Design and synthesis of thioether-imidazolium chlorides as efficient ligands for palladium-catalyzed Suzuki-Miyaura coupling of aryl bromides with arylboronic acids

Article abstract of DOI:10.1016/j.tet.2007.06.097

The catalyst composed of 0.25-0.025 mol % of [Pd(allyl)Cl]₂ and 0.5-0.05 mol % of the thioether-imidazolium chloride 3c was proven to be efficient in the Suzuki-Miyaura cross-coupling reactions of aryl bromides with arylboronic acids.

Full text of DOI:10.1016/j.tet.2007.06.097

Tetrahedron 63 (2007) 9393–9400
Design and synthesis of thioether-imidazolium chlorides as
efficient ligands for palladium-catalyzed Suzuki–Miyaura
coupling of aryl bromides with arylboronic acids
*
Masami Kuriyama, Rumiko Shimazawa and Ryuichi Shirai
*
Faculty of Pharmaceutical Sciences, Doshisha Women’s College of Liberal Arts,
Kodo, Kyotanabe, Kyoto 610-0395, Japan
Received 14 June 2007; revised 28 June 2007; accepted 28 June 2007
Available online 10 July 2007
Abstract—The catalyst composed of 0.25–0.025 mol % of [Pd(allyl)Cl]2 and 0.5–0.05 mol % of the thioether-imidazolium chloride 3c was
proven to be efficient in the Suzuki–Miyaura cross-coupling reactions of aryl bromides with arylboronic acids.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
transition metal-catalyzed reactions with only three excep-
tions in asymmetric reactions.11 We now report the synthesis
of the novel thioether-imidazolium chlorides (3a–f) and
their application in palladium-catalyzed Suzuki–Miyaura
cross-coupling reactions of aryl bromides with arylboronic
acids.
Palladium homogeneous catalysis is known as a versatile
tool for carbon–carbon bond formation in organic synthe-
sis.1 The Suzuki–Miyaura coupling reaction of aryl halides
with arylboronic acids is one of the most important palla-
dium-catalyzed cross-coupling reactions,2 and it has been
applied in the synthesis of pharmaceutical agents, organic
materials, and natural products.3 In this area, great advances
have been made in developing active catalysts, and particu-
larly, tertiary phosphines are known as efficient ligands for
the Suzuki–Miyaura cross-coupling.4
2. Results and discussion
The thioether-imidazolium chlorides (3a–f) were prepared
in the three-step procedure12 as shown in Scheme 1. Bis-
amides (1a–f) were obtained with 54–90% yields by the cou-
pling of N-aryloxamic acids12 with anilines13 using DCC or
oxalyl chloride. The reduction of 1a–f with borane–THF
complex gave ethylenediamine dihydrochlorides (2a–f),
and then 2a–f cyclized upon treatment with triethyl orthofor-
mate to form thioether-imidazolium chlorides (3a–f) in 65–
86% yields (over two steps). These imidazolium chlorides
(3a–f) are stable enough to handle and store in the air.
Because N-heterocyclic carbenes (NHCs) have a pronounced
s-donating property resembling donor phosphines and form
the metal complexes having high stability toward oxygen,
moisture, and heat,5 they have been utilized as alternatives
to phosphine ligands for transition metal-catalyzed reac-
tions, including the Suzuki–Miyaura cross-coupling.6
Although mixed-donor ligands have been used as efficient
systems with attractive and unique reactivity of their metal
complexes arising from different functional groups,7 the
systems bearing NHCs are still developing for transition
metal-catalyzed reactions. As most of them were hybrid
type NHC-based ligands having nitrogen8 or phosphine9
donors,6 bidentate NHC-based ligands containing softer
sulfur atoms10 have advantageous features such as hemila-
bile coordination7a,10c and easy manipulation, and can also
provide stable (Pd/L¼1/1) complexes avoiding the use of
excess ligand and high loadings of palladium. However, sul-
fur donor-functionalized NHCs have not been applied in
The coupling reactions of 4-bromotoluene with phenylbor-
onic acid using 0.5 mol % of catalysts (Pd/L¼1/1)10c gener-
ated in situ9a,c from thioether-imidazolium chlorides (3a–f)
and [Pd(allyl)Cl]2 in the presence of cesium carbonate
were carried out in dioxane at 90 ꢀC for 1 h under an argon
atmosphere, and we found that thioether-imidazolium chlo-
rides (3a,c) were proven to be superior ligands, affording
82% and 92% yields, respectively (Table 1, entries 1–6). A
series of palladium sources was examined, and the reactions
using [Pd(allyl)Cl]2 and Pd(OAc)2 gave the coupling prod-
ucts in 65% and 63% yields, respectively (entries 6–10). It
was revealed that active palladium–NHC species were
formed conveniently in situ from thioether-imidazolium
* Corresponding authors. E-mail addresses: mkuriyam@dwc.doshisha.ac.
jp; rshirai@dwc.doshisha.ac.jp
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.06.097

9394
M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
R2
O
OH
O
salts and palladium sources under basic conditions. The ex-
i) (COCl)2
cat. DMF
DCC
HOBT
periment with the addition of thioanisole or no imidazolium
salt showed a significant decrease in catalytic activity (en-
tries 11 and 12).
or
R1
NH
H3N
R3S
+
THF, 0 °C
ii) Et3N
CH2Cl2, rt
(1c-f)
R2
R2
(1a, b)
R3S
HN
Investigations into the influence of bases suggested that
Cs2CO3 was the reagent of choice. K3PO4 and CsF proved
to be less effective, and other bases such as K2CO3,
Na2CO3, and CsOAc were ineffective (entries 13–17). A
series of solvents was examined, and dioxane proved to be
suitable. Highly polar solvents such as DMA, DMF, and
DMSO led to moderate results (entries 18–21).
O
i) BH3-THF ii) conc. HCl.
reflux
R1
NH
O
R2
1a-f (1a: 90%, 1b: 69%, 1c: 68%,
1d: 62%, 1e: 58%, 1f: 54%)
R3S
R2
R2
H2N
NH2
2a-f
HC(OEt)3
100 °C
The cross-coupling reaction of 4-bromotoluene with phenyl-
boronic acid using the optimized condition was carried out
for 12 h to give the product in 99% yield with complete com-
sumption of 4-bromotoluene (entry 22). This reaction could
be performed in air as well but required prolonged reaction
time (entry 23). While the cross-coupling of 4-iodotoluene
using 0.005 mol % of the catalyst led to 99% yield of the
product, the reaction of 4-chlorotoluene under reflux condi-
tion was very slow to give the product in 5% yield (entries 24
and 25).
R1
2Cl
R2
3a : R1= Me, R2= Me, R3= Me (76%)
3b: R1= Me, R2= Me, R3= Ph (71%)
3c : R1= Me, R2= Me, R3= i-Pr (86%)
3d: R1= H, R2= i-Pr, R3= Me (66%)
3e : R1= H, R2= i-Pr, R3= Ph (65%)
3f : R1= H, R2= i-Pr, R3= i-Pr (69%)
Cl
N
N
R1
R2 R3S
3a-f
Scheme 1. Synthesis of thioether-imidazolium chlorides (3a–f).
