SiO2-NHC-CuI-catalyzed N-arylation of imidazoles with arylboronic acids under base-free reaction conditions

Article abstract of DOI:10.1080/00397911.2011.563024

(Chemical Equation Presented) N-Arylation of imidazoles with arylboronic acids was efficiently carried out in the presence of a catalytic amount of SiO₂-NHC-Cu^I in methanol at room temperature under base-free reaction conditions. The reactions of a variety of arylboronic acids with imidazoles generated the corresponding products N-arylimidazoles in good to excellent yields. In addition, SiO₂-NHC-Cu^I could be recovered and recycled for six consecutive trials without significant loss of its reactivity. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397911.2011.563024

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I
SiO -NHC-Cu –Catalyzed N-Arylation of
2
Imidazoles with Arylboronic Acids Under
Base-Free Reaction Conditions
a
a
a b
Ping Liu , Pinhua Li & Lei Wang
a
Department of Chemistry , Huaibei Normal University , Huaibei ,
Anhui , China
b
State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences ,
Shanghai , China
Accepted author version posted online: 02 Jan 2012.Published
online: 29 May 2012.
I
To cite this article: Ping Liu , Pinhua Li & Lei Wang (2012) SiO -NHC-Cu –Catalyzed N-Arylation of
2
Imidazoles with Arylboronic Acids Under Base-Free Reaction Conditions, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 42:17, 2595-2605,
DOI: 10.1080/00397911.2011.563024
To link to this article: http://dx.doi.org/10.1080/00397911.2011.563024
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1
Synthetic Communications , 42: 2595–2605, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.563024
I
SiO -NHC-Cu –CATALYZED N-ARYLATION OF
2
IMIDAZOLES WITH ARYLBORONIC ACIDS UNDER
BASE-FREE REACTION CONDITIONS
1
Ping Liu, Pinhua Li, and Lei Wang
1
1,2
1
Department of Chemistry, Huaibei Normal University, Huaibei,
Anhui, China
2
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
GRAPHICAL ABSTRACT
Abstract N-Arylation of imidazoles with arylboronic acids was efficiently carried out in the
I
-NHC-Cu in methanol at room temperature under
presence of a catalytic amount of SiO
base-free reaction conditions. The reactions of a variety of arylboronic acids with imida-
2
zoles generated the corresponding products N-arylimidazoles in good to excellent yields.
I
-NHC-Cu could be recovered and recycled for six consecutive trials
In addition, SiO
without significant loss of its reactivity.
2
Keywords Arylboronic acid; copper(I); heterogeneous catalyst; imidazoles; N-arylation;
NHC
Received October 4, 2010.
Address correspondence to Lei Wang, Department of Chemistry, Huaibei Normal University,
Huaibei, Anhui 235000, China. E-mail: leiwang@chnu.edu.cn
2
595

2596
P. LIU, P. LI, AND L. WANG
INTRODUCTION
C–N bond formation via transition-metal catalysis is currently a subject of great
interest, and intensive research is being carried out to ensure useful organic transfor-
[
1]
mations. N-Arylimidazoles are common motifs in pharmaceutical research, and the
synthesis of N-arylimidazoles has attracted significant interest because of the frequent
[
2,3]
occurrence of these structural units in biologically active inhibitors. After the
initial reports of Chan and Lam, Cu-catalyzed cross-coupling between N-heterocycles
and arylboronic acids has become an important synthetic methodology in modern
[4a–c]
organic synthesis.
The discovery and development of the catalytic pathway for
N-arylation of N-heterocycles by Buchwald with bromoarenes and iodoarenes by
using copper as catalyst in the presence of a ligand generated greater interest in indus-
[
4d,e]
try.
nitrogen-chelating bidentate ligands have been successful used in the coupling of imi-
Later, Collman and coworkers reported that Cu(II) complexes with
[
5]
dazoles. Very recently, Lan and coworkers developed the simple copper salt CuI-
catalyzed cross-coupling of imidazoles with arylboronic acids in protic solvent with-
out any base. Thus, the development of mild and cost-effective catalytic procedures
[
for the N-arylation of imidazoles still remains an active research area.
