Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles using silica chloride as an efficient and recyclable catalyst under solvent-free conditions

Article abstract of DOI:10.1016/j.crci.2013.12.003

An efficient solvent-free synthesis of various 2,4,5-triaryl imidazoles and 1,2,4,5-tetraaryl imidazoles has been developed using silica chloride as a heterogeneous catalyst. The present methodology offers several advantages, such as excellent yields, shorter reaction times, economic availability, and reusability of catalyst.

Full text of DOI:10.1016/j.crci.2013.12.003

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C. R. Chimie xxx (2014) xxx–xxx
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Full paper/M e´ moire
Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst
under solvent-free conditions
a,
b
Hemant V. Chavan *, Dattatraya K. Narale
a
Department of Chemistry, ASP College, Devrukh, Dist: Ratnagiri 415 804, Maharashtra, India
Department of Chemistry, Gopal Krishna Gokhale College, Kolhapur 416001, Maharashtra, India
b
A R T I C L E I N F O
A B S T R A C T
Article history:
An efficient solvent-free synthesis of various 2,4,5-triaryl imidazoles and 1,2,4,5-tetraaryl
imidazoles has been developed using silica chloride as a heterogeneous catalyst. The
present methodology offers several advantages, such as excellent yields, shorter reaction
times, economic availability, and reusability of catalyst.
Received 11 August 2013
Accepted after revision 5 December 2013
Available online xxx
ß 2013 Acad e´ mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords:
Imidazole
Silica chloride
Solvent-free method
Reusability
1
. Introduction
In recent years, considerable interest has been devoted
[6], plant growth regulators [7] and therapeutic agents [8].
Owing to the wide range of pharmacological and biological
activities, the development of synthetic methods enabling
facile access to this heterocycle is still desirable. Several
methods have been reported for the synthesis of imidazoles.
2,4,5-Triaryl-1H-imidazoles are generally synthesized by
to finding new methodologies for the synthesis of
numerous organic compounds under solvent-free condi-
tions. The toxicity and volatile nature of many organic
solvents, particularly chlorinated hydrocarbons that are
widely used in large amounts for organic reactions have
posed a serious threat to the environment [1]. Thus, the
design of solvent-free catalytic reactions has received
tremendous attention in recent times in the area of green
synthesis [2]. Imidazoles are common scaffolds in highly
significant biomolecules, including biotin, the essential
amino acid histidine, histamine, the pilocarpine alkaloids [3],
and other alkaloids, which have been shown to exhibit
interesting biological activities, such as antimicrobial, antic-
ryptococcal, cytotoxic activities and inhibition of nitric oxide
synthase [4], Many of the substituted imidazoles are known
as inhibitors of P38 MAP kinase [5], fungicides and herbicides
three-component cyclocondensation of
a 1,2-diketone,
a
-hydroxyketone or -ketomonoxime with an aldehyde
a
and ammonium acetate, which comprises the use of
microwaves [9], ionic liquids [10] europium triflate [11],
oxalic acid [12], TBAB [13], CAN [14], refluxing in AcOH [15]
and silica sulfuric acid [16]. On the other hand, the synthesis
of 1,2,4,5-tetraaryl-1H-imidazoles are carried out by four-
component condensation of a 1,2-diketone,
tone or -ketomonoxime with an aldehyde, a primary amine
and ammonium acetate using microwaves [17], hetero-
polyacid [18], silica gel/NaHSO [19] InCl O [20] or
Á3H
HClO –SiO [21]. In addition, they can also be accessed by
hetero-Cope rearrangements [22] and condensation of a
,2-diketone with an aryl nitrile and primary amine under
a-hydroxyke-
a
4
3
2
4
2
1
microwave irradiation [23]. Despite their potential utility,
these methods have a number of drawbacks, including poor
yields, utilization of excessive glacial AcOH, prolonged
*
Corresponding author.
E-mail address: hemantchavan.sus@rediffmail.com (H.V. Chavan).
