Phosphomolybdic acid catalyzed facile one-pot synthesis of 2,4,5-triaryl-1H-imidazoles from benzil and aromatic aldehydes

Article abstract of DOI:10.1002/jhet.5570450533

(Chemical Equation Presented) A facile one-pot synthesis of 2,4,5-triaryl-1H-imidazoles with better yields and shorter reaction time from the condensation of benzil, ammonium acetate and aromatic aldehydes using the catalyst phosphomolybdic acid is described.

Full text of DOI:10.1002/jhet.5570450533

Sep-Oct 2008
1461
Phosphomolybdic acid Catalyzed Facile One-pot Synthesis of
2,4,5-Triaryl-1H-imidazoles From Benzil and Aromatic Aldehydes
Siddheshwar D. Jadhav [1], Nagnnath D. Kokare[2] , Sunil D. Jadhav* [3]
[1] Department of Chemistry, Karmveer Bhaurao Patil College, Pandharpur - 413304 (MS) India.
[2] New Drug Discovery, Wocckhardt Research Centre, Aurangabad - 431210 (MS) India.
[3] Department of Chemistry, Annasaheb Aate College, Manchar - 410503 (MS) India.
E-mail: sdjchem@gmail.com
Received June 11, 2007
5 mol%
phosphomolybdic
acid
CHO
O
O
H
N
N
+
OHC
N
H
N
NH4OAc
A facile one-pot synthesis of 2,4,5-triaryl-1H-imidazoles with better yields and shorter reaction time
from the condensation of benzil, ammonium acetate and aromatic aldehydes using the catalyst
phosphomolybdic acid is described
J. Heterocyclic Chem., 45, 1461 (2008).
INTRODUCTION
desirable. Herein, we have presented a novel, mild and
efficient method for synthesis of 2,4,5-triarylimidazole
using phosphomolybdic acid (H3PO4.12MoO3.24H2O)
catalyst. The use of phosphomolybdic acid as a catalyst is
increasing due to its mild acidic character. It is widely used
for the bulk polymerization of styrenes and the catalytic
and selective deprotection of tert-butyldimethyl-silyl ether
[15]. In the present article, we have used phosphomolybdic
acid catalyst to develop a simple and facile synthetic
method for preparation of triarylimidaz-oles using benzil,
ammonium acetate and aromatic alde-hydes.
Substituted imidazoles are one of the most important
heterocyclic compounds found in a large number of natural
products and pharmacologically active compounds like the
amino acid histidine, the hypnotic agent etomidate, [1] the
antiulcerative agent cimetidine, [2] the proton pump
inhibitor omeprazole, [3] the fungicide ketoconazole, [4]
and the benzodiazepine antagonist flumazenil [5]. Also, the
substituted imidazoles are substantially used in ionic
liquids, [6] that have been given a new approach to ‘Green
Chemistry’. In addition, they are used in photography as
photosensitive compound [7]. There are several methods in
the literature for synthesis of these compounds, mainly
using nitriles and esters [8] as the starting substrates. Japp
and Radziszewski proposed the first synthesis of the
imidazole core in 1882, starting from 1,2-dicarbonyl
compounds aldehydes and ammonia, to obtain 2,4,5-
triphenyl-1H-imidazoles. [9] Subsequently, many other
syntheses of this important heterocycle have been published
[10]. For example, 2,4-diaryl-1H-imidazoles are often
obtained from amidines and ꢀ-bromo arylketones [11].
Moreover, Zhang and Chen described an efficient
procedure to obtain unsymmetrical, C5 unsubstituted 2,4-
diarylimid-azoles. In this approach acetophenones are
oxidized in situ to ꢀ-tosyloxyacetophenones, which then
are condense with arylamidines to obtain the desired
compounds [12]. However, some of theses previous
methods have suffered from one or more drawbacks like
high temperature requirement, highly acidic conditions, and
the use of metal cyanides for preparation of the nitrile
compounds that limit their uses [13]. Some of methods
require harsh conditions [14]. Therefore, the development
of a mild, efficient and versatile method is still strongly
RESULTS AND DISCUSSION
The reaction conditions were standardized for the
representative example of the preparation of 2,4,5-tri-
phenyl-1H-imidazole (3) from benzil, ammonium acetate
and benzaldehyde (Scheme – 1) in different solvents and
various mol% of phosphomolybdic acid catalyst (Table - 1).
Scheme 1
Synthesis of 2,4,5-triarylimidazoles using benzil, aromatic aldehydes,
ammonium acetate and 5 mol% phosphomolybdic acid catalyst.