Silica modified with different functionalities such as –NH , –SH, diamines, and
[6]
7]
2
amino acids was reported to be an excellent inorganic support for various transition
metals such as Pd, Cu, Sc, Ru, Pt, and V, etc. and was used in different organic trans-
[
formations. N-Heterocyclic carbenes (NHCs) have been widely used as effective
8]
ligands in inorganic and organometallic chemistry since Arduengo and coworkers
[
isolated the first stable N-heterocyclic carbene in 1991. NHCs were first considered
9]
[
10]
as simple phosphane mimics in organometallic chemistry.
experimental data clearly showed that NHC–metal catalysts can surpass their
phosphane-based counterparts in both activity and scope.
However, increasing
[
11]
NHCs are stronger r
donors and weaker p acceptors, causing the properties of NHC–metal complexes
to be notably different from those of a corresponding phosphane complex. Because
of their specific coordination chemistry, NHCs can both stabilize and activate metal
centers in quite different key catalytic steps of organic syntheses, for example, C–C,
[
12]
C–H, C–O, and C–N bond formation reactions.
polymer-, PEG, or silica-supported NHC–metal complexes were synthesized and
To avoid catalyst leaching,
[
13]
applied successfully in a variety of organic reactions.
Because new types of silica-supported catalysts have theoretical and practical
significance, currently the preparation of 3-[(2-aminoethyl)amino]propyl-functiona-
lized silica-anchored copper and subsequently its uses as highly efficient and recycl-
able catalysts for the Sonogashira reaction and 1,3-dipolar cycloaddition reaction
[14]
were reported. In this article, we report the synthesis of NHC functionalized silica
I
immobilized Cu(I) catalyst, SiO -NHC-Cu (Scheme 1), which was found to be
2
the effective catalysts for the N-arylation of imidazoles with arylboronic acids.
N-Arylation of imidazoles with arylboronic acids was efficiently carried out in the
I
presence of a catalytic amount of SiO -NHC-Cu in methanol under base-free reac-
2
tion conditions. The reactions of a variety of arylboronic acids with imidazoles
generated the corresponding products N-arylimidazoles in good to excellent yields.
I
In addition, SiO -NHC-Cu could be recovered and recycled for six consecutive trials
without significant loss of its reactivity.
2

N-ARYLATION OF IMIDAZOLES
2597
Scheme 1.
I
The SiO -NHC-Cu catalyst was readily prepared in a three-step procedure
2
(
Scheme 1). Activated silica was treated with trichloro[4-(chloromethyl)phenyl]silane
ꢀ
in dry toluene at 120 C under nitrogen for 24 h to afford the benzyl chloride–
functionalized silica. The obtained functionalized silica material was then treated
with N-mesitylimidazole in toluene at 80 C for 24 h to generate the corresponding
silica-supported ionic liquid. The silica-supported ionic liquid was then treated with
freshly prepared CuI in the presence of t-BuONa in dry tetrahydrofuran (THF) at
I
room temperature under an inert gas for 6 h. Then, the SiO -NHC-Cu catalyst
ꢀ
2
was obtained as a gray-green powder, and the copper content of the catalyst was
ꢂ1
found to be 0.86 mmolꢁg
.