1
631-0748/$ – see front matter ß 2013 Acad e´ mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.crci.2013.12.003
Please cite this article in press as: Chavan HV, Narale DK. Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst under solvent-free conditions. C. R. Chimie (2014), http://
dx.doi.org/10.1016/j.crci.2013.12.003

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O
O
O
Si Cl
O
O
N
Ar
+
Ar-CHO + NH OAc
4
o
neat, 80 C
N
H
1
2
3
Scheme 1. Silica chloride catalyzed synthesis of 2,4,5-triaryl-1H-imidazoles.
reaction times, high cost of most conventional room
temperature ionic liquids, use of hazardous and expensive
catalysts and use of toxic organic solvent that limit their
utility.
Hence, the development of clean, safe, effective,
economical, high-yielding and environmentally benign
protocols is still desirable and much in demand.
3
the effect of solvents, like CH CN, toluene, EtOH, MeOH and
THF for the above reaction. The results in Table 2 indicate
that solvents affected the efficiency of the reaction and
very poor yields were obtained after 1 h. The best results
were obtained under solvent-free conditions (Table 2).
Under optimized reaction conditions, a mixture of
benzil (1 mmol), an aromatic aldehyde (1 mmol), NH
(10 mmol) and SiO –Cl (250 mg) was stirred at 80 8C for the
appropriate time (Table 3). After completion of the
reaction (TLC), CH Cl (20 mL) was added, and the solid
4
OAc
Silica chloride (SiO
2
–Cl) is gaining importance as a
2
heterogeneous catalyst and is used in various organic
transformations. It is a good solid acid in terms of
convenience, cheapness, easy production, and insolubility
in all organic solvents. Due to its insolubility in organic
solvents, excellent in situ proton generation, and accepting
different nucleophiles, it can be used for different purposes
in organic chemistry. It has been used as a dehydrating
agent [24], and some cyclocondensations yielding dihy-
dropyrimidinone [25], 2-aminothiazoles [26], 6-methyl-3-
propynylthio-1,2,4-triazin-5(2H)-one [27], pyranoquino-
lines, or furanoquinolines [28] are catalyzed by silica
chloride. The use of silica chloride to expedite oxidation of
alcohol [29], esterification and transesterification [30]
transdithioacetalization of acetals [31], deprotection of
oximes/hydrazones/semicarbazones [32] synthesis of
nitriles and amides [33], synthesis of sulfoxide [34],
synthesis of bisindolylmethanes [35], etc. has been well
explored.
2
2
catalyst was recovered by filtration. The solvent was
distilled off and the crude product was purified by column
2
chromatography using (SiO , hexane:AcOEt) as an eluent
to afford pure 2,4,5-trisubstituted imidazoles in good to
excellent yields. Moreover, the catalyst recovered from the
reaction mixture was reused for successive reactions
Table 1
Synthesis of 2,4,5-triaryl-1H-imidazole(3a) under various conditions.
Entry
SiO
2
–Cl
Temperature
Time
Yield
a
b
(mg/mmol)
(8C)
(min)
(%)
1
2
3
4
5
6
7
8
9
–
80
80
180
120
120
90
00
45
58
65
72
75
55
80
80
79
80
78
50
100
150
200
200
250
250
250
300
300
300
80
80
80
60
Considering the significance of the silica chloride and
in continuation of our interest in developing new and
rapid synthetic methods for the construction of biologi-
cally important structural scaffolds [36], we report herein
a rapid, efficient, economic, environmentally benign and
easy to scale-up method for the synthesis of 2,4,5-triaryl-
100
60
60
60
80
30
100
80
30
10
11
12
30
100
120
30
30
1
H-imidazoles using silica chloride as a heterogeneous
and recyclable catalyst under solvent-free conditions
Scheme 1).
a
Reaction conditions: benzil (1 mmol); benzaldehyde (1 mmol);
ammonium acetate (10 mmol); neat.
b
(
Yields of isolated products.
2
. Results and discussion
Table 2
2
Effect of solvent for SiO –Cl catalyzed synthesis of 2,4,5-triaryl imidazole
(
3a).
