Pentiptycene-based concave NHC-metal complexes

Article abstract of DOI:10.1039/c6dt01724j

The reaction of 1-amino,4-hydroxy-pentiptycene with diacetyl or acenaphthene-1,2-dione gave the respective diimines, followed by alkylation of the hydroxyl groups, and cyclization of the alkylated diimines to the respective bispentiptycene-imidazolium sal

Full text of DOI:10.1039/c6dt01724j

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Pentiptycene-based concave NHC–metal
complexes†
Cite this: DOI: 10.1039/c6dt01724j
Roman Savka, Sabine Foro and Herbert Plenio*
The reaction of 1-amino,4-hydroxy-pentiptycene with diacetyl or acenaphthene-1,2-dione gave the
respective diimines, followed by alkylation of the hydroxyl groups, and cyclization of the alkylated diimines
to the respective bispentiptycene-imidazolium salts NHC·HCl. The azolium salts, being precursors to
N-heterocyclic carbenes, were converted into metal complexes [(NHC)MX] (MX = CuI, AgCl, AuCl) and
Received 2nd May 2016,
Accepted 4th June 2016
DOI: 10.1039/c6dt01724j
2
[(NHC)IrCl(cod)] and [(NHC)IrCl(CO) ] in good yields. In the solid state [(NHC)AgCl] displays a bowl-
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shaped structure of the ligand with the metal center buried within the concave unit.
Triptycene phosphines have been used in organometallic
Introduction
1
4–19
chemistry,
as well as the recently reported bistriptycene-
2
0
Iptycenes are a class of aromatic molecules with arenes fused based NHC ligands, but to the best of our knowledge, pentip-
1
to a bicyclo[2.2.2]octane framework, which have found tycene-based NHC ligands have not been reported. The use of
numerous applications in polymer chemistry, molecular pentiptycenes for NHC ligands offers interesting prospects,
2
3
,4
5–7
machines, materials science and in host–guest chemistry.
since the pentiptycene unit confers a bowl type shape to the
Triptycene, the first representative of this family of compounds respective NHC. In this contribution, we want to report on the
8
was published by Bartlett et al. in 1942 (Scheme 1). The syn- synthesis of bispentiptycene-based NHC ligands and metal
thesis of pentiptycene was reported in 1974 by Skvarche and
9
10
Shalaev, but despite significant improvements, its synthesis
1
remains cumbersome. Pentiptycene quinone, on the other
hand, is easily available from the reaction of anthracene and
benzoquinone followed by the oxidation of the initial Diels–
1
1,12
Alder product.
This quinone can be converted into the
respective amino-pentiptycene (Scheme 2), which (like most
1
3
anilines) should serve as an excellent precursor for N-hetero-
cyclic carbenes and the respective transition metal complexes.
Scheme 1 Structures of triptycene and pentiptycene.
Organometallic Chemistry, Alarich-Weiss-Str. 12, TU Darmstadt, 64287 Darmstadt,
Germany. E-mail: plenio@tu-darmstadt.de
Scheme 2 Three-step synthesis of pentiptycene aminophenol.
Reagents and conditions: (a) p-chloranil, AcOH, reflux 16 h; (b)
†
Electronic supplementary information (ESI) available. CCDC 1424889. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c6dt01724j
NH
reflux 3 h.
2
OH·HCl, 4% aq. HCl, THF, reflux 3 d; (c) N
2
H
4
·H
2
O, Pd/C (5%), THF
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complexes with this new ligand as well as preliminary catalytic
studies.
Our attempts to obtain the respective diimines with glyoxal
and aminophenol 3 appeared promising. However, an impure
product was always obtained, which could neither be purified
to a satisfactory level nor cleanly converted into the desired
azolium salts. Based on the idea, that this might be due to the
incomplete conversion of reactants and the formation of
diimine isomers with extremely bulky pentiptycene units, we
tried the analogous reactions of aminophenol 3 with ace-
naphthene-1,2-dione. The clean formation of such diimines
Results and discussion
Synthesis of pentiptycene NHC ligands
The reaction of two equivalents of anthracene with 1,4-benzo-
quinone in the presence of chloranil leads to pentiptycene
quinone 1 according to a procedure from Chen et al.
2
2
with conventional anilines as well as their cyclization to
1
2
2
3,24
(Scheme 2).
azolium salts has been shown before.
Furthermore, the
In order to obtain a sufficient amount of pentiptycene for
acenaphthene backbone enforced Z-geometry of the diimines
the synthesis of the NHC ligands, the scale of the reaction was
considerably increased (almost 20-fold) with respect to the lit-
erature procedure. This scaling up turned out to be unproble-
matic and it is now possible to synthesize 75 g of pentiptycene
quinone 1 in a single run, using cheap commercially available
starting materials. Quinone 1 was converted into monooxime 2
employing a literature procedure. In contrast to literature
reports claiming low stability of this compound, in our
hands 2 turned out to be stable. Monooxime 2 was reduced to
the amino-hydroxy-pentiptycene 3 using hydrazine hydrate
and Pd/C. This procedure appears to be more convenient than
facilitates the formation of the respective azolium salts with
2
5
sterically highly demanding N-aryl substituents, whose for-
2
6
mation can be very difficult otherwise.
The respective
azolium salts were obtained in good yields as shown in
Scheme 3.
We next tested the reaction of aminophenol 3 with diacetyl
2
7,28
according to standard procedures,
which also leads to the
2
1
respective diimine in good yields (Scheme 3). Following alkyl-
ation of the phenolic –OH group with MeI or BuI, the diimines
were cyclized to the respective azolium salts 6a/6b·HCl or
2
5,29
9
·HCl using ClCH OEt.
The use of this alkylating agent
2
the literature procedure using SnCl
provided impure materials, whose purification required sig-
2
/HCl, which in our hands
provides much better yields than with paraformaldehyde
employed previously for the cyclization of related diimines.
3
0
2
1
nificant effort. In contrast to literature reports, the pentipty-
cene aminophenol 3 displays reasonable solubility in several
1
13
Synthesis of metal complexes
organic solvents and recording H and C NMR spectra poses
no problem. In general, we notice that the pentiptycene deriva- In order to evaluate the coordinating properties of the new
tives display significantly better solubility than the related trip- NHC ligands, several new metal complexes were synthesized.
2
0
tycene compounds also reported by us.
The synthesis of metal complexes with the new carbenes 6a,
Scheme 3 Synthesis of bispentiptycene-NHC·HCl ligands. Reagents and conditions: (a) acenaphthene-1,2-dione, MeCN, AcOH, 90 °C; (b) MeI,
3
CO , DMF, 50 °C or hexyliodide, K CO , DMF, 70 °C; (c) EtOCH Cl, 80 °C; (d) 2,3-butanedione, iPrOH, HCOOH, 80 °C; (e) butyliodide, K CO ,
K
2
3
2
3
2
2
DMF, 70 °C.
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Scheme 4 Synthesis of metal complexes with acenaphthene-based bispentiptycene NHC ligands. Reagents and conditions: (a) Ag
2 2 2
O, CH Cl ,
40 °C; (b) [AuCl(Me
2
S)], K
2
CO
3
, acetone, 60 °C; (c) CuI, K
2
CO
3
, acetone, 60 °C; (d) [IrCl(cod)]
2
, sodium tert-pentoxide, THF, rt; (e) CO, CH
2
Cl , rt.
2
6
b and 9 turned out to be unproblematic (Schemes 4 and 5). numbers might be difficult to obtain. Despite testing several
Several metal complexes with Cu, Ag and Au with coordination different approaches the respective Pd(II) complex with
number 2 were prepared in good yields according to standard carbene 9 could not be synthesized. On the other hand, the
3
1
32
33,34
procedures for Cu, Ag and Au.
