Facile method for one-step synthesis of 2,4,5-triarylimidazoles under catalyst-free, solvent-free, and microwave-irradiation conditions

Article abstract of DOI:10.1080/00397910903043025

A green and efficient method for the synthesis of 2,4,5-triarylimidazoles by one-step condensation reaction of benzil, aromatic aldehyde, and ammonium acetate under catalyst-free, solvent-free, and microwave-irradiation conditions is reported. This method had many dramatic advantages, such as the short reaction time (3-5min), good yields (80-99%), environmental friendliness, and convenient operation.

Full text of DOI:10.1080/00397910903043025

This article was downloaded by: [Duke University Libraries]
On: 25 April 2013, At: 00:25
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Facile Method for One-Step Synthesis of
2,4,5-Triarylimidazoles Under Catalyst-
Free, Solvent-Free, and Microwave-
Irradiation Conditions
Jian-Feng Zhou a b , Gui-Xia Gong b , Xiao-Jun Sun a & Yu-Lan Zhu a
a Department of Chemistry, Huaiyin Teachers College, Jiangsu Key
Laboratory for Chemistry of Low-Dimensional Materials, Huaian,
China
b School of Chemistry and Chemical Engineering, Key Laboratory of
Organic Synthesis of Jiangsu Province, Suzhou University, Suzhou,
China
Version of record first published: 12 Mar 2010.
To cite this article: Jian-Feng Zhou , Gui-Xia Gong , Xiao-Jun Sun & Yu-Lan Zhu (2010): Facile Method
for One-Step Synthesis of 2,4,5-Triarylimidazoles Under Catalyst-Free, Solvent-Free, and Microwave-
Irradiation Conditions, Synthetic Communications: An International Journal for Rapid Communication
of Synthetic Organic Chemistry, 40:8, 1134-1141
To link to this article: http://dx.doi.org/10.1080/00397910903043025
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,

demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

Synthetic Communications1, 40: 1134–1141, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903043025
FACILE METHOD FOR ONE-STEP SYNTHESIS OF
2,4,5-TRIARYLIMIDAZOLES UNDER CATALYST-FREE,
SOLVENT-FREE, AND MICROWAVE-IRRADIATION
CONDITIONS
Jian-Feng Zhou,1,2 Gui-Xia Gong,2 Xiao-Jun Sun,1 and
Yu-Lan Zhu1
1Department of Chemistry, Huaiyin Teachers College, Jiangsu Key
Laboratory for Chemistry of Low-Dimensional Materials, Huaian, China
2School of Chemistry and Chemical Engineering, Key Laboratory of Organic
Synthesis of Jiangsu Province, Suzhou University, Suzhou, China
A green and efficient method for the synthesis of 2,4,5-triarylimidazoles by one-step
condensation reaction of benzil, aromatic aldehyde, and ammonium acetate under
catalyst-free, solvent-free, and microwave-irradiation conditions is reported. This method
had many dramatic advantages, such as the short reaction time (3–5 min), good yields
(80–99%), environmental friendliness, and convenient operation.
Keywords: Aromatic aldehyde; benzil; catalyst-free; microwave irradiation; solvent-free; triarylimidazole
Triarylimidazole derivatives have many biological activities, such as herbicidal,[1]
fungicidal,[2] anti-inflammatory,[3] and antithrombotic activities.[4] In addition, they
are used in photography as photosensitive compounds.[5] Some substituted triaryli-
midazole are selective antagonists of the glucagon receptor[6] and inhibitors of
IL-1 biosynthesis.[7] The great biological importance of the imidazole nucleus over
the years has prompted the development of new improved methodologies. Grimmett
proposed the synthesis of the imidazole using nitriles and esters.[8] A literature survey
reveals several methods for the synthesis of 2,4,5-triarylimidazoles using ZrCl4,[9]
zeolites HY=silica gel,[10] NaHSO3,[11] sulfanilic acid,[12] iodine,[13] ionic liquid,[14]
and ceric ammonium nitrate.[15] Each of these methods for this reaction has its
own merits, but some of the methods are plagued by the limitations of poor yield,
longer reaction time, difficult workup, and effluent pollution.[16,17] We have also pre-
viously reported an efficient synthesis of 2-aryl-4,5-diphenyl-imidazoles by one-step
cyclocondensation of benzil and aromatic aldehyde in the presence of NH4OAc in
HOAc as the solvent under microwave irradiation.[18]
Received March 7, 2009.
Address correspondence to Jian-Feng Zhou, Department of Chemistry, Huaiyin Teachers College,
223300 Huaian, China. E-mail: orgjfzhou@yahoo.com.cn
1134

