Efficient room-temperature synthesis of tri- and tetrasubstituted imidazoles catalyzed by ZrCl4

Article abstract of DOI:10.1080/00397910600773825

A general protocol has been developed for the rapid synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles in high yields using ZrCl₄ as an efficient catalyst at room temperature. A variety of aromatic, aliphatic, and terpenoidal aldehydes underwent condensation with NH₄OAc/amines to give the imidazoles. Similarly, the imidazole glycoconjugates are prepared in good yields from the corresponding glycosyl aldehydes. Copyright Taylor & Francis Group, LLC.

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Efficient Room‐Temperature Synthesis of Tri‐
and Tetrasubstituted Imidazoles Catalyzed by
ZrCl4
a
a
a
G. V. M. Sharma , Y. Jyothi & P. Sree Lakshmi
a
D‐211, Discovery Laboratory, Organic Chemistry Division III, Indian Institute
of Chemical Technology, Hyderabad, India
Version of record first published: 16 Feb 2007.
To cite this article: G. V. M. Sharma , Y. Jyothi & P. Sree Lakshmi (2006): Efficient Room‐Temperature
Synthesis of Tri‐ and Tetrasubstituted Imidazoles Catalyzed by ZrCl , Synthetic Communications: An
4
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Synthetic Communications , 36: 2991–3000, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600773825
Efficient Room-Temperature Synthesis of
Tri- and Tetrasubstituted Imidazoles
Catalyzed by ZrCl4
G. V. M. Sharma, Y. Jyothi, and P. Sree Lakshmi
Discovery Laboratory, Organic Chemistry Division III, Indian Institute of
Chemical Technology, Hyderabad, India
Abstract: A general protocol has been developed for the rapid synthesis of 2,4,5-
trisubstituted and 1,2,4,5-tetrasubstituted imidazoles in high yields using ZrCl as an
efficient catalyst at room temperature. A variety of aromatic, aliphatic, and terpenoidal
4
4
aldehydes underwent condensation with NH OAc/amines to give the imidazoles.
Similarly, the imidazole glycoconjugates are prepared in good yields from the
corresponding glycosyl aldehydes.
Keywords: 1,2-Diarylethanedienones, imidazole glycoconjugates, three/four-
component coupling reaction, tri/tetrasubstituted imidazoles
INTRODUCTION
Imidazoles are heterocycles with a wide range of applications and are
[
1]
receiving growing attention. The imidazole ring system is of particular
interest because it is a component of histidine and its decarboxylation metab-
[
2]
olite, histamine. The potency and wide applicability of the imidazole phar-
macophore can be attributed to its hydrogen bond donor–acceptor capability
as well as its high affinity for metals, which are present in many protein active
[3]
sites (e.g., Zn, Fe, Mg). Also improved pharmokinetics and bioavailability
of peptide-based protease inhibitors have been observed by replacing an
Received in India March 23, 2006
IICT Communication No. 051119.
Address correspondence to G. V. M. Sharma, D-211, Discovery Laboratory,
Organic Chemistry Division III, Indian Institute of Chemical Technology,
Hyderabad 500 007, India. E-mail: esmvee@iict.res.in or sharmagvm@yahoo.com
2
991

2
992
G. V. M. Sharma, Y. Jyothi, and P. S. Lakshmi
[4]
amide bond with an imidazoles. In addition, they constitute an essential
[5]
moiety of a number of therapeutic agents, fungicides and herbicides, and
[
plant-growth regulators, besides being known as inhibitors of p38 MAP
6]
[
kinase. Furthermore, a recent report indicates that synthetic imidazoles
7]
[8]
are potent inhibitors of protein–protein interactions.
The original synthesis of imidazole utilized glyoxal, formaldehyde, and
ammonia and established that the formation of four N-C bonds was a viable
[
9,10]
route.
the reaction suffered low yields, harsh conditions, high temperature, and
Although classical methods were derived from this early success,
[
11]
mixture of products.
