Asymmetric Intra- and Intermolecular Hydroamination Catalyzed by 3,3′-Bis(trisarylsilyl)- and 3,3′-Bis(arylalkylsilyl)-Substituted Binaphtholate Rare-Earth-Metal Complexes

Article abstract of DOI:10.1021/acs.organomet.8b00510

The series of novel 3,3′-bis(trisarylsilyl)- and 3,3′-bis(arylalkylsilyl)-substituted binaphtholate rare-earth-metal complexes 2a-i (SiR₃ = Si(o-biphenylene)Ph (a), SiCyPh₂ (b), Si-t-BuPh₂ (c), Si(i-Pr)₃ (d), SiCy₂Ph (e), Si(2-tolyl)Ph₂ (f), Si(4-t-Bu-C₆H₄)₃ (g), Si(4-MeO-C₆H₄)Ph₂ (h), SiBnPh₂ (i)) have been prepared via arene elimination from [Ln(o-C₆H₄CH₂NMe₂)₃] (Ln = Y, Lu) and the corresponding 3,3′-bis(silyl)-substituted binaphthol. The complexes exhibit high catalytic activity in the hydroamination/cyclization of aminoalkenes, with activities exceeding 1000 h^-1 for (R)-2f-Ln, (R)-2g-Ln, and (R)-2h-Ln in the cyclization of 2,2-diphenylpent-4-enylamine (3a) at 25 °C, while the rigid dibenzosilole-substituted complexes (R)-2a-Ln and the triisopropylsilyl-substituted complexes (R)-2d-Ln exhibited the lowest activity in the range of 150-270 h^-1. Catalysts (R)-2b-Lu, (R)-2c-Lu, (R)-2f-Lu, and (R)-2i-Lu provide the highest selectivities for the majority of the substrates, while the yttrium congeners are usually less selective. The highest enantioselectivities of 96% ee were observed using (R)-2a-Lu and (R)-2c-Lu in the cyclization of (4E)-2,2,5-triphenylpent-4-enylamine (9). The reactions show apparently zero-order rate dependence on substrate concentration and first-order rate dependence on catalyst concentration, with some reactions exhibiting a slightly accelerated rate at high conversion due to a shift in the equilibrium between a less active, higher coordinate catalyst species in favor of a more active, lower coordinate species as a result of weaker binding of the hydroamination product in comparison to the aminoalkene substrate. The shift in equilibrium from the higher to the lower coordinate species is also entropically favored at elevated temperatures, which results in an unusual increase in selectivity in the cyclization of 2,2-dimethylpent-4-enylamine (3d), presumably due to a higher selectivity of the lower coordinate catalyst species. All binaphtholate yttrium complexes, except (R)-2a-Y, are catalytically active in the intermolecular hydroamination of benzylamines with terminal alkenes. The highest selectivity of 66% ee was observed for the reaction of benzylamine with 4-phenyl-1-butene using (R)-2h-Y at 110 °C.

Full text of DOI:10.1021/acs.organomet.8b00510

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Asymmetric Intra- and Intermolecular Hydroamination Catalyzed by
3,3′-Bis(trisarylsilyl)- and 3,3′-Bis(arylalkylsilyl)-Substituted
Binaphtholate Rare-Earth-Metal Complexes
†
†
‡
†
̈
Hiep N. Nguyen, Hyeunjoo Lee, Stephan Audorsch, Alexander L. Reznichenko,
Agnieszka J. Nawara-Hultzsch,§ Bernd Schmidt,‡ and Kai C. Hultzsch*,†,§
†Department of Chemistry & Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New
Jersey 08854-8087, United States
‡Institut fu
̈
r Chemie, Organische Synthesechemie, Universitat Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Golm, Germany
̈
§
̈
University of Vienna, Faculty of Chemistry, Institute of Chemical Catalysis, Wahringer Strasse 38, 1090 Vienna, Austria
S
* Supporting Information
ABSTRACT: The series of novel 3,3′-bis(trisarylsilyl)- and
3,3′-bis(arylalkylsilyl)-substituted binaphtholate rare-earth-
metal complexes 2a−i (SiR3 = Si(o-biphenylene)Ph (a),
SiCyPh2 (b), Si-t-BuPh2 (c), Si(i-Pr)3 (d), SiCy2Ph (e),
Si(2-tolyl)Ph2 (f), Si(4-t-Bu-C6H4)3 (g), Si(4-MeO-C6H4)Ph2
(h), SiBnPh2 (i)) have been prepared via arene elimination
from [Ln(o-C6H4CH2NMe2)3] (Ln = Y, Lu) and the
corresponding 3,3′-bis(silyl)-substituted binaphthol. The com-
plexes exhibit high catalytic activity in the hydroamination/
cyclization of aminoalkenes, with activities exceeding 1000 h−1
for (R)-2f-Ln, (R)-2g-Ln, and (R)-2h-Ln in the cyclization of 2,2-diphenylpent-4-enylamine (3a) at 25 °C, while the rigid
dibenzosilole-substituted complexes (R)-2a-Ln and the triisopropylsilyl-substituted complexes (R)-2d-Ln exhibited the lowest
activity in the range of 150−270 h−1. Catalysts (R)-2b-Lu, (R)-2c-Lu, (R)-2f-Lu, and (R)-2i-Lu provide the highest selectivities
for the majority of the substrates, while the yttrium congeners are usually less selective. The highest enantioselectivities of 96%
ee were observed using (R)-2a-Lu and (R)-2c-Lu in the cyclization of (4E)-2,2,5-triphenylpent-4-enylamine (9). The reactions
show apparently zero-order rate dependence on substrate concentration and first-order rate dependence on catalyst
concentration, with some reactions exhibiting a slightly accelerated rate at high conversion due to a shift in the equilibrium
between a less active, higher coordinate catalyst species in favor of a more active, lower coordinate species as a result of weaker
binding of the hydroamination product in comparison to the aminoalkene substrate. The shift in equilibrium from the higher to
the lower coordinate species is also entropically favored at elevated temperatures, which results in an unusual increase in
selectivity in the cyclization of 2,2-dimethylpent-4-enylamine (3d), presumably due to a higher selectivity of the lower
coordinate catalyst species. All binaphtholate yttrium complexes, except (R)-2a-Y, are catalytically active in the intermolecular
hydroamination of benzylamines with terminal alkenes. The highest selectivity of 66% ee was observed for the reaction of
benzylamine with 4-phenyl-1-butene using (R)-2h-Y at 110 °C.
hydroamination reactions of aminoalkenes.11 However, inter-
INTRODUCTION
■
molecular hydroamination reactions remain highly challen-
ging,2c,g,3,12 especially when they are carried out in a
stereoselective manner. Most studies focused on activated or
strained alkene substrates, such as vinylarenes, 1,3-dienes, and
norbonene, generally applied to amines with low nucleophil-
icity, such as anilines, carboxamides, sulfonamides, and other
protected amines.13 Only a few systems have been reported for
the hydroamination of simple, unactivated alkenes.14,15
The synthesis of nitrogen-containing molecules has drawn
significant interest, because of their omnipresence in the
majority of naturally occurring compounds and their relevance
as biologically active substances.1 Therefore, catalytic methods
for the preparation of amines are highly desirable. The
hydroamination reaction2−7 represents a highly attractive
process in which an amine N−H functionality is added to an
unsaturated carbon−carbon linkage, because it is 100% atom
economical without formation of any waste byproduct. As
many of the targeted amine products are chiral, the
development of chiral catalyst systems for asymmetric
hydroamination reactions has been the focus of a large number
of studies over the last two decades.8 We9 and others10 have
reported catalyst systems that exceed 90% ee in intramolecular
Special Issue: Organometallic Complexes of Electropositive Ele-
ments for Selective Synthesis
Received: July 20, 2018
© XXXX American Chemical Society
A
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We have previously studied rare-earth-metal complexes
based on biphenolate, binaphtholate, and aminodiolate ligands
as catalysts for the asymmetric hydroamination of alkenes
(Chart 1).9a,14b,16 Our important finding for the biphenolate-
Scheme 1. Synthesis of 3,3′-Disilyl-Substituted Binaphthols
Chart 1
chlorosilanes, e.g. triphenylchlorosilane, while sterically more
hindered chlorosilanes gave inferior (<15%) yields in our
hands. The bis(silyl) ether intermediates were prepared from
(R)-3,3′-dibromo-1,1′-binaphthalene-2,2′-diol either by se-
quential treatment with KH and a tris(aryl)chlorosilane,
while sterically more congested chlorosilanes, e.g. chloro-
(cyclohexyl)diphenylsilane, tert-butylchlorodiphenylsilane,
chlorotriisopropylsilane, or chlorodicyclohexyl(phenyl)silane
gave better yields utilizing an optimized version of the classical
silyl ether synthesis18 involving imidazole (up to 6 equiv) and
an excess of the respective chlorosilane (up to 4 equiv) in
DMF.
Synthesis and Characterization of Binaphtholate
Rare-Earth-Metal Complexes. Prospective rare-earth-metal
complexes for efficient hydroamination catalysis generally
possess at least one reactive Ln−C or Ln−N bond to allow
catalyst activation via protonolysis to occur. While a number of
suitable tris-amido and tris-alkyl precursors, such as [Ln{N-
(SiHMe2)2}3(THF)2], [Ln{N(SiMe3)2}3], and [Ln{CH-
(SiMe3)2}3], may be used for the synthesis of diolate rare-
earth-metal complexes through amine and alkane elimination,
respectively,9a,16a,c the resulting diolate amido complexes suffer
from inferior catalytic activity in hydroamination reactions due
to incomplete catalyst activation,9a,16a,20 while the tris-alkyl
precursors [Ln{CH(SiMe3)2}3] are prepared in a rather
tedious three-step synthesis.21 In a previous study9a we
identified the tris-aryl complexes [Ln(o-C6H4CH2NMe2)3]
(Ln = Y, Lu),22 which are available in a single-step procedure
on a multigram scale, as suitable precursors for the preparation
of the highly active hydroamination catalysts (R)-IIIa-Ln and
(R)-IIIb-Ln (Chart 1).
and binaphtholate-based catalysts I−III was that steric bulk at
the 3- and 3′-positions of the binaphtholate ligand played a
crucial role in preventing the formation of higher aggregates
and in stabilizing rare-earth-metal precatalysts. More impor-
tantly, highly sterically demanding silyl substituents at these
positions significantly enhance catalytic activity and/or
enantioselectivities in the intramolecular hydroamination of
aminoalkenes. While the highest enantioselectivity of 95% ee
was observed with IIIa-Sc, a catalyst containing the larger
yttrium, IIIa-Y, cyclized aminopentenes with a high turnover
frequency of up to 840 h−1 at the expense of selectivity.9a
Furthermore, binaphtholate complexes III and NOBIN-based
aminodiolate complexes IV were active in the asymmetric
hydroamination of terminal alkenes with simple primary
amines, producing secondary amines with up to 61% ee.14b,16e
In an extension of these previous studies focusing on
catalysts for asymmetric hydroamination of alkenes, we report
herein the synthesis of rare-earth-metal complexes based on
binaphtholate ligands bearing a variety of sterically demanding
silyl substituents at the 3- and 3′-positions and their
application in asymmetric intra- and intermolecular hydro-
amination reactions.17
RESULTS AND DISCUSSION
■
Synthesis of 3,3′-Bis(silyl)-Substituted Binaphtholate
Ligands. A number of binaphtholate ligands with different
sterically demanding silyl substituents at the 3- and 3′-
positions are available through an established18 two-step
reaction sequence starting from (R)-3,3′-dibromo-1,1′-binaph-
thalene-2,2′-diol via the bis(silyl ethers), followed by a retro-
Brook rearrangement, in 33−82% overall yield (Scheme 1). An
alternative approach involving direct silylation of 3,3′-
dilithiated MOM-protected binaphthol in the presence of
HMPA19 is only suitable for sterically less demanding
Indeed, reaction of the bulky binaphthols (R)-1a−i with
[Ln(o-C6H4CH2NMe2)3] (Ln = Y, Lu) resulted in clean
formation of the rare-earth-metal complexes (R)-2a−i in
quantitative yields (by 1H NMR spectroscopy) at room
temperature in less than 2 h (Scheme 2). The formation of
B
DOI: 10.1021/acs.organomet.8b00510
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yttrium complexes was generally completed more quickly than
that of the corresponding lutetium complexes.
trace amounts of free N,N-dimethylbenzylamine (in addition
to one coordinated amine molecule), which proved to be
difficult to remove. Attempts to purify the complexes further
via recrystallization or washing with pentane or hexanes were
unsuccessful. Therefore, the complexes were generally
prepared in situ as stock solutions in C6D6 or toluene-d8 that
were then used directly for catalytic experiments without
isolation.23
Scheme 2. Synthesis of Binaphtholate Rare-Earth-Metal
Complexes (R)-2a−i
Asymmetric Intramolecular Hydroamination of Ami-
noalkenes. The binaphtholate rare-earth-metal complexes
2a−i were evaluated with aminoalkenes for asymmetric
intramolecular hydroamination/cyclization (Tables 1−5).
While aminopentenes 3a−d and aminohexene 5 were
commonly cyclized smoothly at room temperature using 2
mol % catalyst loading, aminoheptene 7 required higher
catalytic loadings and elevated temperatures to generate
azepane 8 (Table 3). As has been commonly observed,2,3 the
hydroamination/cyclization reaction rates decreased with
increasing sizes of heterocyclic rings: 5 > 6 ≫ 7. For example,
the turnover frequencies in the hydroamination using (R)-2b-Y
decreased in the following sequence: aminopentene 3a (750
h−1 at 25 °C) > aminohexene 5 (6.5 h−1 at 25 °C) ≫
aminoheptene 7 (0.17 h−1 at 80 °C) (Table 1, entry 3; Table
3, entries 3 and 16).
The Thorpe−Ingold effect24 of the gem-diaryl/-dialkyl
substituents plays a significant role in enhancing the cyclization
rates of the gem-disubstituted aminopentenes 3a,b,d in
comparison to that of the unsubstituted aminopentene 3c.
As expected, the rates of the hydroamination reactions
decrease with decreasing size of the substituents in the order
3a > 3b > 3d > 3c (Tables 1 and 2). Ring closing of the gem-
diphenyl-substituted aminopentene 3a proceeded at room
temperature using 2 mol % of the catalysts with the highest
turnover frequency of >1000 h−1 (Table 1, entries 11, 13, 15,
17, 19, and 20) when the trisarylsilyl-substituted yttrium and
lutetium catalysts (R)-2f−h were employed, whereas the
unsubstituted aminopentene 3c required either elevated
reaction temperatures or higher catalytic loadings to achieve
complete cyclization in a reasonable period of time in most
cases (Table 1, entries 47−62).
Complexes (R)-2a−i were prepared in either C6D6 or
toluene-d8 and stored at room temperature for 7 days without
decomposition. Attempts to crystallize the complexes from
toluene, hexanes/toluene, and pentane/toluene mixtures
yielded finely powdered materials, which were not suitable
for X-ray crystallographic analysis. After the solvents were
removed under vacuum, white or pale yellow solids were
While generally the catalytic activity decreases with
decreasing ionic radius for most binaphtholate catalysts,
there are notable exceptions (e.g., Table 1, entry 9 vs entry
10 and Table 3, entry 11 vs entry 12).
1
generally obtained in quantitative yields. On the basis of H
and 13C NMR spectra, the observation of methylene and
methyl groups of N,N-dimethylbenzylamine suggests that the
complexes retain 1 equiv of N,N-dimethylbenzylamine.
Exchange between coordinated and free N,N-dimethylbenzyl-
amine is slow on the NMR time scale at 6 °C, but NMR
spectra collected at 25 °C tend to have broadened signals due
to the onset of exchange between coordinated and free N,N-
The enantioselectivities observed for the gem-diphenyl-
substituted aminopentene 3a range from 47% ee up to 95%
ee (Figure 1), with the highest selectivities being obtained
using the sterically demanding cyclohexyldiphenylsilyl-sub-
stituted (R)-2b-Lu (95% ee), the tert-butyldiphenylsilyl-
substituted (R)-2c-Lu (95% ee), the diphenyl(o-tolyl)silyl-
substituted (R)-2f-Lu (92% ee), and the benzyldiphenylsilyl-
substituted (R)-2i-Ln (Ln = Lu (95% ee), Y (90% ee)), which
are comparable to those for the triphenylsilyl-substituted (R)-
IIIa-Ln (Ln = Sc (95% ee), Lu (93% ee))9a (compare Table 1,
entries 4, 6, 13, 21, and 22, with entries 24 and 25). The lowest
selectivities were observed for the complex (R)-2a-Y (66% ee)
containing the rigid dibenzosilole moiety and the tris(4-tert-
butylphenyl)silyl-substituted complex (R)-2g-Y (47% ee at 25
°C) (Table 1, entries 1 and 15). The selectivity of the latter
catalyst increased to 62% ee when the reaction was performed
at 60 °C (Table 1, entry 16). Furthermore, the selectivity of
(R)-2f-Y also increased from 75% ee at 25 °C to 90% ee at 60
°C (Table 1, entries 11 and 12). Similar unusual temperature
dimethylbenzylamine. The overall symmetry of the 1H and 13
C
NMR spectra is indicative of a C1-symmetric monomeric
structure in solution in accordance with observations made for
the binaphtholate complexes IIIa-Ln and IIIb-Ln. The ipso
carbon of the ortho-metalated N,N-dimethylbenzylamine
appears as a single doublet in the 13C{1H} NMR spectrum
of the yttrium complexes, indicating coupling to a single
yttrium atom. The complexes exhibit good solubility in
aromatic solvents, whereas dimeric biphenolate and binaph-
tholate complexes are generally much less soluble.16a,c
Although the complexation reactions proceeded cleanly by
NMR spectroscopy, the isolated complexes retained varying
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Table 1. Asymmetric Intramolecular Hydroamination of Primary Aminopentenes Catalyzed by Binaphtholate Rare-Earth-
a
Metal Complexes
b
c
entry
subst
cat.