The influence of varying arylboronic acids in the Suzuki–
Miyaura cross-coupling with 0.5–0.05 mol % of the catalyst
using 4-bromotoluene was investigated (Table 2). The phe-
nylboronic acids bearing a phenyl group at the 4- or 3-
position were easily converted to give the desired products
with excellent yields (entries 1 and 2). The reaction using
sterically hindered 2-biphenylboronic acid required reflux
conditions to afford 99% yield (entry 3). 2-Naphthylboronic
acid led to 99% yield (entry 4). The reaction using 1-
naphthylboronic acid gave the product with 85% yield (entry
5). The arylboronic acid bearing 4-methoxy and 4-fluoro
substituents led to 88% and 80% yields, respectively (entries
6 and 7). The cross-coupling reaction of 3-cyanophenylbor-
onic acid was carried out in dioxane/H2O (10/1),14 leading to
an excellent result (entry 8).
Table 1. The Suzuki–Miyaura cross-coupling using thioether-imidazolium
chlorides under various reaction conditionsa
Ligand (0.5 mol %)
Br
Pd (0.5 mol %)
+
base (2 equiv)
Me
(HO)2B
solvent
Me
90 °C, 1 h
1.5 equiv
Entry Ligand Pd
Base
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
3a
3b
3c
3d
3e
3f
3f
3f
3f
3f
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 82
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 60
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 92
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 56
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 58
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 65
Pd(acac)2
Pd(OAc)2
Pd(dba)2
Pd2(dba)3
Cs2CO3 Dioxane
6
Investigations of aryl bromides in the Suzuki–Miyaura
cross-coupling using phenylboronic acid were also con-
ducted (Table 3). The reactions using sterically less hindered
aryl bromides took place smoothly, giving the desired
products with good yields (entries 1, 2, and 4). Moreover,
sterically hindered aryl bromides such as 2-bromotoluene,
1-bromonaphthalene, and 2-bromo-1-methylnaphthalene
also reacted efficiently (entries 3, 5, and 6). 4-Bromoanisole
was smoothly converted, affording a 99% yield (entry 7).
However, 4-bromo-N,N-dimethylaniline was slightly less
reactive to give the product with 82% yield (entry 8). The
coupling reactions with activated aryl bromides having elec-
tron-withdrawing groups were carried out efficiently, afford-
ing excellent results (entries 9–11). Heteroaryl bromides
containing a coordinating atom such as 3-bromopyridine
and 4-bromoisoquinoline led to 98% and 88% yields,
respectively (entries 12 and 13).
Cs2CO3 Dioxane 63
Cs2CO3 Dioxane 14
Cs2CO3 Dioxane 11
9
10
11
12
13
14
15
16
17
18
19
20
21
22c
23d
24e
25f
PhSMe [Pd(allyl)Cl]2 Cs2CO3 Dioxane 18
None
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
3c
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 11
[Pd(allyl)Cl]2 K2CO3 Dioxane 36
[Pd(allyl)Cl]2 Na2CO3 Dioxane
2
[Pd(allyl)Cl]2 K3PO4
[Pd(allyl)Cl]2 CsF
[Pd(allyl)Cl]2 CsOAc
[Pd(allyl)Cl]2 Cs2CO3 Toluene
[Pd(allyl)Cl]2 Cs2CO3 DMA
[Pd(allyl)Cl]2 Cs2CO3 DMF
[Pd(allyl)Cl]2 Cs2CO3 DMSO
Dioxane 86
Dioxane 73
Dioxane
5
32
61
58
56
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 99
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 88
[Pd(allyl)Cl]2 Cs2CO3 Dioxane
[Pd(allyl)Cl]2 Cs2CO3 Dioxane 99
5
a
Reaction conditions: 4-bromotoluene (1.0 mmol), phenylboronic acid
(1.5 mmol), Pd (0.5 mol %), ligand (0.5 mol %), base (2.0 mmol), solvent
(2 mL), 90 ꢀC, 1 h.
Isolated yield.
The reaction was carried out for 12 h.
The reaction was carried out for 20 h under air.
The reaction using 4-chlorotoluene was carried out for 20 h under reflux.
The reaction with 0.005 mol % of 3c and 0.0025 mol % of [Pd(allyl)Cl]2
using 4-iodotoluene was carried out for 40 h.
b
c
d
e
f
3. Conclusion
In summary, novel thioether-imidazolium chlorides were
prepared and their application in palladium-catalyzed

M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
9395
Table 2. The Suzuki–Miyaura coupling of 4-bromotoluene with various arylboronic acids using thioether-imidazolium chloride 3ca
Ligand 3c
Br
Ar
[PdCl(allyl)]2
(HO)2B-Ar
1.5 equiv
+
Cs2CO3 (2 equiv)
dioxane
Me
Me
90 °C
Entry
1
Arylboronic acid
(HO)2B Ph
Product
Cat. (mol %)
0.5
Time (h)
15
Yieldb (%)
97
Me
Me
Ph
(HO)2B
2
0.05
20
95
Ph
Ph
(HO)2B
Me
3c
4
0.05
0.05
20
20
99
99
Ph
Ph
Me
(HO)2B
(HO)2B
Me
5
0.5
12
85
6c
7
0.05
0.05
12
12
88
80
(HO)2B
OMe
F
Me
OMe
F
Me
Me
(HO)2B
(HO)2B
8d
0.5
12
98
CN
CN
a
Reaction conditions: 4-bromotoluene (1.0 mmol), arylboronic acid (1.5 mmol), Pd/ligand 3c¼1/1, Cs2CO3 (2.0 mmol), dioxane (2 mL), 90 ꢀC.
b
c
d
Isolated yield.
The reaction was carried out under reflux.
The reaction was carried out in dioxane/H2O (10/1).
Suzuki–Miyaura cross-coupling reactions of aryl bromides
4.2. Materials
with arylboronic acids was investigated. The coupling reac-
tions of a broad range of aryl bromides with various arylbor-
onic acids using 0.5–0.05 mol % of the catalyst were carried
out efficiently. This initial investigation revealed that the
thioether-NHC system represented a promising class of li-
gands for Suzuki–Miyaura cross-coupling reactions. Mech-
anistic studies and further application to other transition
metal-catalyzed reactions are currently under investigation.
All chemicals were purchased from Aldrich or Wako Pure
Chemical Industries. Aryl bromides, aryl chlorides in the
form of solid, arylboronic acids, and all palladium com-
plexes were used as received. Aryl bromides and aryl chlo-
rides in the form of liquid were distilled under argon
before use. Toluene and dioxane were distilled from sodium
benzophenone ketyl under argon. DMA, DMF, and DMSO
were distilled from calcium hydride under argon. Cesium
carbonate, cesium acetate, sodium carbonate, and potassium
carbonate were used as received. Potassium phosphate triba-
sic and cesium fluoride were ground to a fine powder prior to
use.
