes-H), 130.36 (2C, CMes-H),
129.0 (1C, CBI-H), 128.5 (1C, Cq), 128.3 (1C, Cq), 128.26 (1C, CBI-H),
127.8 (1C, CBI-H), 127.3 (1C, CBI-H), 122.9 (1C, Cq), 122.7 (1C, Cq),
121.5 (1C, Cq), 115.4 (1C, CBI-H), 114.7 (1C, CBI-H), 113.7 (1C, CBI-H),
113.0 (1C, CBI-H), 71.1 (1C, CCyHN), 68.3 (1C, CCyHN), 45.9(1C, CAr-
CH2-NBI), 45.5(1C, CAr-CH2-NBI), 34.7 (1C, C(CH3)3), 34.6 (1C, C(CH3)3),
31.7 (1C, (CH2)Cy), 31.6 (3C, C(CH3)3), 31.4 (3C, C(CH3)3), 29.0 (1C,
(CH2)Cy), 25.6, 25.0 (1C, (CH2)Cy), 24.9 (1C, (CH2)Cy), 21.4 (1C, (CH3)Mes),
21.3 (1C, (CH3)Mes), 17.91 (1C, (CH3)Mes), 17.90 (1C, (CH3)Mes), 17.6 (1C,
(CH3)Mes), 17.4 (1C, (CH3)Mes). IR (solid): 3747, 3450 (b), 2949, 2860,
1364, 2161, 2040, 1621, 1545, 1440, 1279, 1228, 1034, 834, 750, 675,
597. HRMS (ESI) m/z: calculated for (C62H70N6O3Ti)2+: 497.2493, found:
497.2481.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-methyl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}diphenylethyl-titanium(IV))tetrabromide (5b): Salen ligand 4b (8.8
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5b
was formed as a mixture of two isomers (5.0:1,, quantitative conversion,
yellow solid). C92H104Br4N12O6Ti2. MW: 1889.27 g mol–1. M.p.: decomp. >
1
200 °C. [α]20D (c = 0.1 g·dL-1, CH2Cl2) = 210. H-NMR (500 MHz, CD2Cl2,
21 °C): δ = 10.10 (s, 1H, NCHNIm), 9.97 (s, 1H, NCHNIm), 8.48 (s, 1H,
(CH=CH)Im), 8.21 (d, J = 1.5, 1H, N=CH), 8.10 (s, 1H, (CH=CH)Im), 8.08
(d, J = 1.4, 1H, N=CH), 7.92 (d, J = 2.3, 1H, CAr-H), 7.54 (b, 2H,
(CH=CH)Im and CAr-H), 7.42 (d, J = 2.3, 1H, CAr-H), 7.37 (t, J = 7.4, 2H,
CPh-H), 7.32 (m, 3H, CPh-H), 7.29 (d, J = 2.3, 1H, CAr-H), 7.02 (t, J = 7.6,
1H, CPh-H), 6.88 (d, J = 7.3, 2H, CPh-H), 6.77 (t, J = 7.6, 2H, CPh-H), 6.73
(s, 1H, (CH=CH)Im), 5.79 (d, J = 14.5, 1H, CAr-CH2-NIm), 5.56 (d, J = 14.5,
1H, CAr-CH2-NIm), 5.48 (d, J = 14.5, 1H, CAr-CH2-NIm), 5.46 (d, J = 10.5,
1H, CEtHN), 5.44 (d, J = 13.9, 1H, CAr-CH2-NIm), 5.15 (d, J = 10.7, 1H,
CEtHN), 4.04 (s, 3H, NIm-CH3), 3.95 (sept, J = 6.4, Ti-O-CH(CH3)2), 3.51
(s, 3H, NIm-CH3), 1.20 (s, 9H, (CH3)3), 1.14 (d, J = 6.3, 12H, Ti-O-
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
CH(CH3)2), 1.13 (s, 9H, (CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ =
167.0 (1C, N=CH), 161.8 (1C, N=CH), 161.2 (1C, CAr-OH), 157.3 (1C,
CAr-OH), 142.4 (1C, Cq), 140.6 (1C, Cq), 138.4 (1C, Cq), 136.7 (1C,
NCHN), 136.3 (1C, NCHN), 135.0 (1C, CAr-H), 132.7 (1C, CAr-H), 131.7
(2C, CPh-H), 130.7 (1C, CAr-H), 128.9 (1C, CPh-H), 128.7 (2C, CPh-H),
128.1 (2C, CPh-H), 127.7 (2C, CPh-H), 127.6 (1C, CPh-H), 123.8 (1C,
(CH=CH)Im), 122.7 (1C, (CH=CH)Im), 121.8 (1C, Cq), 121.4 (1C, Cq),
121.2 (1C, CHIm), 121.1 (1C, Cq), 120.7 (1C, CHIm), 120.0 (1C, Cq), 74.8
(1C, CEtHN), 74.7 (1C, CEtHN), 63.3 (2C, Ti-O-CH(CH3)2), 49.0 (1C, CAr-
CH2-NIm), 47.1 (1C, CAr-CH2-NIm), 35.9 (1C, (CH3)Im), 35.4 (1C, (CH3)Im),
33.5 (1C, C(CH3)3), 33.3 (1C, C(CH3)3), 30.3 (3C, C(CH3)3), 30.2 (3C,
C(CH3)3), 24.4 (4C, Ti-O-CH(CH3)2). IR (solid): 3400, 3141, 3061, 2953,
1620, 1556, 1454, 1304, 1276, 1159, 985, 851, 701, 542. HRMS (ESI)
m/z: calculated for (C46H52BrN6O3Ti)+:863.2765, found: 863.2757.
κN}diphenylethyl-titanium(IV))tetrabromide (5f): Salen ligand 4f (10.9
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5f was
formed as a mixture of two isomers (3.3:1, quantitative conversion,
yellow solid). C124H136Br4N12O6Ti2. MW: 2305.88 g mol–1. M.p.: decomp.
T > 200 °C. [α]20 (c = 0.5 g·dL-1, CH2Cl2) = 238. 1H-NMR (500 MHz,
D
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.18 (s, 1H,
NCHNIm
1H, NCHNIm
8.40 (s, 1H, (CH=CH)Im)mii, 8.24 (s, 1H, (CH=CH)Im)mii, 8.21 (s, 1H,
N=CH)mii, 8.17 (d, J = 1.4, 1H, N=CH)mii, 8.07 (d, J = 1.5, 1H, N=CH)mai
8.03 (d, J = 2.3, 1H, CAr-H)mai, 7.97 (d, J = 2.0, 1H, N=CH)mai, 7.91 (t, J =
1.5, 1H, (CH=CH)Im mai, 7.78 (t, J = 1.6, 1H, (CH=CH)Im mai, 7.71 (d, J =
1.8, 1H, CAr-H)mai, 7.51 (d, J = 2.2, 1H, CAr-H)mii, 7.39 (d, J = 2.2, 1H, CAr-
H)mai, 7.35 – 7.22 (m, 5H, CPh-H)mai+mii, 7.04 (d, J = 2.0, 1H, CAr-H)mai
)mii, 10.42 (s, 1H, NCHNIm)mii, 10.37 (s, 1H, NCHNIm)mai, 10.33 (s,
)
mai, 8.91 (s, 1H, (CH=CH)Im mai, 8.64 (d, J = 2.2, 1H, CAr-H)mii,
)
,
)
)
,
6.97 – 6-93 (m, 5H, CPh-H)mai+mii, 6.84 (s, 2H, CMes-H)mai, 6.78 (s, 2H,
CMes-H)mai+mii, 6.76 (s, 2H, CMes-H)mai, 6.25 (d, J = 13.7, 1H, CAr-CH2-
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-phenyl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
NIm
(CH=CH)Im
1H, CAr-CH2-NIm)mii, 5.85 (d, J = 14.0, 1H, CAr-CH2-NIm
14.2, 1H, CAr-CH2-NIm)mii, 5.56 (d, J = 14.0, 1H, CAr-CH2-NIm)mai, 5.34 (dd,
J = 11.1, J = 0.8, 1H, CEtHN)mai, 5.08 (m, 1H, CAr-CH2-NIm mii, 5.07 (dd, J
= 11.4, J = 1.3 1H, CEtHN)mai, 4.99 (d, J = 10.7, 1H, CEtHN)mii,3.86 (sep, J
= 5.8, 2H, Ti-O-CH(CH3)2)mai, 2.25 (s, 3H, (CH3)Mes mai, 2.24 (s, 3H,
(CH3)Mes mii, 2.23 (s, 3H, (CH3)Mes mii, 2.22 (s, 3H, (CH3)Mes mai, 2.01 (s, 3H,
(CH3)Mes mai, 1.99 (s, 3H, (CH3)Mes mii, 1.86 (s, 3H, (CH3)Mes mai, 1.84 (s,
3H, (CH3)Mes mii, 1.70 (s, 3H, (CH3)Mes mai, 1.60 (s, 3H, (CH3)Mes mii, 1.59 (s,
3H, (CH3)Mes mii, 1.21 (s, 9H, (CH3)3)mii, 1.11 (s, 9H, (CH3)3)mai, 1.05 (d, J
= 6.2, 12H, Ti-O-CH(CH3)2)mai, 0.87 (s, 9H, (CH3)3)mai, 0.81 (s, 9H,
)
mai, 6.10 (d, J = 13.7, 1H, CAr-CH2-NIm
mai, 6.04 (m, 2H, CAr-CH2-NIm and CEtHN)mii, 5.94 (d, J = 14.2,
mai, 5.63 (d, J =
)mai, 6.09 (t, J = 1.6, 1H,
κN}diphenylethyl-titanium(IV))tetrabromide (5d): Salen ligand 4d
(10.0 mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5d
was formed as a mixture of two isomers (2.0:1, quantitative conversion,
yellow solid). C112H112Br4N12O6Ti2. MW: 2137.56 g mol–1. M.p.: decomp.
)
)
)
T > 200 °C. [α]20 (c = 1.0 g·dL-1, CH2Cl2) = 254. 1H-NMR (500 MHz,
D
)
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.46 (s, 1H,
NCHN)mii, 11.35 (s, 1H, NCHN)mai, 10.98 (s, 1H, NCHN)mii, 10.88 (s, 1H,
)
)
)
)
)
)
NCHN)mai, 8.83 (s, 1H, (CH=CH)Im)mai, 8.66 (s, 2H, (CH=CH)Im)mai+mii
,
)
)
)
8.34 (d, J = 2.3, 1H, CAr-H)mii, 8.32 (d, J = 1.3, 1H, N=CH)mii, 8.30 (d, J =
1.6, 1H, N=CH)mii, 8.13 (d, J = 1.3, 1H, N=CH)mai, 8.11 (d, J = 2.3, 1H,
CAr-H)mai, 8.08 (d, J = 1.7, 1H, N=CH)mai, 7.96 (s, 1H, (CH=CH)Im)mii, 7.91
(d, J = 2.3, 1H, CAr-H)mai, 7.86 (m, 2H)mai+mii, 7.80 (d, J = 2.3, 1H, CAr-H)mii
7.78 (m, 2H)mai, 7.47 - 7.23 (m, 36H)mai+mii, 7.03 (m, 2H)mai+mii, 6.82 (m,
)
(CH3)3)mii
.
13C-NMR (125MHz, CD2Cl2, 21 °C): δ = 167.0 (1C, N=CH)mai
,
,
,
,
163.3 (1C, N=CH)mai, 162.9 (1C, CAr-OTi)mai, 158.8 (1C, CAr-OTi)mai
143.5 (1C, Cq)mai, 141.9 (1C, Cq)mai, 141.7 (1C, Cq)mai, 141.69 (1C, Cq)mai
4H)mai, 6.46 (s, 1H, (CH=CH)Im
= 11.8, 1H, CEtHN)mii, 6.57 (d, J = 14.0, 1H, CAr-CH2-NIm)mai, 6.00 (d, J =
13.2, 1H, CAr-CH2-NIm mai, 5.87 (d, J = 14.0, 1H, CAr-CH2-NIm mii, 5.74 (d,
J = 14.0, 1H, CAr-CH2-NIm)mai, 5.73 (d, J = 14.0, 1H, CAr-CH2-NIm mii, 5.59
(d, J = 14.0, 1H, CAr-CH2-NIm mii, 5.58 (d, J = 14.0, 1H, CAr-CH2-NIm
5.41 (d, J = 11.4, 1H, CEtHN)mii, 5.13 (d, J = 14.0, 1H, CAr-CH2-NIm
J = 11.1, 1H, CEtHN)mai, 5.06 (d, J = 11.1, 1H, CEtHN)mai, 3.95 (sep, J =
6.1, 3H, Ti-O-CH(CH3)2)mai, 1.30 (s, 9H, (CH3)3)mii, 1.17 (s, 9H, (CH3)3)mai
1.14 (d, J = 6.5, 12H, Ti-O-CH(CH3)2)mai, 1.08 (s, 9H, (CH3)3)mai, 0.99 (s,
9H, (CH3)3)mii
13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 167.6 (1C,
N=CH)mai 163.6 (1C, N=CH)mai 162.7 (1C, N=CH)mai 162.3 (1C,
)mai, 6.41 (s, 1H, (CH=CH)Im)mii, 6.40 (d, J
139.2 (1C, Cq)mai, 138.5 (1C, NCHN)mai, 137.9 (1C, NCHN)mai, 135.9 (1C,
CAr-H)mai, 134.6 (1C, Cq)mai, 134.4 (1C, Cq)mai, 134.3 (1C, Cq)mai, 133.1
(1C, CAr-H)mai, 132.2 (1C, CAr-H)mai, 132.0 (1C, CAr-H)mai, 131.2 (1C,
Cq)mai, 131.0 (1C, Cq)mai, 130.2 (1C, CPh-H)mai, 130.1(1C, CPh-H)mai, 130.0
(1C, CPh-H)mai, 129.9 (1C, CPh-H)mai, 129.7(1C, CPh-H)mai, 129.5 (2C,
CMes-H)mai, 129.3 (1C, CMes-H)mai, 128.7 (1C, CPh-H)mai, 126.3 (1C,
)
)
)
)
)
mai
,
)mii, (d,
(CH=CH)Im
)
mai, 124.4 (1C, Cq)mai, 123.5 (1C, (CH=CH)Im)mai, 123.2 (1C,
mai, 122.7 (1C, (CH=CH)Im mai, 122.6 (1C, Cq)mai, 122.56 (1C,
75.7 (1C, CEtHN)mai 64.4 (2C, Ti-O-
CH(CH3)2)mai, 50.1 (1C, CAr-CH2-NIm mai, 47.2 (1C, CAr-CH2-NIm mai, 34.5
(1C, C(CH3)3)mai, 34.4 (1C, C(CH3)3)mai, 31.5 (3C, C(CH3)3)mai, 31.1 (3C,
C(CH3)3)mai, 25.5 (4C, Ti-O-CH(CH3)2)mai, 21.2 (1C, (CH3)Mes mai, 21.15
(1C, (CH3)Mes mai, 18.4 (1C, (CH3)Mes mai, 18.2 (1C, (CH3)Mes mai, 17.9 (1C,
(CH3)Mes mai,17.8 (1C, (CH3)Mes mai. IR (solid): 3353, 3143, 3029, 2952,
,
(CH=CH)Im
)
)
Cq)mai
,
76.3 (1C, CEtHN)mai
,
,
.