In our preliminarily investigation on the model reaction of phenylboronic acid
with imidazole, it was found that the reaction could be finished under very simple
I
reaction conditions in the presence of a catalytic amount of SiO -NHC-Cu (5 mol%)
2
in the absence of any additive, which gives the desired 1-phenyl-1H-imidazole in 90%
yield (Table 1, entry 1). The effects of solvent, catalyst, reaction temperature, and
time on the reaction were investigated. It was found that CH OH is the best solvent
3
among the solvents tested, and the reaction proceeded smoothly in CH OH and gen-
3
erated the desired product in 90% yield, while dimethylformamide (DMF) or
C H OH afforded trace amounts of the desired product (entries 1, 4, and 5). More-
over, the use of toluene, THF, and CH CN as solvents led to no occurrence of posi-
2
5
3
tive reactions (entries 2, 3, and 6). Fortunately, the reaction also generated the
desired product in 80% yield when the reaction was carried out in ethanol=H O
2
ꢀ
(9=1). A reaction temperature of 50 C for 3 h was found to be optimal. Thus, the
optimized reaction conditions for the reaction were found to be SiO -NHC-Cu
(
I
2
ꢀ
5 mol%) in CH OH at 50 C for 3 h.
3

2598
P. LIU, P. LI, AND L. WANG
a
Table 1. Effect of solvent on the N-arylation of imidazole with phenylboronic acid
b
Yield (%)
Entry
Solvent
OH
1
2
3
4
5
6
7
CH
3
90
Toluene
THF
DMF
NR
NR
Trace
Trace
NR
80
C
2
H
5
OH
CN
OH=H
CH
3
C
2
H
5
2
O (9=1)
a
I
-NHC-Cu (containing Cu 0.05 mmol, 5 mol%), imidazole (1.1 mmol), and phenyl-
SiO
boronic acid (1.0 mmol) was carried out in solvent (3.0 mL) at 50 C for 3 h under air.
2
ꢀ
b
Isolated yields.
We chose a variety of structurally divergent arylboronic acids possessing a wide
range of functional groups to understand scope and generality of the SiO -NHC-
2
I
Cu –catalyzed N-arylation of imidazoles, which affords the corresponding N-
arylated imidazoles. The results are summarized in Table 2. An arylboronic acid with
an electron-withdrawing group such as 4-trifluoromethphenylboronic acid greater
yield than that of the arylboronic acid with an electron-donating group, such as
4
-methoxyphenylboronic acid or 4-tert-butylphenylboronic acid (Table 2, entry 7
vs entries 2 and 4). 2-Methyl, 3-methyl, and 4-methylphenylboronic acid reacted
similarly with phenylboronic acid to generate the corresponding N-arylated imida-
zoles, which showed that there is not much more ortho-, meta-, and para-substitution
effect on the substituted phenylboronic acid (Table 2, entries 3, 8, and 9). The results
listed in Table 2 also indicated that the reactions of imidazole with other aromatic
boronic acids, such as naphthalen-1-ylboronic acid, naphthalen-2-ylboronic acid,
and biphenyl-4-ylboronic acid, gave good yields of the desired coupling products
under the optimized reaction conditions (Table 2, entries 12–14). Meanwhile, an
ortho-substitution effect on CHO- substituted phenylboronic acid was observed
(Table 2, entry 15). It is important to note that no side product, such as deboro-
nation of organoboronic acid, was observed in N-arylation of imidazole with
phenylboronic acid, and the selectivity of 1-phenyl-1H-imidazole is > 99%. Other
N-heterocycles, such as 1H-pyrazole, benzimidazole, and phthalimide, also coupled
smoothly with phenylboronic acid to produce the desired products in good yields
(83–90%) under the present reaction conditions (Table 2, entries 16–18). It is note-
worthy to point out that when the reaction was conducted in the absence of air, there
was no any desired coupling product observed, which clearly emphasizes that the
process is redox. Further investigation on the reaction mechanism is under way in
our laboratory.