4. Experimental
4.1. General
All melting points are not corrected. IR spectra were ob-
tained with JASCO FT/IR-4100 and expressed in cmꢁ1. 1H
and 13C NMR spectra were taken at 500 and 125 MHz, re-
spectively, with Bruker Avance 500. Chemical shift values
are expressed in parts per million relative to internal or exter-
nal TMS. Abbreviations are as follows: s, singlet; d, doublet;
t, triplet; q, quartet; m, multiplet; br, broad. Mass spectra
(EIMS) were recorded with Shimadzu GCMS-QP 5050A
Mass Spectrometer, and high-resolution mass spectra
(HRMS) were recorded with JEOL JMS-DX303 HF spec-
trometer using electron ionization (EI) mass spectrometry.
The products were isolated by silica gel column chromato-
graphy with KANTO SilicaGel 60.
4.3. Synthetic procedure of thioether-imidazolium
chlorides
4.3.1. N-(2-(Methylthio)phenyl)-N0-(mesityl)-oxalamide
(1a). Under argon atmosphere, N-(mesityl)-oxamic acid12
(2.07 g, 10 mmol) and 1-hydroxybenzotriazole (2.30 g,
15 mmol) were stirred in 100 mL of THF at 0 ꢀC. To this
mixture was added 1,3-dicyclohexylcarbodiimide (2.47 g,
12 mmol) in 13 mL of CH2Cl2, and it was stirred at 0 ꢀC
for 1 h. Then, 2-methylthioaniline (1.25 mL, 10 mmol)
was added to the mixture, and it was stirred at 0 ꢀC for
18 h. The solvent was removed and AcOEt was added to
make a suspension, which was then filtered. The filtrate

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M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
Table 3. The Suzuki–Miyaura coupling of various aryl bromides with
phenylboronic acid using thioether-imidazolium chloride 3ca
129.0, 129.6, 133.1, 134.6, 136.8, 137.5, 157.6, 158.1. IR
(Nujol): 1580, 1690, 3340 cmꢁ1. EIMS m/z: 328 (M+).
Anal. Calcd for C18H20N2O2S: C, 65.83; H, 6.14; N, 8.53.
Found: C, 65.76; H, 6.23; N, 8.52.
Ligand 3c
[PdCl(allyl)]2
+
Ar-Br
Cs2CO3 (2 equiv)
dioxane
(HO)2B
1.5 equiv
Ar
4.3.2. N-(2-(Phenylthio)phenyl)-N0-(mesityl)-oxalamide
(1b). This compound was synthesized in the similar proce-
dure of 1a (2.07 g (10 mmol) of N-(mesityl)-oxamic
acid,12 2.30 g (15 mmol) of 1-hydroxybenzotriazole, 2.47 g
(12 mmol) of 1,3-dicyclohexylcarbodiimide, and 2.01 g
(10 mmol) of 2-phenylthioaniline were used), giving
2.68 g (6.9 mmol, 69% yield) of the product 1b as a colorless
cube of mp 136–137 ꢀC. 1H NMR (CDCl3): 2.16 (6H, s), 2.28
(3H, s), 6.91 (2H, s), 7.14–7.16 (1H, m), 7.21–7.23 (5H, m),
7.49 (1H, t, J¼7.5 Hz), 7.69 (1H, d, J¼7.5 Hz), 8.49 (1H, d,
J¼7.5 Hz), 8.66 (1H, br s), 10.46 (1H, br s). 13C NMR
(CDCl3): 18.3, 20.9, 120.5, 123.1, 125.5, 126.7, 128.95,
129.00, 129.1, 129.6, 130.6, 134.6, 135.1, 136.6, 137.5,
90 °C
Entry
Aryl bromide
Product
Cat.
(mol %) (h) (%)
Time Yieldb
Me
Me
1
2
0.05
0.05
20
20
99
99
Br
Br
Me
Me
Br
Me
3
4
0.05
0.05
20
20
99
98
Me
Me
138.1, 157.5, 157.9. IR (Nujol): 1580, 1670, 3300 cmꢁ1
.
Br
EIMS m/z: 390 (M+). Anal. Calcd for C23H22N2O2S: C,
70.74; H, 5.68; N, 7.17. Found: C, 70.60; H, 5.72; N, 7.10.
Br
4.3.3. N-(2-(Isopropylthio)phenyl)-N0-(mesityl)-oxal-
amide (1c). Under argon atmosphere, oxalyl chloride
(0.96 mL, 11 mmol) was added to the solution of N-
(mesityl)-oxamic acid12 (2.07 g, 10 mmol) in 50 mL of dry
CH2Cl2 at room temperature, followed by 0.025 mL
(0.32 mmol) of DMF. The reaction mixture was stirred for
4 h, and then the solvent was removed completely to give
the pale yellow solid. It was dissolved in 25 mL of dry
CH2Cl2. To the solution, a mixture of 2-isopropylthioani-
line13 (1.67 g, 10 mmol) and triethylamine (1.95 mL,
14 mmol) in 5 mL of dry CH2Cl2 was added at 0 ꢀC and
stirred at room temperature for 18 h. The solvent was re-
moved, and then water and AcOEt were added. The aqueous
layer was extracted with AcOEt, and the combined organic
layers were washed with 10% HCl, satd NaHCO3, and brine.
They were dried over Na2SO4 and concentrated to give the
crude product. It was recrystallized from AcOEt and hexane,
giving the product 1c as a pale yellow prism of mp 156–
5
6
0.05
0.5
20
20
99
97
Me
Br
7
0.05
0.5
20
20
12
15
12
99
82
99
97
99
MeO
Me2N
MeCO
NC
Br MeO
Br Me2N
Br MeCO
8
9
0.05
0.5
10
11
Br
NC
0.05
O2N
Br O2N
1
157 ꢀC (2.43 g, 6.8 mmol, 68% yield). H NMR (CDCl3):
Br
Br
12
0.5
0.5
15
15
98
88
N
N
N
1.26 (6H, d, J¼6.5 Hz), 2.24 (6H, s), 2.29 (3H, s), 3.18 (1H,
septet, J¼6.5 Hz), 6.94 (2H, s), 7.15 (1H, t, J¼7.5 Hz), 7.43
(1H, t, J¼7.5 Hz), 7.60 (1H, d, J¼7.5 Hz), 8.54 (1H, d,
J¼7.5 Hz), 8.78 (1H, br s), 10.82 (1H, br s). 13C NMR
(CDCl3): 18.3, 20.9, 23.1, 40.6, 119.4, 123.6, 125.0, 129.0,
129.7, 130.0, 134.7, 137.1, 137.5, 138.9, 157.5, 158.2. IR
(Nujol): 1580, 1670, 3300 cmꢁ1. EIMS m/z: 356 (M+).
Anal. Calcd for C20H24N2O2S: C, 67.38; H, 6.79; N, 7.86.
Found: C, 67.38; H, 6.85; N, 7.81.
N
13
a
Reaction conditions: aryl bromide (1.0 mmol), phenylboronic acid
(1.5 mmol), Pd/ligand 3c¼1/1, Cs2CO3 (2.0 mmol), dioxane (2 mL),
90 ꢀC.