)
)
,
,
,
N=CH)mii, 162.28 (1C, N=CH)mii, 159.1 (1C, CAr-OTi)mai, 158.9 (1C, CAr-
OTi) mii, 144.0 (1C, Cq)mii, 143.6 (1C, Cq)mai, 142.0 (1C, Cq)mai, 141.9 (1C,
Cq)mii, 139.3 (1C, Cq)mai, 138.9 (1C, Cq)mii, 136.5 (1C, CAr-H)mai, 136.3 (1C,
)
)
)
)
)
)
NCHN)mai, 136.0 (1C, NCHN)mii, 135.8 (1C, NCHN)mii, 135.4 (1C,
2865, 1619, 1555, 1306, 1197, 852, 770, 701, 531. HRMS (ESI) m/z:
calculated for (C62H68BrN6O3Ti)+: 1071.4019, found: 1071.4020.
NCHN)mii, 134.9, 134.4, 134.3, 134.2, 133.6, 132.8, 132.2, 132.1, 131.1,
130.9, 130.7 (2C), 130.5, 130.4, 130.3, 130.1, 130.06, 129.9, 129.8,
129.7, 129.4, 129.2, 129.1, 128.7, 124.6 (1C, (CH=CH)Im
)mai, 123.7 (1C,
(CH=CH)Im mii, 122.9, 122.7, 122.6 (1C, (CH=CH)Im)mai, 122.4, 122.3,
122.28, 122.0, 121.8 (2C), 121.6 (2C), 121.5, 121.3, 121.26, 120.5 (1C,
)
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
Cq)mai, 119.8 (1C, (CH=CH)Im)mii, 119.5 (1C, (CH=CH)Im)mai, 76.5 (1C,
κN}diphenylethyl-titanium(IV))tetrachloride (5k): Salen ligand 4k (10.0
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5k
was formed as a mixture of two isomers (3.3:1, quantitative conversion,
yellow solid). C124H136Cl4N12O6Ti2. MW: 2128.06 g mol–1. M.p.: decomp.
CEtHN)mii, 76.4 (1C, CEtHN)mii, 76.3 (1C, CEtHN)mai, 75.8 (1C, CEtHN)mai
64.4 (2C, Ti-O-CH(CH3)2)mai, 50.1 (1C, CAr-CH2-NIm mai, 49.4 (1C, CAr-
CH2-NIm mii, 48.5 (1C, CAr-CH2-NIm mii, 47.3 (1C, CAr-CH2-NIm)mai, 34.8 (1C,
C(CH3)3)mii, 34.6 (1C, C(CH3)3)mii, 34.6 (1C, C(CH3)3)mai, 34.5 (1C,
C(CH3)3)mai 31.6 (3C, C(CH3)3)mii 31.5(3C, C(CH3)3)mii 31.4 (3C,
,
)
)
)
,
,
,
T > 200 °C. [α]20 (c = 1.0 g·dL-1, CH2Cl2) = 221. 1H-NMR (500 MHz,
D
C(CH3)3)mai, 31.3 (3C, C(CH3)3)mai, 25.6 (4C, Ti-O-CH(CH3)2)mai. IR
(solid): 3400, 3061, 2964, 1619, 1547, 1454, 1201, 1072, 760, 688, 526.
HRMS (ESI) m/z: calculated for (C56H56BrN6O3Ti)+: 987.3079, found:
987.3071.
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.46 (s, 1H,
NCHNIm
)mii, 10.73 (s, 1H, NCHNIm)mai, 10.72 (s, 1H, NCHNIm
)mii, 10.59 (s,
1H, NCHNIm
)mai, 8.93 (t, J = 1.5, 1H, (CH=CH)Im)mai, 8.80 (d, J = 2.4, 1H,
CAr-H)mii, 8.43 (s, 1H, (CH=CH)Im)mii, 8.38 (s, 1H, (CH=CH)Im)mii, 8.16 (d, J
= 1.4, 2H, N=CH)mii, 8.08 (d, J = 1.4, 1H, N=CH)mai, 8.00 (d, J = 2.3, 1H,
CAr-H)mai, 7.98 (t, J = 1.5, 1H, (CH=CH)Im
)mai, 7.94 (d, J = 1.8, 1H,
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
N=CH)mai, 7.88 (t, J = 1.6, 1H, (CH=CH)Im mai, 7.86 (b, 1H, CAr-H), 7.72 (d,
)
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
J = 2.3, 1H, CAr-H)mii, 7.43 (d, J = 2.5, 1H, CAr-H)mii, 7.42 (t, J =1.5, 1H,
1H, CAr-CH2-NBI)mai, 5.55 (d, J = 13.7, 1H, CAr-CH2-NBI)mai, 5.55 (m, 1H,
CAr-CH2-NBI)mii, 5.49 (d, J = 10.5, 1H, CEtHN)mai, 5.42 (d, J = 13.7, 1H,
CAr-CH2-NBI)mii, 5.16 (m, 1H, CEtHN)mai, 5.13 (d, J = 14.1, 1H, CAr-CH2-
NBI)mai, 5.07 (d, J = 10.2, 1H, CEtHN)mai, 4.98 (d, J = 14.1, 1H, CAr-CH2-
NBI)mii, 3.96 (s, 3H, (CH3)BI)mai, 3.95 (s, 3H, (CH3)BI)mii, 3.88 (sep, J = 5.8,
(CH=CH)Im
)
mii, 7.39 (d, J = 2.4, 1H, CAr-H)mai, 7.35 – 7.12 (m, 10H, CPh
-
H)mai+mii, 7.15 (t, J = 1.8, 1H, (CH=CH)Im
)
mii, 7.13 (d, J = 2.4, 1H, CAr-H)mii
,
7.01 (d, J = 2.4, 1H, CAr-H)mai, 6.99 – 6.83 (m, 9H, CPh-H)mai+mii, 6.83 (s,
2H, CMes-H)mai, 6.79 – 6.74 (m, 5H, CMes-H und CPh-H)mii, 6.76 (s, 2H,
CMes-H)mai, 6.18 (d, J = 14.3, 1H, CAr-CH2-NIm
CAr-CH2-NIm mai, 6.01 (m, 2H, (CH=CH)Im und CEtHN)mai+mii, 5.81 (d, J =
14.2, 1H, CAr-CH2-NIm mai, 5.61 (d, J = 14.2, 1H, CAr-CH2-NIm mii, 5.52 (d,
J = 14.0, 1H, CAr-CH2-NIm mai, 5.34 (dd, J = 11.0, J = 0.9, 1H, CEtHN)mai
4.98 (m, 3H, CAr-CH2-NIm und CEtHN)mai+mii, 3.85 (sep, J = 6.2, 2H, Ti-O-
CH(CH3)2)mai, 2.25 (s, 3H, (CH3)Mes mai, 2.23 (s, 6H, (CH3)Mes mii, 2.22 (s,
3H, (CH3)Mes mai, 1.99 (s, 3H, (CH3)Mes mai, 1.96 (s, 3H, (CH3)Mes mii, 1.83
(s, 3H, (CH3)Mes mai, 1.81 (s, 3H, (CH3)Mes mii, 1.67 (s, 3H, (CH3)Mes mai
1.66 (s, 3H, (CH3)Mes mai, 1.58 (s, 3H, (CH3)Mes mii, 1.55 (s, 3H, (CH3)Mes mii
1.21 (s, 9H, (CH3)3)mii, 1.11 (s, 9H, (CH3)3)mai, 1.04 (d, J = 6.0, 12H, Ti-O-
CH(CH3)2)mai, 0.84 (s, 9H, (CH3)3)mai, 0.80 (s, 9H, (CH3)3)mii
13C-NMR
(125MHz, CD2Cl2, 21 °C): δ = 165.8 (1C, N=CH)mai, 165.7 (1C, N=CH)mii
162.2 (1C, N=CH)mai, 161.9 (1C, CAr-OTi)mai, 161.6 (1C, CAr-OTi)mii, 157.7
(1C, CAr-OTi)mai, 157.3 (1C, CAr-OTi)mii, 143.4 (1C, Cq)mii, 142.5 (1C,
Cq)mai, 140.9 (1C, Cq)mii, 140.8 (1C, Cq)mai, 140.6 (1C, Cq)mii, 140.5 (1C,
Cq)mai, 140.4 (1C, Cq)mai, 140.2 (1C, Cq)mii, 138.0 (2C, Cq)mai, 137.6 (1C,
NCHN)mai, 137.6 (1C, NCHN)mai, 137.3 (1C, Cq)mii, 135.1 (1C)mii, 134.9
(1C)mii, 134.7 (1C)mai, 133.4 (1C)mai, 133.3 (1C)mai, 133.2 (1C)mai, 133.1
(1C)mai, 133.0 (1C)mai, 132.9 (1C)mii, 132.8 (1C)mii, 132.6 (1C)mii, 131.9
(1C)mii, 131.8 (1C)mai, 131.7 (1C)mii, 130.9 (1C)mii, 130.9 (2C)mai, 130.2
(1C)mii, 130.2 (1C)mai, 129.9 (1C)mai, 129.7 (1C)mii, 129.3 (1C)mii, 129.1
(1C)mai, 129.0 (1C)mai, 128.9 (2C)mai, 128.7 (1C)mai, 128.6 (1C)mai, 128.3
(2C)mai, 128.1 (2C)mai, 127.8 (1C)mii, 127.5 (1C)mai, 126.7 (1C)mii, 125.1
(1C)mii, 124.9 (1C)mai, 122.9 (1C)mai, 122.7 (1C)mii, 122.5 (1C)mii, 122.4
(1C)mai, 122.3 (1C)mii, 121.9 (1C)mai, 121.8 (1C)mai, 121.7 (1C)mai, 121.5
(1C)mai, 121.3 (1C)mii, 121.2 (1C)mai, 121.0 (1C)mii, 119.8 (1C)mii, 75.7 (1C,
)
mai, 6.17 (d, J = 14.0, 1H,
2H, Ti-O-CH(CH3)2), 3.78 (s, 3H, (CH3)BI)mai, 3.62 (m, 1H, CAr-CH2-NBI)mii,
)
3.61 (s, 3H, (CH3)BI)mii, 1.39 (s, 9H, (CH3)3)mii, 1.07 (d, J = 6.2, 12H, Ti-O-
CH(CH3)2), 1.06 (s, 9H, (CH3)3)mai, 1.02 (s, 9H, (CH3)3)mai, 0.84 (s, 9H,
13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 168.5 (1C, N=CH)mai
(CH3)3)mii. ,
168.1 (1C, N=CH)mii, 162.8 (1C, CAr-OTi)mai, 161.8 (1C, CAr-OTi)mii, 161.4
(1C, N=CH)mii, 162.3 (1C, N=CH)mai, 158.8 (1C, CAr-OTi)mii, 158.1 (1C,
CAr-OTi)mai, 144.3 (1C, NCHN)mai, 144.2 (1C, Cq)mii, 143.7 (1C, Cq)mai,
)
)
)
,
)
)
)
)
)
)
)
)
,
142.7 (1C, NCHN)mai, 142.0 (1C, Cq)mai, 141.8 (1C, Cq)mii, 139.9 (1C,
Cq)mai, 139.3 (1C, Cq)mii, 136.8 (1C, CAr-H)mii, 136.7 (1C, CAr-H)mai, 134.3
)
)
) ,
(1C)mai, 133.5 (1C)mii, 132.9 (1C, Cq)mai, 132.6 (1C)mai, 132.3 (1C)mii
,
.