GREEN SYNTHESIS OF 2,4,5-TRIARYLIMIDAZOLES
1135
Scheme 1. Synthesis of 2,4,5-triarylimidazoles under catalyst-free, solvent-free, and microwave irradiation
conditions. R1 ¼ H1, CH3, Cl; R2 ¼ H, CH3, OCH2O, N(CH3)2, Cl, OCH3, OH.
It is known that microwave irradiation has been utilized as one of the most
convenient and efficient ways to promote organic reactions.[19–20] In particular, the
use of microwave energy to directly heat chemical reactions has become an increas-
ingly popular technique in the scientific community. Therefore, in recent years,
the combination of several prominent green chemistry principles—microwaves,
solvent-free, and catalyst-free—has become very popular and received substantial
interest because of the work of chemists[21–24] who demonstrated that a great variety
of synthetic organic transformations can be carried out very efficiently and rapidly
under these environmentally benign conditions.
Recently, we reported an efficient synthesis of quinoxalines from benzils and
1,2-diaminobenzenes under catalyst-free, solvent-free, and microwave-irradiation
conditions.[25] Herein, we report an efficient method for synthesis of 2,4,5-triarylimi-
dazoles by one-step cyclocondensation of benzil, aromatic aldehyde, and ammonium
acetate under catalyst-free, solvent-free, and microwave-irradiation conditions. Our
research shows that this method has many dramatic advantages such as the short
reaction time (3–5 min), good yields (80–99%), environmental friendliness, and
convenient operation.
RESULTS AND DISCUSSION
First of all, we studied the effects of different reaction conditions in the
synthesis of 2,4,5-triphenylimidazole (4a), and results are summarized in Table 1.
As can been from Table 1, when a mixture of benzil 1 (R1 ¼ H, entry 1), benzal-
dehyde 2 (1 mmol), and NH4OAc 3 (3 mmol) (reactant molar ratio 1:2:3 ¼ 1:1:3)
Table 1. Optimization of reaction conditions and yields of 2,4,5-triarylimidazoles
Entry
Reactant molar ratio (1:2:3)
Temp. (ꢀC)a
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
1.0:1.0:1.5
1.0:1.0:2.1
1.0:1.0:2.1
1.0:1.0:2.1
1.0:1.0:2.1
1.0:1.0:2.1
1.0:1.0:2.5
1.0:1.0:3.0
1.0:1.0:3.5
120
120
120
120
130
110
120
120
120
5
4
5
6
5
5
5
5
5
73
70
90
86
88
85
91
93
92
aMicrowave irradiated at 150 W.
bAll yields refer to isolated products.

1136
J.-F. ZHOU ET AL.
Table 2. Synthesis of 2,4,5-triarylimidazoles 4a–n under catalyst-free, solvent-free, and
microwave-irradiation conditions
Entry
1
R1
H
ArCHO
Time (min)a
Products
Yieldb (%)
5
93
2
H
4
97
3
4
5
6
H
H
H
H
4
5
4
3
80
80
98
85
7
4-CH3
5
88
8
9
4-CH3
4-CH3
4
4
96
95
10
11
4-CH3
4-Cl
4
4
91
99
(Continued )