Isolated yield.
b
was washed with 10% citric acid solution, satd NaHCO3,
and brine. It was dried over Na2SO4 and the solvent was re-
moved, leaving a solid, which was purified by column chro-
matography (hexane/AcOEt¼10/1), giving the product 1a as
a yellow solid (2.96 g, 9.0 mmol, 90% yield). The solid was
recrystallized from AcOEt and hexane to give the product 1a
as colorless needles of mp 123–124 ꢀC (2.51 g, 7.7 mmol,
4.3.4. N-(2-(Methylthio)phenyl)-N0-(2,6-diisopropyl-
phenyl)-oxalamide (1d). This compound was synthesized
in the similar procedure of 1c (0.96 mL (11 mmol) of oxalyl
chloride, 2.49 g (10 mmol) of N-(2,6-diisopropylphenyl)-
oxamic acid,12 1.25 mL (12 mmol) of 2-methylthioaniline,
and 1.95 mL (14 mmol) of triethylamine were used), giving
2.38 g (6.2 mmol, 62% yield) of the product 1d as colorless
needles of mp 175–176 ꢀC. 1H NMR (CDCl3): 1.22 (12H, d,
J¼6.5 Hz), 2.43 (3H, s), 3.05 (2H, septet, J¼6.5 Hz), 7.18
(1H, dt, J¼1.0, 7.5 Hz), 7.22 (2H, t, J¼7.5 Hz), 7.33–7.39
(2H, m), 7.56 (1H, dd, J¼1.0, 7.5 Hz), 8.44 (1H, d,
J¼7.5 Hz), 8.82 (1H, br s), 10.45 (1H, br s). 13C NMR
1
77% yield). H NMR (CDCl3): 2.24 (6H, s), 2.30 (3H, s),
2.43 (3H, s), 6.94 (2H, s), 7.17 (1H, t, J¼7.5 Hz), 7.37
(1H, t, J¼7.5 Hz), 7.56 (1H, d, J¼7.5 Hz), 8.43 (1H, d,
J¼7.5 Hz), 8.79 (1H, br s), 10.47 (1H, br s). 13C NMR
(CDCl3): 18.3, 18.9, 20.9, 112.0, 125.5, 126.9, 128.7,

M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
9397
(CDCl3): 18.8, 23.6, 28.9, 120.0, 123.6, 125.5, 127.0, 128.7,
128.8, 129.7, 133.0, 136.7, 145.8, 157.7, 159.2. IR (Nujol):
1580, 1660, 3240 cmꢁ1. EIMS m/z: 370 (M+). Anal. Calcd
for C21H26N2O2S: C, 68.08; H, 7.07; N, 7.56. Found: C,
68.03; H, 7.30; N, 7.46.
(3H, s), 2.51 (6H, s), 2.56 (3H, s), 4.58 (2H, t, J¼11.5 Hz),
4.96 (2H, t, J¼11.5 Hz), 6.98 (2H, s), 7.32 (1H, d, J¼
7.5 Hz), 7.35 (1H, t, J¼7.5 Hz), 7.44 (1H, d, J¼7.5 Hz),
8.30 (1H, d, J¼7.5 Hz), 8.45 (1H, s). 13C NMR (CDCl3):
15.9, 18.1, 20.9, 51.9, 52.5, 126.9, 127.0, 128.2, 129.9,
130.2, 130.6, 132.9, 134.8, 135.3, 140.4, 158.7. IR (Nujol):
1590, 1620 cmꢁ1. HRMS (EI) calcd for C19H23ClN2S (M+):
346.1270. Found: 346.1273.
4.3.5. N-(2-(Phenylthio)phenyl)-N0-(2,6-diisopropyl-
phenyl)-oxalamide (1e). This compound was synthesized
in the similar procedure of 1c (0.96 mL (11 mmol) of oxalyl
chloride, 2.49 g (10 mmol) of N-(2,6-diisopropylphenyl)-
oxamic acid,12 2.01 g (10 mmol) of 2-phenylthioaniline,
and 1.95 mL (14 mmol) of triethylamine were used), giving
2.50 g (5.8 mmol, 58% yield) of the product 1e as a pale
4.3.8. 1-(Mesityl)-3-(2-(phenylthio)phenyl)-4,5-dihydro-
imidazolium chloride (3b). This compound was synthe-
sized in the similar procedure of 3a (1.76 g (4.5 mmol) of
1b, 36 mL (36 mmol) of BH3–THF, and 14 mL (84 mmol)
of triethyl orthoformate were used), giving 1.30 g
(3.20 mmol, 71% yield) of the product 3b as a white solid
1
brown solid of mp 203–204 ꢀC. H NMR (CDCl3): 1.17
(12H, d, J¼6.5 Hz), 2.95 (2H, septet, J¼6.5 Hz), 7.14–
7.16 (1H, m), 7.19–7.25 (7H, m), 7.33 (1H, t, J¼7.5 Hz),
7.50 (1H, t, J¼7.5 Hz), 7.71 (1H, d, J¼7.5 Hz), 8.51 (1H,
d, J¼7.5 Hz), 8.69 (1H, br s), 10.47 (1H, br s). 13C NMR
(CDCl3): 23.6, 28.9, 120.5, 123.3, 123.7, 125.6, 126.8,
128.9, 129.2, 129.5, 130.7, 135.0, 136.6, 138.1, 145.8,
157.5, 159.0. IR (Nujol): 1580, 1680, 3300 cmꢁ1. EIMS
m/z: 432 (M+). Anal. Calcd for C26H28N2O2S: C, 72.19; H,
6.52; N, 6.48. Found: C, 71.93; H, 6.65; N, 6.32.
1
of mp 204–205 ꢀC. H NMR (CDCl3): 2.30 (3H, s), 2.41
(6H, s), 4.48 (2H, t, J¼10.5 Hz), 4.96 (2H, t, J¼10.5 Hz),
6.95 (2H, s), 7.22 (2H, d, J¼7.5 Hz), 7.30–7.42 (5H, m),
7.53 (1H, t, J¼7.5 Hz), 8.46 (1H, s), 8.51 (1H, d, J¼
7.5 Hz). 13C NMR (CDCl3): 18.1, 20.9, 51.9, 52.8, 127.9,
128.8, 129.8, 129.9, 130.0, 130.2, 130.7, 130.8, 133.2, 133.6,
135.3, 135.4, 140.5, 158.5. IR (Nujol): 1590, 1620 cmꢁ1
.
HRMS (EI) calcd for C24H25ClN2S (M+): 408.1427. Found:
408.1423.