I
To screen the recyclability of SiO -NHC-Cu catalyst, a more practical method
2
was applied to the reaction of imidazole and phenylboronic acid under the present
reaction conditions. After separation of the product and the recovery of the SiO -
2
I
NHC-Cu , fresh starting materials and CH OH were charged into the reaction
3

N-ARYLATION OF IMIDAZOLES
2599
I
-NHC-Cu –catalyzed N-arylation of imidazoles with arylboronic acids
a
Table 2. SiO
2
b
Yield (%)
Entry
1
Azole
Arylboronic acid
Product
90
2
3
4
5
6
7
72
82
76
86
88
96
8
9
80
77
89
1
0
1
1
1
2
83
70
13
72
(
Continued )

2600
P. LIU, P. LI, AND L. WANG
Table 2. Continued
b
Yield (%)
Entry
Azole
Arylboronic acid
Product
14
77
1
1
5
6
40
88
1
1
7
8
90
83
a
I
-NHC-Cu (containing Cu 0.05 mmol, 5 mol%), azole (1.1 mmol), and arylboronic acid (1.0 mmol)
SiO
2
ꢀ
was carried out in CH
b
3
OH (3.0 mL) at 50 C for 3 h under air.
Isolated yields.
I
a
2
Table 3. Successive trials by using recoverable SiO -NHC-Cu catalyst
I
b
Yield (%)
Entry
Reused SiO
Fresh
2
-NHC-Cu
1
2
3
4
5
6
90
90
88
89
87
86
First reuse
Second reuse
Third reuse
Forth reuse
Fifth reuse
a
I
-NHC-Cu (containing Cu 0.05 mmol, 5 mol%), imidazole (1.1 mmol), and phenylboronic
Reused SiO
2
ꢀ
acid (1.0 mmol) was carried out in CH
b
3
OH (3.0 mL) at 50 C for 3 h under air.
Isolated yields.

N-ARYLATION OF IMIDAZOLES
2601
system. The reactions still proceeded well, and no unreacted substrates were detected
I
at the end of the reaction. The SiO -NHC-Cu catalyst was recovered and recycled
for six consecutive trials without any decrease in its activity.
2
CONCLUSION
I
In conclusion, SiO -NHC-Cu has been demonstrated to be a highly selective
2
and efficient catalyst for the N-arylation of imidazoles with arylboronic acids. The
reactions were performed smoothly to generate the desired products N-arylimida-
zoles in good yields under base-free and simple reaction conditions. The notable
advantages of this methodology are mild conditions, short reaction times, and good
yields free from any side reaction products. This method offers one of the important
motifs for synthesis of N-arylimidazoles as natural products, biologically active
compounds, and pharmaceutical agents.
EXPERIMENTAL
1
13
All H NMR and C NMR spectra were recorded on a 400-MHz Bruker
FT-NMR spectrometer. All chemical shifts are given as d values (ppm) with refer-
ence to tetramethylsilane (TMS) as an internal standard. Products were purified
by flash chromatography on 230- to 400-mesh silica gel, SiO2.
The chemicals and solvents were purchased from commercial suppliers either
from Aldrich, Fluka, USA, or Shanghai Chemical Company, China, and were used
without purification prior to use.
Preparation of Benzyl Chloride–Functionalized Silica
Anhydrous toluene (30 mL), activated silica (Qingdao Haiyang Chemical Com-
2
pany, China, specific surface area 300–400 m =g, pore size 280–600 mm, and pore vol-
ume 0.7 mL=g, 5.0 g), and trichloro[4-(chloromethyl)phenyl]silane (2.0 g) were
introduced successively in a 100-mL, round-bottom flask. The mixture was refluxed
ꢀ
at 120 C under nitrogen for 24 h. Then the solution was filtered, and the solid was
washed subsequently with toluene, dichloromethane, and methanol and dried under
ꢀ
reduced pressure at 80 C for 10 h to yield benzyl chloride functionalized silica
(5.81 g). The loading of the modified silica was readily quantified by CHN
microanalysis and found to be 1.12 mmol g based on nitrogen content. The surface
ꢂ1
2
area and pore volume of the modified silica were found to be 433 m g and
ꢂ1
3
.53 cm g , respectively.