132.0 (1C, Cq)mai, 131.8 (1C)mai, 131.7 (1C, CAr-H)mai, 131.6 (1C)mii, 131.5
,
(1C)mii, 131.2 (1C, Cq)mai, 130.9 (1C)mii, 130.8 (1C, Cq)mai, 130.4 (1C)mii
130.1 (1C, Cq)mai, 129.9 (1C)mai, 129.7 (1C)mii 129.4 (2C, CBI-H)mai
121.7(1C)mii, 128.8 (1C)mai, 128.7 (2C)mai, 127.9 (1C)mii, 127.5 (1C)mai
127.4 (1C)mai, 127.1 (1C, CBI-H)mai, 126.8 (1C, CBI-H)mai, 126.8 (1C)mii
,
,
,
,
126.1 (1C)mii, 122.7 (1C, Cq)mii, 122.5 (1C, Cq)mii, 122.4 (1C, Cq)mii, 122.3
(1C, Cq)mai, 122.1 (1C, Cq)mai, 121.9 (1C, Cq)mai, 120.6 (1C, Cq)mii, 120.5
(1C, Cq)mai, 115.1 (1C, CBI-H)mii, 114.5 (1C, CBI-H)mii, 114.3 (1C, CBI-H)mai
,
113.9 (1C, CBI-H)mai, 113.4 (1C, CBI-H)mai, 113.3 (1C, CBI-H)mai, 113.1 (1C,
CBI-H)mii, 112.4 (1C, CBI-H)mii, 76.4 (1C, CEtHN)mii, 76.1 (1C, CEtHN)mai
76.0 (1C, CEtHN)mai, 75.4 (1C, CEtHN)mii, 64.4 (2C, Ti-O-CH(CH3)2)mai
,
,
46.9 (1C, CAr-CH2-NBI)mai, 46.5 (1C, CAr-CH2-NBI)mai, 46.1 (1C, CAr-CH2-
NBI)mii 45.1 (1C, CAr-CH2-NBI)mii 35.1 (1C, C(CH3)3)mii 34.6 (1C,
C(CH3)3)mai, 34.5 (1C, C(CH3)3)mai, 34.4 (1C, (CH3)BI)mai, 34.37 (1C,
,
,
,
(CH3)BI)mii
(CH3)BI)mii
,
,
34.2 (1C, (CH3)BI)mai
31.8 (3C, C(CH3)3)mii
,
,
34.1 (1C, C(CH3)3)mii
31.4 (3C, C(CH3)3)mai
,
34.0 (1C,
, 31.3 (3C,
CEtHN)mii, 75.4 (1C, CEtHN)mii, 75.2 (1C, CEtHN)mai, 74.6 (1C, CEtHN)mai
63.2 (2C, Ti-O-CH(CH3)2)mai, 48.7 (1C, CAr-CH2-NIm mai, 48.6 (1C, CAr-
CH2-NIm mii, 46.2 (1C, CAr-CH2-NIm mai, 45.7 (1C, CAr-CH2-NIm mii, 33.7 (1C,
C(CH3)3)mii, 33.4 (1C, C(CH3)3)mai, 33.2 (1C, C(CH3)3)mai, 33.1 (1C,
C(CH3)3)mii, 30.3 (3C, C(CH3)3)mii, 30.3 (3C, C(CH3)3)mai, 29.8 (3C,
,
C(CH3)3)mii, 31.27 (3C, C(CH3)3)mai, 25.6 (4C, Ti-O-CH(CH3)2)mai. IR
(solid): 3490, 3062, 2954, 2854, 1620, 1564, 1455, 1279, 1227, 760, 702,
529. HRMS (ESI) m/z: calculated for (C54H56BrN6O3Ti)+: 963.3079,
found: 963.3070.
)
)
)
)
C(CH3)3)mai, 24.4 (4C, Ti-O-CH(CH3)2)mai, 20.2 (1C, (CH3)Mes mii
(CH3)Mes mai, 20.0 (1C, (CH3)Mes mai, 19.9 (1C, (CH3)Mes mii
(CH3)Mes mii, 17.2 (1C, (CH3)Mes mii, 17.1 (1C, (CH3)Mes mai
(CH3)Mes mai, 16.7 (1C, (CH3)Mes mii, 16.7 (1C, (CH3)Mes mai
(CH3)Mes mai, 16.4 (1C, (CH3)Mes)mii. IR (solid): 3450 (b), 3143, 3030, 2952,
) , 20.1 (1C,
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-phenyl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}diphenylethyl-titanium(IV))tetrabromide (5r): Salen ligand 4r (11.1
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5r was
formed as a mixture of two isomers (1.1:1, quantitative conversion,
yellow solid). C128H120Br4N12O6Ti2. MW: 2337.80 g mol–1. M.p.: decomp.
)
)
)
)
)
)
)
)
)
)
, 17.3 (1C,
, 16.9 (1C,
, 16.6 (1C,
1619, 1545, 1453, 1306, 1197, 852, 701, 540. HRMS (ESI) m/z:
calculated for (C62H68ClN6O3Ti)+: 1027.4523, found: 1027.4535.
T > 200 °C. [α]20 (c = 0.5 g·dL-1, CH2Cl2) = –60. 1H-NMR (500 MHz,
D
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-methyl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}diphenylethyl-titanium(IV))tetrabromide (5p): Salen ligand 4p (9.8
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5p
was formed as a mixture of two isomers (3.8:1, quantitative conversion,
yellow solid). C108H112Br4N12O6Ti2. MW: 2089.51 g mol–1. M.p.: decomp.
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.56 (s, 1H,
NCHNIm), 11.26 (s, 1H, NCHNIm), 11.08 (s, 1H, NCHNIm), 11.01 (s, 1H,
NCHNIm), 9.32 (d, J = 2.3, CAr-H), 8.43 (d, J = 2.4, CAr-H), 8.31 (s, 1H,
N=CH), 8.28 (d, J = 8.3, CBI-H), 8.18 (s, 1H, N=CH), 8.14 (d, J = 2.4, CAr-
H), 8.07 (s, 1H, N=CH), 8.04 (d, J = 8.6, CBI-H), 7.98 (d, J = 8.5, CBI-H),
7.93 (d, J = 8.1, CBI-H), 7.92 (s, 1H, N=CH), 7.75 - 7.71 (m, 4H), 7.68 -
7.65 (m, 4H), 7.59 - 7.47 (m, 13H), 7.42 (d, J = 2.4, CAr-H), 7.39 - 7.32 (m,
15H), 7.30 - 7.24 (m, 9H), 7.19 (d, J = 2.4, CAr-H), 7.09 (d, J = 8.4, CBI-H),
7.06 (d, J = 8.0, CBI-H), 7.04 (d, J = 2.5, CAr-H), 7.00 (m, 4H), 6.95 (t, J =
7.4, CBI-H), 6.69 (d, J = 10.9, 1H, CEtHN), 6.62 (t, J = 8.1, 1H, CBI-H),
6.29 (d, J = 13.8, 1H, CAr-CH2-NIm), 6.25 (d, J = 13.8, 1H, CAr-CH2-NIm),
6.15 (t, J = 8.1, 1H, CBI-H), 6.02 (d, J = 13.3, 1H, CAr-CH2-NIm), 5.89 (d, J
= 13.8, 1H, CAr-CH2-NIm), 5.58 (d, J = 10.9, 1H, CEtHN), 5.56 (d, J = 13.6,
1H, CAr-CH2-NIm), 5.44 (d, J = 10.5, 1H, CEtHN), 5.27 (d, J = 13.8, 1H,
CAr-CH2-NIm), 4.81 (d, J = 11.1, 1H, CEtHN), 4.42 (d, J = 13.7, 1H, CAr-
CH2-NIm), 3.87 (sep, J = 5.8, 2H, Ti-O-CH(CH3)2), 3.72 (d, J = 14.0, 1H,
CAr-CH2-NIm), 1.43 (s, 9H, (CH3)3), 1.23 (s, 9H, (CH3)3), 1.07 (d, J = 6.2,
12H, Ti-O-CH(CH3)2), 1.01 (s, 9H, (CH3)3), 0.85 (s, 9H, (CH3)3). 13C-NMR
(125 MHz, CD2Cl2, 21 °C): δ = 168.2 (1C, N=CH), 167.7 (1C, N=CH),
162.5 (1C), 162.2 (1C) 162.0 (1C), 161.6 (1C), 159.4 (1C, CAr-OTi),
T > 200 °C. [α]20 (c = 1.0 g·dL-1, CH2Cl2) = 17. 1H-NMR (500 MHz,
D
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 10.88 (s, 1H,
NCHNBI)mii, 10.78 (s, 1H, NCHNBI)mai, 10.58 (s, 1H, NCHNBI)mii, 10.48 (s,
1H, NCHNBI)mai, 8.72 (d, J = 1.9, 1H, (CH=CH)Im)mii, 8.30 (d, J = 0.9, 1H,
(CH=CH)Im
)mai, 8.24 (d, J = 1.5, 1H, (CH=CH)Im)mii, 8.14 (d, J = 2.3, 1H,
CAr-H)mai, 8.03 (d, J = 1.1, 1H, N=CH)mii, 8.01 (d, J = 2.4, 1H, CAr-H)mii
,
7.99 (b, 1H)mii, 7.85 (d, J = 8.5, 1H, CBI-H)mai, 8.08 (d, J = 8.5, 1H, CBI-
H)mii, 7.76 (d, J = 8.5, 1H, CBI-H)mii, 7.71 (d, J = 8.4, 1H, CBI-H)mai, 7.62 (t,
J = 8.5, 1H, CBI-H)mii, 7.58 (d, J = 8.5, 1H, CBI-H)mai, 7.49 – 7.11 (m, 18H,
CAr-H, CBI-H and CPh-H)mai+mii, 7.37 (d, J = 2.4, 1H, CAr-H)mii, 7.34 (d, J =
2.3, 1H, CAr-H)mai, 6.86 (t, J = 7.5, 1H, CBI-H)mai, 6.79 (t, J = 7.6, 2H, CBI-
H)mai, 6.76 (m, 1H, CEtHN)mai, 6.71 (t, J = 7.9, 2H, CBI-H)mii, 6.14 (d, J =
15.1, 1H, CAr-CH2-NBI)mai, 6.06 (t, J = 7.7, 2H, CBI-H)mii, 5.58 (d, J = 15.1,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
159.3 (1C, CAr-OTi), 144.6 (1C, Cq), 144.0 (1C, Cq), 139.8 (1C, Cq), 138.7
(1C, Cq), 142.5 (1C, NCHN), 142.2 (1C, NCHN), 142.1 (1C, NCHN),
141.9 (1C, NCHN), 138.0 (1C, CAr-H), 137.1 (1C, CAr-H), 136.9 (1C, CAr-
H), 136.7 (1C, CAr-H), 133.7 (1C), 133.5 (1C), 133.46 (2C), 133.3 (1C),
133.1 (1C), 133.0 (1C), 132.7 (1C), 132.5 (1C), 132.1 (1C), 132.0 (1C),
131.5 (1C), 131.49 (1C), 131.2 (1C), 131.1 (2C), 131.0 (2C), 130.9 (2C),
130.86 (1C), 130.8 (2C), 130.7 (1C), 130.6 (1C), 130.57 (1C), 130.4 (1C),
130.3 (1C), 130.2 (1C), 129.9 (1C), 129.86 (2C), 129.8 (1C), 129.5 (1C),
129.3 (1C), 129.2 (2C), 129.1 (1C), 129.0 (1C), 128.9 (1C), 128.0 (1C,
CBI-H), 127.7 (1C, CBI-H), 127.3(1C, CBI-H), 127.0 (1C, CBI-H), 126.2(1C,
CBI-H), 123.2 (1C, Cq), 123.1 (1C, Cq), 123.0 (1C, Cq), 122.9 (1C, Cq),
122.5 (1C, Cq), 122.3 (1C, Cq), 122.2 (1C, Cq), 121.8 (1C, Cq), 121.6 (1C,
Cq), 115.9 (1C, CBI-H), 115.3 (1C, CBI-H), 115.2 (1C, CBI-H), 114.8 (1C,
CBI-H), 114.5 (1C, CBI-H), 113.5 (1C, CBI-H), 113.2 (1C, CBI-H), 113.0 (1C,
CBI-H), 76.5 (1C, CEtHN), 76.3 (1C, CEtHN), 76.1 (1C, CEtHN), 76.08 (1C,
CEtHN), 64.4 (2C, Ti-O-CH(CH3)2), 46.6 (1C, CAr-CH2-NIm), 46.4 (1C, CAr-
CH2-NIm), 45.3 (1C, CAr-CH2-NIm), 44.7 (1C, CAr-CH2-NIm), 35.2 (1C,
C(CH3)3), 34.9 (1C, C(CH3)3), 34.5 (1C, C(CH3)3), 34.4 (1C, C(CH3)3),
31.8 (3C, C(CH3)3), 31.6 (3C, C(CH3)3), 31.4 (3C, C(CH3)3), 31.1 (3C,
C(CH3)3), 25.6 (4C, Ti-O-CH(CH3)2). IR (solid): 3480, 3062, 2953, 2865,
1619, 1552, 1455, 1308, 1199, 759, 697, 528. HRMS (ESI) m/z:
calculated for (C64H60BrN6O3Ti)+: 1087.3394, found: 1087.3400.