4.3.6. N-(2-(Isopropylthio)phenyl)-N0-(2,6-diisopropyl-
phenyl)-oxalamide (1f). This compound was synthesized
in the similar procedure of 1c (0.96 mL (11 mmol) of oxalyl
chloride, 2.49 g (10 mmol) of N-(2,6-diisopropylphenyl)-
oxamic acid,12 1.67 g (10 mmol) of 2-isopropylthioaniline,13
and 1.95 mL (14 mmol) of triethylamine were used), giving
2.14 g (5.4 mmol, 54% yield) of the product 1f as pale yellow
needles of mp 116–117 ꢀC. 1H NMR (CDCl3): 1.22 (12H, d,
J¼7.0 Hz), 1.26 (6H, d, J¼7.0 Hz), 3.05 (2H, septet, J¼
7.0 Hz), 3.16 (1H, septet, J¼7.0 Hz), 7.16 (1H, t, J¼
7.5 Hz), 7.22 (2H, d, J¼7.5 Hz), 7.34 (1H, t, J¼7.5 Hz),
7.44 (1H, t, J¼7.5 Hz), 7.60 (1H, d, J¼7.5 Hz), 8.53 (1H,
d, J¼7.5 Hz), 8.81 (1H, br s), 10.83 (1H, br s). 13C NMR
(CDCl3): 23.1, 23.6, 28.9, 40.7, 119.5, 123.7, 125.0, 128.9,
129.7, 130.1, 137.1, 138.9, 145.9, 157.5, 159.4. IR (Nujol):
1580, 1670, 3270 cmꢁ1. EIMS m/z: 398 (M+). Anal. Calcd
for C23H30N2O2S: C, 69.31; H, 7.59; N, 7.03. Found: C,
69.23; H, 7.66; N, 6.89.
4.3.9. 1-(Mesityl)-3-(2-(isopropylthio)phenyl)-4,5-dihy-
dro-imidazolium chloride (3c). This compound was syn-
thesized in the similar procedure of 3a (1.60 g (4.5 mmol)
of 1c, 36 mL (36 mmol) of BH3–THF, and 14 mL (84 mmol)
of triethyl orthoformate were used), giving 1.45 g (3.87
mmol, 86% yield) of the product 3c as a white solid of
mp 237–238 ꢀC. 1H NMR (CDCl3): 1.33 (6H, d, J¼
7.0 Hz), 2.32 (3H, s), 2.52 (6H, s), 3.46 (1H, septet, J¼
7.0 Hz), 4.60 (2H, t, J¼11.5 Hz), 5.01 (2H, t, J¼11.5 Hz),
6.99 (2H, s), 7.41 (1H, dt, J¼1.5, 7.5 Hz), 7.45 (1H, dt,
J¼1.5, 7.5 Hz), 7.52 (1H, dd, J¼1.5, 7.5 Hz), 8.32 (1H,
dd, J¼1.5, 7.5 Hz), 8.34 (1H, s). 13C NMR (CDCl3): 18.1,
20.9, 23.0, 39.2, 51.9, 53.1, 127.8, 128.8, 129.9, 130.1,
130.2, 131.3, 132.6, 135.4, 135.6, 140.5, 158.3. IR (Nujol):
1590, 1620 cmꢁ1. EIMS m/z: 374 (M+). Anal. Calcd for
C21H27ClN2S: C, 67.27; H, 7.26; N, 7.47. Found: C,
67.13; H, 7.36; N, 7.30.
4.3.7. 1-(Mesityl)-3-(2-(methylthio)phenyl)-4,5-dihydro-
imidazolium chloride (3a). Under argon atmosphere,
1.48 g (4.5 mmol) of 1a was charged in a round-bottom
flask. To this was added 36 mL (36 mmol) of BH3–THF
(1 M in THF) at room temperature. The reaction mixture
was refluxed for 18 h. It was cooled to room temperature,
and then methanol was added slowly, until all bubbling
ceased. Concd HCl (1.5 mL) was added, and the solvent
was removed. To the resulting solid was added methanol,
and the solvent was removed again. This process was re-
peated twice more to give the solid 2a. To this solid was
added 14 mL (84 mmol) of triethyl orthoformate at room
temperature, and the mixture was stirred at 100 ꢀC for 3 h.
The reaction mixture was cooled to room temperature and
the solvent was removed completely, giving the solid. It
was dissolved in a small amount of CH2Cl2 and treated
with AcOEt, and then a white solid precipitated. The result-
ing solid was filtered and washed with a small amount of
AcOEt, giving the product 3a as a white solid of mp 211–
4.3.10. 1-(2,6-Diisopropylphenyl)-3-(2-(methylthio)-
phenyl)-4,5-dihydro-imidazolium chloride (3d). This
compound was synthesized in the similar procedure of 3a
(1.67 g (4.5 mmol) of 1d, 36 mL (36 mmol) of BH3–THF,
and 14 mL (84 mmol) of triethyl orthoformate were used),
giving 1.15 g (2.97 mmol, 66% yield) of the product 3d as
1
a white solid of mp 219–220 ꢀC. H NMR (CDCl3): 1.30
(6H, d, J¼6.5 Hz), 1.38 (6H, d, J¼6.5 Hz), 2.56 (3H, s),
3.42 (2H, septet, J¼6.5 Hz), 4.63 (2H, t, J¼10.5 Hz), 5.10
(2H, t, J¼10.5 Hz), 7.30 (2H, d, J¼8.0 Hz), 7.34 (1H, d,
J¼8.0 Hz), 7.38 (1H, t, J¼8.0 Hz), 7.44–7.49 (2H, m),
8.14 (1H, s), 8.35 (1H, d, J¼8.0 Hz). 13C NMR (CDCl3):
16.1, 24.4, 25.1, 28.6, 53.0, 54.5, 125.0, 127.4, 128.3,
129.6, 130.7, 131.3, 132.9, 134.4, 146.8, 158.0. IR (Nujol):
1580, 1610 cmꢁ1. HRMS (EI) calcd for C22H29ClN2S (M+):
388.1740. Found: 388.1740.
4.3.11. 1-(2,6-Diisopropylphenyl)-3-(2-(phenylthio)-
phenyl)-4,5-dihydro-imidazolium chloride (3e). This
compound was synthesized in the similar procedure of 3a
1
212 ꢀC (1.18 g, 3.42 mmol, 76%). H NMR (CDCl3): 2.31

9398
M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
(1.95 g (4.5 mmol) of 1e, 36 mL (36 mmol) of BH3–THF,
and 14 mL (84 mmol) of triethyl orthoformate were used),
giving 1.32 g (2.93 mmol, 65% yield) of the product 3e as
(3H, s), 7.27 (2H, d, J¼7.5 Hz), 7.36 (1H, t, J¼7.5 Hz),
7.46 (2H, t, J¼7.5 Hz), 7.55 (2H, d, J¼7.5 Hz), 7.64 (2H,
d, J¼7.5 Hz), 7.66 (4H, m). 13C NMR (CDCl3): 21.1,
126.9, 127.0, 127.3, 127.4, 128.8, 129.5, 137.1, 137.8,
139.8, 140.0, 140.8. IR (Nujol): 1580 cmꢁ1. EIMS m/z:
244 (M+).
1
a white solid of mp 193–194 ꢀC. H NMR (CDCl3): 1.27
(6H, d, J¼7.0 Hz), 1.33 (6H, d, J¼7.0 Hz), 3.34 (2H, septet,
J¼7.0 Hz), 4.55 (2H, t, J¼10.5 Hz), 5.08 (2H, t, J¼
10.5 Hz), 7.23 (2H, d, J¼7.5 Hz), 7.28 (2H, d, J¼7.5 Hz),
7.31–7.41 (5H, m), 7.46 (1H, t, J¼7.5 Hz), 7.54 (1H, dt,
J¼1.0, 7.5 Hz), 8.22 (1H, s), 8.52 (1H, d, J¼7.5 Hz). 13C
NMR (CDCl3): 24.4, 25.1, 28.6, 53.3, 54.5, 125.0, 128.1,
128.7, 129.5, 129.9, 130.1, 130.3, 130.7, 130.8, 131.3, 132.9,
4.4.3. 4-Methyl-(1,10,30,100)-terphenyl17 (Table 2, entry 2).