Initially, to optimize the amount of catalyst and the
a
reaction temperature, the reaction of benzil (1, 1 mmol),
benzaldehyde (2a, 1 mmol), and NH OAc (10 mmol) was
studied under solvent-free conditions in the presence of
SiO –Cl at different temperatures; the results are sum-
marized in Table 1. They revealed that, when 250 mg/
mmol SiO –Cl at 80 8C were used, the reaction proceeded
Entry
Solvent
Temperature
8C)
Time
Yield
b
(
(min)
(%)
4
1
2
3
4
5
6
CH
3
CN
Reflux
Reflux
Reflux
Reflux
Reflux
80
60
60
60
60
60
30
20
40
30
35
25
80
Toluene
EtOH
MeOH
THF
2
2
smoothly and gave product 3a in highest yield (80%).
none
Further increase in the amount of silica chloride above
a
Reaction conditions: benzil (1 mmol); benzaldehyde (1 mmol);
2
50 mg/mmol did not lead to substantial change in the
ammonium acetate (10 mmol), solvent (5 mL).
b
yield and the reaction time (Table 1). Then, we examined
Yields of isolated products.
Please cite this article in press as: Chavan HV, Narale DK. Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst under solvent-free conditions. C. R. Chimie (2014), http://
dx.doi.org/10.1016/j.crci.2013.12.003

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3
Table 3
Synthesis of 2,4,5-triaryl-1H-imidazole derivatives.
a
Entry
Ar
Time (min)
Yield (%)
MP (8C)
Found
Reported
b
1
2
3
4
5
6
7
8
9
C
6
H
5
3a
3b
3c
3d
3e
3f
30
35
30
30
30
40
30
25
30
30
35
40
45
35
30
80, 78, 77
76
275
314
236
198
261
202
250
205
266
227
145
199
260
298
232
275–276 [9]
313–315 [9]
235–238 [9]
199–201 [10]
258–260 [9]
201–202 [10]
248–249 [10]
204–205 [10]
265–267 [10]
226–228 [9]
142–143 [13]
196–198 [10]
261–262 [13]
297–298 [13]
233–235 [13]
3-NO
4-NO
2
C
C
6
H
H
4
4
2
6
78
2-ClC
4-ClC
6
H
H
4
80
6
4
82
2-BrC
4-BrC
6
H
H
4
4
75
6
3g
3h
3i
84
2-OHC
4-OHC
6
H
H
4
4
80
6
85
1
1
1
1
1
1
0
1
2
3
4
5
4-MeOC
3,4-(MeO)
3-MeO,4-OHC
6
H
4
3j
90
2
C
6
H
3
3k
3l
87
6
H
3
84
3,4,5-(MeO)
1-Naphthyl
2-Furyl
3
C
6
H
2
3m
3n
3o
82
80
86
a
Yields of isolated products.
b
2
SiO –Cl was recovered and reused for three consecutive runs.
without appreciable loss of activity (Table 3, entry 1). With
the optimized procedure in hand, we have extended the
same reaction up to 10-fold scale, and similar yields of
product were obtained with slight increase in reaction
time. A plausible mechanism for the formation of triaryl
imidazoles in the presence of silica chloride is postulated in
Fig. 1, indicating that silica chloride is an excellent source
for the generation of HCl.
NH OAc
4
SiO2
SiO2
Cl-
SiO2
O
.
.
Cl
O
NH
2
Ph
Ph
Ph
Ph
O
NH3
Ph
Ph
.
.
+
+
H
H
N
-HCl
.
.
+
-
Cl
O
O
O
Ar
Cl
Cl-
SiO2
SiO2
SiO2
..
NH
NH3
Ar-CHO
N
Ar
SiO2
OH
Cl-
H
Ph
Ph
Ph
Ph
NH
N +
..
Ar
Ar
-
HCl
H
N
N
N
Cl-
Ph
Ph
Ph
Ph
N
+
Ar
Cl
SiO2
OH
SiO -HCl
2
SiO2
Ar
N
H
3
a
2
Fig. 1. Plausible mechanism for the formation of trisubstituted imidazoles in the presence of SiO –Cl.
Please cite this article in press as: Chavan HV, Narale DK. Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst under solvent-free conditions. C. R. Chimie (2014), http://
dx.doi.org/10.1016/j.crci.2013.12.003

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H.V. Chavan, D.K. Narale / C. R. Chimie xxx (2014) xxx–xxx
O
O
O
O
O
Si
Cl
N
+
ArCHO + R-NH
2
+ NH
4
OAc
o
neat, 80 C
Ar
N
R
1
2
4
5a-e
Scheme 2. Silica chloride catalyzed synthesis of 1,2,4,5-tetraary-1H-imidazole.