GREEN SYNTHESIS OF 2,4,5-TRIARYLIMIDAZOLES
1137
Table 2. Continued
Entry
12
R1
ArCHO
Time (min)a
Products
Yieldb (%)
4-Cl
4
95
13
14
4-Cl
4-Cl
4
4
91
80
aMicrowave irradiated at 150 W and 120 ꢀC.
bAll yield refers to isolated products.
was irradiated at 150 W and 120 ꢀC in catalyst-free and solvent-free conditions,
the reaction was completed after 5 min. The crude product was purified by
recrystallization from 95% ethanol to afford product 4a with an excellent yield of
93%. Subsequently, to examine the efficiency and applicability of this protocol,
the reaction was extended to other substituted benzils 1 (R1 ¼ H CH3, Cl, entries
2–14) and substituted benzaldehyde 2 [R2 ¼ H, CH3, OCH2O, N(CH3)2, Cl,
OCH3, OH] under catalyst-free, solvent-free, and microwave-irradiation conditions.
To our delight, these actions proceeded smoothly to afford a series of 2,4,5-
triarylimidazole derivatives 4 in excellent yields (entries 2–14 of Table 2). The results
showed that the scope of the reaction is quite broad in regard to the benzils, 1,
and aromatic aldehydes, 2. The structures of these compounds were established by
infrared (IR), 1H NMR, 13C NMR, mass spectrometry (MS), and elemental analysis.
In conclusion, we have developed a novel, efficient method for synthesis of
2,4,5-triarylimidazoles. Lack of catalyst and solvent, the short reaction time, excel-
lent yields of the products, environmental friendliness, and convenient workup are
the advantages of this method.
EXPERIMENTAL
The reactions were performed in a CEM Discover monomode microwave
reactor. Melting points were determined with an WRS-1B digital melting-point
apparatus and are uncorrected. 1H NMR and 13C NMR were measured on a
Burke 400-MHz spectrometer in CDCl3 or dimethylsulfoxide (DMSO-d6) using
tetramethylsilane (TMS) as an internal standard. IR spectra were recorded on a
Nicolet Avatar 360 Fourier transform (FT)–IR instrument. Mass spectra (MS) were
recorded on an LCQ Advantage instrument. Elemental analysis were determined
using a Perkin-Elmer 240C elemental analyzer. All the reagents are commercially
available.