Additionally, reagents for these procedures are not
readily or commercially available, a key deficiency where developing con-
ditions for library synthesis. Of the several methods reported in the literature
for the synthesis of imidazoles, the four-component one-pot condensation of
aryl glyoxals, aldehydes, amines, and NH OAc in refluxing acetic acid is
4
[
12]
the most desirable and convenient method.
number of procedures involve microwave-assisted synthesis,
A majority of these limited
[13]
apart from
Further, methods for the synthesis of
highly substituted imidazole rings are limited and generally cannot be
[14]
the recently reported ionic liquids.
[15]
carried out under neutral conditions. Herein, we report an efficient
synthesis of tri/tetrasubstituted imidazoles, including the imidazole glycocon-
jugates, using ZrCl (20 mol%) as an acid catalyst under neutral reaction con-
4
ditions at room temperature (Scheme 1).
RESULTS AND DISCUSSION
The synthetic strategy is based on the condensation of 1,2-diarylethanedie-
nones with aldehydes or aldehydes and amines in the presence of an excess
of NH OAc, resulting in 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imi-
4
dazoles respectively using 20 mol% of ZrCl as catalyst. Initially, benzal-
4
dehyde 1 in acetonitrile was treated with an equimolar quantity of benzil,
excess of NH OAc, and ZrCl (20 mol%) at room temperature for 0.75 h to
4
4
furnish 2,4,5-triphenyl imidazole 1a (Table 1) in 95% yield. Encouraged by
this success, the reaction of benzil was examined with a range of other
aromatic aldehydes 2–5, which afforded the products 2a–5a in high yields.
Note that the reaction of benzil with p-anisaldehyde and excess of NH OAc
4
was only 50% complete, and reaction at reflux was of no use. Reaction with
Scheme 1.

Tri- and Tetrasubstituted Imidazoles
Table 1. ZrCl -catalyzed synthesis of tri/tetrasubstituted imidazoles
2993
4
Entry
1
Starting material
Product
Time (h)
Yield (%)
1
2
3
4
1a R ¼ H
2a R ¼ Cl
3a R ¼ F
4a R ¼ NO
0.75
95
93
96
89
2
3
4
10
5
2
7
5
6
95
6
7
8
2
91
84
84
4
4.5
9
6
84
88
1
1
0
1
1.25
1.5
87
1
1
2
3
1.5
2
85
87
(
continued)

2
994
Table 1. Continued
Entry Starting material
G. V. M. Sharma, Y. Jyothi, and P. S. Lakshmi
Product
Time (h)
1
Yield (%)
86
14
15
16
0.75
1.25
88
89
aliphatic 6 (entry 6) and terpenoidal 7 and 8 aldehydes (entries 7 and 8) was
also facile and gave the products 6a–8a respectively in high yields. Similarly,
terepthaldehyde 9 (entry 9) with 2 equiv of benzil and excess of NH OAc gave
4
bis imidazolyl benzene 9a in 84% yield.
In view of the importance attained by the glycoconjugates as bioactive
[16]
compounds and our interest on the synthesis of new saccharides,
the
study was extended to sugar aldehydes. Accordingly, aldehyde 10 (entry 10)
underwent a smooth three-component coupling catalyzed by ZrCl4 and
afforded C-5 glycosyl imidazole 10a in 88% yield. Further study on 11, 12,
and anomeric aldehyde 13 (entries 11, 12, and 13) resulted in the C-linked
imidazole glycoconjugates 11a and 12a and anomeric glycosyl imidazole
13a respectively in very good yields.