5 mol%
CHO
O
O
phosphomolybdic
acid
N
+
NH4OAc
+
R1
N
H
R1
1
2
3
From the results obtained, the optimized reaction conditions were use of
acetonitrile-water (1:1) solvent system and 5 mol% of phosphomolybdic
acid catalyst at heating (80 °C).

1462
S. D. Jadhav, N. D. Kokare, and S. D. Jadhav
Vol 45
Table 1
The methodology was also extended for the synthesis of
bis-imidazoles like 4,5-diphenyl-2-(4-(4,5-diphenyl-1H-
imidazol-2-yl)phenyl)-1H-imidazole (Scheme 2) using
two equivalents of substituted benzil, ammonium acetate
and the benzene-1,4-dicarboxaldehyde. The results
obtained were summarized in table 3. The method was
found to be efficient and yields obtained were in the range
of 87% to 96%. All the synthesized compounds were
Optimization of reaction conditions for synthesis of 2,4,5-triaryl-1H-
imidazoles using 5 mol% phosphomolybdic acid catalyst.
Solvent
Reaction time (min)
Yield (%)
Acetonitrile
THF
DMF
THF-water (1:1)
Acetonitrile
- water (1:1)
50
55
50
45
40
86
81
78
92
98
1
characterized with mass, and H NMR and found to be
matching with the corresponding compounds.
Using the optimized reaction conditions, a range of
2-aryl-4,5-diphenyl-1H-imidazoles were synthesized and
the results are summarized in Table 2. From the results
obtained, the aromatic aldehydes with elctron-donationg
substituents (3a, and 3b) favor the reaction and reaction
times are shorter reaction than for the aldehydes with
electron withdrawing substituents (3f). For the p-nitro-
benzaldehyde (3f), the reaction was very slow and also it
was a low yielding reaction. The method was also found
to be effective for hetero-aromatic aldehydes for the
synthesis 2-heteroaryl-4,5-diphenylimidazoles with higher
yields (3i, 3j, and 3k). The present method was superior
to the available methods with regards to yields and
reaction time [16]. Especially for the preparation of 2-(4-
methylphenyl)-4,5-diphenyl-1H-imidazole (3b) which
was synthesized in 96% yield while the reported yield was
74 % and also 2-(2-chlorophenyl)-4,5-diphenyl-1H-imid-
azol (3e) was synthesized in 94% while the reported yield
was 85 % [17].
Table 3
Synthesis bis-2,4,5-triaryl-1H-imidazoles using benzil,
ammonium acetate, benzene-1,4-dicarboxaldehyde and 5 mol%
phosphomolybdic acid.
Entry
1
Benzil
Reaction
Time (min)
55
Yield (%)
93
O
O
(5a)
O
2
3
4
5
O
50
60
50
50
81
94
91
92
Br
Br
(5b)
O
O
Cl
Cl
(5c)
Scheme 2
O
O
Synthesis bis-(2,4,5-triaryl-1H-imidazoles) using benzil,
ammonium acetate, benzene-1,4-dicarboxaldehyde and 5 mol%
phosphomolybdic acid
OH
HO
(5d)
O
CHO
H
N
O
O
O
2 NH4OAc
N
2
+
H
OHC
N
N
H
(5e)
Table 2
Synthesis 2,4,5-triaryl-1H-imidazoles using benzil, ammonium acetate, aromatic aldehydes, and 5 mol% phosphomolybdic acid.
Entry No.
Ar-CHO
Compound No.
Reaction time
(min)
Yield
(%)
Melting points
Found
Lit.17,18,19
275-27617
230-23117
226-22817
267-26817
196-19717
238-23917
261-26217
256-25817
254-25518
235-23619
202-20317
1
2
Ph-
3a
3b
3c
3d
3e
3f
45
97
96
94
95
95
87
93
92
89
92
95
275 - 277
230 - 231
226 - 227
268 - 269
196 - 197
235 - 237
258 - 261
255 - 257
253 -255
234 - 236
199 - 202
4-Me-Ph-
4-OMe-Ph-
4-OH-Ph-
2-Cl-Ph-
40
45
50
50
70
60
55
65
50
50
3
4
5
6
4-NO2-Ph-
4-Cl-Ph-
4-(CH3)2N-Ph-
2-thionyl-
4-Pyridyl-
2-Furyl-
7
8
3g
3h
3i
9
10
11
3j
3k

Sep-Oct 2008
Phosphomolybdic acid Catalyzed Facile One-pot Synthesis of 2,4,5-Triaryl-1H-imidazoles
1463
2-(4-Methylphenyl)-4,5-diphenyl-1H-imidazole (3b). Off-
white solid, HPLC purity - 99%; 1H NMR (400 MHz, DMSO): ꢀ
= 2.25 (s, 3H), 6.72–6.75 (d, J=8.6 Hz, 2H), 7.25 –7.55 (m,
10H), 8.0 (d, J=8.6 Hz, 2H), 12.0 (brs, 1H); MS (EI, 70 eV): m/z
= 310 [M+H]+; C22H18N2 (310): calcd C, 85.13, H, 5.85, N, 9.02;
found C, 85.19, H, 5.88, N, 8.98.