1138
J.-F. ZHOU ET AL.
General Procedure for Synthesize of 2,4,5-Triarylimidazole
Derivatives
Benzil 1 (1 mmol), aromatic aldehyde 2 (1 mmol), and NH4OAc 3 (3 mmol)
were mixed in a vial and sealed with a cap containing a septum. The loaded
vial was then placed into the cavity of the microwave reactor and heated at 150 W
and 120 ꢀC for 3–5 min (as indicated by thin-layer chromatography, TLC). After
completion of the reaction, the reaction mixture was then allowed to cool to room
temperature, resulting in the precipitation of the solid product. The product was
filtered off and dried. The crude products were recrystallized from 95% ethanol to
afford the pure products 3a–n.
Selected Data
Compound 3a. Mp 277 ꢀC (276–277 ꢀC).[17b] 1H NMR (400 MHz, CDCl3) d:
7.30–8.10 (m, 15H, Ar-H).
Compound 3b. Mp 237–238 ꢀC (231–232 ꢀC).[11] 1H NMR (400 MHz,
CDCl3) d: 2.40 (s, 3H, CH3), 7.24–7.80 (m, 14H, Ar-H).
Compound 3c. Mp 254 ꢀC (300 ꢀC).[18] 1H NMR (400 MHz, CDCl3) d: 6.02
(s, 2H, CH2), 6.85–7.53 (m, 13H, Ar-H).
Compound 3d. Mp 259–260 ꢀC (259–260 ꢀC).[17b] 1H NMR (400 MHz,
CDCl3) d: 3.05 (s, 6H, CH3), 6.74–7.82 (m, 14H, Ar-H).
Compound 3e. Mp 265 ꢀC (264–265 ꢀC).[17b] 1H NMR (400 MHz, CDCl3) d:
7.30–7.88 (m, 14H, Ar-H).
Compound 3f. Mp 234 ꢀC (230–232 ꢀC).[17b] 1H NMR (400 MHz, CDCl3) d:
3.86 (s, 3H, CH3), 6.94–7.85 (m, 14H, Ar-H).
Compound 3g. Mp 269–270 ꢀC. IR (KBr): 3421, 3028, 1519, 1494, 1458,
1
1410, 1124, 820, 692 cmꢁ1. H NMR (400 MHz, DMSO-d6) d: 12.56 (s, 1H, NH),
8.07 (d, 2H, J ¼ 7.60 Hz), 7.48 (d, 2H, J ¼ 7.60 Hz), 7.45–7.35 (m, 5H), 7.25 (d,
2H, J ¼ 8.00 Hz), 7.11 (d, 2H, J ¼ 8.00 Hz), 2.35 (s, 3H, CH3), 2.30 (s, 3H, CH3);
13C NMR (100 MHz, DMSO-d6) d: 145.6, 137.5, 137.4, 135.9, 132.9, 130.9, 129.6,
129.2, 129.1, 128.7, 128.6, 128.3, 127.5, 125.6. MS m=z (%): (M þ H)þ ¼ 325.5
(100). Anal. calcd. for C23H20N2: C, 85.15; H, 6.21; N, 8.63. Found: C, 84.84; H,
6.23; N, 8.57.
Compound 3h. Mp 250–251 ꢀC. IR (KBr): 3423, 3027, 1614, 1499, 1441,
1248, 1030, 822, 737 cmꢁ1. 1H NMR (400 MHz, CDCl3) d: 7.84 (d, 2H, J ¼ 8.80 Hz),
7.42 (d, 4H, J ¼ 8.00 Hz), 7.13 (d, 4H, J ¼ 8.00 Hz), 6.94 (d, 2H, J ¼ 8.40 Hz), 3.85 (s,
3H, OCH3), 2.36 (s, 6H, CH3); 13C NMR (100 MHz, DMSO-d6) d: 159.8, 145.8,
137.3, 137.0, 135.8, 133.1, 129.6, 129.2, 128.9, 128.6, 127.7, 127.5, 127.1, 123.8,
114.5. MS m=z (%): (M þ H)þ ¼ 355.4 (100). Anal. calcd. for C24H22N2O: C,
81.33; H, 6.26; N, 7.90. Found: C, 81.02; H, 6.28; N, 7.82.
Compound 3i. Mp 238–239 ꢀC. IR (KBr): 3019, 1520, 1498, 1435, 1122, 819,
.
728 cmꢁ1 1H NMR (400 MHz, DMSO-d6) d: 12.48 (s, 1H, NH), 9.77 (d, 2H,