[cat.]/[subst] (%)
T (°C)
t (h)
Nt (h−1
)
ee (%)
1
2
3
4
5
6
7
8
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3b
3c
3c
3c
3c
3c
3c
3c
3c
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2d-Y
(R)-2d-Lu
(R)-2e-Y
(R)-2e-Lu
(R)-2f-Y
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
5
10
2
2
5
5
5
10
25
25
25
25
25
25
25
25
25
25
25
60
25
100
25
60
25
60
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
100
25
25
25
25
25
25
25
25
25
25
25
60
60
25
25
25
25
0.27
0.30
185
167
750
750
750
700
270
150
320
66
82
85
95
87
95
78
81
77
86
75
90
92
92
47
62
83
73
73
82
90
95
0.067
0.067
0.067
0.071
0.18
0.33
9
0.158
0.083
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
0.046
0.05
<0.16
<0.16
0.06
0.25
0.6
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
600
>1000
>1000
>1000
>1000
>1000
>1000
>1000
>1000
1090
1000
≥300
≥300
≥840
≥180
110
98
84
600
590
640
340
220
97
(R)-2f-Y
(R)-2f-Lu
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Y
(R)-2g-Lu
(R)-2g-Lu
(R)-2h-Y
(R)-2h-Lu
(R)-2i-Y
(R)-2i-Lu
(R)-IIIa-Y
(R)-IIIa-Lu
(R)-IIIa-Sc
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2d-Y
(R)-2d-Lu
(R)-2e-Y
(R)-2e-Lu
(R)-2f-Y
d
84
93
95
d
d
0.50
0.58
0.083
0.083
0.075
0.14
49
75
80
89
69
86
43
59
73
87
80
84
88
45
72
65
81
80
95
0.22
0.50
0.183
0.233
0.15
<0.05
0.15
270
210
330
>1000
330
1000
330
375
(R)-2f-Y
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Lu
(R)-2h-Y
(R)-2h-Lu
(R)-2i-Y
(R)-2i-Lu
(R)-IIIa-Lu
(R)-IIIa-Sc
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Lu
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2d-Y
0.05
0.15
0.133
0.233
<0.16
<0.16
0.11
6
31.0
46.0
1.5
1.58
27.0
10.0
35.0
210
≥300
≥300
460
11
0.65
0.22
32
31
0.73
2.0
0.57
0.22
d
83
85
d
49
67
70
87
83
71
75
31
46.0
D
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Table 1. continued
b
c
entry
subst
cat.
[cat.]/[subst] (%)
T (°C)
t (h)
Nt (h−1
)
ee (%)
55
56
57
58
59
60
61
62
63
64
65
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
(R)-2d-Lu
(R)-2e-Y
(R)-2e-Lu
(R)-2f-Y
(R)-2f-Y
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Lu
(R)-IIIa-Y
(R)-IIIa-Lu
(R)-IIIb-Lu
10
5
5
2
2
2
2
2
2
2
5
25
25
25
25
60
60
60
60
25
60
22
140.0
11.5
49
23.0
1.4
3.0
0.50
2.0
0.07
1.7
0.41
2.2
46
59
75
83
82
88
75
39
15
100
25
2.6
18
1.7
76
d
24.0
4
16.5
70
72
90
d
d
a
b
General reaction conditions: 0.1 M (3a,b) and 0.25 M (3c), solution of substrate in C6D6, Ar atm. Reaction time at which at least 95% NMR
c
conversion relative to ferrocene internal standard was obtained. Enantiomeric excess determined by 19F NMR spectroscopy of the Mosher amides.
d
Taken from ref 9a.
dependences of enantioselectivities were observed for the gem-
dimethyl-substituted aminopentene 3d (vide infra).
Table 2. Asymmetric Intramolecular Hydroamination of
2,2-Dimethylpent-4-enylamine (3d) Catalyzed by
Binaphtholate Rare-Earth-Metal Complexes
a
The cyclization of 3b proceeded smoothly at room
temperature with turnover rates as high as 1000 h−1, generating
pyrrolidine 4b with moderate to excellent enantioselectivities
(43−95% ee) (Figure 2, Table 1, entries 26−46) with lutetium
complexes generally leading to significantly better selectivities
in comparison to the larger yttrium. The highest enantiose-
lectivities were observed for benzyldiphenylsilyl-substituted
(R)-2i-Lu (95% ee), the cyclohexyldiphenylsilyl-substituted
(R)-2b-Lu (89% ee), the diphenyl(o-tolyl)silyl-substituted
(R)-2f-Lu (88% ee), and the dicyclohexylphenylsilyl-substi-
tuted (R)-2e-Lu (87% ee), exceeding selectivities observed for
the triphenylsilyl-substituted (R)-IIIa-Ln (Ln = Sc (85% ee),
Lu (83% ee))9a (compare Table 1, entries 29, 35, 38, and 44
with entries 45 and 46). The lowest selectivities were observed
for the triisopropylsilyl-substituted (R)-2d-Ln (Ln = Lu (59%
ee), Y (43% ee)), the tris(4-tert-butylphenyl)silyl-substituted
complex (R)-2g-Y (45% ee), and the dibenzosilole-substituted
(R)-2a-Y (49% ee) (Table 1, entries 26, 32, 33, and 39).
Cyclization of the unsubstituted aminopentene 3c proceeds
significantly more slowly at room temperature in comparison
to the reaction of the gem-dialkyl-activated aminopentene
derivatives 3a,b,d. The slowest rates were observed for the
triisopropylsilyl-substituted (R)-2d-Ln (Ln = Lu (0.07 h−1,
46% ee), Y (0.22 h−1, 31% ee)), which coincidentally afforded
also the lowest selectivities in the formation of 4c, while the
highest rates were afforded by the diphenyl(o-tolyl)silyl-
substituted (R)-2f-Y (2.2 h−1) and the tert-butyldiphenylsilyl-
substituted (R)-2c-Y (2.0 h−1), which are comparable to that
of the triphenylsilyl-substituted (R)-IIIa-Y (2.6 h−1) (Table 1,
entries 52, 54, 55, 58, and 63). More expedient rates of up to
100 h−1 (for the tris(4-tert-butylphenyl)silyl-substituted
complex (R)-2g-Y, Table 1, entry 61) were observed at 60 °C.
The highest enantioselectivities in the cyclization of 3c were
observed for the diphenyl(o-tolyl)silyl-substituted (R)-2f-Ln
(Ln = Lu (88% ee at 60 °C), Y (83% ee at 25 °C)) and the
cyclohexyldiphenylsilyl-substituted (R)-2b-Lu (87% ee at 60
°C) (Table 1, entries 50, 58, and 60). Interestingly, (R)-2b-Lu
formed pyrrolidine 4c with a slightly lower selectivity of 83%
ee at 25 °C (Table 1, entry 51). A similar temperature
dependence of enantioselectivity has been observed in the
cyclization of 3d (vide infra).
b
c
entry
cat.
T (°C)
t (h)
Nt (h−1
)
ee (%)
1
2
3
4
5
6
7
8
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Lu
(R)-2b-Lu
(R)-2b-Lu
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2d-Y
(R)-2d-Lu
(R)-2e-Y
(R)-2e-Lu
(R)-2f-Y
25
25
25
25
40
60
13.5
17.0
3.75
5.25
0.67
0.17
<0.025
2.5
4
3
13
10
75
26
60
59
84
87
89
90
50
78
22
39
59
73
63
72
71
76
81
77
30
49
53
42
55
57
41
59
70
92
290
>2000
20
d
110
25
25
25
25
25
25
25
60
9
23.0
4.0
10.0
7.0
9.0
1.8
2.2
12.3
4.8
7.0
5.4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
25
250
>1000
20
250
>1000
17.5
250
(R)-2f-Y
(R)-2f-Y
0.2
d
100
<0.05
2.9
(R)-2f-Lu
(R)-2f-Lu
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Y
(R)-2g-Y
(R)-2g-Lu
(R)-2g-Lu
(R)-2g-Lu
(R)-2h-Y
(R)-2h-Lu
(R)-2i-Y
25
60
0.2
d
100
<0.05
2.75
0.2
<0.05
8.5
25
60
d
100
>1000
4.9
250
25
60
0.2
d
100
<0.05
8.5
20.5
2.75
4.2
>1000
25
25
25
25
60
22
5.8
2.4
19.7
11.4
480
2.4
(R)-2i-Lu
(R)-IIIa-Y
(R)-IIIa-Lu
e
f
0.07
27.5
65
69
f
a
General reaction conditions: 0.2 M solution of substrate 3d in C6D6,
b
Ar atmosphere. Reaction time at which at least 95% NMR
conversion relative to ferrocene internal standard was obtained.
c
Enantiomeric excess determined by 19F NMR spectroscopy of the
The cyclization of the gem-dimethyl-substituted amino-
pentene 3d proceeds smoothly at room temperature within a
d
e
f
Mosher amides. In toluene-d8. 3 mol % cat. Taken from ref 9a.
E
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Table 3. Asymmetric Intramolecular Hydroamination of Aminohexene 5 and Aminoheptene 7 Catalyzed by Binaphtholate
a
Rare-Earth-Metal Complexes
b
c
entry
subst
cat.
[cat.]/[subst] (%)
T (°C)
t (h)
Nt (h−1
)
% ee
1
2
3
4
5
6
7
8
5
5
5
5
5
5
5
5
5
5
5
5
5
5
7
7
7
7
7
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Y
(R)-2b-Lu
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2f-Y
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Lu
(R)-2i-Y
(R)-2i-Lu
(R)-2a-Y
(R)-2b-Y
(R)-2b-Lu
(R)-2d-Y
(R)-IIIa-Lu
5
5
2
2
2
2
5
5
2
2
2
2
2
2
10
5
10
10
4
25
25
25
60
25
60
25
25
60
60
25
25
25
25
80
80
80
90
80
29.0
36.2
7.5
0.58
38.0
1.17
25.0
44.5
2.5
1.2
0.8
0.3
4.1
27
0.68
0.55
6.5
85
1.3
41
0.78
0.44
20
42
62
170
12
51
21
46
43
9
5
36
33
47
48
13
7
27
16
44
50
9
10
11
12
13
14
15
16
17
18
19
1.7
169
0.06
0.17
0.08
0.06
0.35
116
124
165
72
8
d
−8
55
a
b
General reaction conditions: 0.1 M solution of substrate in C6D6, Ar atmosphere. Reaction time at which at least 95% NMR conversion relative
c
d
to ferrocene internal standard was obtained. Enantiomeric excess determined by 19F NMR spectroscopy of the Mosher amides. Inverse
configuration was observed.
Figure 2. Enantioselectivity of complexes (R)-2a−i in the hydro-
amination of substrate 3b at 25 °C.
Figure 1. Enantioselectivity of complexes (R)-2a−i in the hydro-
amination of the gem-diphenyl-substituted aminopentene 3a at 25 °C.
reasonable period of time (Table 2). however, the rates of
cyclization are substantially slower in comparison to the more
activated substrates 3a,b. For example, the rate of cyclization of
3a (>1000 h−1) and 3b (330 h−1) using (R)-2f-Y at room
temperature (Table 1, entries 11 and 36) was much faster than
the reaction rate of 25 h−1 observed for the cyclization of 3d
under the same catalytic reaction conditions (Table 2, entry
14). Overall, the rates of cyclization of 3d fall in the range of
2.2−25 h−1 at room temperature.
cyclohexyldiphenylsilyl-substituted (R)-2b-Lu (84% ee at 25
°C) (Table 2, entries 4 and 29), whereas the lowest
selectivities at 25 °C were observed for the rigid
dibenzosilole-substituted (R)-2a-Y (26% ee), the triisopropyl-
silyl-substituted (R)-2d-Ln (Ln = Lu (39% ee), Y (22% ee)),
and the tris(4-tert-butylphenyl)silyl-substituted complex (R)-
2g-Y (30% ee) (Table 2, entries 1, 10, 11, and 20).
It is noteworthy that enantioselectivities tend to increase for
the formation of 4d using (R)-2b-Lu and (R)-2g-Ln (Ln = Y,
Lu) with increasing temperature, reaching the maximum
enantioselectivity of 90% ee using (R)-2b-Lu at 110 °C
(Figure 3, Table 2, entries 4−7 and 20−25). The selectivity for
The highest enantioselectivity in the formation of
pyrrolidine 4d at 25 °C was observed for the benzyldiphe-
nylsilyl-substituted (R)-2i-Lu (92% ee at 25 °C) and the
F
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substituted aminopentene 3a. While the rate of cyclization of 5
at 25 °C falls in the range of 0.44−12 h−1 for catalysts 2a−c,i,
the sterically highly shielded tris(4-tert-butylphenyl)silyl-
substituted catalysts (R)-2g-Ln significantly excelled with
rates of 62 h−1 (for Ln = Y) and 170 h−1 (for Ln = Lu),
with the latter example also being one of the rare instances
where the metal with a smaller ionic radius achieves a higher
catalytic activity (r(Lu3+) = 0.977 Å, r(Y3+) = 1.019 Å).26 The
rigid dibenzosilole-substituted (R)-2a-Y afforded piperidine 6
with a moderate enantioselectivity of 51% ee at 25 °C,
followed by the diphenyl(o-tolyl)silyl-substituted (R)-2f-Ln
(Ln = Lu (48% ee), Y (47% ee). both at 60 °C) and the
cyclohexyldiphenylsilyl-substituted complex (R)-2b-Y (46% ee
at 25 °C) (see Table 3, entries 1, 3, 9, and 10). The
enantiomeric excess of the hydroamination product 6
depended only slightly on the reaction temperature (see
Table 3, entries 3−6). Interestingly, the enantioselectivity of
the formation of piperidine 6 dropped markedly with
decreasing ionic radius of the metal (e.g., Table 3, entry 1 vs
entry 2 and entry 3 vs entry 5), except for complexes 2c,f. This
observation is in contrast with the general trend observed in
the cyclization of aminopentenes 3a−d (Tables 1 and 2).
Cyclization of the gem-diphenyl-substituted aminoheptene 7
required harsher reaction conditions. Prolonged heating to
80−90 °C and higher catalyst loadings were required to
achieve complete cyclization of 7. The highest selectivity was
observed for the cyclohexyldiphenylsilyl-substituted complex
(R)-2b-Y (50% ee), slightly below the selectivity observed for
(R)-IIIa-Lu (55% ee) (Table 3, entries 16 and 19). The
smaller lutetium catalyst (R)-2b-Lu produced the azepane 8
with significantly lower enantioselectivity in comparison to its
yttrium congener (Table 3, entries 16 and 17). Also
noteworthy seems to be the observation that the triisopro-
pylsilyl-substituted binaphtholate complex (R)-2d-Y produced
the azepane 8 with reversed absolute configuration, though the
selectivity was very low (8% ee) (Table 3, entry 18).
Figure 3. Temperature dependence of enantiomeric excess in the
hydroamination/cyclization of 3d ([subst.]0 = 0.20 mol L−1) with
(R)-2b-Lu, (R)-2f-Ln, and (R)-2g-Ln ([cat.] = 0.004 mol L−1) at
variable temperatures in C6D6 (T = 25−60 °C) and toluene-d8 (T =
100−110 °C), respectively. The lines are drawn as guides for the eye.
(R)-2f-Ln (Ln = Y, Lu) also increases from 25 to 60 °C but
decreases slightly at 100 °C (Table 2, entries 14−19). This
unusual behavior can be explained by an equilibrium between
the two species A and B, as depicted in Scheme 3.9a,25 While
the lower coordinate species A is believed to be catalytically
more active and more selective, the electronically more
saturated species B is expected to be less active and
presumably also less selective due to steric crowding.9a As
the temperature increases, the equilibrium between species A
and B is shifted toward the entropically favored lower
coordinate species A, thus resulting in an increase in the
observed selectivity.