ꢂ1
0
Preparation of Silica-Supported Ionic Liquid
Under nitrogen, 1-mesityl-1H-imidazole (0.41 g, 5.0 mmol) and benzyl chloride
functionalized silica (2.0 g) were mixed in toluene (15 mL) in a round-bottom flask.
ꢀ
The reaction was carried out at 80 C for 24 h. Then the solution was filtered, and the
solid was washed with chloroform, methanol, and ethyl acetate and dried under
ꢀ
vacuum at 60 C to yield a silica-supported ionic liquid (pale powder, 2.08 g). The
loading of the silica-supported ionic liquid was quantified by CHN microanalysis

2
602
P. LIU, P. LI, AND L. WANG
ꢂ1
and found to be 0.96 mmol g based on nitrogen content. The surface area and pore
3
2
volume of the silica-supported ionic liquid were found to be 308 m g and 0.43 cm
ꢂ1
ꢂ1
29
g
, respectively. Si NMR (solid): d ¼ ꢂ79.4 (br., SiC), ꢂ111.5 (br., SiO ) ppm.
2
I
Preparation of SiO -NHC-Cu Catalyst
2
In an oven-dried Schlenk flask, freshly prepared CuI (0.190 g, 1.0 mmol),
t-BuONa (0.096 g, 1.0 mmol), silica-supported ionic liquid (1.0 g), and THF (5 mL)
were added. The resulting suspension was stirred at room temperature under nitro-
gen for 6 h. Then the solution was filtered, and the solid was washed with water,
ꢀ
methanol, and acetone and dried under vacuum at 60 C for 12 h. The SiO -
2
I
NHC-Cu catalyst was obtained as a gray-green powder (1.14 g). The copper content
ꢂ1
of the catalyst was found to be 0.86 mmol g based on AAS analysis. The surface
I
area and pore volume of SiO -NHC-Cu were found to be 275 m g and 0.38 cm g ,
2
ꢂ1
3
ꢂ1
2
2
9
respectively. Si NMR (solid): d ¼ ꢂ78.7 (br., SiC), ꢂ111.5 (br., SiO ) ppm.
2
General Procedure for N-Arylation of Imidazoles with
Arylboronic Acid
I
An oven-dried, round-bottomed flask was charged with SiO -NHC-Cu
2
(
0.05 mmol), imidazole (1.1 mmol), arylboronic acid (1.0 mmol), and CH OH (3 mL).
3
ꢀ
The mixture was stirred at 50 C for 3 h under an atmosphere of air. The progress of
the reaction was monitored by TLC. On completion of the reaction, the mixture was
filtered. The solution was concentrated under reduced pressure and purified by col-
umn chromatography on silica gel (hexane–EtOAc, 70:30) to afford the correspond-
ing pure N-arylated imidazole.
Selected Data
[
15]
1
1
-Phenyl-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.57 (s, 1H),
3
1
.45–7.41 (m, 2H), 7.34–7.30 (m, 3H), 7.23 (br s, 1H), 7.17 (br s, 1H); C NMR
3
7
(
100 MHz, CDCl ) d: 137.1, 135.3, 130.1, 129.7, 127.3, 121.3, 118.1.
3
[
15]
1
1
-(4-Methoxyphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d:
3
7
3
1
.76 (s, 1H), 7.28–7.24 (m, 2H), 7.19–7.15 (m, 2H), 6.97–6.92 (m, 2H), 3.83 (s,
1
3
H); C NMR (100 MHz, CDCl ) d: 158.7, 135.5, 130.5, 129.9, 122.9, 118.6,
3
14.6, 55.3.
[
15]
1
1
-(4-Methylphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.81
3
1
s, 1H), 7.25–7.24 (m, 5H), 7.18 (s, 1H), 2.38 (s, 3H); C NMR (100 MHz, CDCl3)
3
(
d: 137.2, 135.4, 134.8, 131.9, 130.1, 121.2, 118.1, 20.7.