Silica gel column chromatography (hexane/ether¼200/1)
gave 232 mg (0.95 mmol, 95% yield) of the product as
1
a white solid of mp 78–79 ꢀC. H NMR (CDCl3): 2.41
133.3, 135.2, 146.7, 157.7. IR (Nujol): 1580, 1620 cmꢁ1
.
(3H, s), 7.26 (2H, d, J¼7.5 Hz), 7.37 (1H, t, J¼7.5 Hz),
7.46 (2H, t, J¼7.5 Hz), 7.50 (1H, d, J¼7.5 Hz), 7.54–7.56
(4H, m), 7.65 (2H, d, J¼7.5 Hz), 7.79 (1H, s). 13C NMR
(CDCl3): 21.1, 125.8, 125.9, 126.0, 127.1, 127.3, 127.3,
128.8, 129.1, 129.5, 137.2, 138.3, 141.3, 141.7, 141.7. IR
(Nujol): 1520 cmꢁ1. EIMS m/z: 244 (M+).
HRMS (EI) calcd for C27H31ClN2S (M+): 450.1896. Found:
450.1897.
4.3.12. 1-(2,6-Diisopropylphenyl)-3-(2-(isopropylthio)-
phenyl)-4,5-dihydro-imidazolium chloride (3f). This
compound was synthesized in the similar procedure of 3a
(1.80 g (4.5 mmol) of 1f, 36 mL (36 mmol) of BH3–THF,
and 14 mL (84 mmol) of triethyl orthoformate were used),
giving 1.30 g (3.11 mmol, 69% yield) of the product 3f as
4.4.4. 4-Methyl-(1,10,20,100)-terphenyl17 (Table 2, entry 3).
Silica gel column chromatography (hexane/ether¼200/1)
gave 242 mg (0.99 mmol, 99% yield) of the product as col-
1
1
a white solid of mp 198–199 ꢀC. H NMR (CDCl3): 1.31
orless oil. H NMR (CDCl3): 2.30 (3H, s), 7.00–7.04 (4H,
(6H, d, J¼7.0 Hz), 1.35 (6H, d, J¼7.0 Hz), 1.38 (6H, d,
J¼7.0 Hz), 3.41 (2H, septet, J¼7.0 Hz), 3.49 (1H, septet, J¼
7.0 Hz), 4.64 (2H, t, J¼10.5 Hz), 5.13 (2H, t, J¼10.5 Hz),
7.31 (2H, d, J¼8.0 Hz), 7.41–7.51 (4H, m), 8.02 (1H, s),
8.36 (1H, d, J¼8.0 Hz). 13C NMR (CDCl3): 22.9, 24.4,
25.1, 28.4, 39.1, 53.4, 54.4, 124.9, 127.8, 128.6, 129.5,
130.2, 131.2, 131.3, 131.8, 135.0, 146.6, 157.5. IR (Nujol):
1580, 1620 cmꢁ1. EIMS m/z: 416 (M+). Anal. Calcd for
C24H33ClN2S: C, 69.12; H, 7.98; N, 6.72. Found: C,
68.83; H, 8.10; N, 6.57.
m), 7.14–7.16 (2H, m), 7.20–7.24 (3H, m), 7.38–7.43 (4H,
m). 13C NMR (CDCl3): 21.1, 126.4, 127.2, 127.4, 127.8,
128.6, 129.7, 129.9, 130.6, 136.0, 138.5, 140.5, 141.7. IR
(neat): 1520, 1600 cmꢁ1. EIMS m/z: 244 (M+).
4.4.5. 2-(4-Methylphenyl)naphthalene18 (Table 2, entry
4). Silica gel column chromatography (hexane/ether¼200/
1) gave 216 mg (0.99 mmol, 99% yield) of the product as
1
a white solid of mp 96–97 ꢀC. H NMR (CDCl3): 2.42
(3H, s), 7.30 (2H, d, J¼7.5 Hz), 7.48 (2H, m), 7.63 (2H, d,
J¼7.5 Hz), 7.74 (1H, d, J¼7.5 Hz), 7.86 (1H, d, J¼
7.5 Hz), 7.89 (2H, t, J¼7.5 Hz), 8.02 (1H, s). 13C NMR
(CDCl3): 21.1, 125.4, 125.5, 125.7, 126.2, 127.2, 127.6,
128.1, 128.3, 129.6, 132.5, 133.7, 137.1, 138.2, 138.5. IR
(Nujol): 1500 cmꢁ1. EIMS m/z: 218 (M+).
4.4. Palladium/thioether-imidazolium chloride system-
catalyzed Suzuki–Miyaura cross-coupling
Under argon atmosphere, a reaction tube was charged with
cesium carbonate (652 mg, 2 mmol), and 1 mL of dioxane
and 1 mL of 5ꢂ10ꢁ4 M dioxane solution of [Pd(allyl)Cl]2
and an imidazolium salt were added. The mixture was stirred
for 15 min at 80 ꢀC and cooled to room temperature. Then
1.0 mmol of aryl bromide and 1.5 mmol of arylboronic
acid were added, and the reaction mixture was stirred at
90 ꢀC. The mixture was cooled to room temperature and wa-
ter was added, and then, it was extracted with ether. The
combined organic layers were washed with brine, and then
dried over MgSO4. Concentration and purification through
silica gel column chromatography gave the product.
4.4.6. 1-(4-Methylphenyl)naphthalene19 (Table 2, entry
5). Silica gel column chromatography (hexane/ether¼200/
1) gave 185 mg (0.85 mmol, 85% yield) of the product as
1
colorless oil. H NMR (CDCl3): 2.46 (3H, s), 7.30 (2H, d,
J¼7.5 Hz), 7.39–7.43 (4H, m), 7.47–7.53 (2H, m), 7.84
(1H, d, J¼7.5 Hz), 7.91 (2H, t, J¼9.5 Hz). 13C NMR
(CDCl3): 21.2, 125.4, 125.7, 125.9, 126.1, 126.9, 127.4,
128.2, 129.0, 129.9, 131.7, 133.8, 136.9, 137.8, 140.2. IR
(neat): 1510 cmꢁ1. EIMS m/z: 218 (M+).
4.4.7. 4-Methoxy-40-methylbiphenyl20 (Table 2, entry 6).
Silica gel column chromatography (hexane/ether¼50/1)
gave 174 mg (0.88 mmol, 88% yield) of the product as
4.4.1. 4-Methylbiphenyl15 (Table 1, entry 22). Silica
gel column chromatography (hexane/ether¼200/1) gave
166 mg (0.99 mmol, 99% yield) of the product as a white
1
a white solid of mp 109–110 ꢀC. H NMR (CDCl3): 2.38
1
solid of mp 46–47 ꢀC. H NMR (CDCl3): 2.40 (3H, s),
(3H, s), 3.85 (3H, s), 6.96 (2H, d, J¼8.5 Hz), 7.22 (2H, d,
J¼8.0 Hz), 7.45 (2H, d, J¼8.0 Hz), 7.51 (2H, d, J¼
8.5 Hz). 13C NMR (CDCl3): 21.0, 55.3, 114.1, 126.6,
127.9, 129.4, 133.7, 136.3, 138.0, 158.9. IR (Nujol): 1250,
1500 cmꢁ1. EIMS m/z: 198 (M+).