(9)AgCl] indicated that due to the pronounced steric bulk of straightforward, even though the higher coordination number
NHC 9 (see below), metal complexes with higher coordination of Ir in the expected complexes might have caused problems
The crystal structure of synthesis of the four coordinate Ir complexes turned out to be
[
Scheme 5 Synthesis of metal complexes with diacetyl-derived bispentiptycene NHC ligands. Reagents and conditions: (a) Ag
b) [IrCl(cod)] , toluene, 100 °C; (c) CO, CH Cl , rt; (d) [AuCl(Me S)], K CO , CH Cl , rt.
2 2 2
O, CH Cl , 40 °C;
(
2
2
2
2
2
3
2
2
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2
Table 1 (NHC)AuCl/AgNTf -catalyzed cyclization of diethyl 2-allyl-2-
(
prop-2-ynyl)malonate
Catalyst
Reaction time, h
Isolated yield (%) (I : II)
[
[
[
(6b)AuCl]
(9)AuCl]
(IMes)AuCl]
16
16
18
91 (2.6 : 1)
93 (2.4 : 1)
35 (1 : 2.1)
when binding to the very bulky NHC ligand. Two different
Fig. 1 X-ray crystal structure of [(9)AgCl] (space-filling plot). CCDC
established approaches (Schemes 4 and 5) were tried, both of 1424889 contains the supplementary crystallographic data for this
them afforded the desired complexes. The transmetalation structure.
via in situ formed [(9)AgCl] complexes to give [(9)IrCl(cod)]
requires harsh reaction conditions. The formation of
[(6)IrCl(cod)] via the free carbene works under mild reaction
conditions. Despite the very different reaction conditions
employed, both methods produce the respective Ir complexes
in good yields of 70% and 79%. Both complexes were con-
verted into the respective [(NHC)IrCl(CO)
2
] complexes in excel-
lent yields. In order to evaluate the donor properties of NHC
ligands 6 and 9, the redox potentials of [(6a)IrCl(cod)] (E1/2
.862 V) and [(9)IrCl(cod)] (E1/2 = 0.804 V) were determined
and found to be comparable to those of the analogous com-
3
5
=
0
2
7,36
plexes with SIMes ligands.
3
7
Preliminary catalytic studies of the gold complexes [(6b)
AuCl] and [(9)AuCl] show better catalytic activity in the cycliza-
3
8,39
tion of diethyl 2-allyl-2-(prop-2-ynyl)malonate
(Table 1)
than the closely related [(IMes)AuCl] (Table 1), furthermore
the pentiptycene-based catalysts give a much higher selectivity
for the formation of the five-membered ring than the IMes
type catalysts. More detailed studies of the catalytic properties
of such complexes are underway. This appears promising,
since gold complexes with sterically highly demanding ligands
49
Fig. 2 X-ray crystal structure of [(9)AgCl] (ORTEP-plot) (hydrogen
atoms omitted, only α and β-carbon atoms of the disordered butyl chain
are shown). Important bond lengths (pm): Ag–C(NHC) 209.0(5), Ag–Cl
234.8(3).
40,41
have been shown to exhibit excellent catalytic activity.
NHC ligand both lie on a two-fold crystallographic axis. The
bond distances and angles within the coordination sphere of
Crystal structure of [(9)AgCl]
Single crystals of [(9)AgCl] were obtained by slow evaporation silver are unspectacular, since the steric bulk of the NHC
of an isopropanol/CH Cl
solution. The NHC ligand has an ligand cannot act on the two-coordinate metal center. The
approximately rectangular bowl type shape, which is defined silver ion is deeply buried in the roughly hemispherical NHC
2
2
4
2
by six phenyl rings of the two pentiptycene units and the two ligand and even the chloro ligand hardly extends beyond the
43
butoxy groups on the metal-facing side (Fig. 1 and 2). upper rim of the pentiptycene unit. The buried volume of
However, the angles of the planes of the six-membered N-aryl the NHC ligand in complex [(9)AgCl] was calculated as Vbur
rings and of the five-membered heterocyclic ring are tilted by 48.8% (r = 350 pm, d = 200 pm), which is considerably larger
=
4
4
1
7°. Since the two N-aryl units are tilted in opposite directions, than in the related [(iPr)AgCl] complexes (Vbur = 46.5%). The
the two pentiptycene units are inclined at an angle of ca. 35°. rigidity of the pentiptycene units in the crystal results in a
This leads to an interdigitized structure of the four phenyl porous solid structure with large empty voids into which the
rings forming the walls of the bowl. Consequently, two phenyl chloro ligands and the methyl groups of the heterocyclic unit
rings are close to the silver ion (shortest Ag–C distances ca. are pointing. The formation of porous solids has been observed
4
5
3
50 pm), while the two closest carbon atoms of the other pair in other iptycene structures. The presence of solvent accessi-
of phenyl rings are at an Ag–C distance of ca. 510 pm. Two ble pores also explains, why it is very difficult to remove solvent
pairs of Ag–C distances are sufficient for the description of the from such compounds – even after prolonged heating under
structure, since the silver atom and the carbene carbon of the vacuum, elemental analysis provides unsatisfactory values.
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4
6,47
Such bowl shaped NHC ligands are rare
and hold
Synthesis of pentiptycene quinone 1. Anthracene (66.0 g,
potential for selective catalysis or the stabilization of otherwise 0.370 mol), 1,4-benzoquinone (20.0 g, 0.185 mol) and para-
4
8
unstable species.
chloranil (90.0 g, 0.370 mol) were dissolved in 100% AcOH
2.4 L) and heated under reflux for 16 h. The reaction mixture
(
was cooled to room temperature and a yellow precipitate fil-
tered off, washed extensively with diethyl ether, and then dried
in vacuo to provide 77.0 g (88% yield) of a yellow product.
Summary and conclusions
1
H NMR (300 MHz, CDCl ) δ 7.41–7.38 (m, aromatic, 8H),
3
Based on a large scale synthesis of 1-amino,4-hydroxy-pentipty-
cene this aniline was converted into various azolium salts,
which are convenient precursors for the synthesis of N-hetero-
cyclic carbenes. The steric shielding of the pentiptycene wings
provides bowl-shaped NHC ligands, in which the metal center
is buried in a pocket – as shown in the crystal structure of the
respective (NHC)AgCl complex. Such ligands offer the possi-
bility for the kinetic stabilization of unusual coordination geo-
metries and could thus lead to highly active catalysts, which
will be the topic of future studies. Preliminary catalytic tests
1
3
7
.02–6.99 (m, aromatic, 8H), 5.80 (s, 4H). C NMR (75 MHz,
CDCl ): δ 180.11 (CvO), 151.09 (CvC), 143.83 (Ar–C), 125.61
Ar–CH), 124.39 (Ar–CH), 47.56 (CHAr3).
Synthesis of pentiptycene monooxime 2. Pentiptycene
3
(
quinone 1 (36.0 g, 0.078 mol) was dissolved in THF (1.2 L) and
a solution of NH OH·HCl (27.15 g, 0.39 mol) in water (90 mL)
2
was added, followed by HCl (11.9 mL, aq. 37%). The mixture
was heated under reflux for 7 days. Next THF was removed
under reduced pressure. The remaining orange solid was dis-
solved in CH
separated and dried over anhydrous MgSO
2
Cl
2
and washed with brine. The organic layer was
, filtered and the
2
employing (NHC)AuCl/AgNTf reveal good catalytic activities in
the cyclization of diethyl 2-allyl-2-(prop-2-ynyl)malonate.