The present study was then extended to a four-component coupling
reaction for the preparation of tetrasubstituted imidazoles. Accordingly,
benzil, on reaction with an equimolar quantity of benzaldehyde 1 and
excess of NH OAc in the presence of benzyl amine 14 in acetonitrile at
4
room temperature furnished 1,2,4,5-tetrasubstituted imidazole 14a (Table 1,
entry 14) in 86% yield. In a further study, when benzaldehyde was treated
at room temperature with aliphatic amine 15 (entry 15) and heterocyclic
amine 16 (entry 16), excess of NH OAc in the presence of ZrCl , it
4
4
underwent a facile four-component coupling to give 1-alkyl and 1-heteroaryl
substituted imidazoles 15a and 16a in good yields.
CONCLUSIONS
In conclusion, the study described an efficient, rapid, and convenient synthesis
of tri- and tetrasubstituted imidazoles in a one-pot, three- and four-component

Tri- and Tetrasubstituted Imidazoles
2995
coupling reaction strategy using inexpensive, nontoxic, and easily available
ZrCl4 (20 mol%) as catalyst in acetonitrile. The present method offers
several advantages including shorter reaction times at room temperature,
higher yields, and easy experimental workup procedure, besides the tolerabil-
ity of the conditions to a variety of substrates such as aromatic, aliphatic, and
terpenoidal aldehydes. The acid-sensitive glycosyl aldehydes underwent facile
one-pot condensation to afford the imidazoles glycoconjugates. Thus, this
simple method would find wide applicability for the highly substituted
imidazole systems.
EXPERIMENTAL
Method A: Synthesis of Trisubstituted Imidazoles
A mixture of aldehyde (1 mmol), benzil (1 mmol), NH OAc (5 mmol), and
4
ZrCl (0.2 mmol) in CH CN (10 mL) was stirred at room temperature. After
4
3
completion of the reaction (TLC analysis), it was diluted with water
(
(
10 mL) and extracted with EtOAc (25 mL). The organic layer was dried
Na SO ) and evaporated to give the products in 84–96% yields as solids.
2
4
Method B: Synthesis of Tetrasubstituted Imidazoles
A mixture of aldehyde (1 mmol), benzil (1 mmol), NH OAc (5 mmol), amine
4
(1 mmol), and ZrCl (0.2 mmol) in CH CN (10 mL) was stirred at room temp-
4 3
erature. After completion of the reaction (TLC analysis), it was diluted with
water (10 mL) and extracted with EtOAc (25 mL). The organic layer was
dried (Na SO ) and evaporated to give the products in 86–89% yields as
2
4
solids.
Data
2
,4,5-Triphenyl-1H-imidazole (1a)
[
14]
Mp 2728C (lit.
2758C); IR (KBr): 638, 874, 1216, 1638, 2470, 2993,
2
1
1
3434 cm ; H NMR (CDCl /DMSO, 200 MHz): d 7.42–8.12 (m, 15H,
Ar), 12.61 (br.s, 1H); EIMS (m/z, %): 296 (M ).
3
þ
2
-(4-Chlorophenyl)-4,5-diphenyl-1H-Imidazole (2a)
Mp 1888C; IR (KBr) 639, 719, 874, 1216, 1592, 1660, 2470, 2993,
2
1 1
3
434 cm ; H NMR (CDCl /DMSO, 200 MH ): d 7.27–7.37 (m, 10H,
3 Z
Ar), 7.45–7.49 (d, 2H, J ¼ 9.00 Hz, Ar), 7.57–7.59 (d, 2H, J ¼ 8.00 Hz,

2
996
G. V. M. Sharma, Y. Jyothi, and P. S. Lakshmi
1
Ar), 12.5 (br.s, 1H, NH); C NMR (CDCl , 75 MHz): d 122.1, 125.4, 125.6,
3
3
þ
1
7
26.3, 127.2, 128.5, 129.1, 133.1 136.5; EIMS (m/z, %): 322 (M ); calcd. C,
6.24; H, 4.57; found C, 76.34; H, 4.69.