[
16]
1
1
-(4-tert-Buthylphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d:
3
7
.82 (s, 1H), 7.48 (s, 1H), 7.46 (s, 1H), 7.30 (s, 1H), 7.28 (s, 1H), 7.24 (s, 1H), 7.19
1
3
(s, 1H), 1.34 (s, 9H); C NMR (100 MHz, CDCl ) d: 150.4, 135.4, 134.6, 130.0,
3
1
26.5, 120.9, 118.0, 34.4, 31.0.

N-ARYLATION OF IMIDAZOLES
17]
2603
[
1
1
-(4-Chlorophenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.83
3
(
1
s, 1H), 7.65 (s, 1H), 7.42 (s, 1H), 7.34 (s, 1H), 7.31 (s, 1H), 7.25 (s, 1H), 7.21 (s,
1
3
H); C NMR (100 MHz, CDCl ) d: 135.7, 135.3, 132.9, 130.5, 129.8, 122.4, 117.9.
3
[
15]
1
1
-(4-Fluorophenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.72
3
1
s, 1H), 7.31– 7.27 (m, 2H), 7.16 (s, 1H), 7.12–7.08 (m, 3H); C NMR (100 MHz,
3
(
CDCl ) d: 162.7, 160.2, 135.5, 133.4, 130.2, 123.3, 123.2, 118.4, 116.6, 116.4.
3
[
18]
1
-(4-(Trifluoromethyl)phenyl)-1H-imidazole . H NMR (400 MHz,
1
CDCl ) d: 7.96 (s, 1H), 7.75–7.71 (m, 2H), 7.54–7.50 (m, 2H), 7.36 (s, 1H), 7.25 (s,
3
1
3
1
H); C NMR (100 MHz, CDCl ) d: 139.6, 135.1, 130.7, 129.4, 129.1, 128.8,
3
1
28.4, 127.4, 126.9, 126.8, 124.7, 122.0, 120.8, 119.3, 117.5.
[
19]
1
1
-(3-Methylphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.83
3
(
3
1
s, 1H), 7.35–7.31 (m, 1H), 7.25 (s, 1H), 7.18–7.17 (m, 3H), 7.15 (s, 1H), 2.41 (s,
3
1
H); C NMR (100 MHz, CDCl ) d: 139.8, 137.1, 135.3, 130.0, 129.4, 128.0,
3
21.9, 118.3, 118.0, 21.2.
[
15]
1
1
-(2-Methylphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.57
3
(
2
1
s, 1H), 7.55–7.32 (m, 2H), 7.30–7.26 (m, 1H), 7.21–7.19 (m, 2H), 7.04 (s, 1H),
1
3
.17 (s, 3H); C NMR (100 MHz, CDCl ) d: 137.2, 136.3, 133.5, 131.0, 129.0,
3
28.5, 126.6, 120.2, 17.3.
[
19]
1
1
-(3-Methoxyphenyl)-1H-imidazole . H NMR (400 MHz, CDCl ) d:
3
7
6
1
.84 (s, 1H), 7.36–7.34 (m, 1H), 7.26 (s, 1H), 7.18 (s, 1H), 6.96–6.93 (m, 1H),
3
1
.91–6.87 (m, 2H), 3.84 (s, 3H); C NMR (100 MHz, CDCl ) d: 160.5, 138.2,
3
35.4, 130.5, 130.1, 118.0, 113.4, 112.4, 107.5, 55.3.
[
20]
1
-(4-Methoxycarbonylphenyl)-1H-imidazole . H NMR (400 MHz,
1
CDCl ) d: 8.17–8.13 (m, 2H), 7.97 (s, 1H), 7.49–7.46 (m, 2H), 7.37 (s, 1H), 7.24 (s,
3
1
3
1
H), 3.94 (s, 3H); C NMR (100 MHz, CDCl ) d: 165.7, 140.5, 135.2, 131.3,
3
1
30.8, 128.8, 120.3, 117.6, 52.1.