4
volatiles evaporated under reduced pressure. The residue was
triturated with pentane, filtered and the product was dried
in vacuo (35.4 g, 95% yield). This material thus obtained is
sufficiently pure for the next steps; the product may be purified
further by recrystallization from ethanol/DMF. However, this
Experimental
General experiments
leads to the formation of a stable solvate complex 2·DMF, from
1
All chemicals were purchased as reagent grade from commer- which it is very difficult to completely remove DMF. H NMR
cial suppliers and used without further purification, unless (300 MHz, CDCl
3
) δ 9.12 (s, OH, 1H), 7.40–7.30 (m, aromatic, 8
otherwise noted. All reactions involving metal complexes were H), 6.98–6.95 (m, aromatic, 8 H), 6.77 (s, 1 H), 5.95 (s, 1 H),
1
3
performed under an atmosphere of nitrogen (except gold and 5.90 (s, 1 H), 5.84 (s, 1 H). C NMR (75 MHz, CDCl ) δ 178.35
3
copper complexes). Tetrahydrofuran was dried over sodium, (CvO), 154.55, 148.50, 146.05, 145.14, 144.57, 144.43, 144.37,
distilled under an argon atmosphere and stored over mole- 144.25, 143.82, 125.56 (Ar–CH), 125.53 (Ar–CH), 125.28 (Ar–
cular sieves (4 Å). Dichloromethane and toluene were refluxed CH), 125.14 (Ar–CH), 124.32 (Ar–CH), 124.21 (Ar–CH), 124.01
3 3
over calcium hydride, distilled under a nitrogen atmosphere (Ar–CH), 123.92 (Ar–CH), 52.99 (CHAr ), 49.16 (CHAr ), 47.36
1
13
and stored over molecular sieves (4 Å). H and C NMR (CHAr
spectra were recorded on a Bruker AC300 or a DRX500 spectro- Synthesis of pentiptycene aminophenol 3. Monooxime 2
meter. The chemical shifts are given in parts per million (26.9 g, 0.056 mol) was dissolved in THF (800 mL). To the solu-
ppm) on the delta scale (δ) and are referenced to the residual tion was added Pd/C (5% Pd, 3.38 g), followed by the slow
3 3
), 47.13 (CHAr ).
(
1
13
peak of chloroform ( H NMR = 7.26, C NMR = 77.16 ppm), addition of hydrazine hydrate (14.5 mL, 0.3 mol) and leading
dimethyl sulfoxide ( H NMR = 2.50, C NMR = 39.52 ppm) or to the evolution of gas. The reaction mixture was refluxed for
methylene chloride ( H NMR = 5.32, C NMR = 53.84 ppm). 3 hours. The cold suspension was filtered over a glass filter, to
Abbreviations for NMR: s = singlet, d = doublet, t = triplet, q = separate Pd/C. Since the product is poorly soluble in THF, the
quartet, quint = quintet, sep = septet, sex = sextet, m = multi- residue remaining on the filter should be extensively washed
1
13
1
13
2 2
plet, br = broad signal. Thin layer chromatography (TLC) was with CH Cl . The volatiles were removed under reduced
performed by using silica 60 F 254 (0.2 mm) on aluminum pressure and the residue was triturated with pentane. The
plates. Preparative chromatography was done on Merck silica white precipitate was collected by filtration and dried in vacuo
1
6
0 (0.063–0.2 mm). Cyclic voltammograms were recorded in to yield the product (23.0 g, 89% yield). H NMR (300 MHz,
dry CH Cl under an argon atmosphere at ambient tempera- DMSO-d ) δ 8.38 (s, OH, 1H), 7.34–7.30 (m, aromatic, 8 H),
2
2
6
1
3
ture. A three-electrode configuration was employed. The 6.92–6.88 (m, aromatic, 8 H), 5.84 (s, 2 H), 5.80 (s, 2 H).
working electrode was a Pt disk (diameter 1 mm) sealed in soft NMR (75 MHz, DMSO-d ) δ 146.16, 145.96, 138.25, 131.78,
glass with a Pt wire as a counter electrode. The pseudo- 130.49, 128.34 (Ar–CH), 124.36 (Ar–CH), 123.26 (Ar–CH),
reference electrode was an Ag wire. Potentials were calibrated 123.21 (Ar–CH), 46.88 (CHAr ), 46.82 (CHAr ).
internally against the formal potential of octamethylferrocene Synthesis of diimine 4. Acenaphthene-1,2-dione (395 mg,
E1/2 = −0.01 V (CH Cl )) and NBu PF (0.1 mol L ) was used 2.17 mmol) was suspended in acetonitrile (30 mL) and the
C
6
3
3
−
1
(
2
2
4
6
as a supporting electrolyte. Compounds 1, 2 and 3 have been mixture was heated to 90 °C. After 10 min acetic acid (10 mL)
1
3
reported previously in the literature, however no C data were was added and heated until the dione had dissolved comple-
1
2,21
given.
tely. To the hot solution was added aniline 3 (2.0 g,
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4
.33 mmol) in several portions. Within a few minutes the for- diacetyl (303 µL, 3.48 mmol) and three drops of formic acid.
mation of an orange precipitate was observed. The suspension The reaction mixture was stirred for 4 days at 80 °C. The
was stirred at 90 °C overnight and then cooled to −30 °C and formed yellow suspension was cooled to room temperature
an orange precipitate was collected by filtration. After washing and concentrated to a half of its original volume. The yellow
the solid with acetonitrile and drying in vacuo at 70 °C, precipitate was collected by filtration, washed with iPrOH and
1
diimine 4 was obtained as an orange powder (1.69 g, 73% dried in vacuo (2.27 g, 67% yield). H NMR (300 MHz, CD
yield). H NMR (500 MHz, CD
2
Cl
2
)
1
2 2 3
Cl ) δ 7.73 (d, J = 8.1 Hz, 2H), δ 7.47–7.33 (m, 16H), 7.07–6.92 (m, 16H), 5.80 (s, 4H, CHAr ),
.46 (dd, J = 6.6, 1.7 Hz, 4H), 7.42 (dd, J = 6.6, 1.7 Hz, 4H), 7.38 5.33 (s, 4H, CHAr ), 5.14 (s, 2H, OH), 2.17 (s, 6H, Me).
1
3
7
C
3
(
d, J = 7.2 Hz, 4H), 6.98 (quint d, J = 7.5, 1.3 Hz, 8H), 6.87 (td, NMR (75 MHz, CDCl
3
) δ 172.29 (CvN), 145.66, 145.36, 145.17,
3
J = 7.3, 1.2 Hz, 4H), 6.61–6.51 (m, 10H), 5.85 (s, 4H, CHAr ), 142.14, 136.06, 131.94, 130.47, 125.41, 125.39, 123.90, 123.79,
1
3
5
.74 (d, J = 7.2 Hz, 2H), 5.61 (s, 4H, CHAr3). C NMR (75 MHz, 123.68, 50.00 (CHAr ), 47.85 (CHAr ), 17.74 (CH ). HRMS (EI):
3
3
3
+
CDCl
3
) δ 164.90 (CvN), 145.56, 145.45, 145.23, 144.85, 142.52, m/z calcd for C72
H
48
N
2
O
2
: 972.3710 [M] ; found: 972.3720.
1
1
4
41.33, 137.57, 132.58, 131.16, 130.60, 128.81, 128.48, 127.72,
25.38, 125.31, 124.75, 124.56, 124.44, 123.67, 123.44, 123.42, 7 (1.09 g, 1.12 mmol) in 50 mL of DMF was added K CO
Synthesis of alkylated diimine 8. To a suspension of diimine
2
3
9.96 (CHAr
: 1068.3710 [M] ; found: 1068.3723.