Table 4
Synthesis of 1,2,4,5-tetraaryl-1H-imidazole derivatives.
a
Entry
Ar
R
Time (min)
Yield (%)
MP (8C)
Found
Report
1
2
3
4
5
C
6
H
5
C
C
C
C
C
6
H
6
H
6
H
6
H
6
H
5
5
5
5
5
5a
5b
5c
5d
5e
40
30
35
30
30
78
85
87
82
85
220
245
186
282
190
221–222 [18]
244–246 [18]
184–185 [18]
280–281 [18]
187–189 [18]
3-NO
4-MeOC
4-OHC
4-ClC
2
C
6
H
4
6 4
H
6
H
4
6 4
H
a
Yields of isolated products.
In order to demonstrate the versatility of this protocol,
we extended our study to the synthesis of a wide variety of
was removed to dryness under reduced pressure (1 Torr).
The resulting white-grayish powder was flask-dried and
stored in a tightly capped bottle.
2
,4,5-triaryl imidazoles (3a–o) using different aromatic
aldehydes under optimized reaction conditions. All these
reactions showed rapid formation of 2,4,5-triaryl imida-
zole derivatives with high efficiency. The nature (electron-
withdrawing or electron-donating) and position of the
substituent on the aromatic ring did not show any
significant differences in the yield of 2,4,5-triaryl imida-
zole derivatives. The products were characterized by IR, H
NMR, and mass spectroscopy data.
In the next attempt, identical reaction conditions were
applied to the synthesis of 1,2,4,5-tetraaryl-1H-imidazoles
via the one-pot, four-component condensation of benzil 1,
4
1
.2. General procedure for the preparation of 2,4,5-triaryl-
H-imidazoles (3a–o)
A mixture of benzil (1 mmol), aldehyde (1 mmol),
2
ammonium acetate (10 mmol) and SiO –Cl (250 mg) was
1
stirred at 80 8C for the appropriate time (Table 4). After
completion of the reaction (TLC), dichloromethane (20 mL)
was added, and the solid catalyst was recovered by filtration.
The solvent was distilled out and the crude product was
purified by silica gel column chromatography using
(hexane:ethyl acetate) as an eluent to afford pure 2,4,5-
4
aldehydes 2, aniline 4 and NH OAc (Scheme 2). To our
trisubstituted-1H-imidazoles in good to excellent yields.
delight, the 1,2,4,5-tetraaryl-1H-imidazoles were also
obtained in high yields (Table 4).
4
1
.3. General procedure for the synthesis of 1,2,4,5-tetraaryl-
H-imidazoles (5a–5f)
3
. Conclusion
A mixture of benzil (1 mmol), aldehyde (1 mmol),
In conclusion, we have developed a highly efficient,
aromatic primary amine (1 mmol), ammonium acetate
5 mmol) and SiO –Cl (250 mg) was stirred at 80 8C for the
multicomponent protocol for the synthesis of 2,4,5-triaryl
imidazoles and 1,2,4,5-tetraaryl imidazoles under solvent-
free conditions using silica chloride as a heterogeneous
catalyst in excellent yields. This method offers many attractive
features, such as short reaction time, high yield, recovery and
reusability as well as economic availability of the catalyst.
(
2
appropriate time. After completion of the reaction (TLC),
dichloromethane (20 mL) was added, and the solid catalyst
was recovered by filtration. The solvent was distilled out
and the crude product was purified by silica gel column
chromatography using (hexane:ethyl acetate) as an eluent
to afford pure 1,2,4,5-tetrasubstituted-1H-imidazoles in
good to excellent yields.
4
. Experimental
4.1. General procedure for the preparation of SiO
2
–Cl
4.4. Spectral data of representative compounds
To a well-stirred silica gel (20 g) in CH
added dropwise SOCl (20 g) at room temperature.