7.25 (2H, d, J¼7.0 Hz), 7.32 (1H, t, J¼7.5 Hz), 7.42 (2H,
t, J¼7.5 Hz), 7.49 (2H, d, J¼7.0 Hz), 7.58 (2H, d, J¼
7.5 Hz). 13C NMR (CDCl3): 21.1, 126.9, 127.0, 128.7,
129.5, 137.0, 138.3, 141.1. IR (Nujol): 1490 cmꢁ1. EIMS
m/z: 168 (M+).
4.4.8. 4-Fluoro-40-methylbiphenyl21 (Table 2, entry 7).
Silica gel column chromatography (hexane/ether¼200/1)
gave 149 mg (0.80 mmol, 80% yield) of the product as
4.4.2. 4-Methyl-(1,10,40,100)-terphenyl16 (Table 2, entry 1).
Silica gel column chromatography (hexane/CH2Cl2¼9/1)
gave 237 mg (0.97 mmol, 97% yield) of the product as
1
a white solid of mp 78–79 ꢀC. H NMR (CDCl3): 2.39
1
a white solid of mp 208–209 ꢀC. H NMR (CDCl3): 2.41
(3H, s), 7.11 (2H, t, J¼8.5 Hz), 7.24 (2H, d, J¼8.0 Hz),

M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
9399
7.44 (2H, d, J¼8.0 Hz), 7.52 (2H, dd, J¼5.5, 8.5 Hz). 13C
NMR (CDCl3): 21.1, 115.5 (d, J¼21.4 Hz), 126.8, 128.4
(d, J¼8.0 Hz), 129.5, 137.0, 137.2 (d, J¼3.4 Hz), 137.4,
162.3 (d, J¼245.8 Hz). IR (Nujol): 1160, 1230,
1500 cmꢁ1. EIMS m/z: 186 (M+).
4.4.15. 4-Methoxybiphenyl25 (Table 3, entry 7). Silica gel
column chromatography (hexane/ether¼50/1) gave 182 mg
(0.99 mmol, 99% yield) of the product as a white solid of
1
mp 86–87 ꢀC. H NMR (CDCl3): 3.86 (3H, s), 6.98 (2H,
d, J¼7.5 Hz), 7.30 (1H, t, J¼7.5 Hz), 7.41 (2H, t, J¼
7.5 Hz), 7.53 (2H, d, J¼7.5 Hz), 7.55 (2H, d, J¼7.5 Hz).
13C NMR (CDCl3): 55.3, 114.2, 126.6, 126.7, 128.1, 128.7,
4.4.9. 3-Cyano-40-methylbiphenyl22 (Table 2, entry 8).
Silica gel column chromatography (hexane/ether¼30/1)
gave 189 mg (0.98 mmol, 98% yield) of the product as a
133.8, 140.8, 159.1. IR (Nujol): 1250, 1490, 1610 cmꢁ1
.
EIMS m/z: 184 (M+).
1
white solid of mp 74–75 ꢀC. H NMR (CDCl3): 2.41 (3H,
s), 7.29 (2H, d, J¼7.5 Hz), 7.46 (2H, d, J¼7.5 Hz), 7.52 (1H,
t, J¼7.5 Hz), 7.60 (1H, d, J¼7.5 Hz), 7.80 (1H, d, J¼
7.5 Hz), 7.85 (1H, s). 13C NMR (CDCl3): 21.1, 112.9, 118.9,
126.9, 129.5, 129.8, 130.3, 130.4, 131.2, 135.9, 138.4, 142.3.
IR (Nujol): 1600, 2230 cmꢁ1. EIMS m/z: 193 (M+).
4.4.16. 4-N,N-Dimethylaminobiphenyl27 (Table 3, entry
8). Silica gel column chromatography (hexane/benzene¼1/
1) gave 162 mg (0.82 mmol, 82% yield) of the product as
1
a white solid of mp 121–122 ꢀC. H NMR (CDCl3): 2.98
(6H, s), 6.80 (2H, d, J¼8.0 Hz), 7.25 (1H, t, J¼7.0 Hz),
7.39 (2H, t, J¼7.0 Hz), 7.50 (2H, d, J¼8.0 Hz), 7.55 (2H,
d, J¼7.0 Hz). 13C NMR (CDCl3): 40.6, 112.8, 126.0, 126.3,
4.4.10. 3-Methylbiphenyl23 (Table 3, entry 2). Silica gel
column chromatography (hexane/ether¼200/1) gave
166 mg (0.99 mmol, 99% yield) of the product as colorless
oil. 1H NMR (CDCl3): 2.43 (3H, s), 7.17 (1H, d,
J¼7.5 Hz), 7.33 (2H, t, J¼7.5 Hz), 7.39–7.45 (4H, m),
7.59 (2H, d, J¼7.5 Hz). 13C NMR (CDCl3): 21.5, 124.3,
127.1, 127.2, 127.97, 127.98, 128.6, 128.7, 138.3, 141.2,
141.4. IR (neat): 1480, 1600 cmꢁ1. EIMS m/z: 168 (M+).
127.7, 128.6, 129.2, 141.2, 150.0. IR (Nujol): 1490 cmꢁ1
.
EIMS m/z: 197 (M+).
4.4.17. 4-Acetylbiphenyl23 (Table 3, entry 9). Silica gel
column chromatography (hexane/ether¼10/1) gave 194 mg
(0.99 mmol, 99% yield) of the product as a white solid of
mp 121–122 ꢀC. 1H NMR (CDCl3): 2.65 (3H, s), 7.41 (1H,
t, J¼7.5 Hz), 7.48 (2H, t, J¼7.5 Hz), 7.63 (2H, d, J¼7.5 Hz),
7.69 (2H, d, J¼8.0 Hz), 8.04 (2H, d, J¼8.0 Hz). 13C NMR
(CDCl3): 26.6, 127.2, 127.3, 128.2, 128.9, 129.0, 135.9,
139.9, 145.8, 197.7. IR (Nujol): 1600, 1680 cmꢁ1. EIMS
m/z: 196 (M+).
4.4.11. 2-Methylbiphenyl21 (Table 3, entry 3). Silica gel
column chromatography (hexane/ether¼400/1) gave
166 mg (0.99 mmol, 99% yield) of the product as colorless
1
oil. H NMR (CDCl3): 2.28 (3H, s), 7.23–7.27 (4H, m),
7.32–7.35 (3H, m), 7.41 (2H, t, J¼7.5 Hz). 13C NMR
(CDCl3): 20.4, 125.7, 126.7, 127.2, 128.0, 129.2, 129.8,
130.3, 135.3, 141.9, 142.0. IR (neat): 1480 cmꢁ1. EIMS m/
z: 168 (M+).