Synthesis of alkylated diimines 5a and 5b. To the solution of reaction mixture was stirred overnight at 70 °C. The yellow sus-
diimine 4 (1.5 g, 1.4 mmol) in DMF (75 mL) at 50 °C was pension was cooled to room temperature and poured into
added K CO (2.3 g, 16.8 mmol). The mixture was stirred for water (300 mL). The yellow precipitate was collected by fil-
min and MeI (348.8 µL, 5.6 mmol) was added. The reaction tration and washed few times with water and methanol. After
3
), 47.88 (CHAr
3
). HRMS (EI): m/z calcd for (1.85 g, 13.4 mmol). The mixture was stirred for 1 min and
+
80 48 2 2
C H N O
then BuI (510 µL, 4.48 mmol) was added in one portion. The
2
3
1
mixture was stirred overnight at 50 °C. The orange suspension drying in vacuo, the product was obtained as a yellow powder
was cooled to room temperature and poured into 300 mL of (1.08 g, 89% yield).
1
water. The orange precipitate was collected by filtration,
H NMR (300 MHz, CDCl ) δ 7.48–7.38 (m, 12H, H ), 7.36
3 Ar
washed with water, methanol and diethyl ether. After drying (d, J = 7.2 Hz, 4H, HAr), 7.08–6.90 (m, 16H, HAr), 5.81 (s, 4H,
in vacuo at 70 °C, the product was obtained as an orange powder CHAr ), 5.34 (s, 4H, CHAr ), 4.05 (t, J = 6.7 Hz, 4H, OCH ), 2.19
1.34 g, 87% yield). Diimine 5b was prepared following the (s, 6H, Me), 2.10 (dt, J = 14.5, 6.8 Hz, 4H, OCH CH CH CH ),
3
3
2
(
2
2
2
3
same procedure using 2.5 equiv. of 1-iodohexane. The mixture 1.82 (sep, J = 7.3 Hz, 4H, OCH
2
CH
). C NMR (75 MHz, CDCl
after addition of water was collected by filtration, washed with (CvN), 146.54, 145.87, 145.45, 145.29, 137.92, 135.99, 131.83,
water and methanol (1.37 g, 79% yield). 125.43, 125.33, 123.85, 123.59, 76.31 (OCH ), 50.00 (CHAr ),
) δ 7.61 (d, J = 8.1 Hz, 2H), 48.69 (CHAr ), 32.90 (CH ), 19.98 (CH ), 17.84 (CH ), 14.39
.51–7.47 (m, 4H), 7.46–7.42 (m, 4H), 7.38 (d, J = 7.4 Hz, 4H), (CH , hexyl). HRMS (EI): m/z calcd for C H N O : 1084.4962
2
CH
2
CH
3
), 1.22 (t, J = 7.3 Hz,
1
3
was stirred overnight at 70 °C. The orange precipitate obtained 6H, OCH
2
CH
2
CH
2
CH
3
3
) δ 171.96
2
3
1
5
a: H NMR (500 MHz, CDCl
3
3
2
2
3
7
7
3
80 64 2 2
+
.04–6.96 (m, 8H), 6.86–6.80 (m, 4H), 6.51–6.44 (m, 10H), 5.86 [M] ; found: 1084.4965.
), 5.62 (s, 4H, CHAr ), 5.40 (d, J = 7.2 Hz, 2H), Synthesis of imidazolium salts 6a·HCl and 6b·HCl. A flame
.11 (s, 6H, OMe). C NMR (126 MHz, CDCl ) δ 164.71 (CvN), dried Schlenk flask containing diimine 5a (600 mg,
(s, 4H, CHAr
3
3
1
3
4
1
1
1
3
47.60, 145.59, 145.39, 145.06, 143.82, 141.30, 139.81, 136.52, 0.546 mmol) was evacuated and back-filled with nitrogen three
32.70, 130.53, 128.81, 128.37, 127.69, 125.62, 125.44, 125.38, times. Next, chloromethyl ethyl ether (2.5 mL, 26.9 mmol
24.81, 124.72, 124.45, 124.41, 123.56, 123.54, 123.33, 63.53 stored overnight over K CO under nitrogen) was added. The
2
3
(
C
OCH
H N O
82 53 2 2
5
3
), 49.96 (CHAr
(M + H) 1097.4, found 1097.6.
b: H NMR (500 MHz, CDCl ) δ 7.59 (d, J = 8.1 Hz, 2H), material was collected by filtration and washed with diethyl
3
), 48.55 (CHAr
3
). MS (ESI) calcd for reaction mixture was stirred for 5 h at 80 °C. After cooling to
room temperature, diethyl ether was added, the insoluble
1
3
7
7
.52–7.47 (m, 4H), 7.44–7.40 (m, 4H), 7.37 (d, J = 7.2 Hz, 4H), ether. Purification by column chromatography (first CH
2 2
Cl to
.03–6.98 (m, 8H), 6.85–6.79 (m, 4H), 6.48–6.44 (m, 8H), 6.42 remove impurities, followed by CH Cl /MeOH, 1 : 1, v/v to
2
2
(t, J = 7.7 Hz, 2H), 5.83 (s, 4H, CHAr ), 5.62 (s, 4H, CHAr ), 5.33 elute pure product) provides the azolium salt 6a·HCl (363 mg,
3 3
(d, J = 7.2 Hz, 2H), 4.17 (t, J = 6.6 Hz, 4H, OHex), 2.17 (quint, 58% yield) as a pale yellow powder. The azolium salt 6b·HCl
J = 6.7 Hz, 4H, OHex), 1.84 (quint, J = 7.3 Hz, 4H, OHex), (272 mg, 50% yield) was obtained as a pale yellow powder
1
3
1
.66–1.52 (m, 8H, OHex), 1.09 (t, J = 7.1 Hz, 6H, OHex).
C
from diimine 5b (530 mg, 0.428 mmol) and chloromethyl ethyl
NMR (126 MHz, CDCl
3
) δ 164.85 (CvN), 146.73, 145.56, ether (2.5 mL, 26.9 mmol stored overnight over K CO under
2
3
1
1
1
3
45.47, 145.43, 145.12, 141.26, 139.75, 136.63, 130.48, 128.74, nitrogen) using a similar procedure. After stirring the mixture
28.36, 127.57, 125.39, 125.34, 124.73, 124.68, 124.44, 123.60, for 20 h at 80 °C, diethyl ether was added and the obtained
23.52, 123.24, 76.63 (OCH ), 49.95 (CHAr ), 48.76 (CHAr ), solution was sonicated for a few minutes. The obtained pre-
2.09 (CH ), 30.83 (CH ), 26.41 (CH ), 22.98 (CH ), 14.37 cipitate was collected by filtration and washed with diethyl
2
3
3
2
2
2
2
(
C
CH ). HRMS (EI): m/z calcd for C H N O : 1151.4571 [M − ether affording the pure product.
3
86 59 2 2
+
1
6
H
13] ; found: 1151.4561.