2-(4-Fluorophenyl)-4,5-diphenyl-1H-imidazole (3a)
Mp 1908C; IR (KBr) 639, 719, 874, 1210, 1320, 1450, 1592, 1660, 2470,
2
1 1
2
993, 3434 cm ; H NMR (CDCl /DMSO, 200 MH ): d 7.28–7.37 (t, 6H,
3 Z
J ¼ 10.94 Hz, Ar), 7.40 (br.s, 1H, -NH), 7.48–7.49 (t, 6H, J ¼ 10.94 Hz,
1
3
Ar), 7.57–7.59 (t, 2H, J ¼ 9.38 Hz, Ar); C NMR (CDCl , 75 MHz):
3
d 116.0, 126.3, 127.5, 128.8, 129.1, 129.3, 129.5, 147.6, 162.9; EIMS (m/z, %):
þ
3
16 (M þ 2); calcd. C, 80.24; H, 4.81; found C, 80.35; H, 4.83.
-(4-Nitrophenyl)-4,5-diphenyl-1H-imidazole (4a)
2
Mp 1968C; IR (KBr): 639, 719, 845, 1210, 1443, 1522, 1540, 1602, 2993,
2
1 1
3
434 cm ; H NMR (CDCl /DMSO, 200 MH ): d 7.25–7.57 (m, 10H,
3 Z
Ar), 7.78 (d, 2H, J ¼ 9.0 Hz, Ar), 8.50 (d, 2H, J ¼ 9.0 Hz, Ar), 12.59 (br.s,
1
H, -NH); C NMR (CDCl , 75 MHz): d 121.6, 127.5, 128.4, 128.8, 129.3,
3
1
3
þ
133.1, 147.6, 148.4; EIMS (m/z, %): 343 (M þ 1).
2-(2-Furyl)-4,5-diphenyl-1H-imidazole (5a)
Mp 185–1878C; IR (KBr): 639, 719, 874, 1169, 1210, 1660, 2470, 2993,
2
1
1
3
316 cm ; H NMR (CDCl /DMSO, 200 MH ): d 7.21 (m, 1H, NH),
3 Z
1
3
7.46–7.58 (m, 4H, Ar), 7.60–7.70 (m, 3H, Ar), 7.96–8.02 (m, 6H, Ar);
NMR (CDCl , 75 MHz): d 33.0, 39.1, 70.8, 77.4, 127.5, 128.8, 129.3,
C
3
þ
1
33.1, 146.7; EIMS (m/z, %): 287 (M þ 1); calcd. C, 79.70; H, 4.93;
found C, 79.79; H, 4.99.
-Isopropyl-4,5-diphenyl-1H-imidazole (6a)
Mp 187–1908C; IR (KBr): 639, 718, 873, 1210, 1663, 2470, 2925,
2
2
1
1
3
317 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.20–1.22 (2 s, 6H,
3 Z
2
CH ), 3.35–3.40 (m, 1H, -CH), 7.40–7.43 (m, 6H, Ar), 7.67–7.69
3
1
m, 4H, Ar); C NMR (CDCl , 75 MHz): d 23.1, 33.3, 127.5, 128.8, 129.3,
3
(
3
þ
133.1, 147.6; EIMS (m/z, %): 262 (M ); calcd. C, 82.57; H, 7.29; found C,
82.66; H, 7.37.
2-[(1E)-2,6-Dimethyl-1,5-heptadienyl]-4,5-diphenyl-1H-imidazole (7a)
Mp 189–1948C; IR (KBr): 642, 718, 874, 1210, 1675, 2476, 2924,
2
1 1
3
385 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.59 (s, 3H, CH ), 1.70
3 Z 3
(
s, 3H, CH ), 1.72 (s, 3H, CH ), 2.82 (m, 2H, -CH ), 5.07 (m, 1H, olefinic),
3 3 2
6.52 (m, 1H, olefinic), 7.40–7.43 (m, 6H, Ar), 7.67–7.69 (m, 4H, Ar), 8.43

Tri- and Tetrasubstituted Imidazoles
2997
1
br.s, 1H, NH); C NMR (CDCl , 75 MHz): d 19.6, 23.1, 26.4, 39.4, 120.2,
3
(
3
1
23.5, 127.5, 128.8, 129.3, 129.5, 136.1, 138.8; EIMS (m/z, %): 330
þ
(M þ 2); calcd. C, 83.75; H, 8.43; found C, 83.86; H, 8.55.