The use of the cheap and easily available phospho-
molybdic acid as a catalyst is an advantageous aspect of
the present method. Since, the reaction protocol and
work-up used is simple and practical, the methodology
could be useful for multi-scale reactions. Water was
utilized in reaction as solvent and for work-up also.
Therefore, the presented method was also supporting to
the Green Chemistry.
In conclusion, using 5 mol% phosphomolybdic acid
catalyst, 2,4,5-triaryl-1H-imidazoles were efficiently
synthesized with moderate to excellent yields from benzil,
ammonium acetate and aromatic aldehydes. Also the
method was efficiently used for the synthesis of bis-
substituted imidazoles from substituted benzil substrates,
ammonium acetate and 1,4-phenyl dicarboxaldehyde. The
advantages of the reported method are the use of cheap
and easily available catalyst, shorter reaction time and
better yields.
2-(4-Methoxy-phenyl)-4,5-diphenyl-1H-imidazole
(3c).
1
Off-white solid, HPLC purity - 97 %; H NMR (400 MHz,
DMSO): ꢀ = 3.85 (s, 3H), 6.93–6.96 (d, J=8.4 Hz, 2H), 7.25 –
7.59 (m, 10H), 8.02–8.05 (d, J=8.4 Hz, 2H), 12.52 (brs, 1H); MS
(EI, 70 eV): m/z = 327 [M+H]+; C22H18N2O (326): calcd C,
80.96, H, 5.56, N, 8.58; found C, 81.13, H, 5.52, N, 8.60.
2-(4-Hydroxyphenyl)-4,5-diphenyl-1H-imidazole (3d). Off-
1
white solid, HPLC purity - 96 %; H NMR (400 MHz, DMSO):
ꢀ =5.2 (bs, 1H), 6.93-6.97(d, J=8 Hz, 2H), 7.52-7.87(m, 10H),
7.88-7.92 (d, J= 8.5Hz, 2H), 12.58 (brs, 1H); MS (EI, 70 eV):
m/z = 312 [M+H]+; C21H16N2O (312): calcd C, 80.75, H, 5.16,
N, 8.97; found C, 80.68, H, 5.05, N, 8.90.
2-(2-Chorophenyl)-4,5-diphenyl-1H-imidazole (3e). Off-
1
white solid, HPLC purity - 97 %; H NMR (400 MHz, DMSO):
ꢀ = 7.27-7.37(m, 10H), 7.45-7.49 (dd, J = 9 Hz, 1H), 7.57-7.59
(d, J = 8 Hz, 2H), 8.02-8.05 (dd, J =8.79 Hz, 1H), 12.5(brs, 1H);
MS (EI, 70 eV): m/z = 330 [M+H]+; C21H15ClN2: calcd C,
76.24, H, 4.57, N, 8.47; found C, 76.12, H, 4.49, N, 8.38.
2-(4-Nitro-phenyl)-4,5-diphenyl-1H-imidazole (3f). Off-
EXPERIMENTAL
1H NMR spectra were recorded on a 400 MHz Varian-Gemini
spectrometer and are reported as parts per million (ppm)
downfield from a tetramethylsilane internal standard. The
following abbreviations are used; singlet (s), doublet (d), triplet
(t), quartet (q), multiplate (m) and broad (br). Mass spectra were
taken with Micromass - QUATTRO-II of WATER mass
spectrometer. HPLC was performed using Zorbax SB-C18
reverse phase column (0.46 X 25 cm) on Shimadzu instrument
equipped with an automatic injector with UV-PDA detector.