Synthesis of diimine 7. To the solution of pentiptycene 3 acenaph.), 8.07 (s, 1H, NCHN), 7.49–7.42 (m, 12H, HAr), 7.32
3.21 g, 6.95 mmol) in iPrOH (250 mL) at 80 °C were added (t, J = 7.3 Hz, 2H, acenaph.), 7.26 (d, J = 7.1 Hz, 4H, HAr),
3
6a·HCl: H NMR (500 MHz, CDCl ) δ 8.11 (d, J = 8.2 Hz, 2H,
(
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7
.05–6.96 (m, 8H, HAr), 6.87–6.80 (m, 8H, HAr), 6.73 (d, J = 7.0 (d, J = 7.5 Hz, 4H, HAr), 7.48 (d, J = 7.1 Hz, 4H, HAr), 7.41 (d, J =
Hz, 2H, acenaph.), 6.34 (s, 4H, CHAr ), 5.95 (s, 4H, CHAr ), 7.3 Hz, 4H, H ), 7.18 (t, J = 7.3 Hz, 2H, acenapht.), 7.04–6.99
3
3
Ar
1
3
4
.18 (s, 6H, OMe). C NMR (126 MHz, CDCl
3
) δ 152.70 (m, 8H, HAr), 6.91–6.86 (m, 8H, HAr), 6.81 (td, J = 7.3, 1.2 Hz,
(
NCHN), 144.64, 144.32, 144.16, 143.96, 142.04, 139.81, 139.22, 4H, HAr), 6.45 (d, J = 7.0 Hz, 2H, acenapht.), 5.96 (s, 4H,
1
3
1
1
4
35.57, 131.66, 131.33, 130.19, 127.96, 126.14, 126.04, 125.75, CHAr ), 5.46 (s, 4H, CHAr ), 4.16 (s, 6H, OMe). C NMR
3
3
25.58, 124.53, 124.16, 123.79, 122.23, 120.80, 63.23 (OCH
9.34 (CHAr ), 48.41 (CHAr ). MS (ESI) calcd for C83
3
), (126 MHz, CD
2
Cl
2
) δ 189.58 (Ccarbene), 152.18, 145.88, 145.04,
3
3
H
53
N
2
O
2
145.02, 144.27, 141.91, 139.62, 138.26, 131.44, 130.32, 129.35,
128.07, 126.50, 126.40, 126.21, 125.62, 125.59, 125.43, 124.63,
) δ 8.12 (d, J = 8.0 Hz, 124.31, 123.67, 63.87 (OCH ), 50.92 (CHAr ), 48.86 (CHAr ).
(M − I) 1171.3, found
+
(M − Cl) 1109.4, found 1109.8.
1
6
b·HCl: H NMR (500 MHz, CDCl
3
3
3
3
+
2
2
H), 8.08 (s, 1H, NCHN), 7.48–7.40 (m, 12H), 7.31 (t, J = 7.4 Hz, MS (ESI) calcd for C83
H), 7.27–7.20 (br, 4H), 7.02 (t, J = 7.4 Hz, 4H), 6.99 (t, J = 7.4 1171.7.
2 2
H52CuN O
Hz, 4H), 6.88–6.80 (m, 8H), 6.71 (d, J = 6.9 Hz, 2H), 6.24 (s, 4H,
CHAr ), 5.92 (s, 4H, CHAr ), 4.23 (t, J = 6.7 Hz, 4H, OHex), 2.19 flask containing azolium salt 6b·HCl (155.6, 0.121 mmol) or
quint, J = 6.8 Hz, 4H, OHex), 1.81 (quint, J = 7.4 Hz, 4H, 9·HCl (138 mg, 0.121 mmol) and Ag O (84.8 mg, 0.365 mmol)
Synthesis of [(6b)AgCl] and [(9)AgCl]. A flame dried Schlenk
3
3
(
2
OHex), 1.65–1.51 (m, 8H, OHex), 1.07 (t, J = 7.1 Hz, 6H, OHex). was evacuated and backfilled with nitrogen three times.
1
3
3 2 2
C NMR (126 MHz, CDCl ) δ 152.17 (NCHN), 144.66, 144.34, CH Cl (5 mL) was added via syringe. The reaction mixture was
1
1
1
44.13, 143.92, 141.77, 139.74, 139.24, 135.65, 131.62, 131.45, stirred overnight at 40 °C, cooled to room temperature and fil-
30.19, 127.97, 126.11, 126.02, 126.00, 125.74, 125.57, 125.49, tered through celite. The filtrate was concentrated under
24.46, 124.15, 123.79, 122.12, 120.48, 76.65 (OCH ), 49.44 reduced pressure, the residue was washed with pentane and
2
(
CHAr ), 48.62 (CHAr ), 31.98 (CH ), 30.81 (CH ), 26.23 (CH ), the precipitate was collected by filtration, to afford the desired
3
3
2
2
2
2
C
2.93 (CH
2
3
), 14.32 (CH ). HRMS (EI): m/z calcd for silver complex [(6b)AgCl] as a yellow powder (123 mg, 73%
+
87
H
60
N
2
O
2
: 1164.4649 [M − Cl − C
6
H13] ; found: 1164.4620.
yield) or [(9)AgCl] as a white powder (97.5 mg, 65% yield). The
Synthesis of imidazolium salt 9·HCl. A flame dried Schlenk limited solubility and the weak signal of the carbene C (two
1
3
flask containing diimine 8 (1.09 g, 1.0 mmol) was evacuated doublets) prevent the detection of the C signal.
1
and back-filled with nitrogen three times. Next, chloromethyl
3
[(6b)AgCl]: H NMR (500 MHz, CDCl ) δ 7.84 (d, J = 8.2 Hz,
ethyl ether (stored overnight over K CO under nitrogen, 2H), 7.47 (d, J = 7.4 Hz, 4H), 7.43 (d, J = 7.2 Hz, 4H), 7.33 (d, J =
2
3
2
.50 mL, 26.9 mmol) was added under a stream of nitrogen. 7.3 Hz, 4H), 7.10 (t, J = 7.6 Hz, 2H), 6.99 (q, J = 6.1 Hz, 8H),
The reaction mixture was stirred overnight at 80 °C. After 6.93 (t, J = 7.4 Hz, 4H), 6.79–6.72 (m, 8H), 6.29 (d, J = 7.0 Hz,
cooling to room temperature, diethyl ether was added, the in- 2H), 5.91 (s, 4H, CHAr ), 5.41 (s, 4H, CHAr ), 4.27 (t, J = 6.7 Hz,
3
3
soluble material was collected by filtration and recrystallized 4H, OHex), 2.21 (quint, J = 6.8 Hz, 4H, OHex), 1.85 (quint, J =
from CH Cl /Et O. The corresponding salt 9·HCl (680 mg, 60% 7.4 Hz, 4H, OHex), 1.69–1.54 (m, 8H, OHex), 1.10 (t, J = 7.1 Hz,
yield) was obtained as an off-white powder.
500 MHz, CDCl ) δ 8.05 (br, 4H, HAr), 7.80 (s, 1H, NCHN), 144.49, 144.24, 143.67, 141.33, 139.76, 139.71, 137.90, 130.68,
.44–7.38 (m, 8H, HAr), 7.34 (d, J = 7.2 Hz, 4H, HAr), 7.09 (br, 129.70, 128.81, 127.61, 126.47, 126.16, 125.68, 125.05, 124.79,
H, H ), 7.05 (t, J = 6.9 Hz, 4H, H ), 6.95 (t, J = 7.2 Hz, 4H, 124.34, 124.24, 124.13, 123.94, 123.77, 123.69, 76.62 (OCH2),
2
2
2
1
13
H
NMR 6H, OHex). C NMR (126 MHz, CDCl ) δ 151.09, 145.40,
3
(
3
7
4
Ar
Ar
H
Ar), 6.79 (t, J = 7.0 Hz, 4H, HAr), 6.09 (s, 4H, CHAr
), 4.14 (t, J = 6.7 Hz, 4H, OCH ), 2.45 (s, 6H, Me), (CH
.16–2.09 (m, 4H, OCH CH CH CH ), 1.86–1.77 (m, 4H, C H N O : 1164.4649 [M
3
), 5.84 (s, 50.59 (CHAr
3
), 48.74 (CHAr
3
), 32.07 (CH
2 2
), 30.90 (CH ), 26.28
4
H, CHAr
3
2
2
), 23.01 (CH
2
), 14.38 (CH
3
). HRMS (EI): m/z calcd for
+
2
− AgCl − C H ] ; found:
6 12
2
2
2
3
87 60
2
2
OCH
2
CH
2
CH
2
CH
3
), 1.22 (t, J = 7.4 Hz, 6H, OCH
) δ 151.88 (NCHN), 144.85, 144.34,
44.28, 141.96, 138.70, 133.41, 131.63, 126.20, 125.98, 125.82, 4H, H ), 7.41 (d, J = 7.0 Hz, 4H, H ), 7.37 (d, J = 7.1 Hz, 4H,
2
CH
2
CH
2
CH
3
). 1164.4630.