GREEN SYNTHESIS OF 2,4,5-TRIARYLIMIDAZOLES
1139
J ¼ 8.00 Hz), 7.44 (d, 2H, J ¼ 8.00 Hz), 7.38 (d, 2H, J ¼ 8.00 Hz), 7.29 (d, 2H,
J ¼ 8.00 Hz), 7.24 (d, 2H, J ¼ 8.00 Hz), 7.11 (d, 2H, J ¼ 7.60 Hz), 2.35 (s, 6H,
CH3), 2.23 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) d: 145.8, 138.0, 137.4,
137.2, 136.0, 129.7, 129.6, 129.1, 128.8, 128.6, 128.3, 128.0, 127.5, 125.6. MS m=z
(%): (M þ H)þ ¼ 339.6 (100). Anal. calcd. for C24H22N2: C, 85.17; H, 6.55; N,
8.28. Found: C, 84.84; H, 6.57; N, 8.19.
Compound 3j. Mp 263–264 ꢀC. IR (KBr): 3423, 3023, 1517, 1491, 1434, 1089,
1
820, 729 cmꢁ1. H NMR (400 MHz, DMSO-d6) d: 12.67 (s, 1H, NH), 8.09 (d, 2H,
J ¼ 8.80 Hz), 7.54 (d, 2H, J ¼ 8.40 Hz), 7.44 (d, 2H, J ¼ 8.00 Hz), 7.39 (d, 2H,
J ¼ 8.00 Hz), 7.25 (d, 2H, J ¼ 8.00 Hz), 7.11 (d, 2H, J ¼ 8.00 Hz), 2.35 (s, 3H,
CH3), 2.30 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) d: 144.6, 137.6, 137.5,
136.1, 133.1, 132.8, 129.8, 129.6, 129.2, 129.1, 128.7, 128.6, 127.5, 127.3. MS m=z
(%): (M þ H)þ ¼ 359.6 (100). Anal. calcd. for C23H19ClN2: C, 76.98; H, 5.34; N,
7.81. Found: C, 76.69; H, 5.36; N, 7.73.
Compound 3k. Mp 290–291 ꢀC. IR (KBr): 3439, 3057, 1407, 1093, 833,
729 cmꢁ1 1H NMR (400 MHz, DMSO-d6) d: 12.79 (s, 1H, NH), 8.07 (d, 2H,
.
J ¼ 7.20 Hz), 7.56–7.38 (m, 11H); 13C NMR (100 MHz, DMSO-d6) d: 146.5, 136.9,
134.3, 133.0, 131.7, 130.6, 130.5, 130.1, 129.3, 129.2, 128.9, 128.8, 127.8, 125.8.
MS m=z (%): (M)þ ¼ 365.6 (100). Anal. calcd. for C21H14Cl2N2: C, 69.05; H, 3.86;
N, 7.67. Found: C, 68.79; H, 3.88; N, 7.59.
Compound 3l. Mp 274–276 ꢀC. IR (KBr): 3425, 3078, 2891, 1479, 1237, 1091,
1
1039, 833, 740 cmꢁ1. H NMR (400 MHz, CDCl3) d: 7.45 (d, 4H, J ¼ 7.20 Hz), 7.42
(s, 1H), 7.35–7.32 (m, 5H), 6.88 (d, 1H, J ¼ 8.00 Hz), 6.04 (s, 2H, CH2); 13C NMR
(100 MHz, DMSO-d6) d: 148.1, 146.4, 136.6, 134.3, 132.9, 131.6, 130.5, 130.1,
129.3, 129.2, 128.8, 127.4, 124.9, 120.0, 109.0, 106.1, 101.8. MS m=z (%):
(M)þ ¼ 409.5 (100). Anal. calcd. for C22H14Cl2N2O2: C, 64.56; H, 3.45; N, 6.84.
Found: C, 64.30; H, 3.46; N, 6.77.
Compound 3m. Mp 258–259 ꢀC IR (KBr): 3427, 3068, 2961, 1614, 1496,
1441, 1248, 830, 742 cmꢁ1. 1H NMR (400 MHz, CDCl3) d: 7.86 (d, 2H, J ¼ 8.40 Hz),
7.46 (d, 4H, J ¼ 8.00 Hz), 7.32 (d, 4H, J ¼ 8.00 Hz), 6.99 (d, 2H, J ¼ 8.80 Hz), 3.88 (s,
3H, OCH3); 13C NMR (100 MHz, DMSO-d6) d: 160.1, 146.6, 136.5, 136.5, 134.4,
132.8, 131.6, 130.5, 130.2, 129.2, 129.2, 128.8, 127.7, 127.3, 123.3, 114.6. MS m=z
(%): (M)þ ¼ 395.6 (100). Anal. calcd. for C22H16Cl2N2O: C, 66.85; H, 4.08; N,
7.09. Found: C, 66.59; H, 4.10; N, 7.02.
Compound 3n. Mp 271–272 ꢀC. IR (KBr): 3438, 3073, 1654, 1479, 1434,
1
1090, 831, 731 cmꢁ1. H NMR (400 MHz, DMSO-d6) d: 12.86 (s, 1H, NH), 8.09
(d, 2H, J ¼ 8.40 Hz), 7.69 (d, 2H, J ¼ 8.40 Hz), 7.64–7.51 (m, 6H), 7.37 (d, 2H,
J ¼ 6.40 Hz);13C NMR (100 MHz, DMSO-d6) d: 145.4, 137.0.5, 134.1, 133.5, 133.1,
131.8, 130.6, 129.9, 129.4, 129.2, 129.3, 128.9, 128.1, 127.4. MS m=z (%):
(M þ H)þ ¼ 399.7 (100). Anal. calcd. for C21H13Cl3N2: C, 63.10; H, 3.28; N, 7.01.
Found: C, 62.86; H, 3.30; N, 6.94.