Following the general trend that the rate of intramolecular
hydroamination decreases with increasing ring size, cyclization
of the gem-diphenyl-substituted aminohexene 5 (Table 3,
entries 1−14) proceeded significantly more slowly with lower
selectivity in comparison to the reaction of the gem-diphenyl-
In contrast to the reaction of terminal alkenes, the
cyclization of the 1,2-disubstituted olefin 9 proceeds
Scheme 3. Catalytic Cycle of Intramolecular Hydroamination of Aminoalkenes
G
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significantly more slowly than the reaction of the gem-diphenyl-
substituted aminopentene 3a (compare Table 1, entries 1−22,
and Table 4). This observation is in agreement with the
pyrrolidine product 10 with good to excellent enantioselectiv-
ities in the range of 75−96% ee (Table 4). Interestingly, ring
closure of 9 generally proceeds with higher enantioselectivities
in comparison to that of the corresponding terminal alkene
analogue 3a, with the exception of the cyclohexyldiphenylsilyl-
substituted (R)-2b-Ln (Ln = Y, Lu) and the diphenyl(o-
tolyl)silyl-substituted (R)-2f-Lu (compare Table 1, entries 3, 4,
and 13, with Table 4, entries 3, 4, and 10).
Table 4. Asymmetric Intramolecular Hydroamination of the
Internal Alkene 9 Catalyzed by Binaphtholate Rare-Earth-
a
Metal Complexes
Steric congestion around nitrogen, on the other hand,
resulted in significantly increased rates of cyclization in case of
the N-benzyl-substituted aminoalkene 11a using the tert-
butyldiphenylsilyl-substituted binaphtholate complexes (R)-2c-
Ln in comparison to the primary aminoalkene analogue 3d
(Table 2, entries 8 and 9, vs Table 5, entries 1 and 2). While
the cyclization of 11a proceeded more selectively (71% ee)
than that of 3d (50% ee) using (R)-2c-Y, the opposite was true
for the corresponding lutetium complex. A similar rate
acceleration in the cyclization of a secondary amine in
comparison to a primary amine analogue has been observed
for neutral diamidobinaphthyl rare-earth-metal complexes.27
On the basis of the proposed mechanism (Scheme 3), the rate
acceleration can be explained by a shift in the equilibrium
between the higher coordinate species B in favor of the lower
coordinate and more catalytically active species A, facilitated
by the bulkiness of the N-benzyl substituent.
However, the N-benzyl gem-diphenyl-substituted amino-
pentene 11b is sterically more demanding than 11a, leading to
significantly more steric hindrance around the metal center. As
a result, significantly lower activities and enantioselectivities
were observed in the cyclization of the secondary amine 11b
(Table 5, entries 3−12) in comparison to those of the primary
amine analogue 3a and the secondary amine 11a. Moreover,
the hydroamination product 12b was obtained with inverted R
configuration using the tert-butyldiphenylsilyl-substituted
binaphtholate complexes (R)-2c-Ln (Table 5, entries 6−9).
Interestingly, the preferred enantiomer for product 12b
b
c
entry
cat.
t (h)
Nt (h−1
)
ee (%)
1
2
3
4
5
6
7
8
(R)-2a-Y
(R)-2a-Lu
(R)-2b-Y
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Lu
(R)-2d-Y
(R)-2d-Lu
(R)-2f-Y
(R)-2f-Lu
(R)-2g-Y
(R)-2g-Lu
(R)-2i-Y
3.0
7.5
0.3
17
6.4
170
67
50
28
14.3
6.4
75
93
96
83
88
92
96
95
91
93
75
88
91
95
95
0.75
1.0
1.75
3.5
7.75
0.67
1.0
9
10
11
12
13
14
50
0.1
500
330
67
0.15
0.75
0.75
(R)-2i-Lu
67
a
General reaction conditions: 0.1 M solution of substrate in C6D6, Ar
b
atm. Reaction time at which at least 95% NMR conversion relative to
c
ferrocene internal standard was obtained. Determined by 19F NMR
spectroscopy of the Mosher amides.
generally accepted mechanism of hydroamination/cycliza-
tion,25 in which the rate of insertion of the sterically more
hindered olefin is diminished by steric congestion. The
binaphtholate rare-earth-metal complexes furnished the
Table 5. Asymmetric Intramolecular Hydroamination of Secondary Aminoalkenes Catalyzed by Binaphtholate Rare-Earth-
a
Metal Complexes
b
c
entry
subst
cat.
[cat.]/[subst] (%)
T (°C)
t (h)
Nt (h−1
)
ee (%) (confign)
1
2
3
4
5
6
7
8
11a
11a
11b
11b
11b
11b
11b
11b
11b
11b
11b
11b
(R)-2c-Y
(R)-2c-Lu
(R)-2b-Y
(R)-2b-Y
(R)-2b-Lu
(R)-2c-Y
(R)-2c-Y
(R)-2c-Lu
(R)-2c-Lu
(R)-2f-Y
2
2
2
2
2
2
2
2
2
2
2
2
25
25
25
60
25
25
60
25
60
60
60
60
0.33
0.33
15.8
148
148
3.1
8.9
22
3.0
7.5
3.0
24.5
12.5
14
71 (S)
69 (S)
52 (S)
50 (S)
77 (S)
37 (R)
13 (R)
3 (R)
16 (S)
17 (S)
48 (S)
68 (S)
5.5
2.2
16.0
6.5
6.0
2.0
4.0
3.5
3.5
9
10
11
12
(R)-2g-Y
(R)-2g-Lu
14
a
b
General reaction conditions: 0.1 mol L−1 solution of substrate in C6D6, Ar atmosphere. Reaction time at which at least 95% NMR conversion
c
relative to bis(trimethylsilyl)methane internal standard was obtained. Determined by 19F NMR spectroscopy of the Mosher amides after removal
of N-benzyl group.
H
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reversed back to S when the reaction was conducted with (R)-
2c-Lu at 60 °C (Table 5, entry 8 vs entry 9). The other (R)-
binaphtholate catalysts generally furnished the pyrrolidine
products preferentially with S configuration.
Kinetics of the Intramolecular Hydroamination. A
kinetic study was performed with the gem-dimethyl-substituted
aminopentene 3d and (R)-2b-Y at variable temperatures in the
range of 25−60 °C (Figure 4), indicating an approximate zero-
Figure 5. Rate versus catalyst concentration for the hydroamination
of 3d ([subst]0 = 0.2 M) using (R)-2b-Y in C6D6 at 25 °C.
alkenes proceeds via a rate-determining olefin insertion
step.25,29
Unfortunately, attempts to observe species A and B by low-
temperature NMR spectroscopy using stoichiometric amounts
of 2-methylpyrrolidine (4c) or n-propylamine as substrate
mimic have been unsuccessful so far and the NMR spectra
remain broad and featureless over a large temperature range.
No decoalescence to distinguishable species was observed
down to −90 °C, indicating facile amine exchange even under
those conditions. However, additional evidence on the effect of
amine binding on catalytic activity can be inferred from the
reaction of aminodiene 1330 using the triphenylsilyl-substituted
binaphtholate complex (R)-IIIa-Y (Scheme 4). Cyclization of
13 initially leads to the 2,5-disubstituted pyrrolidine inter-
mediate 14 and in a subsequent second cyclization step to the
bicyclic pyrrolizidine 15.31
Figure 4. Time dependence of substrate concentration in the
hydroamination/cyclization of aminopentene 3d (0.2 M) using (R)-
2b-Y ([cat.] = 0.004 M) at variable temperatures in C6D6. The lines
through the data points represents the least-squares fits for the initial
linear part of the data.
order rate dependence on substrate concentration. However,
the plots representing the data for the hydroamination of 3d at
25 and 32 °C show a slight curvature, indicating a slight rate
acceleration during the catalytic reaction. A similar curvature
was also observed for the diphenyl(o-tolyl)silyl-substituted
(R)-2f-Y and tris(4-tert-butylphenyl)silyl-substituted catalyst
(R)-2g-Y (see Figure S1 in the Supporting Information) for
substrate 3d and for the gem-diphenyl-substituted amino-
hexene 5 using (R)-2f-Lu as well (see Figure S4 in the
Supporting Information). Similar catalytic behavior was
previously reported for chiral lanthanocene complexes28 and
the triphenylsilyl-substituted binaphtholate complex (R)-IIIa-
Y9a and can be rationalized to stem from a slight shift between
the catalytically more active, lower coordinate species A and
the less active, higher coordinate species B (Scheme 3).
Species A is slightly more favored at higher conversion,
because of weaker binding of the secondary amine hydro-
amination product in comparison to the sterically less hindered
and stronger binding primary amine starting material.
Scheme 4. Catalytic Hydroamination/Bicyclization of
Aminodiene 13 with (R)-IIIa
The reaction profile indicates that the formation of the
bicyclic product sets in only after consumption of >90% of the
aminodiene starting material with the first trace amounts of
pyrrolizidine 15 becoming noticeable at 98% conversion of
However, it should be mentioned that other catalytic
reactions appear to be strictly zero order up to high
conversions of 90% (see Figures S2−S5 in the Supporting
Information).
1
aminodiene 13 to pyrrolidine 14 (Figure 6; for an H NMR
The plot of the reaction rate versus catalyst concentration
over an 8-fold range (4−32 mmol L−1) (Figure 5) is a straight
line, indicating that the rate of hydroamination/cyclization of
3d using (R)-2b-Y is first order in catalyst concentration and
that the catalytically active species is monomeric.
These findings are in agreement with our previous
investigation using the triphenylsilyl-substituted binaphtholate
complex (R)-IIIa-Y9a and the generally accepted mechanism of
hydroamination, indicating that the cyclization of amino-
stack plot of the various reaction stages see Figure S6 in the
Supporting Information). Most intriguingly, the rate of the
second cyclization step is approximately 6 times faster than the
first cyclization event (k1 = [6.70(8)] × 10−3 s−1, k2 = 0.041(4)
s−1 at 30 °C). This observation contradicts previous studies on
the cyclization of aminodiene 13, in which elevated reaction
temperatures were required to perform the bicyclization step.30
For example, the reaction profile looks quite different when the
simple tris-amido complex [Y{N(SiMe3)2}3] was employed
I
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of 13 in the presence of 10 equiv (relative to catalyst) of n-
propylamine as a nonconsumable mimic of 13. Indeed, no
acceleration effect was observed, and the behavior of the
binaphtholate catalyst (R)-IIIa-Y was similar to that of the tris-
amide [Y{N(SiMe3)2}3] (see Figure S7 in the Supporting
Information).
Asymmetric Intermolecular Hydroamination of Al-
kenes.17 For the initial catalyst screening we chose the
reaction of 1-heptene with benzylamine (Table 6, entries 1−
12). The reactions proceeded smoothly in the presence of 5
mol % binaphtholate catalyst, generating exclusively the
Markovnikov hydroamination product 16. The enantiomeric
excess of the intermolecular hydroamination product 16 was
determined by 19F NMR spectroscopy after the removal of the
N-benzyl group. The absolute configuration of the intermo-
lecular hydroamination product 16 using the R-configured
binaphtholate complexes was found to be R, which is opposite
to that observed for the intramolecular hydroamination of
aminopentenes.
Figure 6. Kinetic profile for the hydroamination/cyclization of 13
([13]0 = 0.67 M) with (R)-IIIa-Y (0.01 M, 1.5 mol %) at 30 °C in
C6D6. The lines are drawn as guides for the eye.
To achieve high conversions within a reasonable amount of
time, the reactions were performed at a temperature as high as
150 °C and a 10−15-fold excess of alkene was used to
accelerate the reaction. Reactions performed with (R)-IIIa-Y at
110 °C required significantly longer in order to achieve high
conversion (Table 6, entry 2), leading to an improved
enantioselectivity of 65% ee in comparison to 58% ee at 150
°C. The excess of alkene was necessary in order to counteract
the poor binding ability of the alkene to the d0 metal in
comparison to the strongly binding amine.32 A lower alkene/
amine ratio resulted in lower conversion and longer reaction
time (Table 6, entry 3), whereas a larger excess of the alkene
significantly reduced the reaction time, concomitant with a
slight reduction in the enantioselectivity (Table 6, entry 4).
The sterically more hindered cyclohexyldiphenylsilyl- and
tert-butyldiphenylsilyl-substituted binaphtholate complexes
(R)-2b-Y and (R)-2c-Y, respectively, exhibited comparable
activity in the intramolecular hydroamination of amino-
pentenes in most cases (Tables 1 and 2); however, the rate
of benzylamine addition to 1-heptene was about 3 times faster
with (R)-2b-Y in comparison to (R)-2c-Y (Table 6, entries 7
and 8). The selectivities achieved with (R)-2b-Y and (R)-2c-Y
of 47% and 46% ee, respectively, were slightly lower than that
observed with (R)-IIIa-Y (Table 6, entries 7 and 8 vs entry 1).
High conversions were observed in most cases, except for
complexes (R)-2d-Y and (R)-2h-Y, which gave lower
conversions (Table 6, entries 9 and 11), and the rigid
dibenzosilole-substituted complex (R)-2a-Y, which was com-
pletely inactive even when it was heated to 170 °C (Table 6,
entry 6). The triisopropylsilyl-substituted binaphtholate
complex (R)-2d-Y displayed not only low activity (60%
conversion in 72 h) but also the lowest enantioselectivity of
38% ee (Table 6, entry 9). This result was expected because
(R)-2d-Y was also the least efficient catalyst among the
binaphtholate catalysts for the intramolecular hydroamination
of aminoalkenes. The p-methoxyphenyl(diphenyl)silyl-substi-
tuted complex (R)-2h-Y displayed the highest enantioselectiv-
ity of up to 60% ee at 150 °C; however, only 45% conversion
was observed due to catalyst decomposition under these
conditions (Table 6, entry 11).
(Figure 7). While the rate of the initial monocyclization step
was quite rapid and formation of 14 was complete within 30
Figure 7. Kinetic profile for the hydroamination/cyclization of 13
([13]0 = 0.67 M) with [Y{N(SiMe3)2}3] (0.02 M, 3 mol %) at 40 °C
in C6D6. The lines are drawn as guides for the eye.
min, the second cyclization proceeded sluggishly (k1:k2
>
500:1 at 40 °C for the linear parts of the respective kinetic
data), with the first traces of 15 becoming noticeable around
80% conversion of 13 to 14. The obvious difference between
(R)-IIIa-Y and [Y{N(SiMe3)2}3] is that the sterically
demanding binaphtholate ligand in (R)-IIIa-Y limits binding
of sterically hindered amines to the metal center, whereas
amine binding to the sterically unshielded tris-amido complex
presumably is unabated. Thus, it can be expected that only the
sterically less hindered primary amine 13 binds to the metal
center of the sterically shielded binaphtholate catalyst, while
the pyrrolidine intermediate 14 does not bind or binds only
very weakly. Upon consumption of the great majority of the
aminodiene starting material, the equilibrium abruptly shifts in
favor of the lower coordinate, significantly more active species
A (Scheme 3), leading to a dramatic increase in the rate of the
second cyclization step. In contrast, it can be assumed that 13
and 14 both bind to the sterically unprotected tris-amide
[Y{N(SiMe3)2}3] with binding constants of comparable
magnitude, taming its catalytic activity toward bicyclization.
In order to test this hypothesis, we performed the cyclization
Further investigations were conducted with other terminal
alkenes and primary amines (Table 6, entries 13−21). The
dicyclohexylphenylsilyl-substituted binaphtholate complex
(R)-2e-Y catalyzed the intermolecular hydroamination of 1-
J
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Article
Table 6. Asymmetric Intermolecular Hydroamination of Unactivated Alkenes with a Primary Amine Using Binaphtholate
a
Catalysts
a
b
General reaction conditions: 3.0 mmol of alkene, 0.2 mmol of amine, 10 μmol of cat. (0.1 mL of 0.1 M cat. solution in C6D6 or tol-d8). The
c
d
conversion of amine was determined via 1H NMR spectroscopy. Isolated yield after column chromatography. Determined by 19F NMR
spectroscopy of the Mosher amide after debenzylation. 8 mol % cat. was used. 4 mol % cat. was used.
e
f
octene with benzylamine at about the same rate as (R)-IIIa-Y;
however, this occurred with significantly lower enantioselec-
tivity (Table 6, entry 14).
The addition of benzylamine to 4-phenyl-1-butene was
achieved with an alkene to amine ratio as low as 10:1. The p-
methoxyphenyl(diphenyl)silyl-substituted binaphtholate com-
plex (R)-2h-Y delivered the intermolecular hydroamination
product 18 at 110 °C with the same 66% ee selectivity as (R)-
IIIa-Y (Table 6, entries 16 and 18). A higher reaction rate was
observed for (R)-2h-Y in comparison to (R)-IIIa-Y; however,
again full conversion was not obtained with (R)-2h-Y due to
significant decomposition of the catalyst even at the lower
reaction temperature.
Hydroamination reactions with p-methoxybenzylamine
proceeded significantly more slowly (Table 6, entries 19−
21), presumably due to the presence of the coordinating
K
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Article
diol ((R)-H2BINOL-TBDPS; 1c),18 5-chloro-5-phenyldibenzosi-
lole,33 chloro(triisopropyl)silane,34 bromotris(4-tert-butylphenyl)-
silane,35 chloro(4-methoxyphenyl)(diphenyl)silane,36 benzylchlorodi-
phenylsilane,37 [Ln(o-C6H4CH2NMe2)3] (Ln = Y, Lu),22 and (R)-
IIIa-Y9a were synthesized according to literature procedures.