4
,5-Diphenyl-2-(2,6,6-trimethyl-1-cyclohexenyl)-1H-imidazole (8a)
Mp 192–1958C; IR (KBr): 647, 716, 874, 1276, 1413, 1664, 2931,
2
1
1
3
350 cm ; H NMR (CDCl /DMSO, 200 MH ): d 0.81 (s, 6H, 2CH ),
3 Z 3
1
.20 (s, 3H, CH ), 1.34–1.41 (s, 2H, CH ), 1.66 (m, 1H, olefinic), 1.92
2
3
(
(
m, 2H, CH ), 2.26–2.33 (m, 2H, 2CH ), 7.40–7.43 (m, 6H, Ar), 7.67–7.69
2 2
1
m, 4H, Ar); C NMR (CDCl , 75 MHz): d 18.7, 20.8, 25.0, 32.5, 43.0,
3
3
þ
53.4, 127.5, 128.8, 129.2, 129.3, 129.4, 146.7; EIMS (m/z, %): 342 (M );
calcd. C, 83.68; H, 8.19; found C, 83.78; H, 8.26.
2-[4-(4,5-Diphenyl-1H-2-imidazolyl)phenyl]-4,5-diphenyl-1H-
imidazole (9a)
Mp 232–2358C; IR (KBr): 639, 719, 874, 1169, 1210, 1660, 2470, 2993,
2
1 1
3
7
2
1
8
316 cm ; H NMR (CDCl /DMSO, 200 MH ): 7.48–7.58 (m, 10H, Ar),
3 Z
1
.62–7.68 (m, 4H, Ar), 7.94 (m, 10H, Ar); C NMR (CDCl , 75 MHz): d
3
3
6.6, 53.7, 72.1, 78.7, 81.6, 108.0, 111.3, 127.5, 128.8, 129.0, 129.3, 133.1,
þ
51; EIMS (m/z, %): 515 (M þ 1); calcd. C, 84.02; H, 5.09; found C,
5.2; H, 5.29.
2
5
-[(3aS,6aS)-6-Methoxy-2,2-dimethylperhydrofuro[2,3-d][1,3]dioxo-
-yl]-4,5-diphenyl-1H-imidazole (10a)
Mp 215–2178C; IR (KBr): 639, 719, 874, 1019, 1212, 1663, 2470, 2932,
2
1
1
3
411 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.20–1.50 (2s, 6H,
3 Z
CH ), 3.82 (s, 3H, OCH ), 4.01 (d, 1H, J ¼ 7.14 Hz, H-4), 4.48–4.50
3
3
(
m, 1H, NH), 4.72 (d, 1H, J ¼ 7.14 Hz, H-2), 5.41 (d, 1H, J ¼ 7.08 Hz,
H-3), 6.02 (d, 1H, J ¼ 7.14 Hz, H-1), 7.12–7.32 (d, 2H, J ¼ 7.14 Hz, Ar),
7
.42–7.52 (m, 6H, Ar), 7.54–7.72 (d, 2H, J ¼ 14.28 Hz, Ar), 7.89–8.10
1
3
(
d, 2H, J ¼ 14.28 Hz, Ar); C NMR (CDCl , 75 MHz): d 24.0, 26.6, 66.4,
3
7
1
0.3, 70.4, 78.6, 78.7, 84.7, 99.1, 111.6, 127.5, 128.8, 129.0, 129.3, 133.1,
51; EIMS (m/z, %): 392 (M ); calcd. C, 69.63; H, 6.29; found C, 69.75;
þ
H, 6.36.