Evolution of copious amounts of HCl and SO occurred
instantaneously. After stirring for another 6 h, the solvent
2
Cl
2
(50 mL) was
4.4.1. 2,4,5-Triphenyl-1H-imidazole (3a)
À1
1
2
IR (KBr, cm
NMR (CDCl , 200 MHz):
1H); MS (ESI): m/z 296 (M ).
)
n
= 1216, 1638, 2470, 2993, 3434;
H
2
3
d
7.45–8.25 (m, 15H), 12.61 (bs,
+
Please cite this article in press as: Chavan HV, Narale DK. Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst under solvent-free conditions. C. R. Chimie (2014), http://
dx.doi.org/10.1016/j.crci.2013.12.003

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5
M.M. McLaughlin, I.R. Siemens, S.M. Fisher, J.P. Livi, J.R. White, J.L.
Adams, P.R. Young, Nature 372 (1994) 739.
6] Maier, T.; Schmierer, R.; Bauer, K.; Bieringer, H.; Buerstell, H.; Sachse, B
US Patent 4820335, 1989; Chem. Abstr. 1989, 111, 19494.
7] Schmierer, R.; Mildenberger, H. Buerstell, H. German Patent 361464,
1987; Chem. Abstr. 1988, 108, 37838.
4
.4.2. 4-(4,5-Diphenyl-1H-imidazol-2-yl)-phenol (3i)
À1
IR (KBr, cm
H NMR (CDCl
)
n
= 1216, 1638, 2465, 2998, 3432, 3596;
7.05 (d, J = 7 Hz, 2H), 7.45–7.60
[
[
[
1
3
, 200 MHz)
d
(m, 10H), 8.04 (d, J = 7 Hz, 2H), 12.58 (bs, 1H); MS (ESI): m/z
+
3
12 (M ).
8] J. Heeres, L.J.J. Backx, J.H. Mostmans, Van Custem, J. Med. Chem. 22
(1979) 1003.
4
.4.3. 2-(4-Methoxyphenyl)-4,5-diphenyl-1H-imidazole (3j)
[9] (a) A.Y. Usyatinsky, Y.L. Khmelnitsky, Tetrahedron Lett. 41 (2000)
5031;
À1
1
IR (KBr, cm
NMR (CDCl , 200 MHz)
.48–7.57 (m, 10H), 8.18 (d, J = 7 Hz, 2H), 12.52 (bs, 1H);
)
n
= 1216, 1636, 2465, 2893, 3428;
H
(
(
b) H.A. Oskooie, Z. Alimohammadi, M.M. Heravi, Heteroat. Chem. 17
2006) 699.
3
d
3.89 (s, 3H), 7.24 (d, J = 7 Hz, 2H),
7
[10] (a) S.A. Siddiqui, U.C. Narkhede, S.S. Palimkar, T. Daniel, R.J. Lahoti, K.V.
Srinivasan, Tetrahedron 61 (2005) 3539;
+
MS (ESI): m/z 326 (M ).
(b) H. Zang, Q. Yingming Mo, C. Su, Bo-Wen, S. Jun, Ultrasonics Sono-
chem. 17 (2010) 749.
4
.4.4. 2-(4,5-Diphenyl-1H-imidazol-2-yl)-2-methoxyphenol
3l)
IR (KBr, cm
H NMR (CDCl
[11] C.M. Yu, M. Lei, W.K. Su, Y.Y. Xie, Synth. Commun. 37 (2007) 3301.
[
[
12] N.D. Kokare, J.N. Sangshetti, D.B. Shinde, Synthesis 18 (2007) 2829.
13] M.V. Chary, N.C. Keerthysri, S.V.N. Vupallapati, N. Lingaiah, S. Kantevari,
Catal. Commun. 9 (2008) 2013.
(
À1
)
n
= 1230, 1450, 1605, 2924, 3512, 3614;
, 200 MHz) 3.88 (s, 3H), 6.98 (d, J = 6.8 Hz,
H), 7.39–7.56 (m, 10H), 7.65 (d, J = 1.8 Hz, 1H), 7.75 (s, 1H)
1
3
d
[14] J. Sangshetty, N.D. Kokare, S.A. Kotharkara, D.B. Shinde, J. Chem. Sci. 120
2008) 463.