[
21]
1
1
-Biphenyl-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.86 (s, 1H),
3
7
.62–7.60 (m, 2H), 7.56–7.53 (m, 2H), 7.43–7.39 (m, 2H), 7.38–7.35 (m, 3H), 7.26
1
3
(s, 1H), 7.21 (s, 1H); C NMR (100 MHz, CDCl ) d: 140.0, 139.4, 136.1, 135.2,
3
1
30.2, 128.7, 128.2, 127.5, 126.7, 121.3, 117.8.
[
22]
1
1
-(Naphthalen-1-yl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.96
3
(
7
1
s, 1H), 7.92–7.87 (m, 1H), 7.85–7.82 (m, 2H), 7.78–7.77 (m, 1H), 7.57–7.47 (m, 3H),
1
3
.38 (s, 1H), 7.25 (s, 1H); C NMR (100 MHz, CDCl ) d: 134.6, 133.4, 132.1, 130.5,
3
29.9, 127.8, 127.7, 127.3, 126.4, 120.1, 118.9, 118.3.
[
22]
1
1
-(Naphthalen-2-yl)-1H-imidazole . H NMR (400 MHz, CDCl ) d: 7.92
3
(
7
1
s, 1H), 7.85–7.82 (m, 1H), 7.83–7.78 (m, 2H), 7.71 (s, 1H), 7.53–7.45 (m, 2H), 7.43–
3
1
.40 (m, 1H), 7.33 (s, 1H), 7.24 (s, 1H); C NMR (100 MHz, CDCl ) d: 135.5, 134.3,
3
33.2, 131.8, 130.2, 129.7, 127.6, 127.5, 127.1, 126.2, 119.8, 118.6, 118.1.
[
23]
1
2
-(1H-Imidazol-1-yl)benzaldehyde . H NMR (400 MHz, CDCl ) d: 9.75
3
(
7
1
s, 1H), 8.01–7.99 (m, 1H), 7.72–7.68 (m, 2H), 7.59–7.55 (m, 1H), 7.40–7.38 (m, 1H),
1
3
.21 (s, 2H); C NMR (100 MHz, CDCl ) d: 188.3, 139.2, 138.2, 134.9, 130.8, 130.2,
3
29.1, 128.9, 126.8, 121.8.

2
604
P. LIU, P. LI, AND L. WANG
15]
[
1
1
-Phenyl-1H-pyrazole . H NMR (400 MHz, CDCl ) d: 7.90–7.88 (m,
3
1
3
1
H), 7.72–7.67 (m, 3H), 7.43–7.40 (m, 2H), 7.27–7.23 (m, 1H), 6.45 (s, 1H);
C
NMR (100 MHz, CDCl ) d: 141.0, 139.4, 129.3, 126.7, 126.4, 119.2, 107.5.
3
[
15]
1
1
-Phenyl-1H-benzimidazole . H NMR (400 MHz, CDCl ) d: 8.22–8.19
3
1
3
(
m, 4H), 7.56–7.55 (m, 2H), 7.50–7.46 (m, 4H); C NMR (100 MHz, CDCl ) d:
3
1
43.8, 142.0, 135.6, 132.6, 130, 127.9, 124, 123.5, 122.8, 120.6, 110.5.
[
24]
1
2
-Phenyl-iso-indoline-1,3-dione . H NMR (400 MHz, CDCl3) d:
1
.88–7.85 (m, 4H), 7.43–7.41 (m, 4H), 7.17–7.16 (m, 1H); C NMR (100 MHz,
3
7
CDCl ) d: 166.9, 132.5, 132.0, 131.8, 128.7, 127.9, 127.8, 123.5.
3
ACKNOWLEDGMENTS
We gratefully acknowledge financial support by the National Natural Science
Foundation of China (20972057) and the Natural Science Foundation of Anhui
(No. 090416223).
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