(2C), 129.1 (1C), 128.9 (1C), 128.4 (1C), 128.37 (1C), 128.35 (1C),
128.3 (1C), 128.2 (2C), 128.0 (1C), 127.9 (1C), 127.7 (1C), 127.6 (1C),
127.4 (1C), 126.5 (1C, CBI-H), 123.5 (1C, Cq), 123.2 (1C, Cq), 123.0 (1C,
Cq), 122.9 (1C, Cq), 122.6 (1C, Cq), 122.3 (1C, Cq), 122.2 (1C, Cq), 121.1
(1C, Cq), 116.6 (1C, CBI-H), 115.7 (1C, CBI-H), 114.3 (1C, CBI-H), 114.2
(1C, CBI-H), 113.7 (1C, CBI-H), 113.4 (1C, CBI-H), 113.05 (1C, CBI-H),
113.0 (1C, CBI-H), 77.0 (1C, CEtHN), 76.4 (1C, CEtHN), 76.3 (1C, CEtHN),
75.8 (1C, CEtHN), 64.4 (2C, Ti-O-CH(CH3)2), 45.7 (1C, CAr-CH2-NBI), 45.0
(1C, CAr-CH2-NBI), 44.8 (1C, CAr-CH2-NBI), 44.7 (1C, CAr-CH2-NBI), 35.2
(1C, C(CH3)3), 34.6 (2C, C(CH3)3), 34.4 (1C, C(CH3)3), 31.8 (3C,
C(CH3)3), 31.4 (3C, C(CH3)3), 31.3 (3C, C(CH3)3), 31.2 (3C, C(CH3)3),
25.6 (4C, Ti-O-CH(CH3)2), 21.4 (1C, (CH3)Mes), 21.32 (1C, (CH3)Mes), 21.3
(1C, (CH3)Mes), 21.2 (1C, (CH3)Mes), 18.3 (1C, (CH3)Mes), 17.9 (1C,
(CH3)Mes), 17.88 (1C, (CH3)Mes), 17.8 (1C, (CH3)Mes), 17.6 (1C, (CH3)Mes),
17.4 (1C, (CH3)Mes), 17.3 (1C, (CH3)Mes), 16.2 (1C, (CH3)Mes). IR (solid):
3480, 3030, 2953, 2923, 2854, 1619, 1545, 1469, 1324, 752, 702, 526.
HRMS (ESI) m/z: calculated for (C70H72BrN6O3Ti)+: 1171.4333, found:
1171.4341.
Synthesis of Salen Complexes with Alternative Backbones
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}di-(4-
methoxyphenyl)-ethyl-titanium(IV))tetrabromide (5g): Salen ligand 4g
(11.5 mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5g
was formed as a mixture of two isomers (1.7:1, quantitative conversion,
yellow solid). C128H144Br4N12O10Ti2. MW: 2425.98 g mol–1. M.p.: decomp.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-benzo[d]imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}diphenylethyl-titanium(IV))tetrabromide (5t): Salen ligand 4t (11.9
mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5t was
formed as a mixture of two isomers (1.3:1, quantitative conversion,
yellow solid). C140H144Br4N12O6Ti2. MW: 2506.12 g mol–1. M.p.: decomp.
T > 200 °C. [α]20 (c = 0.1 g·dL-1, CH2Cl2) = 196. 1H-NMR (500 MHz,
D
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.29 (s, 1H,
T > 200 °C. [α]20 (c = 1.0 g·dL-1, CH2Cl2) = 153. 1H-NMR (500 MHz,
D
NCHNIm
1H, NCHNIm)mai, 8.99 (s, 1H, (CH=CH)Im
8.61 (s, 1H, (CH=CH)Im)mii, 8.42 (s, 1H, (CH=CH)Im
1H, N=CH)mii, 8.23 (d, J = 1.8, 1H, N=CH)mii, 8.11 (d, J = 1.6, 1H,
N=CH)mai, 8.06 (d, J = 2.4, 1H, CAr-H)mai, 8.03 (d, J = 2.4, 1H, N=CH)mai
)
mii, 10.58 (s, 1H, NCHNIm)mii, 10.38 (s, 1H, NCHNIm)mai, 10.31 (s,
mai, 8.99 (s, 1H, (CH=CH)Im)mii
mii, 8.25 (d, J = 1.0,
CD2Cl2, 21 °C, mai = major isomer, mii = minor isomer): δ = 11.87 (s, 1H,
NCHNBI), 11.76 (s, 1H, NCHNBI), 11.43 (s, 1H, NCHNBI), 11.17 (s, 1H,
NCHNBI), 9.33 (s, 1H), 8.67 (b, 1H), 8.43 (d, J = 2.4, 1H, CAr-H), 8.42 (d,
J = 9.1, 1H, CBI-H), 8.39 (d, J = 2.4, 1H, CAr-H), 8.02 (b, 1H), 7.89 (b, 1H),
7.34 (d, J = 2.3, 1H, CAr-H), 8.20 (d, J = 1.6, 1H, N=CH), 8.13 (d, J = 1.6,
1H, N=CH), 8.06 (d, J = 1.6, 1H, N=CH), 8.03 (s, 1H, N=CH), 7.63 (t, J =
7.8, 1H, CBI-H), 7.47 (t, J = 7.8, 1H, CBI-H), 7.43 – 7.36 (m, 4H), 7.32 –
7.24 (m, 6H), 7.21 (d, J = 8.6, 1H, CBI-H), 7.12 (d, J = 8.3, 1H, CBI-H),
7.07 (m, 4H), 7.01 – 6.90 (m, 12H), 6.85 (d, J = 8.3, 1H, CBI-H), 6.82 –
6.78 (m, 4H), 6.75 (d, J = 12.0, 1H, CEtHN), 6.72 – 6.69 (m, 2H), 6.63 (d,
J = 14.4, 1H, CAr-CH2-NBI), 6.55 (b, 2H, CMes-H), 6.29 (d, J = 14.2, 1H,
CAr-CH2-NBI), 6.26 (d, J = 14.2, 1H, CAr-CH2-NBI), 6.21 (d, J = 13.8, 1H,
CAr-CH2-NBI), 5.83(d, J = 13.8, 1H, CAr-CH2-NBI), 5.74 (t, J = 8.0, 1H, CBI-
H), 5.60(d, J = 13.8, 1H, CAr-CH2-NBI), 5.60(d, J = 13.8, 1H, CAr-CH2-NBI),
5.41 (d, J = 10.4, 1H, CEtHN), 5.34 (d, J = 13.8, 1H, CAr-CH2-NBI), 4.90 (d,
J = 12.0, 1H, CEtHN), 4.88 (d, J = 11.2, 1H, CEtHN), 4.10 (d, J = 13.0, 1H,
CAr-CH2-NBI), 3.87 (sep, J = 6.2, 2H, Ti-O-CH(CH3)2), 2.32 (s, 3H,
(CH3)Mes), 2.29 (s, 3H, (CH3)Mes), 2.27 (s, 3H, (CH3)Mes), 2.24 (s, 3H,
(CH3)Mes), 2.01 (s, 3H, (CH3)Mes), 1.94 (s, 3H, (CH3)Mes), 1.93 (s, 3H,
(CH3)Mes), 1.77 (s, 3H, (CH3)Mes), 1.62 (s, 3H, (CH3)Mes), 1.53 (s, 3H,
(CH3)Mes), 1.38 (s, 9H, (CH3)3), 1.23 (s, 3H, (CH3)Mes), 1.08 (s, 9H,
(CH3)3), 1.06 (d, J = 6.2, 12H, Ti-O-CH(CH3)2), 1.03 (s, 9H, (CH3)3), 0.76
(s, 9H, (CH3)3), 0.69 (s, 3H, (CH3)Mes). 13C-NMR (125 MHz, CD2Cl2,
21 °C): δ = 168.0 (1C, N=CH), 167.5 (1C, N=CH), 162.5 (1C), 162.3 (1C),
161.9 (1C), 161.5 (1C), 159.0 (1C, CAr-OTi), 158.8 (1C, CAr-OTi), 144.6
(1C, Cq), 143.9 (1C, NCHN), 143.8 (1C, NCHN), 143.4 (1C, Cq), 142.3
(1C, Cq), 142.1 (1C, Cq), 142.0 (1C, Cq), 141.9 (1C, Cq), 139.5 (1C, Cq),
139.1 (1C, Cq), 137.8 (1C), 137.1 (1C), 136.2 (1C), 136.0 (1C), 135.6
(1C), 135.5 (1C), 135.35 (1C), 135.3 (1C), 135.1 (1C), 135.0 (1C), 134.5
(1C), 133.8 (1C), 133.7 (1C), 133.5 (1C), 133.0 (1C), 132.5 (1C), 132.1
(1C), 131.8 (1C), 131.6 (1C), 131.5 (1C), 131.3 (1C), 131.24 (1C), 131.2
(2C), 131.1 (1C), 130.9 (1C), 130.6 (1C), 130.5 (2C), 130.5 (1C), 130.4
(1C), 130.2 (1C), 130.0 (1C), 129.9 (2C), 129.8 (1C), 129.5 (1C), 129.2
)
,
)
,
7.97 (s, 1H, (CH=CH)Im)mai, 7.84 (s, 1H, (CH=CH)Im)mai, 7.77 (d, J = 2.4,
1H, CAr-H)mii, 7.74 (d, J = 2.1, 1H, CAr-H)mai, 7.55 (d, J = 2.5, 1H, CAr-H)mii
,
7.48 (d, J = 2.5, 1H, CAr-H)mai, 7.39 (s, 1H, (CH=CH)Im)mii, 7.29 (d, J = 2.5,
1H, CAr-H)mii, 7.22 (d, J = 8.7, 2H, CPh-H)mai, 7.11 (d, J = 2.5, 1H, CAr-
H)mai, 7.02 - 6.95(m, 11H)mai+mii, 6.92 (s, 2H, CMes-H)mai, 6.91 (s, 2H, CMes
H)mii, 6.78 (d, J = 8.5, 2H, CPh-H)mii, 6.74 (d, J = 8.7, 2H, CPh-H)mii, 6.38 (d,
J = 8.7, 2H, CPh-H)mai, 6.33 (d, J = 14.1, 1H, CAr-CH2-NIm mai, 6.27 (d, J =
13.3, 1H, CAr-CH2-NIm)mii, 6.12 (d, J = 11.7, 1H, CAr-CH2-NIm mai, 6.11 (s,
-
)
)
1H, (CH=CH)Im)mai, 6.10 (d, J = 12.1, 1H, CAr-CH2-NIm)mii, 5.92 (d, J =
11.3, 1H, CEtHN)mai, 5.92 (d, J = 14.0, 1H, CAr-CH2-NIm)mii, 5.66 (d, J =
13.9, 1H, CAr-CH2-NIm)mii, 5.60 (d, J = 13.8, 1H, CAr-CH2-NIm
1H, (CH=CH)Im)mii, 5.33 (dd, J = 10.0, J = 1.4, 1H, CEtHN)mii, 5.08 (d, J =
13.2, 1H, CAr-CH2-NIm mai, 5.01 (dd, J = 11.3, J = 1.7, 1H, CEtHN)mai, 4.91
)mai, 5.48 (s,
)
(dd, J = 11.3, J = 1.6, 1H, CEtHN)mii, 3.95 (sept, J = 6.1, 12H,
TiOCH(CH3)2), 3.80 (s, 3H, OCH3)mai, 3.75 (s, 3H, OCH3)mii, 3.74 (s, 3H,
OCH3)mii, 3.67 (s, 3H, OCH3)mai, 2.33 (s, 3H, (CH3)Mes mai
(CH3)Mes mii, 2.31 (s, 3H, (CH3)Mes mii, 2.29 (s, 3H, (CH3)Mes mai
(CH3)Mes mii, 2.06 (s, 3H, (CH3)Mes mai, 1.96 (s, 3H, (CH3)Mes mii
(CH3)Mes mai, 1.89 (s, 3H, (CH3)Mes mii
3H, (CH3)Mes mai, 1.65 (s, 3H, (CH3)Mes mii
3H, (CH3)3)mii 1.21 (s, 3H, (CH3)3)mai
TiOCH(CH3)2), 0.94 (s, 3H, (CH3)3)mai, 0.86 (s, 3H, (CH3)3)mii
(125 MHz, CD2Cl2, 21 °C): δ = 166.5 (1C, N=CH)mai, 163.2 (1C, N=CH)mai
)
, 2.32 (s, 3H,
, 2.08 (s, 3H,
) , 1.93 (s, 3H,
)
)
)
)
)
)
)
, 1.79 (s, 3H, (CH3)Mes mai
, 1.62 (s, 3H, (CH3)Mes mii
1.14 (d, 6.1, 12H,
13C-NMR
)
, 1.74 (s,
)
)
) , 1.30 (s,
,
,
J =
.