1
3
1
C NMR (126 MHz, CDCl
3
[(9)AgCl]: H NMR (500 MHz, CDCl ) δ 7.47 (d, J = 6.7 Hz,
3
1
1
Ar
Ar
25.63, 124.34, 124.16, 123.72, 119.97, 76.31 (OCH
), 48.53 (CHAr ), 32.90 (CH ), 19.86 (CH ), 14.32 (CH
hexyl). HRMS (EI): m/z calcd for C H N O : 1097.5041 [M − 4.20 (t,
2
), 49.24
H
Ar), 7.32 (d, J = 6.6 Hz, 4H, HAr), 7.07–6.97 (m, 12H, HAr), 6.94
(t, J = 7.3 Hz, 4H, HAr), 5.85 (s, 4H, CHAr ), 5.19 (s, 4H, HAr),
6.7 Hz, 4H, OCH2), 2.18–2.12 (m, 4H,
(CHAr
3
3
2
3
3
,
3
J
=
8
1
65 2 2
+
Cl] ; found: 1097.5024.
OCH
2
CH
CH
2
CH
2
CH
CH
3
), 1.88 (s, 6H, Me), 1.87–1.80 (m, 4H,
), 1.24 (t, J = 7.4 Hz, 6H, OCH CH CH CH ).
Synthesis of [(6a)CuI]. A vial was charged, under air, with OCH
2
2
CH
2
3
2
2
2
3
1
3
6
a·HCl (60 mg, 0.052 mmol), CuI (10.8 mg, 0.056 mmol) and
finely powdered K CO (50 mg, 0.362 mmol). To the mixture 141.53, 137.46, 128.23, 128.18, 126.31, 126.19, 125.89, 125.41,
was added acetone (1.5 mL) and stirred overnight at 60 °C. 124.77, 124.34, 124.26, 124.18, 123.44, 76.35 (OCH ), 50.59
C NMR (126 MHz, CDCl ) δ 145.66, 144.74, 144.22, 143.59,
3
2
3
2
After this time the solvent was removed in vacuo and dichloro- (CHAr ), 48.65 (CHAr ), 32.97 (CH ), 19.86 (CH ), 14.38 (CH ),
3
3
2
2
3
3 64 2 2
methane was added. The mixture was filtered through a pad of 10.20 (CH , butyl). HRMS (EI): m/z calcd for C81H N O :
+
celite. The pad of celite was washed with dichloromethane. 1096.4962 [M − AgCl] ; found: 1096.4950.
The solvent was concentrated and pentane (5 mL) was added, Synthesis of [(6a)AuCl] and [(6b)AuCl]. A vial was charged
affording a yellow solid which was washed with more pentane with 6a·HCl (60 mg, 0.052 mmol), [AuCl(Me S)] (16.7 mg,
2
1
and dried under vacuum (46 mg, 68% yield). H NMR 0.056 mmol) and finely powdered K
2
CO
3
(50 mg, 0.362 mmol).
(
500 MHz, CD Cl ) δ 7.91 (d, J = 8.2 Hz, 2H, acenapht.), 7.50 To the mixture was added acetone (1.5 mL) and stirred over-
2 2
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night at 60 °C. After this time the solvent was removed in vacuo
Synthesis of [(6a)IrCl(cod)]. A flame dried Schlenk flask
and dichloromethane was added. The mixture was filtered containing azolium salt 6a·HCl (169.38 mg, 0.148 mmol) and
through a pad of silica. The pad of silica was washed with di- [IrCl(cod)] (50 mg, 0.074 mmol) was evacuated and back-filled
chloromethane. The solvent was concentrated and pentane with nitrogen three times. Next, THF (15 mL) and a solution of
5 mL) was added, affording a yellowish solid which was sodium tert-pentoxide in THF (2.5 M, 71 µL, 0.177 mmol) were
2
(
washed with further portions of pentane and dried under added at room temperature. The mixture was stirred at room
vacuum (31 mg, 45% yield). The gold complex [(6b)AuCl] temperature for 2 h and the solvent was removed in vacuo. The
(84 mg, 73% yield) was prepared using a similar procedure residue was purified by column chromatography (ethyl acetate/
from 6b·HCl (100 mg, 0.077 mmol), [AuCl(Me S)] (23 mg, cyclohexane, 2 : 1, v/v) to afford the desired product as an
2
1
0
.077 mmol), K
2
CO
3
(32 mg, 0.233 mmol) in acetone (2 mL) at orange microcrystalline powder (150 mg, 70% yield). H NMR
6
0 °C for 3 h.
(500 MHz, CDCl ) δ 8.37 (br, 2H, H ), 7.60 (br, 2H, H ),
) δ 7.84 (d, J = 8.1 Hz, 7.50–7.45 (m, 4H, HAr), 7.39–7.34 (m, 6H, HAr), 7.14–7.00 (m,
3
Ar
Ar
1
[(6a)AuCl]: H NMR (500 MHz, CD
2
Cl
2
2
H, acenapht.), 7.52–7.47 (m, 12H, HAr), 7.06–6.95 (m, 14H, 8H, HAr), 6.77 (t, J = 6.8 Hz, 4H, HAr), 6.61 (br, 2H, HAr), 6.38
H ), 6.76 (dd, J = 7.3, 1.4 Hz, 4H, H ), 6.73 (td, J = 7.2, 1.1 Hz, (dd, J = 8.2, 7.1 Hz, 2H, acenapht.), 6.31 (br, 6H), 6.15 (br, 2H,
Ar
Ar
4
H, HAr), 6.08 (d, J = 6.9 Hz, 2H, acenapht.), 5.98 (s, 4H,
H
Ar), 5.93 (s, 4H, CHAr
3
), 5.37 (br, 2H, HAr), 4.63 (d, J = 7.0 Hz,
13
CHAr
3
), 5.47 (s, 4H, CHAr
3
), 4.21 (s, 6H, OMe). C NMR 2H, acenapht.), 4.33–4.27 (m, 2H, cod), 4.21 (s, 6H, OMe),
(
1
126 MHz, CD Cl ) δ 180.39 (Ccarbene), 145.81, 145.02, 144.75, 3.32–3.27 (m, 2H, cod), 1.16–1.07 (m, 4H, cod), 1.06–0.96 (m,
2 2
44.29, 141.96, 139.08, 138.42, 130.76, 130.15, 129.45, 127.96, 2H, cod), 0.92–0.84 (m, 2H, cod). C NMR (126 MHz, CDCl ) δ
3
1
3
1
26.43, 126.40, 126.20, 125.60, 125.48, 125.07, 124.59, 124.32, 188.09 (Ccarbene), 151.06, 146.71–143.08 (br multiplet), 140.27,
1
23.78, 63.79 (OCH ), 51.08 (CHAr ), 48.89 (CHAr ). MS (ESI) 128.80, 128.73, 128.61, 126.86, 125.85 (br), 125.24 (br), 124.78
2
3
3
+
cod
calcd for C83
calcd for C83
H
2 2 3
52AuClNaN O (M + Na ) 1363.3, found 1363.5; (br), 123.80, 123.43 (br), 121.01, 86.12 (H ), 63.40 (OCH ),
+
cod
cod
H
52AuClKN
2
O
2
(M + K ) 1379.3, found 1379.5.