1140
J.-F. ZHOU ET AL.
ACKNOWLEDGMENTS
We thank the National Natural Science Foundation of China (No. 20671038)
and Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials for
financial support.
REFERENCES
1. Liebl, R.; Handte, R.; Mildenberger, H.; Bauer, K.; Bieringer, H. Preparation of
1-phenyl-2-imidazolidinones and 2-imidazolidinethiones as herbicides. Ger. Offen. 3,
604,042, Aug. 13, 1987; Chem. Abstr. 1988, 108(1), 6018g.
2. Pozherskii, A. F.; Soldatenkov, A. T.; Katritzky, A. Y. Heterocycles in Life and Society;
Wiley: New York, 1997; pp. 179–180.
3. Lombardino, J. G.; Wiseman, E. H. Preparation and antiinflammatory activity of some
nonacidic trisubstituted imidazoles. J. Med. Chem. 1974, 17, 1182–1188.
4. Phillips, A. P.; White, H. L.; Rosen, S. Antithrombotic triphenylimidazole. Eur. Patent
Appl. EP 58,890, Sep. 1, 1982; Chem. Abstr. 1983, 98(7), 53894z.
5. (a) Satoru, I. Imidazoles derivative for chemiluminescence microanalysis. Jpn. Kokkai
Tokyo Koho JP 01,117,867, May 10, 1989; Chem. Abstr. 1989, 111(23), 214482t; (b)
Sensui, H.; Ichikawa, J.; Sato, S. Photosensitive composition containing triphenylimida-
zole dimer. Jpn. Kokkai Tokyo Koho JP 62,94,841, Mar. 4, 1987; Chem. Abstr. 1987,
107(20), 187436q.
6. Chang, L. L.; Sidler, K. L.; Cascieri, M. A.; de Laszlo, S.; Koch, G.; Li, B.; MacCoss, M.;
Mantlo, N.; O’Keefe, S.; Pang, M.; Rolando, A.; Hagmann, W. K. Substituted imidazoles
as glucagon receptor antagonists. Bioorg. Med. Chem. Lett. 2001, 11, 2549–2553.
7. Gallagher, T. H.; Fier-Thompson, S. M.; Garigipati, R. S.; Sorenson, M. E.; Smietana,
J. M.; Lee, D.; Bender, P. E.; Lee, J. C.; Laydon, J. T.; Griswold, D. E.; Chabot-Fletcher,
M. C.; Breton, J. J.; Adams, J. L. 2,4,5-Triarylimidazole inhibitors of IL-1 biosynthesis.
Bioorg. Med. Chem. Lett. 1995, 5, 1171–1176.
8. Grimmett, M. R. In Comprehensive Heterocyclic Chemistry II; A. R. Katritzky, C. W.
Rees, E. F. V. Scriven (Eds.); Pergamon: New York, 1996; vol. 3, p. 77.
9. Sharma, G.; Jyothi, Y.; Lakshmi, P. Efficient room-temperature synthesis of tri- and tetra-
substituted imidazoles catalyzed by ZrCl4. Synth. Commun. 2006, 36, 2991–3000.
10. Balalaie, S.; Arabanian, A.; Hashtroudi, M. S. Zeolite HY and silica gel as new and
efficient heterogenous catalysts for the synthesis of triarylimidazoles under microwave
irradiation. Monat. Chem. 2000, 131, 945–948.
11. Sangshetti, J.; Kokare, N.; Kotharkar, A.; Shinde, D. Sodium bisulfite as an efficient and
inexpensive catalyst for the one-pot synthesis of 2,4,5-triaryl-1H-imidazoles from benzil or
benzoin and aromatic aldehydes. Monat. Chem. 2008, 139, 125–127.
12. Mohammed, A.; Lokare, N.; Sangshetti, J.; Shinde, D. Sulphanilic acid–catalyzed facile
one-pot synthesis of 2,4,5-triarylimidazoles from benzil=benzoin and aromatic aldehydes.
J. Kor. Chem. Soc. 2007, 51, 418–422.
13. Kidwai, M.; Mothsra, P.; Bansal, V.; Goyal, R. Efficient elemental iodine catalyzed
one-pot synthesis of 2,4,5-triarylimidazoles. Monat. Chem. 2006, 137, 1189–1194.
14. Siddiqui, S. A.; Narkhede, U. C.; Palimkar, S. S.; Daniel, T.; Lahoti, R. J.; Srinivasan, K. V.
Room-temperature ionic liquid–promoted improved and rapid synthesis of 2,4,5-triaryl
imidazoles from aryl aldehydes and 1,2-diketones or a-hydroxyketone. Tetrahedron 2005,
61, 3539–3546.
15. Ahmad, S.; Maleki, A.; Benham, M. Tandem oxidation process using ceric ammonium
nitrate: Three-component synthesis of trisubstituted imidazoles under aerobic oxidation
conditions. Synth. Commun. 2009, 39, 102–110.