2
4
-[(3aS,6aS)-6-Methoxy-2,2-dimethylperhydrofuro[3,4-d][1,3]dioxo-
-yl]-4,5-diphenyl-1H-imidazole (11a)
Mp 212–2158C; IR (KBr): 643, 719, 872, 1094, 1211, 1449, 1674, 2993,
2
1 1
3
339 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.20 (s, 3H, CH ), 1.42
3 Z 3
(
s, 3H, CH ), 3.58 (s, 3H, OCH ), 4.32 (d, 1H, J ¼ 9.47 Hz, H-2), 4.48
3
3
(
d, 1H, J ¼ 7.89 Hz, H-4), 4.60 (d, 1H, J ¼ 9.47 Hz, H-3), 5.42 (d, 1H,

2
998
G. V. M. Sharma, Y. Jyothi, and P. S. Lakshmi
J ¼ 7.89 Hz, H-1), 7.48–7.58 (m, 4H, Ar), 7.60–7.78 (m, 2H, Ar), 7.98–8.05
1
3
(
d, 4H, J ¼ 9.47 Hz, Ar); C NMR (CDCl , 75 MHz): d 26.6, 57.7, 71.5,
3
8
1.5, 81.6, 127.5, 128.8, 129.0, 129.3, 133.1, 151; EIMS (m/z, %): 392
þ þ
M ). HRMS (EIMS): m/z calcd. for C H N O (M ) 393.1814; found
23 24 2 4
(
393.1809.
4,5-Diphenyl 2-[(2,2,7,7-Tetramethylperhydrofuro[1,3]dioxolo[4,5-b:4,5-d]
pyran-5-yl)-1H-imidazole (12a)
Mp 208–2128C; IR (KBr): 639, 718, 873, 1021, 1096, 1210, 1661, 2470,
2
1
1
2
963, 3316 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.34 (s, 3H,
3 Z
CH ), 1.40 (s, 3H, CH ), 1.52 (s, 3H, CH ), 4.43 (dd, 1H, J ¼ 1.7, 5.5 Hz,
3
3
3
H-5), 4.60 (dd, 1H, J ¼ 4.5, 7.8 Hz, H-4), 4.75 (dd, 1H, J ¼ 2.50, 5.0 Hz,
H-2), 5.20 (d, 1H, J ¼ 2.5 Hz, H-3), 5.58 (d, 1H, J ¼ 5.56 Hz, H-1), 7.20–
7
8
6
.28 (m, 2H, Ar), 7.46–7.60 (m, 4H, Ar), 7.62–7.70 (m, 2H, Ar), 8.00–
1
3
.12 (d, 4H, J ¼ 7.80 Hz, Ar); C NMR (CDCl , 75 MHz): d 26.6, 26.9,
3
6.5, 75.6, 78.4, 82.6, 104.7, 108.7, 127.5, 128.8, 129.0, 129.3, 133.1, 151;
þ
EIMS (m/z, %): 449 (M þ 1); HRMS (EIMS): m/z calcd. for C H N O
2
6 28 2 5
þ
(
M ) 449.2076; found 449.2068.
2
-[(3aR,3bS,7aS,8aR)-[(2,2,7,7-Tetramethylperhydrofuro[1,3]dioxolo
1
4,5 :4,5]-furo[3,2-d]dioxin-8-yl]-4,5-diphenyl-1H-imidazole (13a)
[
Mp 217–2198C; IR (KBr): 642, 719, 872, 1074, 1210, 1674, 2470, 2993,
2
1 1
3
2
4
316 cm ; H NMR (CDCl /DMSO, 200 MH ): d 1.20–1.50 (br.s, 6H,
3 Z
CH ), 1.60 (s, 3H, CH ), 1.75 (s, 3H, CH ), 4.18 (d, 2H, J ¼ 4.2 Hz, H-3),
3
3
3
.24 (br.s, 1H, H-5), 4.35 (d, 1H, J ¼ 1.42 Hz, H-2), 4.50 (d, 1H,
J ¼ 2.1 Hz, H-4), 7.48–7.56 (m, 4H, Ar), 7.60–7.72 (m, 2H, Ar), 7.90–
1
.10 (m, 4H, Ar); C NMR (CDCl , 75 MHz): d 127.5, 128.0, 128.8,
3
8
1
3
þ
29.3, 129.5, 130.7, 133.1, 147.6; EIMS (m/z, %): 449 (M ); HRMS (ESI):
þ
m/z calcd. for C H N O (M ): 449.2076; found 449.2078.