4.4.18. 4-Cyanobiphenyl15 (Table 3, entry 10). Silica gel
column chromatography (hexane/ether¼30/1) gave 174 mg
(0.97 mmol, 97% yield) of the product as a white solid of
1
mp 87–88 ꢀC. H NMR (CDCl3): 7.43 (1H, t, J¼7.5 Hz),
4.4.12. 2-Phenylnaphthalene24 (Table 3, entry 4). Silica
gel column chromatography (hexane/ether¼100/1) gave
200 mg (0.98 mmol, 98% yield) of the product as a white
7.49 (2H, t, J¼7.5 Hz), 7.59 (2H, d, J¼7.5 Hz), 7.69 (2H,
d, J¼7.5 Hz), 7.73 (2H, d, J¼7.5 Hz). 13C NMR (CDCl3):
110.9, 118.9, 127.2, 127.7, 128.6, 129.1, 132.6, 139.1,
145.6. IR (Nujol): 1580, 2220 cmꢁ1. EIMS m/z: 179 (M+).
1
solid of mp 101–102 ꢀC. H NMR (CDCl3): 7.38 (1H, t,
J¼7.5 Hz), 7.48–7.53 (4H, m), 7.72–7.76 (3H, m), 7.87
(1H, d, J¼7.5 Hz), 7.91 (2H, t, J¼8.5 Hz), 8.05 (1H, s).
13C NMR (CDCl3): 125.6, 125.8, 125.9, 126.3, 127.3,
127.4, 127.6, 128.2, 128.4, 128.8, 132.6, 133.7, 138.6,
141.1. IR (Nujol): 1500 cmꢁ1. EIMS m/z: 204 (M+).
4.4.19. 4-Nitrobiphenyl25 (Table 3, entry 11). Silica gel
column chromatography (hexane/ether¼20/1) gave 197 mg
(0.99 mmol, 99% yield) of the product as a yellow solid of
mp 114–115 ꢀC. 1H NMR (CDCl3): 7.45 (1H, t, J¼
7.5 Hz), 7.50 (2H, t, J¼7.5 Hz), 7.63 (2H, d, J¼7.5 Hz),
7.74 (2H, d, J¼8.5 Hz), 8.31 (2H, d, J¼8.5 Hz). 13C NMR
(CDCl3): 124.1, 127.4, 127.8, 128.9, 129.1, 138.8, 147.1,
147.6. IR (Nujol): 1350, 1510, 1600 cmꢁ1. EIMS m/z: 199
(M+).
4.4.13. 1-Phenylnaphthalene25 (Table 3, entry 5). Silica
gel column chromatography (hexane/ether¼100/1) gave
202 mg (0.99 mmol, 99% yield) of the product as colorless
1
oil. H NMR (CDCl3): 7.42–7.44 (3H, m), 7.48–7.54 (6H,
m), 7.86 (1H, t, J¼8.5 Hz), 7.89–7.92 (2H, m). 13C NMR
(CDCl3): 125.4, 125.7, 126.00, 126.01, 126.9, 127.2,
127.6, 128.2, 130.1, 131.6, 133.8, 140.3, 140.8. IR (neat):
1490 cmꢁ1. EIMS m/z: 204 (M+).
4.4.20. 3-Phenylpyridine24 (Table 3, entry 12). Silica
gel column chromatography (CH2Cl2/AcOEt¼9/1) gave
152 mg (0.98 mmol, 98% yield) of the product as colorless
1
oil. H NMR (CDCl3): 7.37 (1H, t, J¼7.5 Hz), 7.41 (1H, t,
4.4.14. 2-Methyl-1-phenylnaphthalene26 (Table 3, entry
6). Silica gel column chromatography (hexane/ether¼200/
1) gave 211 mg (0.97 mmol, 97% yield) of the product as
J¼7.5 Hz), 7.49 (2H, t, J¼7.5 Hz), 7.59 (2H, d, J¼
7.5 Hz), 7.88 (1H, d, J¼7.5 Hz), 8.59–8.60 (1H, m), 8.86
(1H, s). 13C NMR (CDCl3): 123.5, 127.1, 128.1, 129.0,
1
colorless oil. H NMR (CDCl3): 2.24 (3H, s), 7.27 (2H, d,
134.3, 136.6, 137.8, 148.3, 148.5. IR (neat): 1580 cmꢁ1
.
J¼7.5 Hz), 7.32 (1H, t, J¼7.5 Hz), 7.39–7.44 (4H, m),
7.50 (2H, t, J¼7.5 Hz), 7.78 (1H, d, J¼7.5 Hz), 7.84 (1H,
d, J¼7.5 Hz). 13C NMR (CDCl3): 20.8, 124.7, 125.8,
126.1, 127.0, 127.2, 127.7, 128.4, 128.6, 130.1, 131.9,
EIMS m/z: 155 (M+).
4.4.21. 4-Phenylisoquinoline27 (Table 3, entry 13). Silica
gel column chromatography (hexane/AcOEt¼3/1) gave
180 mg (0.88 mmol, 88% yield) of the product as colorless
132.9, 133.1, 138.2, 139.8. IR (neat): 1490, 1620 cmꢁ1
.
EIMS m/z: 218 (M+).
oil. H NMR (CDCl3): 7.48–7.55 (5H, m), 7.62–7.69 (2H,
1

9400
M. Kuriyama et al. / Tetrahedron 63 (2007) 9393–9400
L. H. Organometallics 2002, 21, 5204–5208; (c) Wang, R.;
Twamley, B.; Shreeve, J. M. J. Org. Chem. 2006, 71, 426–
429; (d) Zeng, F.; Yu, A. J. Org. Chem. 2006, 71, 5274–5281.
9. For example, NHCs bearing phosphine-donors: (a) Yang, C.;
Lee, H. M.; Nolan, S. P. Org. Lett. 2001, 3, 1511–1514; (b)
Tsoureas, N.; Danopoulos, A. A.; Tulloch, A. A. D.; Light,
M. E. Organometallics 2003, 22, 4750–4758; (c) Wang,
A.-E.; Zhong, J.; Xie, J.-H.; Li, K.; Zhou, Q.-L. Adv. Synth.
Catal. 2004, 346, 595–598; (d) Zhong, J.; Xie, J.-H.; Wang,
A.-E.; Zhang, W.; Zhou, Q.-L. Synlett 2006, 1193–1196.
m), 7.92 (1H, d, J¼8.0 Hz), 8.05 (1H, d, J¼8.0 Hz), 8.50
(1H, s), 9.27 (1H, s). 13C NMR (CDCl3): 124.8, 127.1,
127.8, 127.9, 128.4, 128.6, 130.1, 130.5, 133.2, 134.2,
137.0, 142.9, 152.0. IR (neat): 1490, 1620 cmꢁ1. EIMS
m/z: 205 (M+).
Acknowledgements
This work was supported by Grant-in-Aid for Scientific
Research (C) (no. 18590023) from the Japan Society for
the Promotion of Science.
10. (a) Sellmann, D.; Prechtel, W.; Knoch, F.; Moll, M.
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