,
162.8 (1C, N=CH)mii, 162.7 (1C, N=CH)mii, 161.1 (1C, CAr-OTi)mii, 160.7
(1C, CAr-OTi)mai, 160.2 (1C, CAr-OTi)mii, 159.7 (1C, CAr-OTi)mai, 144.6 (1C,
Cq)mii, 143.5 (1C, Cq)mai, 142.3 (1C, Cq)mii, 141.9 (1C, Cq)mai, 141.8 (1C,
Cq)mai, 141.6 (1C, Cq)mii, 138.4 (1C, NCHN)mai, 137.9 (1C, NCHN)mai
,
135.6 (1C), 134.5 (1C), 134.4 (1C), 133.9 (1C), 133.1 (1C), 132.8 (1C),
132.2 (1C), 132.0 (1C), 131.1 (1C), 131.0 (1C), 130.8 (1C), 130.4 (1C),
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
130.3 (1C), 130.2 (1C), 129.3 (1C), 126.5 (1C), 126.4 (1C), 124.8 (1C),
124.4 (1C), 123.7 (1C), 123.3 (1C), 123.2 (1C), 123.0 (1C), 122.8 (1C),
122.6 (1C), 122.5 (1C), 115.2 (1C, CPh-H)mii, 115.1 (1C, CPh-H)mai, 114.9
(1C, CPh-H)mii, 114.8 (1C, CPh-H)mai, 76.4 (1C, CEtHN)mii, 76.1 (1C,
NMR (500 MHz, CD2Cl2, 21 °C): δ = 10.39 (s, 1H, NCHNIm), 10.38 (s, 1H,
NCHNIm), 9.01 (s, 1H, (CH=CH)Im), 8.15 (d, J = 1.4, 1H, N=CH), 8.09 (d,
J = 2.2, 1H, CAr-H), 8.03 (d, J = 1.7, 1H, N=CH), 7.94 (s, 1H, (CH=CH)Im),
7.84 (d, J = 2.5, 1H, CAr-H), 7.82 (s, 1H, (CH=CH)Im), 7.46 (d, J = 2.4, 2H,
CAr-H), 7.10 (d, J = 2.3, 1H, CAr-H), 6.92 (s, 2H, CMes-H), 6.84 (s, 1H,
CMes-H), 6.83 (s, 1H, CMes-H), 6.33 (d, J = 14.1, 1H, CAr-CH2-NIm), 6.20 (d,
J = 14.1, 1H, CAr-CH2-NIm), 6.10 (s, 1H, (CH=CH)Im), 5.92 (d, J = 14.1,
1H, CAr-CH2-NIm), 5.62 (d, J = 13.7, 1H, CAr-CH2-NIm), 5.40 (dd, J = 11.2,
J = 1.2, 2H, (CH2)Et), 5.08 (dd, J = 11.2, J = 1.2, 2H, (CH2)Et), 2.33 (s, 3H,
(CH3)Mes), 2.29 (s, 3H, (CH3)Mes), 2.07 (s, 3H, (CH3)Mes), 1.93 (s, 3H,
(CH3)Mes), 1.81 (s, 3H, (CH3)Mes), 1.76 (s, 3H, (CH3)Mes), 1.18 (s, 9H,
(CH3)3), 0.94 (s, 9H, (CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ =
165.6 (2C, N=CH), 142.1 (2C, b), 141.7 (2C), 138.4 (2C, NCHN), 134.60
(2C), 134.5 (2C), 132.0 (2C, b), 131.1 (2C), 130.2 (2C), 130.1 (2C),
123.9 (2C), 122.8 (2C), 59.7 (2C, b, (CH2)Et), 49.4 (2C, b, CAr-CH2-NIm),
34.5 (2C, C(CH3)3), 31.4 (6C, C(CH3)3), 21.2 (4C, (CH3)Mes), 18.0 (2C,
(CH3)Mes). IR (solid): 3398, 2955, 2866, 2184, 1626, 1556, 1454, 1199,
922, 728, 669, 642, 471. HRMS (ESI) m/z: calculated for
(C50H60N6O3Ti)2+: 420.2101, found: 420.2108.
CEtHN)mai, 75.7 (1C, CEtHN)mai, 74.9 (1C, CEtHN)mii, 56.5 (1C, OCH3)mii
55.8 (1C, OCH3)mai, 55.67 (1C, OCH3)mai, 55.6 (1C, OCH3)mii, 50.2 (1C,
CAr-CH2-NIm mii, 47.1 (1C, CAr-CH2-NIm)mai, 46.5 (1C, CAr-CH2-NIm)mii, 44.3
(1C, CAr-CH2-NIm mai, 35.0 (1C, C(CH3)3)mii, 34.5 (1C, C(CH3)3)mai, 34.4
,
)
)
(1C, C(CH3)3)mai, 34.3 (1C, C(CH3)3)mii, 31.5 (3C, C(CH3)3)mii, 31.49 (3C,
C(CH3)3)mai, 31.1 (3C, C(CH3)3)mai, 31.0 (3C, C(CH3)3)mii, 21.23 (1C,
(CH3)Mes mai
(CH3)Mes mii, 18.2 (1C, (CH3)Mes mai
(CH3)Mes mai, 17.6 (1C, (CH3)Mes mai. IR (CH2Cl2): 3395, 2952, 1613, 1512,
)
, 21.2 (1C, (CH3)Mes mii
)
, 21.15 (1C, (CH3)Mes mai
)
, 21.1 (1C,
)
)
, 17.9 (1C, (CH3)Mes mai
)
, 17.8 (1C,
)
)
1248, 1025, 839, 649, 597, 540. HRMS (ESI) m/z: calculated for
(C64H72N6O5Ti)2+: 526.2520, found: 526.2517.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}dicyclohexylethyl-titanium(IV))tetrabromide (5h): Salen ligand 4h
(11.0 mg, 0.01 mmol, 1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in
dichlormethane, 100 µL, 0.01 mmol, 1.0 equiv.) according to GP3. 5h
was formed in almost isomerically pure form (>50:1, quantitative
conversion, yellow solid). C124H160Br4N12O6Ti2. MW: 2330.07 g mol–1.
M.p.: decomp. T > 200 °C. [α]20D (c = 0.1 g·dL-1, CH2Cl2) = 186. 1H-NMR
(500 MHz, CD2CL2, 21 °C): δ = 10.59 (s, 1H, NCHNIm), 10.33 (s, 1H,
NCHNIm), 8.59 (s, 1H, N=CH), 8.51 (s, 1H, N=CH), 8.06 (d, J = 2.3, CAr-
H), 8.00 (d, J = 2.4, CAr-H), 7.87 (t, J = 1.7, (CH=CH)Im), 7.81 (t, J = 1.8,
(CH=CH)Im), 7.64 (d, J = 2.5, CAr-H), 7.53 (d, J = 2.5, CAr-H), 7.19 (t, J =
1.6, (CH=CH)Im), 7.08 (s, 1H, CMes-H), 7.05 (t, J = 1.6, (CH=CH)Im), 6.98
(s, 1H, CMes-H), 6.78 (s, 1H, CMes-H), 6.73 (s, 1H, CMes-H), 5.94 (d, J =
14.0, 1H, CAr-CH2-NIm), 5.88 (d, J = 14.0, 1H, CAr-CH2-NIm), 5.83 (d, J =
14.3, 1H, CAr-CH2-NIm), 5.60 (d, J = 14.3, 1H, CAr-CH2-NIm), 3.95 (sept., J
= 6.1, 1H, Ti-O-CH(CH3)2), 3.88 (m, 1H, CEtHN), 3.59 (m, 1H, CEtHN),
2.25 (s, 6H, (CH3)Mes), 2.15 (s, 3H, (CH3)Mes), 2.31 (m, 1H, (CH2)Cy), 2.07
(s, 3H, (CH3)Mes), 2.05 (m, 1H, (CH2)Cy), 1.96 (m, 2H, (CH2)Cy), 1.91 (s,
3H, (CH3)Mes), 1.83 (s, 3H, (CH3)Mes), 1.68 (m, 6H, (CH2)Cy), 1.38 (s, 9H,
(CH3)3), 1.37 (s, 9H, (CH3)3), 1.30 (m, 4H, (CH2)Cy), 1.14 (d, J = 6.0, 6H,
Ti-O-CH(CH3)2), 1.07 (m, 4H, (CH2)Cy), 1.00 (m, 4H, (CH2)Cy). 13C-NMR
(125 MHz, CD2CL2, 21 °C): δ = 168.5 (1C, N=CH), 167.0 (1C, N=CH),
161.0 (1C, CAr-OTi), 160.5 (1C, CAr-OTi), 141.0 (1C, Cq), 140.8 (1C, Cq),
140.4 (1C, Cq), 140.0 (1C, Cq), 138.6 (1C, NCHN), 137.8 (1C, NCHN),
134.7 (1C, CAr-H), 134.5 (1C, CAr-H), 134.1 (1C, Cq), 134.0 (1C, Cq),
133.6 (1C, Cq), 133.4 (1C, Cq), 131.5 (1C, CAr-H), 131.3 (1C, CAr-H),
130.1 (1C, Cq), 130.0 (1C, Cq), 129.1 (1C, CMes-H), 129.0 (1C, CMes-H),
128.7 (1C, CMes-H), 128.5 (1C, CMes-H), 122.9 (1C, Cq), 122.88 (1C, Cq),
122.1 (1C, (CH=CH)Im), 122.1 (1C, (CH=CH)Im), 122.0 (1C, (CH=CH)Im),
121.9 (1C, (CH=CH)Im), 121.2 (1C, Cq), 120.2 (1C, Cq), 76.5 (1C, CEtHN),
76.1 (1C, CEtHN), 48.7 (1C, CAr-CH2-NIm), 48.2 (1C, CAr-CH2-NIm), 33.5
(1C, C(CH3)3), 33.4 (1C, C(CH3)3), 41.0 (1C, (CH)Cy), 38.6 (1C, (CH)Cy),
33.5 (3C, C(CH3)3), 33.4 (3C, C(CH3)3), 30.0 (1C, (CH2)Cy), 29.7 (1C,
(CH2)Cy), 29.6 (1C, (CH2)Cy), 28.8 (1C, (CH2)Cy), 25.4 (1C, (CH2)Cy), 25.2
(1C, (CH2)Cy), 25.1 (1C, (CH2)Cy), 25.0 (2C, (CH2)Cy), 20.15 (1C,
(CH3)Mes), 20.1 (1C, (CH3)Mes), 17.1 (1C, (CH3)Mes), 16.9 (1C, (CH3)Mes),
16.6 (1C, (CH3)Mes), 16.6 (1C, (CH3)Mes). IR (solid): 3369, 2151, 2925,
2854, 1617, 1560, 1450, 1225, 1068, 940, 850, 612, 573. HRMS (ESI)
m/z: calculated for[M1/22+]: 502.2884, found: 502.2884.
Synthesis of C1-Symmetric Complexes
Bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-1H-
imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}-2,3-dihydro-
1H-inden-1-yl)-titanium(IV)dibromide (7): Ligand 6 (5.9 mg, 0.01 mmol,
1.0 equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL,
0.01 mmol, 1.0 equiv.) according to GP3. 7 was formed as a mixture of
two isomers (1.4:1, quantitative conversion, yellow solid).
C66H72Br2N6O6Ti2, MW: 1300.88 g mol–1, M.p.: decomp. T > 200 °C.
[α]20D (c = 1.0 g·dL-1, CH2Cl2) = 27. 1H-NMR (300 MHz, CD2Cl2, 21 °C,
mai = major isomer, mii = minor isomer): δ = 10.36 (s, 1H, NCHNIm)mii
10.20 (s, 1H, NCHNIm)mai, 8.86 (s, 1H, N=CH)mii, 8.83 (s, 1H, N=CH)mai
8.31 (d, J = 2.5, 1H, CAr-H)mii, 8.14 (d, J = 2.5, 2H, CAr-H)mai, 7.52 (d, J =
2.6, 1H, CAr-H)mai, 7.26 (d, J = 2.6, 1H, CAr-H)mii, 7.20 – 7.08 (m, 9H, Cind
H and (CH=CH)Im)mai+mii, 6.92 (s, 2H, CMes-H)mai, 6.88 (t, J = 1.7, 1H,
,
,
-
(CH=CH)Im
)mai, 6.85 (s, 1H, CMes-H)mii, 6.83 (t, J = 1.7, 1H, (CH=CH)Im)mai
,
,
6.69 (t, J = 1.7, 1H, (CH=CH)Im)mii, 5.66 (m, 2H, CIndHO and CIndHN)mii
5.49 (m, 3H, CAr-CH2-NIm and CIndHN)mai,5.14 (d, J = 13.4, 1H, CAr-CH2-
NIm mii, 4.98 (d, J = 13.4, 1H, CAr-CH2-NIm mii, 4.84 (td, J = 5.3, J = 1.0, 1H,
CIndHO)mai, 2.50 (dd, J = 16.7, J = 5.3, 2H, (CH2)Ind mii, 2.66 (d, J = 16.7,
1H, (CH2)Ind mii, 2.50 (dd, J = 16.7, J = 5.3, 2H, (CH2)Ind mai, 2.25 (s, 3H,
(CH3)Mes mii, 2.24 (s, 3H, (CH3)Mes mai, 1.93 (s, 3H, (CH3)Mes mai, 1.85 (s,
3H, (CH3)Mes mii, 1.83 (s, 3H, (CH3)Mes mii, 1.79 (m, 1H, (CH2)Ind mai
3H, (CH3)Mes mai, 1.24 (s, 9H, (CH3)3)mai, 1.23 (s, 9H, (CH3)3)mii
)
)
)
)
)
)
)
)
)
)
)
, 1.73 (s,
13C-NMR
)
.