Substrates 2,2-diphenylpent-4-enylamine (3a),38a C-(1-allyl-
cyclohexyl)methylamine (3b),38b pent-4-enylamine (3c),25 2,2-
dimethylpent-4-enylamine (3d),38c 2,2-diphenylhex-5-enylamine
(5),38d 2,2-diphenylhept-6-enylamine (7),38e (4E)-2,2,5-triphenyl-
pent-4-enylamine (9),38f N-benzyl-N-(2,2-dimethylpent-4-enyl)amine
(11a),38b N-benzyl-N-(2,2-diphenylpent-4-enyl)amine (11b),38b and
5-amino-1,8-nonadiene (13)30b were synthesized as described in the
literature. The substrates were distilled from finely powdered CaH2
and stored over molecular sieves. All other chemicals were
commercially available and were used as received unless otherwise
stated. C6D6 and toluene-d8 were distilled from sodium/benzophe-
none ketyl. (S)-Mosher acid was converted into the corresponding
(R)-Mosher acid chloride according to the literature procedure.39 The
hydroamination products 2-methyl-4,4-diphenylpyrrolidine (4a),38a 3-
methyl-2-azaspiro[4,5]decane (4b),40a 2-methylpyrrolidine (4c),25
2,4,4-trimethylpyrrolidine (4d),25 2-methyl-5,5-diphenylpiperidine
(6),38a 2-methyl-6,6-diphenylazepane (8),40b,c 2-benzyl-4,4-diphenyl-
pyrrolidine (10),38e 1-benzyl-2,4,4-trimethylpyrrolidine (12a),38b N-
benzyl-2-methyl-4,4-diphenylpyrrolidine (12b),38b 2-(but-3-en-1-yl)-
5-methylpyrrolidine (14),30b 3,5-dimethylhexahydro-1H-pyrrolizine
(15),30b N-benzylheptan-2-amine (16),14b,41a N-benzyloctan-2-
amine (17),14b,41b N-benzyl-4-phenylbutan-2-amine (18),14b,41a and
N-(4-methoxybenzyl)-4-phenylbutan-2-amine (19)14b,41c are known
compounds and were identified by comparison to the literature NMR
spectroscopic data.
methoxy group that can compete for empty binding sites at the
binaphtholate catalysts, resulting in longer reaction times and
lower conversions.
While the binaphtholate complexes are efficient catalysts for
intermolecular hydroaminations of unactivated alkenes with
simple amines, the substrate scope is limited to primary amines
and unbranched terminal alkenes. Attempts to perform the
reactions involving disubstituted alkenes, such as cyclohexene
and α-methylstyrene, or secondary amines, such as piperidine
and pyrrolidine, were not successful. Moreover, the binaph-
tholate catalysts have a low functional group tolerance; thus,
they are prone to deactivation under catalytic conditions,
particularly in the presence of a methoxy group in the substrate
or the catalyst. The reaction of 1,3-benzodioxol-5-ylmethyl-
amine, a derivative of benzylamine, with 1-octene did not lead
to any conversion, and significant decomposition of the
catalyst was observed.
CONCLUSION
■
A variety of novel 3,3′-bis(trisarylsilyl)- and 3,3′-bis-
(arylalkylsilyl)-substituted binaphtholate rare-earth-metal com-
plexes have been prepared and applied in the intramolecular
hydroamination of aminoalkenes as well as the very challenging
intermolecular hydroamination of nonactivated terminal
alkenes with benzylamines. The complexes exhibit high
catalytic activity and enantioselectivity in the hydroamina-
tion/cyclization of aminoalkenes, which is comparable to or
even surpasses the acitivity and selectivity observed with the
previous disclosed complexes (R)-IIIa-Ln and (R)-IIIb-Ln.9a
The sterically demanding cyclohexyldiphenylsilyl-substituted
complex (R)-2b-Lu, the tert-butyldiphenylsilyl-substituted
complex (R)-2c-Lu, the diphenyl(o-tolyl)silyl-substituted
complex (R)-2f-Lu, and the benzyldiphenylsilyl-substituted
(R)-2i-Lu provide for most substrates the highest selectivities,
while the rigid dibenzosilole-substituted complexes (R)-2a-Ln
and the triisopropylsilyl-substituted complexes (R)-2d-Ln are
often less selective and less active than the other complexes.
However, as an exception, it should be noted that (R)-2a-Lu
(as well as (R)-2c-Lu) provided pyrrolidine 10 with 96% ee,
the highest selectivity observed in this series of complexes.
While all new binaphtholate yttrium complexes, except (R)-2a-
Y and (R)-2d-Y, exhibit catalytic activity comparable to or
even greater than that of (R)-IIIa-Y14b in the intermolecular
hydroamination, they show slightly lower selectivities,
contrasting with the structure−selectivity motif observed in
the intramolecular hydroamination. Only the p-methoxy-
phenyl(diphenyl)silyl-substituted complex (R)-2h-Y exhibited
comparable selectivity; however, this system is plagued by
catalyst decomposition. A plausible explanation for the
differing selectivity patterns of intramolecular vs intermolecular
hydroamination reactions may be construed out of the
observation that the absolute configuration of the intermo-
lecular hydroamination product is opposite to the config-
uration observed in the intramolecular reaction, thus implying
that the stereodetermining olefin insertion steps in these two
processes have different geometries.
1H, 13C, and 19F NMR spectra were recorded on Varian (400 and
500 MHz) spectrometers at 25 °C unless otherwise stated. The
absolute configuration of the hydroamination products was
determined by comparison of the 19F NMR spectroscopic data of
the Mosher amides with the assignments reported previously.9a,14b
Silica gel (230−400 mesh, Sorbent Technologies) was used for
column chromatography. Elemental analyses were performed by
Robertson Microlit Laboratories, Inc., Ledgewood, NJ. Because the
rare-earth-metal complexes 2a−i retain trace amounts of free N,N-
dimethylbenzylamine upon isolation, we have been unable to obtain
correct elemental analyses for these compounds.
Chlorodicyclohexyl(phenyl)silane. To a suspension of finely
cut lithium wire (1.60 g, 226.0 mmol) in pentane (100 mL) was
added slowly chlorocyclohexane (19.2 g, 161.5 mmol) for 1 h with
gentle heating. The resulting mixture was heated to refluxing
temperature overnight. The violet mixture was chilled in an ice
bath, and a solution of trichlorophenylsilane (7.04 g, 32.2 mmol) in
pentane (10 mL) was added dropwise. The resulting mixture was
warmed to room temperature and was stirred overnight. Precipitated
lithium chloride salt and excessive lithium were filtered off. The
filtrate was treated with ice-cold 4 M HCl solution (50 mL) to destroy
the remaining cyclohexyllithium. The organic layer was separated,
dried over anhydrous Na2SO4, and concentrated to give a yellow oil.
The product was purified by vacuum distillation, giving two main
fractions, 130−150 °C and above 150 °C at 0.5 Torr, which solidified
in the refrigerator. Both fractions were shown to be identical and
impure by NMR spectroscopy. An attempt to purify the desired
product from dicyclohexyl(phenyl)silane through recrystallization in
1
pentane did not improve the purity (ca. 77% purity). H NMR (400
MHz, CDCl3): δ 7.64−7.53 (m, 2H, aryl-H), 7.45−7.28 (m, 3H, aryl-
H), 1.99−1.55 (m, 10H, cyclohexyl-H), 1.37−1.00 (m, 12H,
cyclohexyl-H). 13C{1H} NMR (100 MHz, CDCl3): δ 134.3, 129.9,
127.8 (aryl), 27.7, 27.6, 26.7, 26.6, 26.5, 25.2 (Cy).
Chlorodiphenyl(o-tolyl)silane. To a solution of 2-bromotoluene
(5.13 g, 30 mmol) in Et2O (30 mL) was added n-BuLi (12 mL, 2.5 M
in hexanes, 30 mmol) slowly at room temperature. The mixture was
stirred for 4 h, and to it was added dichlorodiphenylsilane (7.60 g, 30
mmol) at −10 °C. The reaction mixture was allowed to reach room
temperature and stirred overnight. The precipitate was filtered off, and
the filtrate was concentrated in vacuo. The product was extracted with
EXPERIMENTAL SECTION
■
All reactions with air- or moisture-sensitive materials were performed
with oven- (120 °C) and flame-dried glassware under an inert
atmosphere of dry nitrogen or argon, employing standard Schlenk and
glovebox techniques. (R)-3,3′-Dibromo-1,1′-binaphthalene-2,2′-
diol,18 (R)-3,3′-bis[tert-butyl(diphenyl)silyl]-1,1′-binaphthalene-2,2′-
L
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hexanes (70 mL), and the extract was then concentrated to a volume
of about 15 mL and placed in a freezer to give white crystals (5.08 g,
55% yield). 1H NMR (400 MHz, CDCl3): δ 7.68−7.56 (m, 4H, aryl-
H), 7.52−7.45 (m, 2H, aryl-H), 7.45−7.33 (m, 6H, aryl-H), 7.26−
7.21 (m, 1H, aryl-H), 7.20−7.14 (m, 1H, aryl-H), 2.33 (s, 3H, aryl-
CH3). 13C{1H} NMR (100 MHz, CDCl3): δ 145.2, 137.2, 135.2,
133.6, 131,4, 131.2, 130.71, 130.68, 128.3, 125.2 (aryl), 23.5 (aryl-
CH3).
29.1 (CH2, Cy), 28.84 (CH2, Cy), 28.78 (CH2, Cy), 27.4 (CH2, Cy),
24.7 (CH, Cy). Anal. Calcd for C56H54O2Si2: C, 82.51; H, 6.68.
Found: C, 82.31; H, 6.69.
((R)-3,3′-Bis(triisopropylsilyl)-1,1′-binaphthalene-2,2′-diol
((R)-H2BINOL-TIPS; 1d). To a solution of (R)-3,3′-dibromo-1,1′-
binaphthalene-2,2′-diol (1.50 g, 3.38 mmol) in DMF (20 mL) were
added imidazole (0.70 g, 10.18 mmol) and chloro(triisopropyl)silane
(1.63 g, 8.45 mmol). The resulting mixture was stirred at 90 °C
overnight. The reaction was quenched by addition of saturated
aqueous NaHCO3 (10 mL), and the product was extracted with Et2O
(3 × 30 mL). The combined ether layers were washed with water (3
× 10 mL) and brine (10 mL) and dried (MgSO4). The product was
purified using column chromatography on silica (hexanes) to afford
the crude bis(silyl ether) as a white powder (1.72 g, 67%) which was
subjected to the next reaction without further purification. The crude
bis(silyl ether) was dissolved in THF (25 mL), and t-BuLi (6.0 mL,
9.0 mmol, 1.5 M in pentane) was added dropwise at −50 °C. The
yellow solution was warmed to room temperature slowly and was
stirred for an additional 1 h. The reaction was quenched by addition
of saturated aqueous NH4Cl (10 mL), and the product was extracted
with CH2Cl2 (3 × 20 mL). The combined organic layers were dried
(MgSO4). The product was purified using column chromatography
on silica to afford the pure product 1d as a light yellow powder (1.25
3,3′-Bis(5-phenyl-5H-dibenzo[b,d]silyl-5-yl)-1,1′-binaphtha-
lene-2,2′-diol ((R)-H2BINOL-PDBS; 1a). To a solution of (R)-3,3′-
dibromo-1,1′-binaphthalene-2,2′-diol (1.51 g, 3.40 mmol) in THF
(65 mL) was added KH (409 mg, 10.2 mmol) in three portions. The
resulting mixture was stirred for 30 min before a solution of 5-chloro-
5-phenyldibenzosilole (2.17 g, 7.40 mmol) in THF (10 mL) was
added at room temperature, to give a light orange reaction mixture
which was then heated to 65 °C overnight. To the reaction mixture
was added t-BuLi (9.1 mL, 13.6 mmol, 1.5 M in pentane) dropwise at
−50 °C. The bright yellow mixture was warmed to room temperature
slowly and was stirred for an additional 1 h. The solvent was
evaporated in vacuo. The residue was dissolved in CH2Cl2 (50 mL),
which was then treated with 1 M HCl (20 mL). The organic layer was
separated, dried (Na2SO4), and concentrated. The product was
purified using column chromatography on silica (hexanes/CH2Cl2
80/20) to afford a yellow solid (1.18 g, 43%) which was crystallized
from pentane, giving the pure product 1a as a white powder (0.91 g,
1
g, 63% overall yield). H NMR (400 MHz, CDCl3): δ 8.13 (s, 2H,
aryl-H), 7.89 (d, 3J(H,H) = 8.22 Hz, 2H, aryl-H), 7.38−7.23 (m, 4H,
1
3
33% overall yield). H NMR (500 MHz, C6D6): δ 8.53 (s, 2H, aryl-
aryl-H), 7.10 (d, J(H,H) = 8.22 Hz, 2H, aryl-H), 5.21 (s, 2H, OH),
3
H), 8.05 (m, 2H, aryl-H), 7.94 (d, J(H,H) = 6.85 Hz, 2H, aryl-H),
1.64−1.51 (m, 6H, CH(CH3)2), 1.15−1.12 (m, 36H, CH(CH3)2).
3
4
13C{1H} NMR (125 MHz, CDCl3): δ 157.2 (CO), 139.9, 134.1,
7.82 (m, 4H, aryl-H), 7.73 (dd, J(H,H) = 7.95 Hz, J(H,H) = 1.59
3
Hz, 4H, aryl-H), 7.48 (d, J(H,H) = 7.83 Hz, 2H, aryl-H), 7.40 (m,
4H, aryl-H), 7.35 (m, 2H, aryl-H), 7.25 (t, J(H,H) = 7.21 Hz, 2H,
129.2, 128.6, 127.6, 124.5, 123.8, 123.6, 109.7 (aryl), 19.0
(CH(CH3)2), 11.7 (CH(CH3)2). Anal. Calcd for C38H54O2Si2: C,
76.19; H, 9.08. Found: C, 75.97; H, 9.14.
3
aryl-H), 7.16 (m, 6H, aryl-H overlapped with C6D5H), 7.1 (d,
3J(H,H) = 8.31 Hz, 2H, aryl-H), 7.04 (m, 2H, aryl-H), 6.97 (m, 2H,
(R)-3,3′-Bis(dicyclohexylphenylsilyl)-1,1′-binaphtholene-
2,2′-diol ((R)-H2BINOL-SiCy2Ph; 1e). To a solution of 3,3′-
dibromo-1,1′-binaphthalene-2,2′-diol (500 mg, 1.13 mmol) in DMF
(5 mL) was added imidazole (466 mg, 6.78 mmol) and
chlorodicyclohexyl(phenyl)silane (1.50 g, ca. 77% purity, 3.67
mmol) at room temperature. The resulting mixture was stirred at
90 °C overnight. The reaction was quenched with a saturated aqueous
NaHCO3 solution (5 mL), and the product was extracted with
CH2Cl2 (3 × 30 mL). The combined organic layers were dried
(NaSO4) and concentrated. The product was purified using column
chromatography on silica (hexanes, then hexanes/CH2Cl2 9/1) to
afford the crude bis(silyl ether) as a white powder (1.04 g, 94%),
which was subjected to the next reaction without further purification.
The bis(silyl ether) was dissolved in THF (30 mL), and t-BuLi (2.7
mL, 4.1 mmol, 1.6 M in pentane) was added dropwise at −60 °C. The
bright yellow reaction mixture was warmed slowly to room
temperature and was stirred for an additional 2 h. The reaction was
quenched with a saturated aqueous NH4Cl solution (5 mL) to obtain
a clear solution. The organic layer was separated, and the product was
extracted with CH2Cl2 (3 × 30 mL). The combined organic layers
were dried (Na2SO4) and concentrated. The product was purified
using column chromatography on silica (hexanes/ethyl acetate 95/5)
to afford the pure product 1e as a white powder (0.72 g, 80% overall
aryl-H), 4.78 (s, 2H, OH). 13C{1H} NMR (125 MHz, C6D6): δ 156.9
(CO), 149.6, 149.1, 140.0, 136.97, 135.95, 135.6, 135.3, 135.1, 133.8,
131.0, 130.9, 129.8, 129.7, 129.0, 128.3, 128.3, 127.96, 127.94, 127.86,
127.81, 127.6, 124.2, 124.0, 123.0, 121.5, 121.4, 110.3 (aryl). Anal.
Calcd for C56H38O2Si2: C, 84.17; H, 4.79. Found: C, 83.87; H, 4.80.
(R)-3,3′-Bis[cyclohexyl(diphenyl)silyl]-1,1′-binaphthalene-
2,2′-diol ((R)-H2BINOL-SiCyPh2; 1b). This compound was
prepared as reported previously14b with optimized reaction con-
ditions. To a solution of (R)-3,3′-dibromo-1,1′-binaphthalene-2,2′-
diol (1.50 g, 3.38 mmol) in DMF (11 mL) were added imidazole
(1.39 g, 20.3 mmol) and chloro(cyclohexyl)diphenylsilane (4.07 g,
13.5 mmol). The resulting mixture was stirred at 90 °C overnight.