[15] J. Wang, R. Mason, D.V. Derveer, K. Feng, X.R. Bu, J. Org. Chem. 68 (2003)
415.
(
1
1
+
2.54 (bs, 1H); MS (ESI): m/z 342 (M ).
5
[
[
[
16] A. Shaabani, A. Rahmati, J. Mol. Catal. A: Chem. 249 (2006) 246.
17] S. Balalaie, A. Arabanian, Green Chem. 2 (2000) 274.
18] (a) E. Rafiee, H. Mahdavi, M. Joshaghani, Mol. Divers. 15 (2011) 125;
4
.4.5. 2-(3,4,5-Trimethoxyphenyl)-4,5-diphenylimidazole
3m)
IR (KBr, cm
241, 1128, 1006, 770, 699; H NMR (CDCl
.81 (s, 3H), 3.93 (s, 6H), 7.51–7.61 (m, 12H), 12.22 (s, 1H);
(
(b) M.M. Heravi, F. Derikvand, F.F. Bamoharram, J. Mol. Catal. A: Chem.
À1
)
n = 3424, 2934, 2835, 1588, 1495, 1485,
263 (2007) 112.
1
1
3
3
, 200 MHz)
d
[19] A.R. Karimi, Z. Alimohammadi, J. Azizian, A.A. Mohammadi, M.R.
Mohammadizadeh, Catal. Commun. 7 (2006) 728.
[
[
20] S.D. Sharma, P. Hazarika, D. Konwar, Tetrahedron Lett. 49 (2008) 2216.
21] S. Kantevari, S.V.N. Vuppalapati, D.O. Biradar, L.J. Nagarapu, Catal. Mol.
A: Chem. 266 (2007) 109.
+
MS (ESI): m/z 387 [M+H] .
[
[
[
22] I. Lantos, W.Y. Zhang, X. Shui, D.S. Eggleston, J. Org. Chem. 58 (1993)
4
.4.6. 2-(1-Naphthyl)-4,5-diphenylimidazole (3n)
7092.
À1
IR (KBr, cm
68, 695; H NMR (CDCl
)
n
= 3422, 3051, 2960, 1599, 1502, 1443,
, 200 MHz) 7.18–7.78 (m, 13H),
.80–7.98 (m, 3H), 9.18 (d, J = 7 Hz, 1H), 12.43 (s, 1H); MS
23] S. Balalaie, M.M. Hashemi, M. Akhbari, Tetrahedron Lett 44 (2003)
1709.
24] H. Firouzabadi, N. Iranpoor, B. Karimi, H. Hazarkhani, Synth. Commun.
1
7
7
3
d
33 (2003) 3653.
+
(ESI): m/z 347 [M + H] .
[25] H. Karade, M. Sathe, M.P. Kaushik, Molecules 12 (2007) 1341.
[26] H. Karade, M. Sathe, M.P. Kaushik, Catal. Commun. 8 (2007) 741.
[27] M.M. Heravi, R. Zadmard, M. Ghassemzadeh, M. Tajbakhsh, N. Riahifar,
Phosphorus Sulfur Silicon 17 (2001) 687.
4.4.7. 2-(2-Furyl)-4,5-diphenylimidazole (3o)
À1
IR (KBr, cm
) n = 3440, 3021, 2922, 2819, 2722, 1523,
[
[
[
28] B. Das, M.R. Reddy, H. Holla, R. Ramu, K. Vekateswarlu, Y.K. Rao, J. Chem.
1
1
2
484, 1445, 1225, 1169, 766, 742, 696. H NMR (CDCl
3
,
Res. 12 (2005) 793.
29] F. Shirini, M.A. Zolfigol, M. Khaleghi, Phosphorus Sulfur Silicon 178
00 MHz) 6.58 (dd, J = 2.34 Hz, J = 1.56 Hz, 1H), 6.99 (d,
d
(2003) 2107.
J = 3.12 Hz, 1H) 7.20–7.62 (m, 11H), 12.50 (s, 1H); MS (ESI):
m/z 287 [M+H] .
30] K.V.N.S. Srinivas, I. Mahender, B. Das, Synthesis (2003) 2479.