(125 MHz, CD2Cl2, 21 °C): δ = 164.6 (1C, N=CH)mii, 163.8 (1C, N=CH)mai
,
159.8 (1C, CAr-OTi)mai, 159.3 (1C, CAr-OTi)mii, 141.6 (1C, Cq)mii, 141.4 (1C,
Cq)mai, 141.1 (1C, Cq)mii, 140.9 (1C, Cq)mai, 140.4 (1C, Cq)mii, 140.3 (1C,
Cq)mai, 140.1 (1C, Cq)mii, 140.0 (1C, Cq)mai, 137.3 (1C, NCHNIm)mai, 136.8
(1C, NCHNIm)mii, 135.4 (1C, CAr-H)mii, 134.9 (1C, CAr-H)mai, 133.7 (1C,
Cq)mai, 133.4 (1C, Cq)mai, 133.3 (1C, Cq)mii, 133.2 (1C, Cq)mii, 130.8 (1C,
CAr-H)mai, 130.5 (1C, CAr-H)mii, 130.0 (1C, Cq)mai, 129.9 (1C, Cq)mii, 129.0
(2C, CMes-H)mii, 128.9 (2C, CMes-H)mai, 128.2 (1C, CPh-H)mii, 127.7 (1C,
CPh-H)mai, 126.0 (1C, CPh-H)mii, 125.6 (1C, CPh-H)mai, 125.4 (1C, CPh-H)mii
,
125.0 (1C, CPh-H)mai, 123.5 (1C, CPh-H)mai, 123.4 (1C, CPh-H)mii, 122.2
(1C, Cq)mai, 122.0 (1C, (CH=CH)Im)mii, 121.8 (1C, (CH=CH)Im)mai, 121.6
(1C, (CH=CH)Im)mii, 121.5 (1C, Cq)mii, 121.3 (1C, (CH=CH)Im)mai, 119.5
(1C, Cq)mii, 119.3 (1C, Cq)mai, 86.2(1C, CIndHO)mai, 85.0(1C, CIndHO)mii
84.2(1C, CIndHN)mai, 82.6(1C, CIndHN)mii, 47.2 (1C, CAr-CH2-NIm mai, 45.8
(1C, CAr-CH2-NIm)mii, 39.6 (1C, (CH2)Ind mai, 39.5 (1C, (CH2)Ind mii, 33.6 (1C,
C(CH3)3)mii, 33. 5 (1C, C(CH3)3)mai, 30.4 (3C, C(CH3)3)mai, 30.3 (3C,
C(CH3)3)mii, 20.1 (1C, (CH3)Mes mii, 20.0 (1C, (CH3)Mes mai, 16.8 (2C,
(CH3)Mes mii, 16.6 (2C, (CH3)Mes mai. IR (solid): 3450 (b), 2961, 2924, 2854,
,
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}ethyl-
titanium(IV))tetrabromide (5i): Salen ligand 4i (9.4 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 5i was formed in almost isomerically
)
)
)
)
)
)
)
pure
form
(>50:1,
quantitative
conversion,
yellow
solid).
1621, 1559, 1458, 1259, 1045, 798, 602, 581. HRMS (ESI) m/z:
calculated for (C66H72BrN6O4Ti)+: 1139.4282, found:1139.4282.
1
C100H120Br4N12O6Ti2. MW: 2001.49 g mol–1. M.p.: decomp. > 200 °C. H-
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
Di-µ-oxo-({[(1R,2R)-[3,5-(tert-butyl)-2-(hydroxy-κO)-
to light- and air-sensitivity and rapid decomposition. 1H-NMR (500 MHz,
CD2Cl2, 21 °C): δ = 8.55 (b, 1H, (CH=CH)Im), 8.33 (s, 1H, N=CH), 8.24 (d,
J = 1.5, 1H, N=CH), 7.67 (d, J = 2.5, 1H, CAr-H), 7.66 (d, J = 2.5, 1H, CAr-
H), 7.19 (d, J = 2.4, 1H, CAr-H), 7.08 (s, 1H), 6.93 (s, 1H), 6.90 (s, 1H),
6.80 (s, 1H,), 6.78 (s, 1H), 6.61 (s, 1H, CMes-H), 6.59 (s, 1H, CMes-H),
6.55 (d, J = 1.5, 1H), 6.12 (d, J = 14.8, 1H, CAr-CH2-NIm), 5.03 (d, J =
12.9, 1H, CAr-CH2-NIm), 5.09 (d, J = 15.3, 1H, CAr-CH2-NIm), 4.62 (d, J =
12.9, 1H, CAr-CH2-NIm), 3.97 (m, 1H, CCyHN), 2.62 (m, 1H, CCyHN), 2.32
(s, 3H, (CH3)Mes), 2.28 (m, 1H, (CH2)Cy), 2.24 (s, 3H, (CH3)Mes), 2.13 (m,
1H, (CH2)Cy), 1.95 (s, 3H, (CH3)Mes), 1.82 (m, 4H, (CH2)Cy), 1.41 (s, 9H,
(CH3)3), 1.33 (s, 3H, (CH3)Mes), 1.24 (s, 3H, (CH3)Mes), 1.18 (s, 9H,
(CH3)3), 1.14 (s, 3H, (CH3)Mes), 0.86 (m, 2H, (CH2)Cy). 13C-NMR (125 MHz,
CD2Cl2, 21 °C): δ = 162.8 (1C, N=CH), 161.5 (1C, N=CH), 156.6 (1C,
CAr-OTi), 155.8 (1C, CAr-OTi), 141.0 (1C, Cq), 138.5 (1C, Cq), 138.03 (1C,
Cq), 138.0 (1C, Cq), 135.4 (1C, Cq), 134.5 (1C, Cq), 134.2 (1C), 134.1
(1C), 134.0 (1C), 133.9 (1C), 130.6 (1C), 129.3 (1C, CAr-H), 128.9 (1C,
CAr-H), 128.2 (1C), 128.1 (1C), 128.07 (1C), 128.0 (1C), 127.8 (1C),
125.8 (1C, (CH=CH)Im), 125.2 (1C), 123.3 (1C, Cq), 121.7 (1C, Cq), 121.0
(1C, (CH=CH)Im), 120.3 (1C, Cq), 120.1 (1C, (CH=CH)Im), 118.6 (1C,
(CH=CH)Im), 69.4 (1C, CCyHN), 66.7 (1C, CCyHN), 51.8 (1C, CAr-CH2-NIm),
46.6 (1C, CAr-CH2-NIm), 33.2 (1C, C(CH3)3), 33.1 (1C, C(CH3)3), 30.4 (3C,
C(CH3)3), 30.2 (3C, C(CH3)3), 30.1 (1C, (CH2)Cy), 27.6 (1C, (CH2)Cy), 24.4
(1C, (CH2)Cy), 24.0 (1C, (CH2)Cy), 23.9 (1C, (CH3)Mes), 20.1 (1C, (CH3)Mes),
20.0 (1C, (CH3)Mes), 16.7 (1C, (CH3)Mes), 16.4 (1C, (CH3)Mes), 16.0 (1C,
(CH3)Mes). IR (solid): 3450, 2965, 2951, 2861, 1623, 1453, 1364, 1322,
1224, 851, 737, 703, 622. HRMS (ESI) m/z: calculated for
(C54H64AgN6O3Ti)+: 999.3574, found: 999.3576.
phenyl]methyl]imino-κN-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl-
titanium(IV))tetrabromide (9): Salen ligand 8 (7.7 mg, 0.01 mmol, 1.0
equiv.) was treated with Ti(OiPr)4 (1.0 M in dichlormethane, 100 µL, 0.01
mmol, 1.0 equiv.) according to GP3. 9 was formed as a mixture of three
isomers
(10.0:3.0:1,
quantitative
conversion,
yellow
solid).
C90H118Br2N8O6Ti2. MW: 1663.53 g mol–1. M.p.: decomp. T > 200 °C.
[α]20D (c = 0.1 g·dL-1, CH2Cl2) = –13. 1H-NMR (500 MHz, CD2Cl2, 21 °C,
only signals of the major isomer are shown): δ = 10.63 (s, 1H, NCHNIm),
10.54 (s, 1H, NCHNIm), 9.19 (s, 1H, (CH=CH)Im), 8.69 (s, 1H, (CH=CH)Im),
8.36 (d, J = 1.6, 1H, N=CH), 8.35 (d, J = 2.4, 1H, CAr-H), 8.23 (b, 1H,
N=CH), 8.19 (b, 1H, N=CH), 8.17 (d, J = 1.0, 1H, N=CH), 8.10 (d, J = 2.2,
1H, CAr-H), 7.60 (d, J = 2.4, 1H, CAr-H), 7.49 (d, J = 2.1, 1H, CAr-H), 7.46
(d, J = 2.1, 1H, CAr-H), 7.44 (d, J = 2.4, 1H, CAr-H), 7.28 (d, J = 2.4, 1H,
CAr-H), 7.14 (d, J = 2.1, 1H, CAr-H), 7.06 (s, 1H, CMes-H), 7.04 (s, 1H,
CMes-H), 7.01 (s, 1H, CMes-H), 6.99 (s, 1H, CMes-H), 6.91 (s, 1H,
(CH=CH)Im), 6.85 (s, 1H, (CH=CH)Im), 6.09 (d, J = 13.3, 1H, CAr-CH2-NIm),
5.97(d, J = 12.7, 1H, CAr-CH2-NIm), 5.57 (d, J = 12.7, 1H, CAr-CH2-NIm),
5.27 (d, J = 12.7, 1H, CAr-CH2-NIm), 4.24 (m, 1H, CCyHN), 3.89 (m, 1H,
CCyHN), 2.90 (m, 1H, CCyHN), 2.70 (m, 1H, CCyHN), 2.48 (m, 1H,
(CH2)Cy), 2.36 (s, 3H, (CH3)Mes), 2.33 (s, 3H, (CH3)Mes), 2.31 (m, 2H,
(CH2)Cy), 2.06 (s, 3H, (CH3)Mes), 2.05 (s, 3H, (CH3)Mes), 2.01 (s, 3H,
(CH3)Mes), 1.76 (s, 3H, (CH3)Mes), 1.91 (m, 4H, (CH2)Cy), 1.82 (m, 4H,
(CH2)Cy), 1.36 (s, 3H, (CH3)3), 1.32 (s, 3H, (CH3)3), 1.27 (s, 3H, (CH3)3),
1.23 (s, 3H, (CH3)3), 1.14 (s, 3H, (CH3)3), 0.91 (s, 3H, (CH3)3), 1.59 (m,
2H, (CH2)Cy), 0.78 (m, 2H, (CH2)Cy), 0.39 (m, 1H, (CH2)Cy). 13C-NMR (125
MHz, CD2Cl2, 21 °C, only signals of the major isomer are shown): δ =
162.5 (1C, N=CH), 161.9 (1C, N=CH), 161.5 (1C, N=CH), 160.4 (1C,
N=CH), 159.7 (1C, CAr-OTi), 158.9 (1C, CAr-OTi), 158.7 (1C, CAr-OTi),
157.2 (1C, CAr-OTi), 140.5 (1C, Cq), 140.47 (1C, Cq), 140.3 (2C, Cq),
140.1 (1C, Cq), 139.2 (1C, Cq), 136.9 (1C, NCHNIm), 136.8 (1C, NCHNIm),
136.0 (1C, Cq), 135.3 (1C, Cq), 134.9 (1C, CAr-H), 134.4 (1C, CAr-H),
133.9 (1C, Cq), 133.8 (1C, Cq), 133.5 (1C, Cq), 133.2 (1C, Cq), 131.2 (1C,
CAr-H), 130.4 (1C, Cq), 130.3 (1C, Cq), 130.1 (2C, Cq), 129.5 (1C, CAr-H),
129.3 (1C, CAr-H), 129.1 (1C, CMes-H), 129.08 (1C, CMes-H), 128.9 (1C,
CMes-H), 128.7 (1C, CAr-H), 128.6 (1C, CMes-H), 128.1 (1C, CAr-H), 127.4
(1C, CAr-H), 124.6 (1C, (CH=CH)Im), 124.3 (1C, (CH=CH)Im), 122.9 (1C,
Cq), 122.87 (1C, Cq), 121.9 (1C, Cq), 121.7 (1C, (CH=CH)Im), 121.2 (1C,
Cq), 121.0 (1C, Cq), 120.5 (1C, (CH=CH)Im), 70.1 (1C, CCyHN), 69.4 (1C,
CCyHN), 67.6 (1C, CCyHN), 67.0 (1C, CCyHN), 47.0 (1C, CAr-CH2-NIm),
46.6 (1C, CAr-CH2-NIm), 34.5 (1C, C(CH3)3), 34.4 (1C, C(CH3)3), 33.5 (1C,
C(CH3)3), 33.4 (2C, C(CH3)3), 32.9(1C, C(CH3)3), 30.4 (6C, C(CH3)3),
30.38 (3C, C(CH3)3), 30.04 (1C, (CH2)Cy), 30.0 (3C, C(CH3)3), 29.3 (3C,
C(CH3)3), 28.9 (1C, (CH2)Cy), 28.6 (3C, C(CH3)3), 27.4 (1C, (CH2)Cy), 27.3
(1C, (CH2)Cy), 24.2 (1C, (CH2)Cy), 24.0 (1C, (CH2)Cy), 23.7 (1C, (CH2)Cy),
23.5 (1C, (CH2)Cy), 20.2 (1C, (CH3)Mes), 20.0 (1C, (CH3)Mes), 17.3 (1C,
(CH3)Mes), 17.1 (1C, (CH3)Mes) 16.6 (1C, (CH3)Mes), 16.5 (1C, (CH3)Mes). IR
(solid): 2948, 2859, 1619, 1544, 1438, 1389, 1304, 1274, 1197, 1156,
1028, 932, 852, 774, 757, 669, 529. HRMS (ESI) m/z: calculated for
(C45H59N4O3Ti)+:751.4066, found: 751.4080.
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-
κN}diphenylethyl)-titanium(IV)silver(I) dibromoargentate (5f-Ag): A
mixture of complex 5f (11.5 mg, 0.01 mmol, 1.0 equiv.), silver(I)nitrate
(3.4 mg, 0.02 mmol, 2.0 equiv.) and dry K2CO3 (5.5 mg, 0.04 mmol, 4.0
equiv.) was stirred in dichlormethane (0.05 M) for 15 h at 30 °C and
subsequently filtered through celite. The solvent was removed by a
constant flow of N2 and after drying under vacuum 5f-Ag was obtained as
a
yellow, light- and air-sensitive powder (quantitative conversion).