The reaction was quenched by addition of saturated aqueous
NaHCO3 (5 mL) and was diluted with CH2Cl2 (150 mL). The
organic layer was separated. The product was extracted with CH2Cl2
(3 × 30 mL). The combined organic layers were washed with water
(3 × 15 mL), dried (Na2SO4) and concentrated in vacuo. The
product was purified using column chromatography on silica
(hexanes, then hexanes/CH2Cl2 9/1) to afford the crude bis(silyl
ether) as a white powder (2.78 g, 84%), which was subjected to the
next reaction without further purification. The crude bis(silyl ether)
was dissolved in THF (50 mL), and a t-BuLi solution (7.2 mL, 11.4
mmol, 1.6 M in pentane) was added dropwise at −60 °C. The yellow
solution was stirred for 5 min at −60 °C and was then allowed to
reach room temperature slowly, after which it was stirred for an
additional 1 h. The reaction was quenched with saturated aqueous
NH4Cl (5 mL), and the product was extracted with CH2Cl2 (3 × 40
mL). The combined organic layers were dried (Na2SO4) and
concentrated, and the product was purified using column chromatog-
raphy on silica (hexanes/CH2Cl2 8/2), to afford the pure product 1b
1
yield). H NMR (500 MHz, 25 °C, C6D6): δ 8.21 (s, 2H, aryl-H),
7.81 (d, 3J(H,H) = 6.36 Hz, 4H, aryl-H), 7.54−7.46 (m, 2H, aryl-H),
7.46−7.29 (m, 6H, aryl-H), 7.22 (d, 3J(H,H) = 7.83 Hz, 2H, aryl-H),
7.13−7.02 (m, 4H, aryl-H), 4.83 (s, 2H, OH), 2.16−1.90 (m, 8H,
CH2), 1.89−1.58 (m, 16H, CH2), 1.55−1.27 (m, 12H, CH2), 1.26−
1.04 (m, 8H, CH2 and CH). 13C{1H} NMR (125 MHz, 25 °C,
C6D6): δ 157.5 (CO), 141.7, 136.2, 134.6, 134.5 129.6, 129.1, 129.0,
128.3, 128.1, 127.9, 127.8, 127.7, 123.9, 123.8, 123.6, 110.2 (aryl),
28.7 (CH2), 28.6 (CH2), 28.53 (CH2), 28.50 (CH2), 28.39 (CH2),
28.33 (CH2), 27.3 (CH2), 27.2 (CH2), 22.9 (CH, Cy), 22.6 (CH,
Cy). Anal. Calcd for C56H66O2Si2: C, 81.30; H, 8.04. Found: C,
82.58; H, 8.29.
1
as a white powder (2.28 g, 82% overall yield): mp 263−265 °C. H
NMR (500 MHz, C6D6): δ 8.20 (s, 2H, aryl-H), 7.80−7.77 (m, 8H,
aryl-H), 7.45−7.42 (m, 2H, aryl-H), 7.30−7.26 (m, 12H, aryl-H),
7.10−7.08 (m, 2H, aryl-H), 7.04−6.98 (m, 4H, aryl-H), 4.59 (s, 2H,
OH), 2.09−2.02 (m, 4H, CH2), 1.95−1.89 (m, 2H, CH2), 1.78−1.71
(m, 6H, CH2), 1.45−1.34 (m, 8H, CH2), 1.23−1.16 (m, 2H, CH,
Cy). 13C{1H} NMR (125 MHz, C6D6): δ 157.3 (CO), 141.4, 136.5,
135.2, 135.1, 135.0, 129.9, 124.2, 124.0, 110.3 (aryl), 29.2 (CH2, Cy),
(R)-3,3′-Bis[diphenyl(o-tolyl)silyl]-1,1′-binaphthyl-2,2′-diol
((R)-H2BINOL-DPTS; 1f). To a solution of (R)-3,3′-dibromo-2,2′-
dihydroxy-1,1′-binaphthyl (2.11 g, 4.75 mmol) in THF (50 mL) was
added KH (0.57 g, 14.2 mmol). The resulting mixture was stirred for
M
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Article
30 min at room temperature, and then chloro[diphenyl(o-tolyl)]silane
(3.08 g, 10 mmol) was added. The reaction mixture was stirred for 4
days at 65 °C. To the reaction mixture was added t-BuLi (12 mL, 1.6
M in pentane, 19 mmol) dropwise at −60 °C over a period of 15 min,
which was then allowed to slowly reach room temperature overnight.
The solvent was removed in vacuo. The residue was dissolved in
CH2Cl2 (70 mL), which was then treated with aqueous HCl solution
(30 mL, 6 M). The organic layer was separated, dried over anhydrous
Na2SO4, and evaporated. The product was purified using column
chromatography on silica (hexanes/CH2Cl2 1/1) to afford pure
(s, 2H, OH), 3.87 (s, 6H, OCH3). 13C{1H} NMR (100 MHz,
CDCl3): δ 160.8 (CO), 156.5 (CO), 142.0, 137.9, 136.2, 134.7,
134.6, 129.4, 129.2, 129.0, 128.1, 127.8, 124.8, 123.93, 123.91, 123.8,
113.6, 110.7 (aryl), 55.0 (CH3O).
(R)-3,3′-Bis(benzyldiphenylsilyl)-2,2′-dihydroxy-1,1′-bi-
naphthyl ((R)-H2BINOL-SiBnPh2; 1i). This compound was
prepared as reported previously.37a To a solution of (R)-3,3′-
dibromo-2,2′-dihydroxy-1,1′-binaphthyl (0.800 g, 1.8 mmol) in
THF (25 mL) was carefully added KH (0.148 g, 3.7 mmol) in two
portions with stirring. The resulting yellow solution was stirred at
room temperature for 30 min, and then benzylchlorodiphenylsilane
(1.17 g, 3.8 mmol) was added. The mixture was stirred at room
temperature for 16 h. Then cold H2O (15 mL) was added carefully
and the mixture stirred for 10 min. The organic layer was separated,
and the aqueous layer was extracted with CH2Cl2. The combined
organic layers were dried over Na2SO4. The solvent was removed by
rotary evaporation, and the residue was flashed through a short Al2O3
pad. Removal of the solvent produced the silyl ether in quantitative
yield (1.60 g), which was used without further purification. A solution
of the silyl ether in THF (40 mL) was cooled to −80 °C, and t-BuLi
(4.1 mL, 1.6 M in pentane, 6.56 mmol) was added dropwise over the
course of 45 min. The reaction mixture was allowed to reach room
temperature overnight. The reaction mixture was quenched with
saturated aqueous NH4Cl (30 mL) and stirred for 10 min. The
organic layer was separated, and the aqueous layer was extracted with
Et2O. The combined organic layers were dried (Na2SO4) and
concentrated. The product was purified using column chromatog-
raphy on silica (hexanes/CH2Cl2 2/1) to afford the pure product 1i as
a white powder (0.70 g, 47%). 1H NMR (400 MHz, 25 °C, C6D6): δ
8.11 (s, 2H, aryl-H), 7.71−7.59 (m, 8H, aryl-H), 7.38−7.32 (d,
3J(H,H) = 7.9 Hz, 2H, aryl-H,), 7.31−6.90 (m, 28H, aryl-H), 4.83 (s,
1
product 1f as a white powder (2.01 g, 51%). H NMR (400 MHz,
CDCl3): δ 8.01 (s 2H, aryl-H), 7.77−7.69 (m, 2H, aryl-H), 7.68−7.58
(m, 8H, aryl-H), 7.43−7.35 (m, 8H, aryl-H), 7.34−7.28 (m, 10H,
aryl-H), 7.24−7.18 (m, 4H, aryl-H), 7.15−7.06 (m, 2H, aryl-H), 5.25
(s, 2H, OH), 2.16 (s, 6H, aryl-CH3). 13C{1H} NMR (100 MHz,
CDCl3): δ 156.6 (CO), 145.0, 141.5, 137.8, 136.5, 136.4, 134.87,
134.82, 134.7, 133.1, 130.3, 130.1, 129.51, 129.45, 129.2, 128.3,
128.00, 127.97, 125.3, 124.3, 124.05, 123.99, 110.9 (aryl), 24.2 (aryl-
CH3).
(R)-3,3′-Bis(tris(4-tert-butylphenyl)silyl)-1,1′-binaphthyl-
2,2′-diol ((R)-H2BINOL-TBPS; 1g). To a solution of (R)-3,3′-
dibromo-2,2′-dihydroxy-1,1′-binaphthyl (0.74 g, 1.67 mmol) in THF
(50 mL) was added KH (0.22 g, 5.5 mmol). The resulting mixture
was stirred for 30 min at room temperature before bromotris(4-tert-
butylphenyl)silane (2.12 g, 4.18 mmol) was added. The reaction
mixture was heated for 5 days at 65 °C. The solvent was evaporated in
vacuo. The residue was dissolved in CH2Cl2 (70 mL), which was then
treated with aqueous HCl solution (30 mL, 6 M). The organic layer
was separated, dried over anhydrous Na2SO4, and evaporated. The
product was purified using column chromatography on silica
(hexanes/CH2Cl2 8/1) to afford the crude bis(silyl ether) as a
white powder (1.86 g, 86%), which was subjected to the next reaction
without further purification. The bis(silyl ether) (1.01 g, 0.78 mmol)
was dissolved in THF (40 mL), and t-BuLi (2 mL, 1.6 M in pentane,
3.2 mmol) was added dropwise at −60 °C. The reaction mixture was
warmed to room temperature slowly and was stirred for an additional
5 h. The reaction was quenched with saturated aqueous NH4Cl (5
mL) before the volatiles were removed in vacuo. The product was
extracted with CH2Cl2 (5 × 20 mL). The organic layers were washed
with brine (10 mL), dried over anhydrous Na2SO4, and evaporated.
The product was purified using column chromatography on silica gel
(hexanes/CH2Cl2 3/1) to afford the pure product 1g (0.51 g, 50%
2H, OH), 3.22 (d, 2J(H,H) = 13.8 Hz, 2H, CH2), 3.16 (d, 2J(H,H) =
13.8 Hz, 2H, CH2). 13C{1H} NMR (125 MHz, C6D6): δ 157.2 (CO),
142.0, 139.3, 136.40, 136.35, 135.3, 135.06, 135.01, 129.82, 129.78,
129.6, 129.4, 128.43, 128.38, 128.29, 128.14, 128.08, 124.9, 124.18,
124.14, 110.6 (aryl), 23.9 (SiCH2). Anal. Calcd for C58H46O2Si2: C,
83.81; H, 5.58; Found: C, 83.71; H, 5.33.
(R)-[Y{BINOL-PDBS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2a-
Y). To a mixture of (R)-H2BINOL-PDBS (1a; 24.0 mg, 0.03
mmol) and [Y(o-C6H4CH2NMe2)3] (14.8 mg, 0.03 mmol) was added
C6D6 (0.70 mL). The mixture was kept at room temperature for 1 h.
1H and 13C NMR spectra showed clean formation of (R)-2a-Y, which
1
1
was used directly for catalytic experiments. H NMR (500 MHz, 25
overall yield). H NMR (400 MHz, CDCl3): δ 7.94 (s, 2H, aryl-H),
7.69 (d, 3J(H,H) = 8 Hz, 2H, aryl-H), 7.59 (d, 3J(H,H) = 8 Hz, 12H,
°C, C6D6): δ 8.56 (s, 2H, aryl-H), 8.37−8.24 (m, 2H, aryl-H), 7.98
3
3
(m, 2H, aryl-H), 7.92 (m, 2H, aryl-H), 7.82 (d, J(H,H) = 7.83 Hz,
aryl-H), 7.37 (d, J(H,H) = 8 Hz, 12H, aryl-H), 7.32−7.21 (m, 6H,
2H, aryl-H), 7.76 (d, 3J(H,H) = 7.58 Hz, 1H, aryl-H), 7.71 (d,
aryl-H), 5.32 (s, 2H, OH), 1.31 (s, 54H, C(CH3)3). 13C{1H} NMR
(100 MHz, CDCl3): δ 156.8 (CO), 152.2, 141.9, 136.2, 134.5, 131.0,
129.1, 129.0, 127.8, 124.7, 124.3, 124.0, 123.5, 110.9 (aryl), 34.7
(C(CH3)3), 31.3 (C(CH3)3). The data were in agreement with the
literature.35
3
3J(H,H) = 7.83 Hz, 1H, aryl-H), 7.63 (d, J(H,H) = 7.58 Hz, 1H,
3
aryl-H), 7.57 (m, 1H, aryl-H), 7.48 (t, J(H,H) = 7.58 Hz, 2H, aryl-
H), 7.43−6.81 (m, 28H, aryl-H including free PhCH2NMe2), 6.76 (q,
3J(H,H) = 7.42 Hz, 3H, aryl H), 6.50 (t, 3J(H,H) = 7.21 Hz, 1H, aryl-
3
2
(R)-3,3′-Bis[4-methoxyphenyl(diphenyl)silyl]-2,2′-dihy-
droxy-1,1′-binaphthyl) ((R)-H2BINOL-MPDPS; 1h). To a solution
of (R)-3,3′-dibromo-1,1′-binaphthalene-2,2′-diol (400 mg, 0.90
mmol) in THF (20 mL) was added KH (80 mg, 2.0 mmol) with
stirring. The mixture was stirred at room temperature for 30 min, and
then chloro(4-methoxyphenyl)(diphenyl)silane (601 mg, 1.85 mmol)
was added. The mixture was heated to 70 °C overnight. The reaction
mixture was cooled to −78 °C, and to that was added dropwise t-BuLi
(2.5 mL, 3.7 mmol, 1.5 M in pentane). The yellow solution was
stirred for 5 min at −78 °C and was then allowed to reach room
temperature slowly, after which it was stirred for an additional 1 h.
The reaction was quenched with saturated aqueous NH4Cl (50 mL),
and the product was extracted with Et2O (3 × 20 mL). The combined
organic layers were dried (Na2SO4) and concentrated. The product
was purified using column chromatography on silica (hexanes/
CH2Cl2 70/30) to afford the pure product 1h as a white powder (535
H), 6.41 (d, J(H,H) = 7.58 Hz, 2H, aryl-H), 3.80 (d, J(H,H) =
14.43 Hz, 1H, o-C6H4CH2Me2), 3.23 (m, 4H, free and coordinated
2
PhCH2NMe2), 2.05 (s, 6H, free PhCH2NMe2), 2.67 (d, J(H,H) =
14.43 Hz, 1H, o-C6H4CH2NMe2), 1.48 (s, 3H, N(CH3)2), 1.42 (s,
3H, N(CH3)2), 1.23 (s, 3H, N(CH3)2), 1.15 (s, 3H, N(CH3)2).
13C{1H} NMR (125 MHz, 25 °C, C6D6): δ 182.2 (d, 1J(Y,C) = 53.5
Hz), 162.3 (CO), 161.8 (CO), 149.30, 149.25, 149.1, 148.4, 140.6,
140.4, 140.0, 139.5, 139.4, 138.3, 138.0, 137.64, 137.61, 137.4, 135.8,
135.7, 135.6, 135.4, 135.2, 135.0, 134.3, 131.7, 131.0, 130.9, 130.0,
129.9, 129.5, 129.3, 129.10, 129.08, 129.0, 128.8, 128.7, 128.6, 128.53,
128.45, 128.4, 128.3, 127.7, 127.2, 126.4, 126.3, 125.7, 125.2, 122.93,
122.89, 122.7, 121.7, 121.3, 117.6, 116.3 (aryl), 67.9 (o-
C6H4CH2NMe2), 64.5 (s, free PhCH2NMe2), 58.2 (PhCH2NMe2),
47.2 (N(CH3)2), 45.4 (s, free PhCH2NMe2), 44.1 (N(CH3)2), 40.51
(PhCH2NMe2), 40.45 (PhCH2NMe2).
(R)-[Lu{BINOL-PDBS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2a-
Lu). To a mixture of (R)-H2BINOL-PDBS (1a; 25.5 mg, 0.032
mmol) and [Lu(o-C6H4CH2NMe2)3] (18.4 mg, 0.032 mmol) was
added C6D6 (0.80 mL). The mixture was kept at room temperature
for 1 h. 1H and 13C NMR spectra showed clean formation of (R)-2a-
1
mg, 69% overall yield). H NMR (400 MHz, CDCl3): δ 7.97 (s, 2H,
3
3
aryl-H), 7.76 (d, J(H,H) = 7.8 Hz, 2H, aryl-H), 7.69 (d, J(H,H) =
3
7.1 Hz, 8H, aryl-H), 7.63 (d, J(H,H) = 8.6 Hz, 4H, aryl-H), 7.48−
7.29 (m, 18H, aryl-H), 6.96 (d, J(H,H) = 8.2 Hz, 4H, aryl-H), 5.36
3
N
DOI: 10.1021/acs.organomet.8b00510
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
Lu, which was used directly for catalytic experiments. H NMR (400
MHz, 25 °C, C6D6): δ 8.63 (s, 1H, aryl-H), 8.61 (s, 1H, aryl-H), 8.33
130.1, 129.3, 129.2, 129.1, 128.9, 128.7, 128.6, 128.53, 128.48, 128.4,
128.3, 128.2, 127.2, 127.1, 127.0, 126.2, 125.9, 125.8, 125.2, 122.4,
122.3, 116.8, 115.9 (aryl), 66.9 (CH2), 64.5 (s, free PhCH2NMe2),
57.7 (PhCH2NMe2), 46.4 (N(CH3)2), 45.4 (s, free PhCH2NMe2),
43.8 (N(CH3)2), 40.9 (PhCH2NMe2), 40.3 (PhCH2NMe2), 29.0
(CH2, Cy), 28.9 (CH2, Cy), 28.8 (CH2, Cy), 28.6 (3C, CH2, Cy),
27.9 (CH2, Cy), 27.8 (CH2, Cy), 27.2 (2C, CH2, Cy), 23.6 (CH, Cy),
23.4 (CH, Cy).