Detection was carried out at 254 nm. The mobile phase consists
of 0.05 % TFA and acetonitrile (1:1, V/V). The products were
eluted at flow rate of 1 mL/min using isocratic method. Flash
column chromatography was performed with 300-400 mesh
silica gel and analytical thin layer chromatography was
performed on precoated silica gel plates (60F-254) with system
(v/v) indicated. Melting points were determined in capillary
tubes and are uncorrected.
1
white solid, HPLC purity - 98 %; H NMR (400 MHz, DMSO):
ꢀ = 7.3 –7.57 (m, 10H), 7.78 (d, 2H), 8.3 (d, 2H), 12.6 (brs, 1H);
MS (EI, 70 eV): m/z = 342 [M+H]+ C21H15N3O2: calcd C, 73.89,
H, 4.43, N, 12.31; found C, 73.83, H, 4.39, N, 12.36.
;
2-(4-Chorophenyl)-4,5-diphenyl-1H-imidazole (3g). Off-
white solid, HPLC purity - 98 %; 1H NMR (400 MHz, CDCl3): ꢀ
= 7.5 - 7.65 (m, 6H), 7.68 – 7.72 (m, 2H), 7.9 – 8.0 (m, 6H), 8.7
(bs, 1H); MS (EI, 70 eV): m/z = 330 [M+H]+; C21H15ClN2: calcd
C, 76.24, H, 4.57, N, 8.47; found C, 76.27, H, 4.59, N, 8.45.
2-(4-N,N-Dimethyl)-4,5-diphenyl-1H-imidazole (3h). Off-
white solid, HPLC purity - 99 %; 1H NMR (400 MHz, CDCl3): ꢀ
= 2.9 (s, 6H), 7.1 (d, J = 8.2 Hz, 2H), 7.4 - 7.55(m, 4H), 7.65 –
7.7 (m, 2H), 7.8 - 7.95 (m, 6H), 8.7 (bs, 1H); MS (EI, 70 eV):
m/z = 339 [M+H]+; C23H21N3: calcd C, 81.39, H, 6.24, N, 12.38;
found C, 81.42, H, 6.23, N, 12.34.
2-(4-Pyridyl)-4,5-diphenyl-1H-imidazole (3i). Off-white
1
solid, HPLC purity - 98 %; mp 256-258, H NMR (400 MHz,
DMSO): ꢀ = 7.27-7.37(m,10H), 7.6-7.65 (d, J= 8.6Hz, 2H), 8.7
– 8.75 (d, J=8.6 Hz, 2H), 12.45(brs, 1H); MS (EI, 70 eV): m/z =
297 [M+H]+; C20H15N3: calcd C, 80.78, H, 5.08, N, 14.13; found
C, 80.81, H, 5.05, N, 14.12.
General method for the synthesis of 2,4,5-triaryl-1H-
imidazoles. A mixture of phosphomolybdic acid (5 mol%),
ammonium acetate (30 mmol), and benzil (10 mmol) was
dissolved in acetonitrile-water (20 mL, 1:1, v/v). To the reaction
mixture, aromatic aldehyde (12 mmol) was added and was
heated at 80 °C untill the reaction is complete (TLC). The
reaction mixture was then cooled to room temperature and
poured on ice-water (50 mL) to obtain the solid precipitated. The
solid was collected by filtration, washed with water and dried to
give the corresponding 2,4,5-triaryl-1H-imidazoles.
2-(2-Thionyl)-4,5-diphenyl-1H-imidazole (3j). Off-white
1
solid, HPLC purity - 98 %; H NMR (400 MHz, DMSO): ꢀ =
6.8 (d, J=8.4 Hz, 1H), 7.1 (dd, J=8.4 and 8.1 Hz, 1H), 7.25-
7.35(m, 11H), 12.2 (brs, 1H); MS (EI, 70 eV): m/z = 302
[M+H]+; C19H14N2S: calcd C, 75.47, H, 4.67, N, 9.26; found C,
75.44, H, 4.70, N, 9.26.
1
All synthesized compounds were characterized with H NMR
2-(2-Furylphenyl)-4,5-diphenyl-1H-imidazole (3k). Off-
1
and mass. Also the melting points were recorded and compared
with those of corresponding literature melting points and found
to be in agreement with literature values. The representative
analytical data are given below:
2,4,5-Triphenyl-1H-imidazole (3a). Off-white solid, HPLC
purity - 98 %; 1H NMR (400 MHz, DMSO): ꢀ = 7.55 - 7.68 (m,
6H), 7.72 – 7.75 (m, 3H), 7.9 - 7.95 (m, 6H), 8.8 (bs, 1H); MS
(EI, 70 eV): m/z = 297 [M+H]+; Anal Calc. C21H16N2 (296):
calcd C, 85.11, H, 5.44, N, 9.45; found C, 85.18, H, 5.33, N,
9.47.
white solid, HPLC purity - 97 %; H NMR (400 MHz, DMSO):
ꢀ = 6.7(d, J =7.8 Hz, 1H), 7.1 (dd, J = 7.8 Hz, 1H), 7.25-7.35(m,
11H), 11.8 (bs, 1H); MS (EI, 70 eV): m/z = 287 [M+H]+;
C19H14N2O: calcd C, 79.72, H, 5.24, N, 9.79; found C, 79.31, H,
5.21, N, 9.74.