GREEN SYNTHESIS OF 2,4,5-TRIARYLIMIDAZOLES
1141
16. (a) Davidson, D.; Weiss, M.; Jelling, M. The action of ammonia on benzil. J. Org. Chem.,
1937, 2, 319–327; (b) Whiten, D. M.; Sonnenberg, J. Infrared spectra of arylimidazoles
and arylisoimidazoles. J. Org. Chem. 1964, 29, 1926–1930.
17. Zhang, E. J.; Moran, E. J.; Woiwode, T. F.; Short, K. M.; Mjalli, A. M. M. The Curtin–
Hammett principle: Stereoselective radical additions to alkenes. Teterahedron Lett. 1996,
37, 351–354.
18. Zhou, J. F.; Song, Y. Z.; Yang, Y. L.; Zhu, Y. L.; Tu, S. J. One-step synthesis of
2-aryl-4,5-diphenylimidazoles under microwave irradiation. Synth. Commun. 2005, 35,
1369–1373.
19. Kappe, C. O. Controlled microwave heating in modern organic synthesis. Angew. Chem.
Int. Ed. 2004, 43, 6250–6284.
20. Ding, D. R.; Li, X.; Wang, X.; Du, Y. L.; Shen, J. K. Microwave-assisted rapid and
straightforward synthesis of 2-aryl-4-quinolones from acylated 20-aminoacetopheinones.
Tetrahderon Lett. 2006, 47, 6997–6999.
21. Loupy, A.; Petti, A.; Hamelin, J.; Texier-Boullet, F.; Jacquault, P.; Mathe, D. New
solvent-free organic synthesis using focused microwaves. Synthesis 1998, 1213–1234.
22. Motiwala, H. F.; Kumar, R.; Chakraborti, A. K. Microwave-accelerated solvent- and
catalyst-free synthesis of 4-aminoaryl=alkyl-7-chloroquinolines and 2-aminoaryl=alkyl-
benzothiazoles. Aust. J. Chem. 2007, 60, 369–374.
23. Jeselnik, M.; Varma, R. S.; Polanc, S.; Kocevar, M. Catalyst-free reactions under
solvent-free conditions: Microwave-assisted synthesis of heterocyclic hydrazones below
the melting points of neat reactants. Chem. Commun. 2001, 21, 1716–1717.
24. Mu, X. J.; Lei, M. Y.; Zou, J. P.; Zhang W. Microwave-assisted free solvent- and
catalyst-free Kabachnik–Fields reactions for a-amino phosphonates. Tetrahedron Lett.
2006, 47, 1125–1127.
25. Zhou, J. F.; Gong, G. X.; Zhi, S. J.; Duan, X. L. Microwave-assisted catalyst-free
and solvent-free method for the synthesis of quinoxalines. Synth. Commun. 2009, 39,
3743–3754.