3
3
(d, J(H,H) = 7.04 Hz, 1H), 8.26 (d, J(H,H) = 7.04 Hz, 1H), 8.05
(m, 2H, aryl-H), 7.99 (d, J(H,H) = 6.65 Hz, 1H, aryl-H), 7.91 (m,
3
3
2H, aryl-H), 7.80 (m, 5H, aryl-H), 7.69 (d, J(H,H) = 7.43 Hz, 1H,
aryl-H), 7.63 (m, 1H, aryl-H), 7.54 (m, 2H, aryl-H), 7.48 (t, 3J(H,H)
= 7.04 Hz, 1H, aryl-H), 7.44−6.84 (m, 24H, aryl-H including free
3
PhCH2NMe2), 6.80 (m, 4H), 6.54 (t, J(H,H) = 7.24 Hz, 1H, aryl-
3
2
H), 6.44 (d, J(H,H) = 7.04 Hz, 2H, aryl-H), 3.81 (d, J(H,H) =
14.48 Hz, 1H, o-C6H4CH2NMe2), 3.36 (s, 2H, PhCH2NMe2), 3.27
(s, 2H, free PhCH2NMe2), 2.67 (d, 2J(H,H) = 14.48 Hz, 1H, o-
C6H4CH2NMe2), 2.09 (s, 6H, CH3 of free PhCH2NMe2), 1.49 (s, 3H,
N(CH3)2), 1.43 (s, 3H, N(CH3)2), 1.30 (s, 3H, N(CH3)2), 1.24 (s,
3H, N(CH3)2). 13C{1H} NMR (100 MHz, 25 °C, C6D6): δ 191.3 (C-
Lu), 162.7 (CO), 162.2 (CO), 149.4, 149.3, 149.2, 148.8, 140.2,
139.9, 139.6, 139.4, 137.7, 137.3, 135.9, 135.7, 135.5, 135.2, 135.1,
131.8, 130.9, 129.9, 129.5, 129.1, 128.9, 128.7, 128.5, 127.6, 127.5,
127.2, 126.62, 126.59, 126.0, 125.7, 125.0, 122.8, 122.7, 121.7, 121.5,
121.3, 117.3, 116.3 (aryl), 67.3 (o-C6H4CH2NMe2), 64.5 (s, free
PhCH2NMe2), 58.4 (PhCH2NMe2), 47.8 (N(CH3)2), 46.2 (N-
(CH3)2), 45.4 (s, free PhCH2NMe2), 44.5 (N(CH3)2), 40.84
(PhCH2NMe2), 40.78 (PhCH2NMe2).
(R)-[Y{BINOL-TBDPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2c-
Y). This complex was prepared as reported previously.14b To a
mixture of (R)-BINOL-TBDPS (1c; 45.6 mg, 0.06 mmol) and [Y(o-
C6H4CH2NMe2)3] (29.3 mg, 0.06 mmol) was added toluene-d8 (0.55
mL). The mixture was kept at room temperature for 1 h. 1H and 13
C
NMR showed clean formation of (R)-2c-Y, which was used directly
1
for catalytic experiments. H NMR (125 MHz, 0 °C, toluene-d8): δ
8.55 (s, 1H, aryl-H), 8.52 (s, 1H, aryl-H), 8.07 (d, 3J(H,H) = 8.1 Hz,
2H, aryl-H), 7.95 (m, 1H, aryl-H), 7.93 (m, 1H, aryl-H), 7.89−7.84
3
(m, 4H, aryl-H), 7.57 (d, J(H,H) = 6.9 Hz, 1H, aryl-H), 7.55 (d,
3J(H,H) = 8.1 Hz, 1H, aryl-H), 7.48−7.46 (m, 1H, aryl-H), 7.34−
6.94 (m, 28H, aryl-H, including 5H from free PhCH2NMe2), 6.77 (d,
3
3J(H,H) = 7.6 Hz, 1H, aryl-H), 6.62 (d, J(H,H) = 6.9 Hz, 2H, aryl-
H), 3.44 (d, 2J(H,H) = 13.9 Hz, 1H, o-C6H4CH2NMe2), 3.20 (s, 2H,
free PhCH2NMe2), 3.09 (br s, 2H, PhCH2NMe2), 2.52 (d, 2J(H,H) =
13.2 Hz, 1H, o-C6H4CH2NMe2), 2.05 (s, 6H, free PhCH2NMe2), 1.44
(s, 9H, t-Bu), 1.41 (s, 3H, o-C6H4CH2NMe2), 1.39 (s, 9H, t-Bu), 1.29
(s, 3H, PhCH2NMe2), 1.24 (s, 3H, PhCH2NMe2), 1.19 (s, 3H, o-
C6H4CH2NMe2). 13C{1H} NMR (125 MHz, 0 °C, toluene-d8): δ
181.9 (d, 1J (Y,C) = 52.6 Hz), 163.4 (CO), 162.8 (CO), 148.3, 141.4,
141.2, 139.3, 138.9, 138.3, 137.18, 137.15, 136.83, 136.75, 136.71,
136.68, 136.5, 131.9, 130.0, 129.7, 129.3, 129.24, 129.23, 128.82,
128.76, 128.6, 128.4, 128.3, 128.2, 128.1, 127.7, 127.5, 127.4, 127.2,
126.0, 125.8, 125.6, 125.5, 122.6, 122.4, 117.18, 117.15 (aryl), 68.0
(o-C6H4CH2NMe2), 64.5 (s, free PhCH2NMe2), 58.0 (PhCH2NMe2),
46.8 (N(CH3)2), 45.4 (s, free PhCH2NMe2), 44.2 (N(CH3)2), 40.4
(PhCH2NMe2), 40.3 (PhCH2NMe2), 29.7 (C(CH3)3), 29.4 (C-
(CH3)3), 19.7 (C(CH3)3), 19.6 (C(CH3)3).
(R)-[Y{BINOL-SiCyPh2}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2b-Y). This complex was prepared as reported previously.14b To a
mixture of (R)-H2BINOL-SiCyPh2 (1b; 48.9 mg, 0.06 mmol) and
[Y(o-C6H4CH2NMe2)3] (29.3 mg, 0.06 mmol) was added C6D6 (0.55
mL). The mixture was kept at room temperature for 1 h. H and 13
C
1
NMR showed clean formation of (R)-2b-Y, which was used directly
1
for catalytic experiments. H NMR (500 MHz, 25 °C, C6D6): δ 8.48
(s, 1H, aryl-H), 8.47 (s, 1H, aryl-H), 7.94−7.91 (m, 2H, aryl-H),
7.29−7.87 (m, 4H, aryl-H), 7.87−7.82 (m, 2H, aryl-H), 7.70−7.68
3
(m, 1H, aryl-H), 7.65 (d, J(H,H) = 6.9 Hz, 1H, aryl-H), 7.60 (d,
3J(H,H) = 8.0 Hz, 1H, aryl-H), 7.55 (m, 2H, aryl-H), 7.34−6.94 (m,
26H, aryl-H including free PhCH2NMe2), 6.80 (d, 3J(H,H) = 7.3 Hz,
1H, aryl-H), 6.67 (m, 2H, aryl-H), 3.25 (s, 2H, free PhCH2NMe2),
3.13 (d, 2J(H,H) = 13.9 Hz, 1H, o-C6H4CH2NMe2), 2.99 (d, 2J(H,H)
= 13.2 Hz, 1H, PhCH2NMe2), 2.93 (d, 2J(H,H) = 13.2 Hz, 1H,
(R)-[Lu{BINOL-TBDPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2c-Lu). To a mixture of (R)-H2BINOL-TBDPS (1c; 22.9 mg,
0.030 mmol) and [Lu(o-C6H4CH2NMe2)3] (17.3 mg, 0.030 mmol)
was added C6D6 (0.50 mL). The mixture was kept at room
temperature for 1.5 h. 1H and 13C NMR spectra showed clean
formation of (R)-2c-Lu, which was used directly for catalytic
experiments. 1H NMR (400 MHz, 25 °C, C6D6): δ 8.63 (s, 2H,
aryl-H), 8.12 (d, 3J(H,H) = 6.65 Hz, 2H, aryl-H), 8.04 (d, 3J(H,H) =
6.26 Hz, 2H, aryl-H), 7.98−7.89 (m, 4H, aryl-H), 7.76−7.62 (m, 2H,
aryl-H), 7.56 (d, 3J(H,H) = 7.04 Hz, 1H, aryl-H), 7.41−7.28 (m, 3H,
aryl-H), 7.06 (m, 25H, aryl-H including free PhCH2NMe3), 6.86 (d,
2
PhCH2NMe2), 2.33 (d, J(H,H) = 13.9 Hz, 1H, o-C6H4CH2NMe2),
2.28−2.12 (m, 6H), 2.09 (s, 6H, free PhCH2NMe2), 1.76−1.60 (m,
10H), 1.44−1.26 (m, 12H), 1.06−0.97 (m, 6H). 13C{1H} NMR (125
1
MHz, 25 °C, C6D6): δ 181.5 (d, J(Y,C) = 53.5 Hz), 163.5 (CO),
162.5 (CO), 148.8, 140.1, 140.0, 139.2, 139.1, 138.3, 136.9, 136.7,
136.2, 135.72, 135.67, 135.57, 135.46, 131.8, 130.3, 129.3, 129.2,
129.1, 128.8, 128.7, 128.51, 128.45, 128.38, 128.29, 127.9, 127.2,
126.0, 125.8, 125.6, 125.5, 124.8, 122.54, 122.48, 116.93, 116.85
(aryl), 67.6 (CH2), 64.5 (s, free PhCH2NMe2), 57.9 (PhCH2NMe2),
46.1 (N(CH3)2), 45.4 (s, free PhCH2NMe2), 43.6 (N(CH3)2), 40.5
(PhCH2NMe2), 40.2 (PhCH2NMe2), 29.0 (CH2, Cy), 28.9 (CH2,
Cy), 28.8 (CH2, Cy), 28.6 (2C, CH2, Cy), 28.5 (CH2, Cy), 27.9
(CH2, Cy), 27.8 (CH2, Cy), 27.21 (CH2, Cy), 27.20 (CH2, Cy), 23.7
(CH, Cy), 23.4 (CH, Cy).
3
3J(H,H) = 7.43 Hz, 1H, aryl-H), 6.68 (d, J(H,H) = 6.65 Hz, 2H,
2
aryl-H), 3.36 (d, J(H,H) = 14.09 Hz, 1H, o-C6H4CH2NMe2), 3.27
(s, 2H, free PhCH2NMe2), 3.20 (d, 2J(H,H) = 13.7 Hz, 1H,
2
PhCH2NMe2), 3.13 (d, J(H,H) = 13.3 Hz, 1H, PhCH2NMe2), 2.50
2
(R)-[Lu{BINOL-SiCyPh2}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2b-Lu). To a mixture of (R)-H2BINOL-SiCyPh2 (1b; 24.9 mg, 0.031
mmol) and [Lu(o-C6H4CH2NMe2)3] (17.6 mg, 0.031 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
(d, J(H,H) = 14.09 Hz, 1H, o-C6H4CH2NMe2), 2.09 (s, 6H, free
PhCH2NMe2), 1.47 (s, 9H, t-Bu), 1.44 (s, 3H, o-C6H4CH2NMe2),
1.42 (s, 9H, t-Bu), 1.35 (s, 3H, PhCH2NMe2), 1.28 (s, 3H,
PhCH2NMe2), 1.21 (s, 3H, o-C6H4CH2NMe2). 13C{1H} NMR (100
MHz, 25 °C, C6D6): δ 191.4 (C-Lu), 163.7 (CO), 163.5 (CO), 148.8,
140.79, 140.76, 140.65, 140.62, 140.0, 139.67, 139.63, 139.4, 139.2,
137.3, 137.2, 136.9 136.8 136.64, 136.55, 132.0, 129.9, 129.1, 128.9,
128.8, 128.7, 128.5, 128.37, 128.32, 127.5, 127.4, 127.3, 127.2, 126.1,
125.9, 125.2, 122.3, 117.4, 116.9 (aryl), 67.3 (o-C6H4CH2Me2), 64.5
(s, free PhCH2NMe2), 58.0 (PhCH2Me2), 46.9 (N(CH3)2), 45.4 (s,
free PhCH2NMe2), 44.3 (N(CH3)2), 40.7 (PhCH2NMe2), 29.5
(C(CH3)3), 29.4 (C(CH3)3), 19.6 (C(CH3)3), 19.5 (C(CH3)3).
(R)-[Y{BINOL-TIPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2d-
Y). To a mixture of (R)-H2BINOL-TIPS (1d; 16.2 mg, 0.027
mmol) and [Y(o-C6H4CH2NMe2)3] (13.3 mg, 0.027 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
for 1 h. 1H and 13C NMR spectra showed clean formation of (R)-2d-
for 1.5 h. H and 13C NMR spectra showed clean formation of (R)-
1
1
2b-Lu, which was used directly for catalytic experiments. H NMR
(500 MHz, 25 °C, C6D6): δ 8.51 (s, 1H, aryl-H), 8.50 (s, 1H, aryl-H),
3
4
8.06−7.80 (m, 8H, aryl-H), 7.66 (dd, J(H,H) = 6.11 Hz, J(H,H) =
3.18 Hz, 1H, aryl-H), 7.47−7.30 (m, 3H, aryl-H), 7.30−6.90 (m,
3
27H, aryl-H including free PhCH2NMe2), 6.85 (d, J(H,H) = 7.34
3
4
Hz, 1H, aryl-H), 6.68 (dd, J(H,H) = 7.34 Hz, J(H,H) = 1.96 Hz,
2H, aryl-H), 3.27 (s, 2H, free PhCH2NMe2), 3.08 (d, 2J(H,H) = 14.2
Hz, 1H, o-C6H4CH2Me2), 2.99 (d, 2J(H,H) = 13.2 Hz, 1H,
PhCH2NMe2), 2.94 (d, 2J(H,H) = 13.2 Hz, 1H, PhCH2NMe2),
2
2.21 (d, J(H,H) = 13.9 Hz, 1H, o-C6H4CH2NMe2), 2.20−2.08 (m,
6H), 2.09 (s, 6H, free PhCH2NMe2), 1.80−1.55 (m, 10H), 1.52−1.25
(m, 12H), 1.11−0.85 (m, 6H). 13C{1H} NMR (125 MHz, 25 °C,
C6D6): δ 191.0 (C-Lu), 164.0 (CO), 163.0 (CO), 149.3, 140.0, 139.6,
139.5, 139.37, 139.33, 139.2, 136.9, 136.7, 136.2, 135.6, 135.5, 131.9,
1
Y, which was used directly for catalytic experiments. H NMR (400
MHz, 25 °C, C6D6): δ 8.42 (s, 1H, aryl-H), 8.39 (s, 1H, aryl-H), 8.10
O
DOI: 10.1021/acs.organomet.8b00510
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
2
(d, J(H,H) = 6.60 Hz, 1H, aryl-H), 8.02−7.78 (m, 3H, aryl-H),
6.91−6.81 (m, 2H, aryl-H), 3.79 (d, J(H,H) = 13.94 Hz, 1H, o-
2
7.66−6.94 (m, 18H, aryl-H including free PhCH2NMe3), 4.28−4.01
(br m, 3H), 3.69−3.36 (br m, 3H), 2.48−2.14 (m, 9H), 2.14−2.07 (s,
4H), 2.07−1.90 (m, 6H, CH(CH3)2), 1.89−1.80 (m, 2H), 1.77 (s, 3
H, N(CH3)2), 1.71−0.90 (m, 36H, CH(CH3)2). 13C{1H} NMR (100
C6H4CH2NMe2), 3.52 (d, J(H,H) = 13.21 Hz, 1H, PhCH2NMe2),
3.33 (d, J(H,H) = 13.45 Hz, 1H, PhCH2NMe2), 3.25 (s, 2H, free
2
PhCH2NMe2), 3.01 (d, 2J(H,H) = 13.94 Hz, 1H, o-C6H4CH2NMe2),
2.45−2.29 (m, 2H), 2.29−2.09 (m, 10H), 2.07 (s, 6H, free
PhCH2NMe2), 2.04−1.03 (m, 43H, Cy and N(CH3)2). 13C{1H}
NMR (125 MHz, 7 °C, C6D6): δ 190.6 (C-Lu), 163.5 (CO), 163.3
(CO), 148.7, 140.3, 139.9, 139.1, 138.8, 136.8, 136.4, 135.8, 132.0,
130.1, 129.1, 128.8, 128.7, 128.5, 127.2, 127.1, 126.4, 126.1, 125.8,
125.7, 116.5, 116.3 (aryl), 67.4 (o-C6H4CH2NMe2), 64.5 (s, free
PhCH2NMe2), 58.1 (PhCH2NMe2), 47.3, 46.1 (N(CH3)2), 45.4 (s,
free PhCH2NMe2), 44.8, 41.2, 40.9 (N(CH3)2), 29.7, 29.5, 29.3, 29.1,
29.0, 28.9, 28.81, 28.76, 28.6, 28.4, 27.7, 27.51, 27.45, 27.3 (CH2,
Cy), 24.4, 24.3, 24.1, 23.3 (CH, Cy).