General method for the synthesis of bis-(2,4,5-substituted-
1H-imidazoles). A mixture of phosphomolybdic acid (5 mol%),
ammonium acetate (60 mmol), and benzil (22 mmol) was
dissolved in acetonitrile-water (30 mL, 1:1, v/v). To the reaction

1464
S. D. Jadhav, N. D. Kokare, and S. D. Jadhav
Vol 45
REFERENCES AND NOTES
mixture, 1.4-phenyl-dicarboxaldehyde (10 mmol) was added and
was heated at 80 °C until the reaction is complete (TLC). The
reaction mixture was cooled to room temperature and poured on
ice-water (70 mL). It was extracted with ethyl acetate twice and
collectively the organic layer washed with brine, dried over
sodium sulphate and purified with silica gel column
chromatography to give the corresponding products. The
representative analytical data for
[1] Wauquier, A.; Van Den Broeck, W. A. E.; Verheyen, J. L.;
Janssen, P. A. J. Eur. J. Pharmacol. 1978, 47, 367.
[2] Brimblecombe, R. W.; Duncan, W. A. M.; Durant, G. J.;
Emmett, J. C.; Ganellin, C. R.; Parons, M. E. J. Int. Med. Res. 1975, 3, 86.
[3] Tanigawara, Y.; Aoyama, N.; Kita, T.; Shirakawa, K.;
Komada, F.; Kasuga, M.; Okumura, K. Clin. Pharmacol. Ther. 1999, 66,
528.
4,5-Diphenyl-2-(4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl)-
1H-imidazole (5a). Off-white solid, HPLC purity - 99%, mp
232-233, H NMR (400 MHz, CDCl3): ꢀ = 7.3-7.45 (m, 10H),
7.65 - 7.7 (m, 4H), 7.9-8.0 (m, 10H), 12.25 (bs, 2H); MS (EI, 70
eV): m/z = 515 [M+H]+; C36H26N4: calcd C, 84.02, H, 5.09, N,
10.89; found C, 83.98, H, 5.11, N, 10.87.
[4] Heers, J.; Backx, L. J. J.; Mostmans, J. H.; Van Cutsem, J. J.
Med. Chem. 1979, 22, 1003.
1
[5] Hunkeler, W.; Mohler, H.; Pieri, L.; Polc, P.; Bonetti, E. P.;
Cumin, R.; Schaffner, R.; Haefely, W. Nature 1981, 290, 514.
[6] [a] Wasserscheid, P.; Keim, W. Angew Chem. Int. Ed. Eng.
2000, 39, 37872; [b] Bourissou, d.; Guerret, O.; Ggabbai, F. T.;
Bertrand, G. Chem Rev. 2000, 100.
4,5-Di-(4-bromophenyl)-2-(4-(4,5-di(4-bromophenyl)-1H-
imidazol-2-yl)phenyl)-1H-imidazole (5b). Off-white solid,
HPLC purity - 97%, mp 211-213, H NMR (400 MHz, CDCl3):
[7] Satoru, I. Imidazoles derivative for chemiluminescence
microanalysis. Japan Kokkai Tokyo Koho JP 01, 117, 867, May 10,
1989. Chem Abstr. 1989, 111 (23), 214482.
1
[8] [a] Grimmett, M. R. In Comprehensive Heterocyclic
Chemistry; Katritzky, A. R., Rees, C. W., Eds.; Pergamon: New York,
1984; Vol. 5, p - 457; [b] Grimmett, M. R. In Comprehensive
Heterocyclic Chemistry II; Katritzky, A. R., Rees, C. W., Scriven, E. F.
V., Eds.; Pergamon: New York, 1996; Vol. 3, p – 77; [c] Balalaie, S.;
Arabanian, A.; Hashtroudi, M. S. Monatsh. Chem. 2000., 131, 945.