C124H132Ag4Br4N12O6Ti2. MW: 2733.32 g mol–1. M.p. and [α]20D: could not
be accurately determined due to light- and air-sensitivity and rapid
decomposition. 1H-NMR, 13C-NMR: decomposition upon measurement in
CD2Cl2. IR (solid): 3480, 2030, 2964, 2952, 2866, 2360, 1620, 1556,
1453, 1364, 1325, 853, 702. HRMS (ESI) m/z: calculated for [M1/2]+:
1097.3732, found: 1097.3717.
Dimerization of Cinnamaldehyde
(+)-Cis-3-Benzyl-4-phenyl-3,4-dihydro-2H-pyran-2-one (12): Salen
complex 5f (0.005 mmol, 0.05 equiv.) was treated with Ag2O (4.6 mg,
0.02 mmol, 0.2 equiv.) for 15 h at 30 °C under exclusion of light in
dichloroethane (1 mL) using
a synthesizer shaking at 500 rpm.
Unreacted Ag2O was then removed by filtration over celite and the filtrate
was evaporated. Additional Ag2O (4.6 mg, 0.02 mmol, 0.2 equiv.), PPh3
(42 mg, 0.160 mmol, 1.6 equiv.) and 4Å molecular sieves were added,
followed by a solution of trans-cinnamaldehyde 10 (12.6 µL, 0.100 mmol,
1.0 equiv.) in dichlorethane (0.25 M). After shaking the reaction mixture
at 500 rpm for 15 h under exclusion of light, n-pentane:ethyl acetate (4:1,
2 mL) was added to precipitate the catalyst and the mixture was
centrifuged. The solution containing the product was decanted and
filtered through a short plug of NH4Cl and silica gel. The samples were
then analyzed by GC/FID using calibration curves to determine
conversion (100%) and yield (0.042 mmol, 42%, cis/trans = 2.7:1
(determined by 1H-NMR). An analytically pure sample was obtained as
colorless oil by preparative TLC (petrolether:ethylacetate = 10:1). The
enantiomeric excess (69%) was determined by HPLC using a chiral
Synthesis of the Silver-NHC Complexes
Di-µ-oxo-bis-({[(1R,2R)-[5-(tert-butyl)-2-(hydroxy-κO)-3-((1-mesityl-
1H-imidazol-3-ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl)-
titanium(IV)silver(I) dibromoargentate (5e-Ag): A mixture of complex
5e (10.5 mg, 0.01 mmol, 1.0 equiv.), silver(I)nitrate (3.4 mg, 0.02 mmol,
2.0 equiv.) and dry K2CO3 (5.5 mg, 0.04 mmol, 4.0 equiv.) was stirred in
dichlormethane (0.05 M) for 15 h at 30 °C and subsequently filtered
through celite. The solvent was removed by a constant flow of N2 and
after drying under vacuum 5e-Ag was obtained as a yellow, light- and air-
sensitive powder (quantitative conversion). C108H128Ag4Br4N12O6Ti2. MW:
2537.11 g mol–1. M.p. and [α]20D: could not be accurately determined due
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
stationary phase (2x Chiracel OD-H, n-hexane:isopropanol (99:1),
cinnamaldehyde 10 (125.9 µL, 1.0 mmol, 1.0 equiv.) in dry
dichloroethane (2.0 mL). After stirring the reaction mixture for 15 h under
exclusion of light, it was poured into n-pentane:ethyl acetate (4:1, 30 mL)
and the mixture was filtered through a plug of NH4Cl and silica gel. 14
was isolated as a colorless solid (38.8 mg, 0.147 mmol, 29%, cis:trans =
1.0 mL/min, detection at 210 nm, tR(cis) = 28.9 min and 83.2 min,
tR(trans) = 38.2 min and 40.3 min). C18H16O2. MW: 264.32 g mol–1. [α]20
D
(c = 0.1 g·dL-1, CH2Cl2) = +72 (sample with 73% ee). H-NMR (300 MHz,
1
CDCl3, 21 °C): δ = 7.33 – 7.21 (m, 6H, CPh-H), 7.09 (m, 2H, CPh-H), 7.04
(m, 2H, CPh-H), 6.66 (d, J = 3.0, 1H, CH=CH-O), 5.50 (t, J = 3.0, 1H,
CH=CH-O), 3.48 (t, J = 3.4, 1H, H1), 3.34 (m, 1H, H2), 3.23 (dd, J = 7.4, J
= 2.6, 1H, CH2), 2.37 (dd, J = 7.5, J = 4.7, 1H, CH2). 13C-NMR (75 MHz,
CDCl3, 21 °C): δ = 170.1 (1C, C(O)O), 140.8 (1C, CH=CH-O), 138,6 (1C,
Cq), 137,6 (1C, Cq), 129.0 (2C, CPh-H), 128.9 (2C, CPh-H), 128.5 (2C,
CPh-H), 128.3 (2C, CPh-H), 127.8 (1C, CPh-H), 126.5 (1C, CPh-H), 110.8
(1C, CH=CH-O), 46.3 (1C, CH1), 40.3 (1C, CH2), 32.3 (1C, CH2). IR
(CDCl3): 3029, 2919, 1765, 1655, 1495, 1454, 1222, 1075, 904, 730, 699,
650. HRMS (EI) m/z: calculated for [C18H16O2]+: 264.1150, found
264.1159.
9.2:1) by preparative TLC (petrolether:ethylacetate
= 10:1). An
analytically pure sample of cis-14 was obtained by preparative TLC.
1
C18H16O2. MW: 264.32 g mol–1. M.p.: 107 – 109 °C. H-NMR (300 MHz,
CDCl3, 21 °C): δ = 7.10 (m, 6H, CPh-H), 6.73 (m, 2H, CPh-H), 6.55 (m, 2H,
CPh-H), 5.42 (t, J = 4.0, 1H, H2), 4.32 (d, J = 3.9, 1H, H1), 3.95 (quin, J =
6.7, 1H, H3), 3.78 (d, J = 6.9, 1H, H4), 2.40 (dd, J = 14.7, J = 5.9, 1H,
CH2), 2.26 (td, J = 14.8, J = 4.6, 1H, CH2). 13C-NMR (75 MHz, CDCl3,
21 °C): δ = 170.6 (1C, C(O)O), 137.9 (1C, Cq), 137,3 (1C, Cq), 128.3 (2C,
CPh-H), 128.1 (2C, CPh-H), 128.0 (2C, CPh-H), 127.9 (2C, CPh-H), 126.9
(1C, CPh-H), 126.8 (1C, CPh-H), 77.4 (1C, CH2), 61.6 (1C, CH1), 49.5 (1C,
CH4), 46.9 (1C, CH3), 32.9 (1C, CH2). IR (CH2Cl2): 3031, 2926, 2357,
1827, 1603, 1454, 1288, 1118, 982, 700. HRMS (ESI) m/z: calculated for
(C18H16NaO2)+: 287.1043, found 287.1043. Analytical data of the trans-
isomer: 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 7.20 (m, 10H, CPh-H),
5.10 (t, J = 4.0, 1H, H2), 4.25 (dd, J = 7.6, J = 3.8, 1H, H1), 3.95 (td, J =
12.1, J = 6.1, 1H, H3), 3.48 (dd, J = 12.1, J = 7.8, 1H, H4), 2.75 (dd, J =
15.0, J =6.1, 1H, CH2), 2.26 (td, J = 12.0, J = 4.2, 1H, CH2). 13C-NMR (75
MHz, CDCl3, 21 °C): δ = 168.7 (1C, C(O)O), 139.6 (1C, Cq), 135.7 (1C,
Cq), 128.7 (2C, CPh-H), 128.5 (2C, CPh-H), 128.3 (2C, CPh-H), 127.5 (2C,
CPh-H), 126.4 (1C, CPh-H), 127.0 (1C, CPh-H), 75.3 (1C, CH2), 61.2 (1C,
CH1), 52.2 (1C, CH4), 45.5 (1C, CH3), 40.0 (1C, CH2). IR (CH2Cl2): 3061,
3029, 2922, 2359, 1815, 1778, 1495, 1453, 1121, 988, 816, 698. HRMS
(ESI) m/z: calculated for (C18H16NaO2)+: 287.1043, found 287.1029.
cis-4-Phenyl-5-((E)-styryl)dihydrofuran-2(3H)-one (cis-11): IMes*HCl
(3.4 mg, 0.01 mmol, 0.2 equiv.) was treated with Ag2O (9.3 mg,
0.04 mmol, 0.8 equiv.) for 15 h at 30 °C under exclusion of light in
dichloroethane (1 mL) using
a synthesizer shaking at 500 rpm.
Unreacted Ag2O was then removed by filtration over celite and the filtrate
was evaporated. Ti(OiPr)4 (3.0 µL, 0.01 mmol, 0.2 equiv.) and PPh3 (10.5
mg, 0.04 mmol, 0.8 equiv.) were added, followed by a solution of trans-
cinnamaldehyde 10 (6.3 µL, 0.05 mmol, 1.0 equiv.) in diglyme (200 µL).
After shaking the reaction mixture at 500 rpm for 15 h under exclusion of
light, n-pentane:ethyl acetate (4:1, 2 mL) was added to precipitate the
catalyst and the mixture was centrifuged. The solution containing the
product was decanted and filtered through a short plug of NH4Cl and
silica gel. The samples were then analyzed by GC/FID using calibration
curves to determine conversion (100%) and yield (0.037 mmol, 74%,
cis/trans = 5.8:1 (determined by 1H-NMR). An analytically pure sample
may be obtained as colorless oil by preparative TLC
(petrolether:ethylacetate = 10:1). For enantiomerically enriched product
using a chiral catalyst instead the enantiomeric excess of the cis-
diastereomer was determined by HPLC using a chiral stationary phase
(Chiracel AD-H, n-hexane:isopropanol (97:3), 2.0 mL/min, detection at
210 nm, tR(cis) = 9.9 min and 11.6 min). C18H16O2. MW: 264.32 g mol–1.
M.p.: 74 – 76 °C. 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 7.35 – 7.16 (m,
10H, CPh-H), 6.62 (d, J = 15.7, 1H, CH=CH), 5.64 (dd, J = 15.7, J = 6.7,
1H, CH=CH), 5.38 (dd, J = 6.7, J = 1.1, 1H, H1), 3.95 (dt, J = 15.1, J =
7.4, 1H, H2), 2.97 (dd, J = 17.3, J = 8.0, 1H, CH2), 2.89 (dd, J = 17.3, J =
7.4, 1H, CH2). The analytical data is in agreement with literature.[40]
Synthesis of other Metal Salen Complexes for Control Experiments
({[(1R,2R)-[5-(tert-Butyl)-2-(hydroxy-κO)-3-((1-mesityl-1H-imidazol-3-
ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl)-
aluminum(III)dibromide: Salen-Ligand 4e (19.8 mg, 0.02 mmol, 1.0
equiv.) in dry dichloromethane (0.05 M) was treated at room temperature
with trimethylaluminum (2.0 M in n-hexane, 10.0 µL, 0.02 mmol, 1.0
equiv.). The red reaction mixture was stirred for 15
h at room
temperature. Subsequently the complex was precipitated by n-pentane.
After centrifugation the solvent was removed by a syringe under N2. The
solid was dried at 0.01 mbar furnishing the aluminum(III) salen complex
(20.6 mg, 0.02 mmol, >99%) as a light-yellow powder. C55H69AlBr2N6O2,
MW: 1032.99 g mol–1. M.p. and [α]20 were not determined because of
D
1
high air sensitivity. H-NMR (500 MHz, CDCl3, 21 °C): δ = 10.38 (s, 1H,
trans-4-Phenyl-5-((E)-styryl)dihydrofuran-2(3H)-one
(trans-11):
NCHNIm), 9.72 (s, 1H, NCHNIm), 8.07 (s, 2H, N=CH), 8.06 (s, 1H,
(CH=CH)Im), 7.84 (s, 1H, (CH=CH)Im), 7.61 (s, 1H, (CH=CH)Im), 7.35 (d, J
= 2.5, 1H, CAr-H), 7.50 (d, J = 2.3, 1H, CAr-H), 7.27 (d, J = 2.5, 1H, CAr-H),
7.05 (d, J = 2.5, 1H, CAr-H), 6.76 (s, 1H, (CH=CH)Im), 6.92 (s, 2H, CMes-H),
6.86 (s, 1H, CMes-H), 6.85 (s, 1H, CMes-H), 5.89 (d, J = 14.2, 1H, CAr-CH2-
NIm), 5.82 (d, J = 14.2, 1H, CAr-CH2-NIm), 5.79 (d, J = 14.2, 1H, CAr-CH2-
NIm), 5.66 (d, J = 14.2, 1H, CAr-CH2-NIm), 3.80 (m, 1H, CCyHN), 2.70 (m,
1H, CCyHN), 2.26 (s, 3H, (CH3)Mes), 2.23 (s, 3H, (CH3)Mes), 2.05 (m, 2H,
(CH2)Cy), 1.96 (s, 3H, (CH3)Mes), 1.91 (s, 3H, (CH3)Mes), 1.80 (m, 2H,
(CH2)Cy), 1.75 (s, 6H, (CH3)Mes), 1.45 (m, 2H, (CH2)Cy), 1.35 (m, 2H,
(CH2)Cy), 1.22 (s, 9H, (CH3)3), 1.07 (s, 9H, (CH3)3). 13C-NMR (125 MHz,
CDCl3, 21 °C): δ = 162.0 (2C, N=CH), 159.0 (2C, CAr-OH), 141.6 (1C, Cq),
141.4 (1C, Cq), 138.5 (1C, NCHNIm), 138.2 (1C, NCHNIm), 134.7 (1C, Cq),
134.6 (1C, Cq), 132.1 (1C, CAr-H), 131.6 (1C, CAr-H), 131.4 (1C, Cq),
131.3 (1C, CAr-H), 130.1 (2C, CMes-H), 129.2 (1C, CAr-H), 126.1 (1C, Cq),
125.3 (1C, Cq), 125.1 (1C, (CH=CH)Im), 124.7 (1C, (CH=CH)Im), 124.4
(1C, (CH=CH)Im), 122.6 (1C, (CH=CH)Im), 121.1 (1C, Cq), 68.7 (1C,
CCyHN), 63.8 (1C, CCyHN), 51.4 (1C, CAr-CH2-NIm), 48.4 (1C, CAr-CH2-
NIm), 34.3 (1C, C(CH3)3), 34.1 (1C, C(CH3)3), 31.6 (3C, (CH3)3), 31.5 (3C,
(CH3)3), 30.1 (1C, (CH2)Cy), 27.8 (1C, (CH2)Cy), 24.8 (1C, (CH2)Cy), 24.6
(1C, (CH2)Cy), 21.2 (1C, (CH3)Mes), 18.2 (1C, (CH3)Mes), 17.9 (1C,
Analytically pure samples were obtained as colorless oils by preparative
TLC (petrolether:ethylacetate = 10:1). For enantiomerically enriched
product using a chiral catalyst the enantiomeric excess of the trans-
diastereomer was determined by HPLC using a chiral stationary phase
(Chiracel AD-H, n-hexane:isopropanol (97:3), 2.0 mL/min, detection at
210 nm, tR(trans) = 13.8 min and 16.8 min). C18H16O2. MW: 264.32 g mol–1.