1
MHz, 25 °C, C6D6): δ 181.5 (d, J(Y,C) = 53.1 Hz), 163.9 (CO),
163.3 (CO), 148.2, 140.8, 140.5, 138.9, 138.5, 138.2, 131,7, 130.5,
129.5, 129.1, 128.7, 128.6, 127.24, 127.19, 126.3, 125.7, 125.6, 125.4,
125.2, 122.8, 122.6, 117.0, 116.6 (aryl), 68.5 (o-C6H4CH2NMe2),
64.5 (s, free PhCH2NMe2), 59.7 (PhCH2NMe2), 47.0 (N(CH3)2),
45.4 (s, free PhCH2NMe2), 44.7 (N(CH3)2), 41.9 (PhCH2NMe2),
19.9 (3C, CH(CH3)2), 19.8 (3C, CH(CH3)2), 19.7 (6C, CH(CH3)2),
12.8 (3C, CH(CH3)2), 12.7 (3C, CH(CH3)2).
(R)-[Lu{BINOL-TIPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2d-
Lu). To a mixture of (R)-H2BINOL-TIPS (1d; 15.0 mg, 0.025
mmol) and [Lu(o-C6H4CH2NMe2)3] (14.4 mg, 0.025 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
for 1 h. 1H and 13C NMR spectra showed clean formation of (R)-2d-
(R)-[Y-{BINOL-DPTS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2f-
Y). To a mixture of (R)-H2BINOL-DPTS (1f; 24.9 mg, 0.03
mmol) and [Y(o-C6H4CH2NMe2)3] (14.7 mg, 0.03 mmol) was added
C6D6 (0.50 mL). The mixture was kept at room temperature for 1 h.
1H and 13C NMR spectra showed clean formation of (R)-2f-Y, which
1
Lu, which was used directly for catalytic experiments. H NMR (400
1
MHz, 25 °C, C6D6): δ 8.45 (s, 1H, aryl-H), 8.43 (s, 1H, aryl-H), 8.21
was used directly for catalytic experiments. H NMR (400 MHz, 25
3
(d, J(H,H) = 6.26 Hz, 1H, aryl-H), 8.13−7.83 (m, 2H, aryl-H),
°C, C6D6): δ 8.41 (br s, 2H, aryl-H), 8.10−7.91 (br m, 6H, aryl-H),
7.60−6.57 (br m, 44H, aryl-H including free PhCH2NMe2), 3.27, (br
s, 4H, free and coordinate PhCH2NMe2), 3.21 (d, partially overlapped
7.82−6.78 (m, 19H, aryl-H including free PhCH2NMe3), 4.24 (br s,
2H), 4.08 (d, 2J(H,H) = 13.7 Hz, 1H, o-C6H4CH2NMe2), 3.51 (br m,
3H including free PhCH2NMe2), 2.32 (s, 6H), 2.20 (s, 3H), 2.10 (s,
6H, free PhCH2NMe2), 2.07−1.94 (m, 6H, CH(CH3)2), 1.85 (s, 3H,
N(CH3)2), 1.80−1.02 (m, 36H, CH(CH3)2). 13C{1H} NMR (100
MHz, 25 °C, C6D6): δ 190.2 (C-Lu), 163.9 (CO), 163.3 (CO), 148.3,
139.8, 139.7, 139.4, 138.8, 138.5, 131.6, 129.6, 128.9, 128.4, 128.2,
126.9, 126.84, 126.80, 126.2, 125.8, 125.6, 125.5, 125.3, 122.3, 122.1,
116.5, 116.4 (aryl), 67.5 (o-C6H4CH2NMe2), 64.3 (s, free
PhCH2NMe2), 59.4 (PhCH2NMe2), 47.0 (N(CH3)2), 45.1 (s, free
PhCH2NMe2), 44.7 (N(CH3)2), 41.8 (PhCH2NMe2), 19.6 (CH-
(CH3)2), 19.51 (CH(CH3)2), 19.46 (CH(CH3)2), 19.45 (CH-
(CH3)2), 12.7 (CH(CH3)2), 12.6 (CH(CH3)2).
2
by other signal, 1H, o-C6H4CH2NMe2), 2.59 (d, J(H,H) = 14.1 Hz,
1H, o-C6H4CH2NMe2), 2.34 (br s 6H, aryl−CH3), 2.07 (s, 6H, free
PhCH2NMe2), 1.59 (s, 3H, N(CH3)2), 1.40 (br s, 6H, PhCH2NMe2),
1.29 (br s, 3H, N(CH3)2). 13C{1H} NMR (100 MHz, 25 °C, C6D6):
1
δ 181.6 (d, J (Y,C) = 52.3 Hz), 163.3 (CO), 160.0 (CO), 148.5,
145.0, 144.8, 141.6, 140.0 (br s), 139.6, 139.5, 138.4, 138.3, 137.0,
136.8, 136.6, 136.3, 136.1, 135.8, 134.3, 134.1, 131.9 (br s), 130.7,
130.0, 129.5, 129.3, 128.9, 128.8, 127.4, 127.5, 127.3, 126.0, 125.73,
125.65, 124.8, 122.5, 117.3, 116.8 (aryl), 67.9, 64.6 (br s, free
PhCH2NMe2), 58.4 (br s, PhCH2NMe2), 46.5 (N(CH3)2), 45.4 (br s,
free PhCH2NMe2), 44.5 (N(CH3)2), 40.6 (br s, PhCH2NMe2), 24.6
(aryl-CH3), 24.4 (aryl-CH3).
(R)-[Y{BINOL-SiCy2Ph}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2e-Y). To a mixture of (R)-H2BINOL-SiCy2Ph (1e; 51.0 mg,
0.061 mmol) and [Y(o-C6H4CH2NMe2)3] (29.9 mg, 0.061 mmol)
was added C6D6 (0.60 mL). The mixture was kept at room
temperature for 1 h. 1H and 13C NMR spectra showed clean
formation of (R)-2e-Y, which was used directly for catalytic
experiments. 1H NMR (500 MHz, 6 °C, C6D6): δ 8.29 (s, 2H,
aryl-H), 7.83 (d, 3J(H,H) = 6.85 Hz, 2H, aryl-H), 7.75 (d, 3J(H,H) =
6.85 Hz, 2H, aryl-H), 7.58 (d, 3J(H,H) = 7.34 Hz, 2H, aryl-H), 7.38−
7.27 (m, 4H, aryl-H), 7.26−6.89 (m, 20H, aryl-H including free
(R)-[Lu-{BINOL-DPTS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2f-Lu). To a mixture of (R)-H2BINOL-DPTS (1f; 24.9 mg, 0.03
mmol) and [Lu(o-C6H4CH2NMe2)3] (17.3 mg, 0.03 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
for 1 h. H and 13C NMR spectra showed clean formation of (R)-2f-
1
1
Lu, which was used directly for catalytic experiments. H NMR (300
MHz, 25 °C, C6D6): δ 8.42 (br s, partially overlapped by other signal,
1H, aryl-H), 8.38 (br s, partially overlapped by other signal, 1H, aryl-
3
H), 8.20−7.82 (br m, 6H, aryl-H), 7.75−7.65 (br d, J(H,H) = 7.70
3
2
Hz, 2H, aryl-H), 7.57−7.50 (br d, J(H,H) = 7.53 Hz, 2H, aryl-H),
PhCH2NMe2), 6.87−6.76 (m, 2H, aryl-H), 3.86 (d, J(H,H) = 13.94
3
Hz, 1H, o-C6H4CH2NMe2), 3.49 (d, 2J(H,H) = 13.45 Hz, 1H,
PhCH2NMe2), 3.32 (d, 2J(H,H) = 13.45 Hz, 1H, PhCH2NMe2), 3.23
(s, 2H, free PhCH2NMe2), 3.08 (d, 2J(H,H) = 13.94 Hz, 1H, o-
C6H4CH2NMe2), 2.42−2.25 (m, 4H, Cy), 2.22−2.08 (m, 6H, Cy),
2.05 (s, 6H, free PhCH2NMe2), 2.01−1.08 (m, 50H, Cy and
N(CH3)2). 13C{1H} NMR (125 MHz, 6 °C, C6D6): δ 181.5 (d,
1J(Y,C) = 53.5 Hz), 163.1 (CO), 162.8 (CO), 148.3, 141.2, 140.00,
7.50−7.40 (br d, J(H,H) = 7.45 Hz, 2H, aryl-H), 7.50−6.85 (m,
3
34H, aryl-H including free PhCH2NMe2), 6.85−6.72 (br d, J(H,H)
3
= 6.79 Hz, 2H, aryl-H), 6.72−6.52 (br d, J(H,H) = 6.63 Hz, 2H,
2
aryl-H), 3.26 (br s, 2H, free PhCH2NMe2), 3.12 (d, J(H,H) = 14.0
Hz, 1H, o-C6H4CH2NMe2), 2.46 (d, 2J(H,H) = 14.7 Hz, 1H, o-
C6H4CH2NMe2), 2.35 (s, 2H, PhCH2NMe2), 2.08 (s, 12H, aryl−CH3
and free PhCH2NMe2), 1.55 (br s, 3Ḩ N(CH3)2), 1.38 (br s, partially
overlapped by other signal, 3H, N(CH3)2), 1.38 (br s, partially
overlapped by other signal, 3H, NCH3), 1.25 (br s, 3H, NCH3).
13C{1H} NMR (100 MHz, 25 °C, C6D6): δ 191.1 (C-Lu), 163.8,
139.97, 139.0, 138.6, 138.4, 137.7, 136.3, 135.7, 131.8, 130.3, 129.4,
129.3, 129.1, 128.8, 128.6, 128.5, 128.3, 127.9, 127.8, 127.3, 126.2,
125.8, 125.5, 125.3, 125.2, 122.8, 122.6, 116.6, 116.4 (aryl), 68.2 (o-
C6H4CH2NMe2), 64.5 (s, free PhCH2NMe2), 58.2 (PhCH2NMe2),
47.0 (N(CH3)2), 45.4 (s, free PhCH2NMe2), 44.7 (N(CH3)2), 40.9,
40.7 (PhCH2NMe2), 29.6, 29.29, 29.25, 29.22, 29.14, 29.05, 28.95,
28.88, 28.84, 28.72, 28.65, 28.62, 28.3, 27.7, 27.5, 27.4, 27.3 (CH2,
Cy), 24.4, 24.1, 23.9, 23.0 (CH, Cy).
(R)-[Lu{BINOL-SiCy2Ph}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2e-Lu). To a mixture of (R)-H2BINOL-SiCy2Ph (1e; 25.9 mg, 0.031
mmol) and [Lu(o-C6H4CH2NMe2)3] (18.1 mg, 0.031 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
for 1 h. 1H and 13C NMR spectra showed clean formation of (R)-2e-
163.4 (CO), 148.9, 147.3, 144.9, 144.8, 141.2, 141.0, 139.9, 139.68,
139.63, 139.57, 138.4, 138.3, 137.3, 137.1, 136.8, 136.6, 136.5, 136,2,
135.8, 134.3, 134.1, 132.0, 130.6, 130.0, 129.93, 129.87, 129.4, 129.3,
129.2, 129.1, 128.9, 128.8, 128.76, 128.72, 128,71, 128.6, 128.53,
128.45, 128.1, 127.3, 127.2, 126.1, 126.0, 125.9, 125.7, 125.5, 125.4,
125.1, 125.0, 122.3, 117.1, 116.6 (aryl), 67.2 (o-C6H4CH2NMe2),
64.5 (free PhCH2NMe2), 58.2 (PhCH2NMe2), 46.7 (N(CH3)2), 46.2
(N(CH3)2), 45.3 (free PhCH2NMe2), 44.5 (N(CH3)2), 40.7
(N(CH3)2), 24.5 (aryl-CH3), 24.3 (aryl-CH3).
(R)-[Y-{BINOL-TBPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-2g-
Y). To a mixture of (R)-H2BINOL-TBPS (1g; 34.9 mg, 0.03 mmol)
and [Y(o-C6H4CH2NMe2)3] (14.7 mg, 0.03 mmol) was added C6D6
(0.50 mL). The mixture was kept at room temperature for 2 h. 1H and
13C NMR spectra showed clean formation of (R)-2g-Y, which was
1
Lu, which was used directly for catalytic experiments. H NMR (500
MHz, 7 °C, C6D6): δ 8.34 (s, 1H, aryl-H), 8.32 (s, 1H, aryl-H), 7.93
(d, 3J(H,H) = 6.60 Hz, 2H, aryl-H), 7.85 (d, 3J(H,H) = 7.09 Hz, 2H,
aryl-H), 7.79 (d, 3J(H,H) = 7.09 Hz, 2H, aryl-H), 7.68−7.60 (m, 6H,
aryl-H), 7.46−6.92 (m, 18H, aryl-H including free PhCH2NMe2),
1
used directly for catalytic experiments. H NMR (400 MHz, 25 °C,
P
DOI: 10.1021/acs.organomet.8b00510
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
C6D6): δ 8.59 (s, 1H, aryl-H), 8.51 (s, 1H, aryl-H), 8.01 (br d,
MHz, 0 °C, toluene-d8): δ 182.4 (d, 1J (Y,C) = 53.0 Hz), 163.4 (CO),
163.1 (CO), 161.41 (CO), 161.36 (CO), 148.9, 141.9, 140.4, 139.81,
139.75, 139.0, 138.8, 138.5, 137.4, 137.3, 137.2, 136.93, 136.88,
136.81, 136.7, 132.3, 130.3, 129.7, 129.5, 129.2, 128.8, 128.7, 127.7,
127.5, 126.6, 126.5, 126.2, 126.0, 122.8, 117.6, 116.9, 114.6, 114.4
(aryl), 68.1 (o-C6H4CH2NMe2), 64.9 (free PhCH2NMe2), 58.4
(PhCH2NMe2), 54.75 (OCH3), 54.69 (OCH3), 46.9 (N(CH3)2),
45.8 (free PhCH2NMe2) 44.5 (N(CH3)2), 40.6 (N(CH3)2).
3
3J(H,H) = 7.8 Hz, 6H, aryl-H), 7.95 (br d, J(H,H) = 8.2 Hz, 6H,
aryl-H), 7.62 (br d, 3J(H,H) = 6.7 Hz, 1H, aryl-H), 7.40 (pt, 3J(H,H)
= 7.6 Hz, 2H, aryl-H), 7.25 (pt, 3J(H,H) = 7.1 Hz, 4H, aryl-H), 7.19
(d, 3J(H,H) = 6.7 Hz, 8H, aryl-H), 7.15−7.05 (m, 12H, aryl-H
3
including free PhCH2NMe2), 7.03 (pt, J(H,H) = 7.4 Hz, 2H, aryl-
H), 6.98−6.87 (m, 4H, aryl-H including free PhCH2NMe2), 6.83 (pt,
3
3J(H,H) = 7.4 Hz, 1H, aryl-H), 6.75 (d, J(H,H) = 7.1 Hz, 1H, aryl-
2
(R)-[Lu{BINOL-MPDPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2h-Lu). To a mixture of (R)-H2BINOL-MPDPS (1h; 31.3 mg,
0.036 mmol) and [Lu(o-C6H4CH2NMe2)3] (20.8 mg, 0.036 mmol)
was added toluene-d8 (0.60 mL). The mixture was kept at room
temperature for 1 h. 1H and 13C NMR spectra showed clean
formation of (R)-2h-Lu, which was used directly for catalytic
H), 6.68 (br d, 1H, aryl-H), 3.77 (br d, J(H,H) = 14.1 Hz, 1H, o-
C6H4CH2NMe2), 3.21 (br d, partially overlapped by other signal, 1H,
PhCH2NMe2), 3.19 (br s, 2H, free PhCH2NMe2), 2.84 (br d,
2
2J(H,H) = 13.3 Hz, 1H, PhCH2NMe2), 2.68 (d, J(H,H) = 14.1 Hz,
1H, o-C6H4CH2NMe2), 2.01 (br s, 6H, free PhCH2NMe2), 1.47 (br s,
3H, N(CH3)2), 1.33 (br s, 3H, N(CH3)2), 1.31 (br s, 3H, N(CH3)2),
1.23 (br s, 3H, N(CH3)2), 1.08 (br s, 54H, C(CH3)3). 13C{1H} NMR
1
experiments. H NMR (500 MHz, 0 °C, toluene-d8): δ 8.49 (s, 1H,
1
aryl-H), 8.45 (s, 1H, aryl-H), 8.06−7.98 (m, 4H, aryl-H), 7.97−
7.91(m, 6H, aryl-H), 7.86 (d, 3J(H,H) = 8.6 Hz, 2H, aryl-H), 7.67 (d,
3J(H,H) = 6.9 Hz, 1H, aryl-H), 7.55 (m, 1H, aryl-H), 7.46 (d,
(100 MHz, 25 °C, C6D6): δ 182.2 (d, J(Y,C) = 52.4 Hz), 163.5
(CO), 162.6 (CO), 151.9, 151.8, 148.1, 141.6, 141.2, 140.0, 139.7,
139.3, 138.3, 137.1, 137.0, 133.3, 133.2, 131.9, 130.3, 130.0, 129.3,
129.1, 128.9, 128.8, 128.7, 128.5, 127.5, 127.3, 127.2, 126.07, 126.00,
125.7 (s), 125.3, 125.2, 125.1, 122.4, 122.3, 117.1, 116.7 (aryl), 67.9
(o-C6H4CH2NMe2), 64.5 (free PhCH2NMe2), 58.0 (PhCH2NMe2),
47.4 (N(CH3)2), 45.4 (free PhCH2NMe2), 43.5 (N(CH3)2), 40.6
(N(CH3)2), 40.3 (N(CH3)2), 34.6 (C(CH3)3), 31.3 (C(CH3)3).