3 3
52.73 (H ), 50.72 (br, CHAr ), 48.59 (br, CHAr ), 32.93 (H ),
1
cod
[
(6b)AuCl]: H NMR (500 MHz, CDCl ) δ 7.80 (d, J = 8.1 Hz, 28.31 (H ). HRMS (EI): m/z calcd for C H N O : 1109.4102
3 83 53 2 2
+
2
H), 7.46 (d, J = 7.3 Hz, 8H), 7.42 (d, J = 7.1 Hz, 4H), 7.05–6.91 [M + H − IrCl(cod)] ; found: 1109.4103.
(m, 14H), 6.73–6.67 (m, 8H), 6.11 (d, J = 7.0 Hz, 2H), 5.90 (s,
Synthesis of [(9)IrCl(cod)]. A flame dried Schlenk flask con-
4
H, CHAr ), 5.44 (s, 4H, CHAr ), 4.27 (t, J = 6.7 Hz, 4H, OHex), taining azolium silver complex [(9)AgCl] (150 mg, 0.121 mmol)
3
3
2
2
.21 (quint, J = 6.8 Hz, 4H, OHex), 1.85 (quint, J = 7.4 Hz, 4H, and [IrCl(cod)] (40.6 mg, 0.06 mmol) was evacuated and back-
OHex), 1.69–1.50 (m, 8H, OHex), 1.10 (t, J = 7.1 Hz, 6H, OHex). filled with nitrogen three times. Next, toluene (5 mL) was
1
3
C NMR (126 MHz, CDCl ) δ 180.53 (Ccarbene), 151.03, 145.50, added and the mixture was stirred overnight at 100 °C. After
3
1
1
1
44.51, 144.22, 143.68, 141.37, 138.47, 137.84, 130.20, 129.54, this time the solvent was removed in vacuo and dichloro-
28.79, 127.58, 126.11, 126.01, 125.58, 125.08, 125.04, 124.45, methane was added. The mixture was filtered through a pad of
24.13, 123.89, 123.57, 76.61 (OCH ), 50.71 (CHAr ), 48.75 silica. The pad of silica was washed with dichloromethane.
2
3
(CHAr
3
), 32.07 (CH
2
), 30.89 (CH
2
), 26.28 (CH
2
2
), 23.01 (CH ), The solvent was concentrated and pentane (5 mL) was added,
1
4.38 (CH
3
). HRMS (EI): m/z calcd for C87
H
60
N
2
O
2
: 1164.4649 affording a yellow solid, which was washed with pentane and
+
1
[M − AuCl − C H ] ; found: 1164.4640.
dried under vacuum (137 mg, 79% yield). H NMR (500 MHz,
6
12
Ar
Ar
3
Synthesis of [(9)AuCl]. A vial was charged with 9·HCl (100 mg, CDCl ) δ 8.41 (br, 2H, H ), 7.68 (br, 2H, H ), 7.47–7.37 (m,
Ar
Ar
Ar
2
0.088 mmol), [AuCl(Me S)] (29 mg, 0.098 mmol) and finely pow- 8H, H ), 7.30–7.24 (m, 4H, H ), 7.10–7.02 (m, 8H, H ),
Ar
dered K CO (100 mg, 0.724 mmol). To the mixture was added 6.99–6.92 (m, 8H, H ), 6.37 (br, 2H, CHAr ), 5.88 (s, 4H,
2
3
3
CH
2
Cl
2
(10 mL) and vigorously stirred for 3 h at room CHAr
3
), 5.27 (br, 2H, CHAr
3
2
), 4.22 (t, J = 6.7 Hz, 4H, OCH ),
cod
cod
temperature in the absence of light. After this time the mixture 4.11–4.06 (m, 2H, H ), 3.23–3.18 (m, 2H, H ), 2.18–2.12 (m,
was filtered through celite which was finally washed with 4H, CH , butyl), 1.90–1.81 (m, 4H, CH , butyl), 1.23 (t, J = 7.4
dichloromethane. The solvent was concentrated and pentane Hz, 6H, CH , butyl), 0.99–0.93 (m, 4H, H ), 0.90 (s, 6H, CH ,
3 3
2
2
cod
cod
cod
(10 mL) was added, affording an off-white solid which was puri- imidazol), 0.88–0.81 (m, 2H, H ), 0.81–0.73 (m, 2H, H ).
1
3
fied by column chromatography on silica (cyclohexane/ethyl
acetate, 2 : 1, v/v) (60 mg, 51% yield). H NMR (500 MHz, CDCl
δ 7.50–7.45 (m, 8H), 7.41 (d, J = 6.7 Hz, 4H), 7.30 (d, J = 6.6 Hz, 123.47 (br), 83.60 (H ), 76.21 (OCH
C NMR (126 MHz, CDCl ) δ 181.38 (Ccarbene), 149.90, 146.82
3
1
3
)
(br), 144.47 (br), 137.25 (br), 128.67, 128.31, 125.13, 123.93,
cod
cod
2
), 52.18 (H ), 50.30
cod
4H), 7.07–6.93 (m, 16H), 5.85 (s, 4H, CHAr ), 5.23 (s, 4H, CHAr ), (CHAr ), 48.75 (CHAr ), 32.80 (CH ), 28.21 (H ), 19.95 (CH2),
3
3
3
3
2
4
.20 (t,
CH
J
=
6.7 Hz, 4H, OCH
2
), 2.19–2.12 (m, 4H, 14.36 (CH
3
), 9.89 (CH
3
, butyl). HRMS (EI): m/z calcd for
+
OCH
2
2
CH
2
CH
3
), 1.85 (sext, J = 7.4 Hz, 4H, OCH
2
CH
2
CH
2
CH
3
),
C
C
81
H
65
N
2
O
2
: 1097.5041 [M + H − IrCl(cod)] ; found: 1097.5028.
1
3
1.77 (s, 6H, Me), 1.25 (t, J = 7.4 Hz, 6H, OCH CH CH CH ).
Synthesis of [(6a)IrCl(CO) ] and [(9)IrCl(CO) ]. [(6a)IrCl(cod)]
2 2
2
2
2
3
NMR (126 MHz, CDCl
3
) δ 173.17 (Ccarbene), 150.85, 145.78, (100 mg, 0.069 mmol) or [(9)IrCl(cod)] (100 mg, 0.069 mmol)
Cl (7 mL) and CO was bubbled through
25.84, 125.39, 124.99, 124.28, 124.23, 123.96, 123.37, 76.35 this solution for 20 min. The solvent was evaporated in vacuo
), 50.65 (CHAr ), 48.67 (CHAr ), 32.98 (CH ), 19.87 (CH ), and the residue was washed with pentane to obtain the yellow
4.38 (CH ), 10.20 (CH butyl). MS (ESI) calcd for complex [(6)IrCl(CO) ] (90 mg, 93% yield) or [(9)IrCl(CO)
(93 mg, 96% yield).
1
1
44.78, 144.18, 143.60, 141.54, 137.38, 127.59, 126.05, 125.99, was dissolved in CH
2
2
(OCH
2
3
3
2
2
1
3
3
,
2
2
]
+
C H N O AuClNa (M + Na ) 1351.4, found 1351.6.
81 64 2 2
Dalton Trans.
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Paper
1
[(6a)IrCl(CO)
2
]: H NMR (500 MHz, CDCl
3
) δ 7.79 (d, J =
2 T. M. Swager, Acc. Chem. Res., 2008, 41, 1181–1190.
7
.0 Hz, 4H, H ), 7.65 (d, J = 8.2 Hz, 2H, acenapht.), 7.44
3 X. Jiang, B. Rodríguez-Molina, N. Nazarian and
M. A. Garcia-Garibay, J. Am. Chem. Soc., 2014, 136, 8871–
8874.