+
[31] H. Firouzabadi, N. Iranpoor, B. Karimi, H. Hazarkhani, Synlett (2000)
63.
2
[
32] F. Shirini, M.A. Zolfigol, M. Khaleghi, I. Mohammadpour-Baltork, Synth.
4
.4.8. 1-(4-Methoxyphenyl)-2,4,5-triphenyl-1H-imidazole
5c)
IR (KBr, cm
NMR (CDCl , 200 MHz)
m, 15H), 6.76 (d, 2H, J = 8.0 Hz), 3.77 (s, 3H); MS (ESI): m/z
Commun. 33 (2003) 1839.
(
[33] K.V.N.S. Srinivas, I. Mahender, B. Das, Chem. Lett. 32 (2003) 738.
[34] F. Mohanazadeh, A.J. Momeni, Sci. I.R. Iran 7 (1996) 261.
[
À1
1
)
n
= 3060, 2956, 1606, 1574, 1482.
H
35] A. Hasaninejad, A. Zare, H. Sharghi, M. Shekouhy, R. Khalifeh, A.S. Beni,
A.R.M. Zare, Can. J. Chem. 85 (2007) 416.
36] (a) H.V. Chavan, S.B. Babar, R.U. Hoval, B.P. Bandgar, Bull. Korean Chem.
Soc. 32 (2011) 3963;
3
d
7.60 (d, 2H, J = 8.0 Hz), 7.02–7.37
(
4
[
+
02 (M ).
(
(
b) H.V. Chavan, L.K. Adsul, B.P. Bandgar, J. Chem. Sci. 123 (2011) 477;
c) H.V. Chavan, B.P. Bandgar, ACS Sustainable Chem. Eng. 1 (2013)
References
9
29–936;
(d) S.S. Jalde, H.V. Chavan, L.K. Adsul, V.D. Dhakane, B.P. Bandgar,
[
1] (a) W.M. Nelson, Green chemistry for solvents, Oxford University
Press, Oxford, 2003;
(
Synth. React. Inorg. Met. Org. Chem. 44 (2014) 623–626;
(e) B.P. Bandgar, B.L. Korbad, S.A. Patil, S.B. Bandgar, H.V. Chavan, B.S.
Hote, Aust. J. Chem. 61 (2008) 700;
(f) V.D. Dhakane, S.S. Gholap, U.P. Deshmukh, H.V. Chavan, B.P. Band-
gar, C. R. Chimie 17 (2014) 431–436;
(g) H.V. Chavan, B.P. Bandgar, L.K. Adsul, V.D. Dhakane, P.S. Bhale, V.N.
Thakare, V. Masand, Bioorg. Med. Chem. Lett. 23 (2013) 1315–1321;
(h) B.P. Bandgar, H.V. Chavan, L.K. Adsul, V.N. Thakare, S.N. Shringare,
R. Shaikh, R.N. Gacche, Bioorg. Med. Chem. Lett. 23 (2013)
912–916.
b) J. Liu, J. Zhao, J. Zhao, Y. Li, L.H. Zhang, Synthesis (2003) 2661.
2] (a) K. Tanaka, F. Toda, Chem. Rev. 100 (2000) 1025;
b) G.W.V. Cave, C.L. Raston, J.L. Scott, Chem. Commun. (2001) 2159.
[
[
(
3] M.R. Grimmett, in: A.R. Katritsky, E.F.V. Scriven (Eds.), Comprehensive
Heterocyclic Chemistry II, Vol. 3, Pergamon, Oxford, 1996, pp. 77–220.
4] L. De Luca, Curr. Med. Chem. 13 (2006) 1.
[
[
5] J.C. Lee, J.T. Laydon, P.C. McDonnell, T.F. Gallagher, S. Kumar, D. Green,
D. McNulty, M. Blumenthal, J.R. Heys, S.W. Landvatter, J.E. Strickler,
Please cite this article in press as: Chavan HV, Narale DK. Synthesis of 2,4,5-triaryl and 1,2,4,5-tetraaryl imidazoles
using silica chloride as an efficient and recyclable catalyst under solvent-free conditions. C. R. Chimie (2014), http://
dx.doi.org/10.1016/j.crci.2013.12.003