(R)-[Lu-{BINOL-TBPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2g-Lu). To a mixture of (R)-H2BINOL-TBPS (1g; 34.9 mg, 0.03
mmol) and [Lu(o-C6H4CH2NMe2)3] (17.3 mg, 0.03 mmol) was
added C6D6 (0.50 mL). The mixture was kept at room temperature
for 1 h. 1H and 13C NMR spectra showed clean formation of (R)-2g-
3
3J(H,H) = 7.6 Hz, 1H, aryl-H), 7.28 (d, J(H,H) = 7.3 Hz, 2H, aryl-
H), 7.25−6.84 (m, 33H, aryl-H including free PhCH2NMe2 and
C7D7H), 6.72 (d, 3J(H,H) = 7.3 Hz, 1H, aryl-H), 6.67−6.54 (m, 6H,
2
aryl-H), 3.24 (d, J(H,H) = 13.5 Hz, partially overlapped by other
signal, 1H, PhCH2NMe2), 3.20 (s, 6H, OCH3), 3.18 (s, 2H, free
2
PhCH2NMe2), 3.15 (d, J(H,H) = 14.2 Hz, 1H, o-C6H4CH2NMe2),
2
2
3.09 (d, J(H,H) = 13.5 Hz, 1H, PhCH2NMe2), 2.34 (d, J(H,H) =
14.2 Hz, 1H, o-C6H4CH2NMe2), 2.05 (s, 6H, free PhCH2NMe2), 1.46
(s, 3H, o-C6H4CH2NMe2), 1.32 (s, 3H, PhCH2NMe2), 1.28 (s, 3H,
PhCH2NMe2), 1.16 (s, 3H, o-C6H4CH2NMe2). 13C{1H} NMR (125
MHz, 0 °C, toluene-d8): δ 192.0 (C-Lu), 164.0 (CO), 163.6 (CO),
161.4 (CO), 161.3 (CO), 149.4, 141.5, 141.3, 140.3, 139.9, 139.8,
139.0, 138.8, 137.4, 137.3, 137.2, 137.0, 136.8, 136.7, 132.4, 130.2,
129.1, 128.95, 128.94, 128.8, 128.4, 127.6, 126.6, 126.5, 126.3, 122.7,
117.4, 116.7, 114.6, 114.3 (aryl), 67.4 (o-C6H4CH2NMe2), 64.8 (free
PhCH2NMe2), 58.3 (PhCH2NMe2), 54.73 (OCH3), 54,67 (OCH3),
47.3 (N(CH3)2), 45.8 (free PhCH2NMe2), 44.5 (N(CH3)2), 40.80
(PhCH2NMe2), 40.78 (PhCH2NMe2).
1
Lu, which was used directly for catalytic experiments. H NMR (400
MHz, 25 °C, C6D6): δ 8.68 (br s, 1H, aryl-H), 8.62 (br s, 1H, aryl-H),
8.24−7.86 (br m, 12H, aryl-H), 7.81−7.73 (br s, 1H, aryl-H), 7.56−
7.44 (m, 2H, aryl-H), 7.44−7.08 (m, 24H, aryl-H including free
PhCH2NMe2), 7.06−6.92 (br s, 4H, aryl-H including free
PhCH2NMe2), 6.92−6.88 (br m, 1H, aryl-H), 6.87−6.80 (br m,
2
1H, aryl-H), 6.80−6.71 (br s, 1H, aryl-H), 3.75 (d, J(H,H) = 14.1
Hz, 1H, o-C6H4CH2NMe2), 3.30 (br d, partially overlapped by other
signal, 1H, PhCH2NMe2), 3.26 (br s, 2H, free PhCH2NMe2), 2.86 (br
d, 2J(H,H) = 13.3 Hz, 1H, PhCH2NMe2), 2.62 (br d, 2J(H,H) = 14.1
Hz, 1H, o-C6H4CH2NMe2), 2.07 (br s, 6H, free PhCH2NMe2) 1.54
(br s, 3H, N(CH3)2), 1.40 (br s, 3H, N(CH3)2), 1.37 (br s, 3H,
N(CH3)2), 1.21 (br s, partially overlapped by other signal, 3H,
N(CH3)2), 1.14 (s, 54H, CH3 of C(CH3)3). 13C{1H} NMR (100
MHz, 25 °C, C6D6): δ 192.0 (C-Lu), 164.0 (CO), 163.1 (CO),
151.84, 151.77, 148.5, 141.0 140.8, 139.7, 139.61, 139.57, 137.1,
137.0, 133.3, 133.2, 130.1, 129.1, 129.0, 128.86, 128.81, 128.7, 128.5,
128.4, 127.2, 127.12, 127.09, 126.2, 126.0, 125.7, 125.2, 125.0, 122.2,
122.1, 116.71, 116.69 (aryl), 67.2 (o-C6H4CH2NMe2), 64.5 (free
PhCH2NMe2), 57.9 (PhCH2Me2), 48.0 (N(CH3)2), 45.3 (free
PhCH2NMe2), 43.3 (N(CH3)2), 41.0 (N(CH3)2), 40.3 (N(CH3)3),
34.57 (C(CH3)3), 34.54 (C(CH3)3), 31.3 (C(CH3)3).
(R)-[Y(BINOL-SiBnPh2)(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2i-Y). In the glovebox, a screw-cap NMR tube was charged with
(R)-H2BINOL-SiBnPh2 (1i; 53.3 mg, 0.064 mmol) and [Y(o-
C6H4CH2NMe2)3] (31.5 mg, 0.064 mmol), and then C6D6 (0.60 mL)
1
was added. The mixture was kept at room temperature for 0.5 h. H
and 13C NMR spectra showed clean formation of (R)-2i-Y, which was
1
used directly for catalytic experiments. H NMR (400 MHz, 25 °C,
C6D6): δ 8.41 (s, 1H, aryl-H), 8.38 (s, 1H, aryl-H), 7.80−7.58 (m,
6H, aryl-H), 7.40−6.71 (m, 46H, aryl-H including free PhCH2NMe2),
3.81 (d, 2J(H,H) = 12.9 Hz, 1H, SiCH2), 3.73 (d, 2J(H,H) = 13.3 Hz,
1H, SiCH2), 3.26 (br s, 5H, free PhCH2NMe2 and SiCH2), 3.01 (d,
2
2J(H,H) = 14.1 Hz, 1H, o-C6H4CH2NMe2), 2.85 (d, J(H,H) = 13.3
Hz, 1H, PhCH2NMe2), 2.82 (d, 2J(H,H) = 13.3 Hz, 1H,
2
PhCH2NMe2), 2.47 (d, J(H,H) = 14.1 Hz, 1H, o-C6H4CH2NMe2),
(R)-[Y{BINOL-MPDPS}(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2h-Y). To a mixture of (R)-H2BINOL-MPDPS (1h; 33.0 mg,
0.039 mmol) and [Y(o-C6H4CH2NMe2)3] (19.3 mg, 0.039 mmol)
was added toluene-d8 (0.55 mL). The mixture was kept at room
temperature for 0.5 h. 1H and 13C NMR spectra showed clean
formation of (R)-2h-Y, which was used directly for catalytic
2.09 (br s, 6H, free PhCH2NMe2), 1.85 (s, 3H, o-C6H4CH2NMe2),
1.35 (br s, 6H, PhCH2NMe2), 1.22 (s, partially overlapped by other
signal, 3H, o-C6H4CH2NMe2). 13C{1H} NMR (100 MHz, 25 °C,
1
C6D6): δ 181.3 (d, J(Y,C) = 52.4 Hz), 163.9 (CO), 162.2 (CO),
148.7, 140.7, 140.4, 140.0, 139.5, 139.4, 139.2, 138.3, 136.9, 136.8,
136.5, 136.1, 135.8, 135.6, 135.2, 129.8, 129.6, 129.5, 129.4, 129.3,
129.1, 128.9, 128.8, 128.63, 128.59, 128.54, 128.48, 128.3, 128.2,
128.1, 127.8, 127.5, 127.4, 127.3, 127.0, 126.19, 126.15, 126.07, 125.6,
124.84, 124.82, 124.6, 122.6, 122.5, 118.0, 116.5 (aryl), 67.4 (o-
C6H4CH2NMe2), 64.5 (free PhCH2NMe2), 58.4 (PhCH2NMe2), 45.8
(N(CH3)2), 45.3 (free PhCH2NMe2)), 44.5 (N(CH3)2), 40.6
(N(CH3)2), 24.0 (SiCH2).
1
experiments. H NMR (500 MHz, 0 °C, toluene-d8): δ 8.46 (s, 1H,
aryl-H), 8.43 (s, 1H, aryl-H), 8.07−7.96 (br m, 4H, aryl-H), 7.96−
7.90 (br m, 6H, aryl-H), 7.85 (d, 3J(H,H) = 8.3 Hz, 2H, aryl-H), 7.55
3
3
(d, J(H,H) = 6.8 Hz, 1H, aryl-H), 7.52 (d, J(H,H) = 7.6 Hz, 1H,
aryl-H),), 7.43 (d, 3J(H,H) = 7.8 Hz, 1H, aryl-H), 7.28 (d, 3J(H,H) =
7.3 Hz, 3H, aryl-H), 7.25−6.84 (m, 30H, aryl-H including free
3
PhCH2NMe2 and C7D7H), 6.70 (d, J(H,H) = 7.6 Hz, 1H, aryl-H),
6.66−6.54 (m, 6H, aryl-H), 3.23 (d, J(H,H) = 13.9 Hz, partially
overlapped by other signal, 1H, CH2), 3.20 (s, 3H, CH2 and free
(R)-[Lu(Binol-SiBnPh2)(o-C6H4CH2NMe2)(Me2NCH2Ph)] ((R)-
2i-Lu). In the glovebox, a screw-cap NMR tube was charged with
(R)-H2BINOL-SiBnPh2 (1i; 42.5 mg, 0.051 mmol) and [Lu(o-
C6H4CH2NMe2)3] (29.5 mg, 0.051 mmol), and then C6D6 (0.50 mL)
2
PhCH2NMe2), 3.19 (s, 3H, OCH3), 3.18 (s, 3H, OCH3), 3.09 (d,
2
2J(H,H) = 13.5 Hz, 1H, PhCH2NMe2), 2.45 (d, J(H,H) = 14.4 Hz,
1
was added. The mixture was kept at room temperature for 0.5 h. H
1H, o-C6H4CH2NMe2), 2.05 (s, 6H, free PhCH2NMe2), 1.49 (s, 3H,
o-C6H4CH2NMe2), 1.33 (s, 3H, PhCH2NMe2), 1.28 (s, 3H,
PhCH2NMe2), 1.19 (s, 3H, o-C6H4CH2NMe2). 13C{1H} NMR (125
and 13C NMR spectra showed clean formation of (R)-2i-Lu, which
1
was used directly for catalytic experiments. H NMR (500 MHz, 25
°C, C6D6): δ 8.42 (s, 1H, aryl-H), 8.38 (s, 1H, aryl-H), 7.77−7.59 (m,
Q
DOI: 10.1021/acs.organomet.8b00510
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
6H, aryl-H), 7.34−6.84 (m, 46H, aryl-H), 6.65−6.50 (m, 3H, aryl-H),
3.80 (d, 2J(H,H) = 13.2 Hz, 1H, SiCH2), 3.71 (d, 2J(H,H) = 13.2 Hz,
1H, SiCH2), 3.27 (s, 2H, free PhCH2NMe2), 3.16 (d, 2J(H,H) = 13.4
μmol, 5 mol %). The tube was then sealed, removed from the
glovebox, and placed into the thermostated oil bath. The progress of
the reaction was monitored by 1H NMR spectroscopy. After
completion of the reaction, the mixture was concentrated in vacuo
and purified by column chromatography on a 3 cm height pad of silica
or alumina.
2
Hz, 1H, SiCH2), 3.10 (d, J(H,H) = 13.4 Hz, 1H, SiCH2), 2.97 (d,
2
2J(H,H) = 14.0 Hz, 1H, CH2), 2.83 (d, J(H,H) = 14.0 Hz, 1H,
2
2
CH2), 2.82 (d, J(H,H) = 14.2 Hz, 1H, CH2), 2.38 (d, J(H,H) =
14.2 Hz, 1H, CH2), 2.09 (s, 6H, free PhCH2NMe2), 1.77 (s, 3H, o-
C6H4CH2NMe2) 1.35 (s, 3H, PhCH2NMe2), 1.31 (s, 3H,
PhCH2NMe2), 1.20 (s, 3H, o-C6H4CH2NMe2). 13C{1H} NMR (125
MHz, 11 °C, C6D6): δ 190.7 (C-Lu), 164.2 (CO), 162.6 (CO), 149.2,
140.3, 140.0, 139.9, 139.7, 139.5, 139.29, 139.26, 139.16, 137.0, 136.8,
136.3, 136.1, 135.9, 135.7, 135.5, 135.1, 135.0, 131.8, 129.9, 129.63,
129.58, 129.54, 129.48, 129.41, 129.3, 129.1, 128.8, 128.64, 128.59,
128.54, 128.46, 128.40, 128.34, 128.29, 128.26, 128.14, 128.08, 127.9,
127.3, 127.2, 126.5, 126.4, 126.2, 126.0, 125.2, 124.6, 122.5, 122.4,
117.6, 116.4 (aryl), 66.6 (o-C6H4CH2NMe2), 64.4 (free
PhCH2NMe2), 58.2 (PhCH2NMe2), 46.0 (N(CH3)2), 45.4 (free
PhCH2NMe2), 44.6 (N(CH3)2), 40.59 (N(CH3)2), 40.58 (N-
(CH3)2), 23.9 (SiCH2).
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00510.
■
S
Additional kinetic data and NMR spectra of ligands,
complexes, and Mosher amides (PDF)
AUTHOR INFORMATION
Corresponding Author
*E-mail for K.C.H.: kai.hultzsch@univie.ac.at.
■
General Procedure for Catalytic Asymmetric Hydroamina-
tion/Cyclization of Aminoalkenes. In a glovebox, a screw-cap
NMR tube was charged with aminoalkene (0.03−0.10 mmol),
ferrocene (3.0 mg, 16.1 μmol), C6D6 (to give a total volume of
0.50 mL), and catalysts (0.60−3.0 μmol, 0.060 M in C6D6). The
NMR tube was capped, immediately removed from the glovebox, and
shaken well to dissolve ferrocene. The progress of cyclization was
ORCID
Bernd Schmidt: 0000-0002-0224-6069
Kai C. Hultzsch: 0000-0002-5298-035X
Notes
The authors declare no competing financial interest.
1
monitored by H NMR spectroscopy by following the disappearance
of the olefinic signals of the substrate relative to the internal standard
ferrocene. The NMR tube was heated in a thermostated oil bath, if
required. The time was recorded after a conversion of at least 95%
was achieved.
General Procedure for Preparing Mosher Amides. The amine
(0.01−0.03 mmol) was dissolved in CDCl3, C6D6, or toluene-d8 (0.50
̈
mL) in a NMR tube. Hunig’s base (2.5 equiv with respect to amine
ACKNOWLEDGMENTS
■
This work was supported by the National Science Foundation
through a NSF CAREER Award (CHE 0956021). S.A. thanks
the Deutscher Akademischer Austauschdienst (DAAD) for an
overseas exchange award.
and (R)-Mosher acid chloride (1.5 equiv with respect to amine) were
added. The enantiomeric excess was determined by 19F NMR
spectroscopy at 60−110 °C.
REFERENCES
■
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