Ar
(d, J = 7.0 Hz, 8H, HAr), 7.01 (td, J = 7.3, 1.4 Hz, 4H, HAr), 6.97
(td, J = 7.4, 1.3 Hz, 4H, HAr), 6.90 (td, J = 7.1, 1.7 Hz, 4H, HAr),
6
5
.76 (dd, J = 8.2, 7.0 Hz, 2H, acenapht.), 6.60–6.53 (m, 8H, HAr),
.94 (s, 4H, CHAr ), 5.72 (s, 4H, CHAr ), 5.52 (d, J = 7.0 Hz, 2H,
) δ 184.63
4 E. R. Kay, D. A. Leigh and F. Zerbetto, Angew. Chem., Int.
Ed., 2007, 46, 72–191.
5 J. H. Chong and M. J. MacLachlan, Chem. Soc. Rev., 2009,
38, 3301–3315.
3
3
13
acenapht.), 4.19 (s, 6H, Me). C NMR (126 MHz, CDCl
3
(Ccarbene), 179.87 (CO), 167.79 (CO), 151.28, 145.99, 144.81,
1
1
1
4
44.26, 144.21, 141.95, 140.01, 137.65, 129.92, 129.26, 128.13,
27.47, 126.72, 126.58, 125.58, 125.28, 125.19, 125.03, 124.17,
23.75, 123.67, 123.33, 123.11, 63.41 (OCH ), 50.82 (CHAr ),
6 J. S. Yang and J. L. Yan, Chem. Commun., 2008, 1501–1512.
7 Y. Jiang and C.-F. Chen, Eur. J. Org. Chem., 2011, 6377–
6403.
8 P. D. Bartlett, M. J. Ryan and S. G. Cohen, J. Am. Chem.
Soc., 1942, 64, 2649–2653.
3
3
8.52 (CHAr
3
). Recording of mass spectra with complex
[(6a)Ir(CO)
2
Cl] was unsuccessful, due to instability of this
complex.
9 R. V. Skvarche and V. K. Shalaev, Dokl. Akad. Nauk SSSR,
1974, 216, 110–112.
1
[(9)IrCl(CO)
2
]: H NMR (500 MHz, CDCl
3
) δ 7.76 (d, J = 7.0
Hz, 4H, HAr), 7.43 (dd, J = 6.8, 1.6 Hz, 4H, HAr), 7.39 (dd, 10 H. Hart, S. Shamouilian and Y. Takehira, J. Org. Chem.,
J = 6.8, 1.4 Hz, 4H, H ), 7.33 (dd, J = 6.8, 1.7 Hz, 4H, H ),
1981, 46, 4427–4432.
), 5.52 (s, 11 J.-S. Yang and T. M. Swager, J. Am. Chem. Soc., 1998, 120,
), 2.16–2.09 11864–11873.
Ar
Ar
7
4
.02–6.93 (m, 16H, HAr), 5.84 (s, 4H, CHAr
3
H, CHAr
3
), 4.16 (t, J = 6.6 Hz, 4H, OCH
2
(
m, 4H, OCH CH CH CH ), 1.83 (sex, J = 7.4 Hz, 4H, 12 X.-Z. Zhu and C.-F. Chen, J. Org. Chem., 2005, 70, 917–924.
2
2
2
3
OCH
OCH
2
CH
CH
2
CH
CH
2
CH
3
), 1.54 (s, 6H, Me), 1.22 (t, J = 7.3 Hz, 6H, 13 L. Benhamou, E. Chardon, G. Lavigne, S. Bellemin-Lapon-
13
2
2
2
CH
3
). C NMR (126 MHz, CDCl
3
) δ 179.67
naz and V. Cesar, Chem. Rev., 2011, 111, 2705–2733.
(Ccarbene), 178.22 (CO), 167.89 (CO), 150.34, 146.58, 145.35, 14 C. Azerraf and D. Gelman, Organometallics, 2009, 28, 6578–
1
1
5
44.26, 144.15, 141.90, 137.20, 128.95, 126.82, 126.22, 125.53,
6584.
25.51, 125.23, 125.21, 124.06, 123.57, 123.33, 76.27 (OCH
2
), 15 O. Grossman, C. Azerraf and D. Gelman, Organometallics,
2005, 25, 375–381.
0.73 (CHAr ), 48.66 (CHAr ), 32.89 (CH ), 19.94 (CH ), 14.37
3
3
2
2
(CH
3
), 10.32 (CH
3
, butyl). MS (ESI) calcd for C83
H
64ClIrNaN
2
O
4
16 C. Azerraf and D. Gelman, Chem. – Eur. J., 2008, 14, 10364–
(M + Na) 1403.4, found 1403.1.
10368.
17 C. Azerraf, O. Grossman and D. Gelman, J. Organomet.
General procedure for cyclization of diethyl 2-allyl-2-(prop-2-
ynyl)malonate
Chem., 2007, 692, 761–767.
18 L. Bini, C. Müller, J. Wilting, L. von Chrzanowski,
A. L. Spek and D. Vogt, J. Am. Chem. Soc., 2007, 129, 12622–
The respective (NHC)AuCl complex (0.01 equiv.) and AgNTf2
0.01 equiv.) were placed into a flame dried 10 mL Schlenk
tube under a nitrogen atmosphere and CH Cl (3 mL) was
added. The mixture was stirred for 15 min at r.t. in the
absence of light. Next, diethyl 2-allyl-2-(prop-2-ynyl)malonate
1
2623.
9 S. Gonell, M. Poyatos and E. Peris, Angew. Chem., Int. Ed.,
013, 52, 7009–7013.
(
1
2
2
2
2
0 R. Savka, M. Bergmann, Y. Kanai, S. Foro and H. Plenio,
Chem. – Eur. J., 2016, 22, DOI: 10.1002/chem.201601474.
1 J.-S. Yang and C.-W. Ko, J. Org. Chem., 2006, 71, 844–847.
2 C. S. Popeney, C. M. Levins and Z. Guan, Organometallics,
(200 mg, 1 equiv.) was added and the mixture was stirred at r.t.
2
2
in the absence of light for the indicated time. Finally, the
solvent was removed on a rotary evaporator and the residue
was purified by column chromatography on silica (pentane/
diethyl ether, 10 : 1, v/v). The fraction containing the mixture
of five- and six-membered products was collected and analyzed
by NMR.
2011, 30, 2432–2452.
2
2
2
2
3 S. Dastgir, K. S. Coleman, A. R. Cowley and M. L. H. Green,
Dalton Trans., 2009, 7203–7214.
4 K. V. Vasudevan, R. R. Butorac, C. D. Abernethy and
A. H. Cowley, Dalton Trans., 2010, 39, 7401–7408.
5 R. Savka and H. Plenio, Eur. J. Inorg. Chem., 2014, 6246–
6253.
Acknowledgements
6 M. Tsimerman, D. Mallik, T. Matsuo, T. Otani, K. Tamao
This work was supported by the DFG via grant Pl 178/13-2. We
and M. G. Organ, Chem. Commun., 2012, 48, 10352–10354.
wish to thank Yuki Kanai and Andreas Hegelein for the syn- 27 S. Leuthäußer, D. Schwarz and H. Plenio, Chem. – Eur. J.,
thesis of pentiptycene.
2007, 13, 7195–7203.
28 H. Türkmen and B. Cetinkaya, J. Organomet. Chem., 2006,
6
91, 3749–3759.
9 T. Tu, Z. Sun, W. Fang, M. Xu and Y. Zhou, Org. Lett., 2012,
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Dalton Trans.
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