6 28 2 5
2
1-Benzyl-2,4,5-triphenyl-1H-imidazole (14a)
Mp 2788C; IR (KBr): 639, 719, 874, 1169, 1210, 1660, 2470, 2993,
2
1 1
3
6
7
316 cm ; H NMR (CDCl /DMSO, 200 MH ): d 5.21 (m, 2H, -CH ),
3 Z 2
.76–7.08 (m, 4H, Ar), 7.21 (br.s, 1H, NH), 7.29–7.47 (m, 6H, Ar), 7.62–
3
.67 (m, 6H, Ar), 7.72–7.76 (m, 2H, Ar), 8.75–8.77 (m, 1H, olefinic);
1
C
NMR (CDCl , 75 MHz): d 40.3, 125.8, 126, 127.5, 127.6, 128.7, 127.8,
3
þ
1
29.1, 129.3, 130.7, 136.3; EIMS (m/z, %): 387 (M þ 1).
-Hexyl-2,4,5-triphenyl-1H-imidazole (15a)
1
21 1
Mp 2958C; IR (KBr): 645, 718, 876, 1214, 1640, 2480, 2990, 3379 cm ; H
NMR (CDCl /DMSO, 200 MH ): d 7.60–7.74 (m, 6H, Ar), 7.48–7.53
3
Z

Tri- and Tetrasubstituted Imidazoles
2999
(
m, 6H, Ar), 7.30–7.42 (m, 3H, Ar), 3.52–3.64 (t, 2H, J ¼ 7.14 H , -NCH ),
Z
2
1
0
2
3
.62–1.74 (t, 2H, J ¼ 6.42HZ, CH ), 1.28–1.40 (s, 5H, -CH , -CH ),
2
3
2
1
3
.85–0.95 (t, 3H, J ¼ 8.57HZ, -CH ); C NMR (CDCl , 75 MHz): d 22.8,
3 3
6.9, 27.5, 31.6, 31.7, 127.5, 128.8, 129.3, 129.8, 153.5; EIMS (m/z, %):
þ
81 (M þ 1); calcd. C, 85.22; H, 7.42; found C, 85.34; H, 7.54.
4
-(2,4,5-Triphenyl-1H-imidazolyl)pyridine (16a)
Mp 2898C; IR (KBr): 639, 719, 874, 1169, 1210, 1660, 2470, 2993,
2
1 1
3
6
7
1
3
316 cm ; H NMR (CDCl /DMSO, 200 MH ): d 5.28 (m, 2H, 2CH ),
3 Z 2
.96–7.08 (m, 4H, Ar), 7.21 (br.s, 1H, NH), 7.29–7.37 (m, 6H, Ar), 7.62–
1
3
.67 (m, 6H, Ar), 7.72–7.76 (m, 2H, Ar); C NMR (CDCl , 75 MHz): d
3
16.1, 122, 127.5, 128.8, 129.3, 130.7, 133.1, 143.9, 150.3; EIMS (m/z, %):
þ
82 (M þ 1); calcd. C, 83.62; H, 5.13; found C, 83.72, H; 5.19.
ACKNOWLEDGMENTS
Y. J. and P. S. L. acknowledge the Council of Scientific and Industrial
Research (CSIR), New Delhi, India, for financial support.
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