[9] [a] Radziszewski, B. Chem. Ber. 1882, 15, 1493.; [b] Japp, F.
R.; Robinson, H. H. Chem. Ber. 1882, 15, 1268.
ꢀ = 7.32-7.40 (m, 8H), 7.52 - 7.55 (m, 4H), 8.0-8.2 (m, 8H),
12.20 (bs, 2H); MS (EI, 70 eV): m/z = 831 [M+H]+;
C36H22Br4N4: calcd C, 52.08, H, 2.67, N, 6.75; found C, 52.14,
H, 2.64, N, 6.71.
4,5-Di-(4-chlorophenyl)-2-(4-(4,5-di(4-bromophenyl)-1H-
imidazol-2-yl)phenyl)-1H-imidazole (5c). Off-white solid,
1
HPLC purity - 98%, mp 249-251, H NMR (400 MHz, CDCl3):
[10] Katritzky, A. R.; Rees, C.; Scriven E. F. V.; Eds.; Pergamon
Press: Elmsford, NY, 1996; Vol. 3, pp-77.
[11] Li, B.; Chiu, C. K. -F.; Hank, R. F.; Murry, J.; Roth, J.;
Tobiassen, H. Org. Proc. Res. Dev. 2002, 6, 682.
[12] Zhang, P.-F.; Chen, Z.-C. Synthesis 2001, 2075.
[13] [a] Davidson, D.; Weiss, M.; Jelling, M. J. Org. Chem. 1937,
2, 319; [b] Zhang, E. J.; Moran, E. J.; Woiwode, T. F.; Short, K. M.;
Mjalli, A. M., Teterahedron Lett. 1996, 37, 351.
ꢀ = 7.22-7.34 (m, 8H), 7.45 - 7.50 (m, 4H), 7.78 -7.95 (m, 8H),
12.20 (bs, 2H); MS (EI, 70 eV): m/z = 653 [M+H]+;
C36H22Cl4N4: calcd C, 66.28, H, 3.40, N, 8.59; found C, 66.29,
H, 3.38, N, 8.63.
4,5-Di-(4-phenoxyl)-2-(4-(4,5-di(4-phenoxyl)-1H-imidazol-
2-yl)phenyl)-1H-imidazole (5d). Off-white solid, HPLC purity
1
- 97%, mp 263-265, H NMR (400 MHz, CDCl3): ꢀ = 4.9(bs,
[14] [a] Usyatinsky, A. Y.; Khmelnitsky, Y. L. Tetrahedron Lett.
2000, 41, 5031; [b] Wasserman, H. H.; Long, Y. O.; Zhang, R.; Parr, J.
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R.; Corbier, A.; Didierlaurent, S.; Fortin, M.; Frechet, D.; Hamon, G.;
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2000, 131, 945.
2H), 6.8-6,85(m, 8H), 7.35 - 7.4(m, 4H), 7.62-7.8 (m, 8H),
11.6(bs, 2H); MS (EI, 70 eV): m/z = 578 [M+H]+; C36H26N4O4:
calcd C, 74.73, H, 4.53, N, 9.68; found C, 73.96, H, 4.58, N,
9.66.
5-Phenyl-2-(4-(5-phenyl-1H-imidazol-2-yl)phenyl)-1H-im-
idazole (5e). Off-white solid, HPLC purity - 98%, mp 187-289,
1H NMR (400 MHz, CDCl3): ꢀ = 6.8(s, 2H), 7.2 - 7.32(m, 6H),
7.45 - 7.48(m, 4H), 7.62-7.65 (m, 4H), 12.9(bs, 2H); MS (EI, 70
eV): m/z = 363 [M+H]+; C24H18N4: calcd C, 79.54, H, 5.01, N,
15.46; found C, 79.59, H, 4.96, N, 15.41.
[17] Jian-Feng Z.; Yuan-Zhi S.; Yan-Ling Y.; Shu-Jiang T.;
Synthetic Comm. 2005, 35, 1369.
Acknowledgement. The authors are thankful to the Principal,
and Head of Department of Chemistry, Karmveer Bhaurao Patil
College, Pandharpur - 413304 (MS) India, for the providing the
laboratory facility for research work.
[18] Kidwai, M.; Mothsra, P.; Bansal, V.; Goyal, R.; Monat.
Chem. 2006, 137, 1189.
[19] Siddiqui, S. A., Narkhrde, U. C.; Palimkar, S. S.; Daniel, T.;
Lahoti, R. J.; Srinivas, K. V. Tetrahedron 2005, 61, 3539.