M.p.: 61 – 63 °C. 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 7.38 – 7.29 (m,
10H, CHPh), 6.60 (d, J = 15.7, 1H, CH=CH), 6.22 (dd, J = 15.9, J = 6.8, ,
1H, CH=CH), 5.03 (dd, J = 6.7, J = 0.9, 1H, CHO), 3.52 (dt, J = 10.5, J =
8.6, 1H, CHPh), 3.03 (dd, J = 17.7, J = 8.5, 1H, CH2), 2.86 (dd, J = 17.4,
J = 10.5, 1H, CH2). The analytical data is in agreement with literature.[40]
cis-2,3-Diphenyl-6-oxabicyclo[3.2.0]heptan-7-one (cis-14): IMes*HCl
(68.2 mg, 0.2 mmol, 0.2 equiv.) was treated with Ag2O (92.7 mg, 0.4
mmol, 0.4 equiv.) for 15 h at 30 °C under exclusion of light in
dichloromethane (10 mL) while stirring. Unreacted Ag2O was then
removed by filtration over celite and the filtrate was evaporated.
Additional Ag2O (46.3 mg, 0.2 mmol, 0.2 equiv.), Ti(OiPr)4 (60.7 µL, 0.2
mmol, 0.2 equiv.), PPh3 (262.3 mg, 1.0 mmol, 1.0 equiv.) and 4Å
molecular sieves were added, followed by
a solution of trans-
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
(CH3)Mes), 17.8 (1C, (CH3)Mes), 17.7 (1C, (CH3)Mes), 14.2 (1C, (CH3)Mes).
IR (solid): 3361 (b), 2948, 2861, 1629, 1554, 1459, 1198, 955, 829, 669.
HRMS (ESI) m/z: not determined because of high air sensitivity..
40 °C and then filtered over celite. All volatiles were evaporated. The
solid was dried at 0.01 mbar furnishing the nickel(II) salen complex (10.5
mg, 0.01 mmol, >99%) as yellow powder. C54H66Br2N6NiO2, MW:
1049.66
g . M.p.: decomp. >
mol–1 200 °C. [α]20 (c = 0.1 g·dL-1,
D
CH2Cl2) = –406. 1H-NMR (500 MHz, CD2Cl2, 21 °C): δ = 10.15 (s, 2H,
NCHNIm), 7.96 (s, 2H, (CH=CH)Im), 7.67 (d, J = 2.0, 2H, CAr-H), 7.56 (s,
2H, N=CH), 7.27 (d, J = 2.0, 2H, CAr-H), 7.24 (s, 2H, (CH=CH)Im), 6.95 (s,
2H, CMes-H), 6.88 (s, 2H, CMes-H), 5.59 (d, J = 13.5, 2H, CAr-CH2-NIm),
5.40 (d, J = 13.8, 2H, CAr-CH2-NIm), 3.04 (m, 2H, CCyHN), 2.51 (m, 2H,
(CH2)Cy), 2.26 (s, 12H, (CH3)Mes), 2.18 (m, 2H, (CH2)Cy), 2.12 (s, 6H,
(CH3)Mes), 2.03 (m, 2H, (CH2)Cy), 1.94 (m, 2H, (CH2)Cy), 1.28 (s, 18H,
(CH3)3). 13C-NMR (125 MHz, CD2Cl2, 21 °C): δ = 160.3 (2C, N=CH),
159.0 (2C, CAr-OH), 141.3 (2C, Cq), 139.5 (2C, NCHNIm), 138.7 (2C, Cq),
134.90 (2C, Cq), 134.88 (2C, Cq), 134.4 (2C, CAr-H), 131.3 (2C, Cq),
131.0 (2C, CAr-H), 130.0 (2C, CMes-H), 129.9 (2C, CMes-H), 124.1 (2C, Cq),
123.8 (2C, (CH=CH)Im), 123.2 (2C, (CH=CH)Im), 120.5 (2C, Cq), 70.7 (2C,
CCyHN), 51.1 (2C, CAr-CH2-NIm), 34.2 (2C, C(CH3)3), 31.5 (6C, (CH3)3),
29.4 (2C, (CH2)Cy), 24.7 (2C, (CH2)Cy), 21.3 (2C, (CH3)Mes), 18.1 (2C,
(CH3)Mes), 18.0 (2C, (CH3)Mes). IR (solid): 3125, 3023, 2947, 2861, 1716,
1619, 1546, 1326, 1253, 1225, 836, 555. HRMS (ESI) m/z: calculated for
(C54H66N6NiO2)2+: 444.2295, found: 444.2277.
({[(1R,2R)-[5-(tert-Butyl)-2-(hydroxy-κO)-3-((1-mesityl-1H-imidazol-3-
ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl)-
magnesium(II)dibromide: Salen-Ligand 4e (9.9 mg, 0.01 mmol, 1.0
equiv.) in dry dichloromethane (0.05 M) was treated at room temperature
with di-n-butylmagnesium (1.0 M in n-hexane, 10.0 µL, 0.01 mmol, 1.0
equiv.). The reaction mixture was stirred for 15 h at room temperature.
Subsequently the complex was precipitated by n-pentane. After
centrifugation the solvent was removed by a syringe under N2. The solid
was dried at 0.01 mbar furnishing the magnesium(II) salen complex (10.2
mg, 0.01 mmol, >99%) as a beige powder. C54H66Br2MgN6O2, MW:
1015.28 g mol–1. M.p.: decomp. > 200 °C. [α]20D (c = 0.1 g·dL-1, CH2Cl2)
= –95. 1H-NMR (300 MHz, CDCl3, 21 °C): δ = 10.16 (s, 2H, NCHNIm),
8.24 (s, 2H, N=CH), 7.84 (s, 1H, (CH=CH)Im), 7.39 (d, J = 2.6, 2H, CAr-H),
7.24 (d, J = 2.6, 2H, CAr-H), 6.97 (s, 1H, (CH=CH)Im), 6.64 (s, 4H, CMes-H),
5.52 (d, J = 11.5, 2H, CAr-CH2-NIm), 4.91 (d, J = 13.2, 2H, CAr-CH2-NIm),
3.43 (m, 2H, CCyHN), 2.45 (m, 2H, (CH2)Cy), 2.21 (s, 6H, (CH3)Mes), 2.09
(s, 6H, (CH3)Mes), 1.98 (m, 2H, (CH2)Cy), 1.84 (s, 6H, (CH3)Mes), 1.44 (m,
2H, (CH2)Cy), 1.30 (s, 18H, (CH3)3), 0.89 (m, 2H, (CH2)Cy). 13C-NMR (125
MHz, CDCl3, 21 °C): δ = 165.4 (2C, N=CH), 158.3 (2C, CAr-OH), 141.1
(2C, Cq), 139.1 (2C, NCHNIm), 135.2 (2C, Cq), 134.9 (2C, Cq), 134.8 (2C,
Cq), 133.4 (2C, CAr-H), 131.2 (2C, CAr-H), 130.1 (2C, Cq), 129.9 (2C,
CMes-H), 129.6 (2C, CMes-H), 124.8 (2C, Cq), 123.6 (2C, Cq), 122.7 (2C,
(CH=CH)Im), 121.5 (2C, (CH=CH)Im), 72.0 (2C, CCyHN), 48.9 (2C, CAr-
CH2-NIm), 33.9 (2C, C(CH3)3), 31.8 (6C, (CH3)3), 28.9 (2C, (CH2)Cy), 24.9
(2C, (CH3)Mes), 24.3 (2C, (CH2)Cy), 21.5 (2C, (CH3)Mes), 18.0 (2C,
(CH3)Mes). IR (CH2Cl2): 3372, 2924, 2854, 1632, 1543, 1480, 1262, 1066,
795, 723, 649, 502. HRMS (ESI) m/z: not determined because of high air
sensitivity.
Acknowledgements
This work was financially supported by the Deutsche
Forschungsgemeinschaft (PE 818/3-1).
Keywords: cooperative catalysis • N-heterocyclic carbene •
lactone • Lewis acid • silver
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ium)-1-ylmethyl)-phenyl]methyl]imino-κN}cyclohexyl)-
zink(II)dibromide: Salen-Ligand 4e (9.9 mg, 0.01 mmol, 1.0 equiv.) in
dry dichloromethane (0.05 M) was treated at room temperature with
diethylzinc (1.0 M in n-hexan, 10.0 µL, 0.01 mmol, 1.0 equiv.). The
reaction mixture was stirred for 15 h at room temperature. Subsequently
the complex was precipitated by n-pentane. After centrifugation the
solvent was removed by a syringe under N2. The solid was dried at 0.01
mbar furnishing the zinc(II) salen complex (10.6 mg, 0.01 mmol, >99%)
as a beige powder. C54H66Br2N6O2Zn, MW: 1056.35 g mol–1. M.p.:
decomp. > 200 °C. [α]20D (c = 0.1 g·dL-1, CH2Cl2) = –165. 1H-NMR (500
MHz, CD2Cl2, 21 °C): δ = 10.16 (b, 2H, NCHNIm), 8.15 (b, 3H), 7.32 (b,
3H), 7.56 (s, 2H), 7.10 (b, 2H), 6.91 (s, 2H, CMes-H), 6.86 (s, 2H, CMes-H),
6.29 (b, 2H, CAr-CH2-NIm), 5.74 (b, 2H, CAr-CH2-NIm), 4.83 (d, J = 13.4,
2H, CCyHN), 2.09 – 1.87 (m, 4H, (CH2)Cy), 2.03 (s, 9H, (CH3)Mes), 1.92 (b,
9H, (CH3)Mes), 1.35 (m, 4H, (CH2)Cy), 1.22 (s, 18H, (CH3)3). 13C-NMR
(125 MHz, CD2Cl2, 21 °C): δ = 166.7 (2C), 161.4 (2C), 140.8 (2C), 135.0
(2C), 133.5 (4C), 131.4 (2C), 129.7 (4C), 129.6 (2C), 125.3 (2C), 122.6
(2C), 119.8 (2C), 64.4 (2C, CCyHN), 44.4 (2C, CAr-CH2-NIm), 33.9 (2C,
C(CH3)3), 31.7 (6C, (CH3)3), 31.5 (2C, (CH2)Cy), 28.4 (2C, (CH2)Cy), 24.8
(2C, (CH2)Cy), 21.4 (2C, (CH2)Cy), 21.3 (2C, (CH3)Mes), 18.0 (4C, (CH3)Mes).
IR (CH2Cl2): 3402, 2950, 2862, 1631, 1542, 1391, 1196, 1022, 854, 732,
670, 650, 577. HRMS (ESI) m/z: calculated for (C54H66BrN6O2Zn)+:
975.3702, found: 975.3698.
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This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
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10.1002/ejoc.201700436
European Journal of Organic Chemistry
FULL PAPER
Entry for the Table of Contents
FULL PAPER
The efforts to develop a cooperative
catalyst system combining a Lewis
acidic metal center and a nucleophilic
N-heterocyclic carbene within the
same chiral catalyst entity are
Cooperative Catalysis
Katja Latendorf, Melanie Mechler, Irina
Schamne, Daniel Mack, Wolfgang Frey,
and René Peters*
described. To generate free carbene
moities under mild conditions, Ag-
NHC complexes were formed
releasing the nucleophilic carbene
upon treatment with PPh3.
Page No. – Page No.
Titanium Salen Complexes with
Appended Silver NHC Groups as
Nucleophilic Carbene Reservoir for
Cooperative Asymmetric Lewis Acid /
NHC Catalysis
This article is protected by copyright. All rights reserved.