Microwave Irradiation Assisted Facile Synthesis of New Imidazole, Pyrazine, and Benzodiazocine Derivatives 367
4-chloro-3-oxo-butyric acid ethyl ester (Aldrich)
were used as received.
101.25 (2qc, NC C C CONH2), 117.50 (CN),
129.00 (2CH, Ar-CH), 130.33 (2CH, Ar-CH), 135.34
(qc, Ar-C), 136.13 (qc, Ar-C), 136.29 (C N), 167.40
(CO); m/z(%) 248 (M2+, 30), 246 [M+] (66), 210
(12), 144 (36), 133 (70), 117 (100), 107 (48), 90 (80),
64 (56), 38 (32), 28 (58), 18 (24). Found: C, 53.29;
H, 2.72; Cl, 14.12; N, 22.52. C11H7ClN4O (246.66)
requires C, 53.57; H, 2.86; Cl, 14.37; N, 22.71%.
General Procedure
A mixture of (0.108 g, 1 mmol) of compound 1 and
(1 mmol) of compounds 4a–f, 6–9 in the presence of
a catalytic amount of triethylamine as a catalyst was
introduced into a microwave oven and heated for
1–3 min in 850 W setting. After cooling to room tem-
perature, the crude product was recrystallized from
the proper solvent to give products 5a–f, 10–13 in
75–90% yield.
4-Cyano-2-(1-naphthyl)-1H-imidazole-5-carboxa-
mide 5e. Pale brown crystals, (0.22 g, 85%), mp
227–228◦C (from EtOH); v˜max (KBr) = 3400 (NH),
3300–3200 (NH2), 3150 (CH), 2220 (CN), 1668 (CO),
1650 (C N) cm−1; δH (CDCl3): 7.05–7.22 (4H, m,
Ar-H), 7.28–7.36 (1H, m, Ar-H), 7.41–7.48 (1H, m,
Ar-H), 7.50–7.60 (1H, m, Ar-H), 10.84 (2H, br, s,
NH2), 11.46 (1H, br, s, NH); δC (CDCl3): 107.47, 87.94
(2qc, NC C C NH2), 117.11 (CN), 125.80 (2CH,
Ar-CH), 126.00 (CH, Ar-CH), 126.40 (CH, Ar-CH),
128.00 (2CH, Ar-CH), 130.30 (CH, Ar-CH), 134.10
(qc, Ar-C), 136.20 (C N), 136.90 (qc, Ar-C), 133.70
(qc, Ar-C), 167.60 (CO); m/z(%) 262 [M+] (80), 235
(30), 191 (14), 154 (18), 126 (10), 107 (100), 80 (85),
53 (90), 42 (20), 37 (50), 27 (67), 17 (70). Found: C,
68.41; H, 3.67; N, 21.15. C15H10N4O (262.27) requires
C, 68.69; H, 3.84; N, 21.36%.
4-Cyano-2-methyl-1H-imidazole-5-carboxamide
5a. Buff crystals, (0.13 g, 88%), mp 187–188◦C
(from CHCl3); v˜max (KBr) = 3350 (NH), 3310–3270
(NH2) 3100 (Ar-CH), 2900 (Aliph-CH), 2215 (CN),
1660 (CO), 1647 (C N) cm−1; δH (CDCl3): 2.20 (3H,
s, CH3), 10.00 (2H, br, s, NH2), 11.10 (1H, br, s,
NH); δC (CDCl3): 19.50 (CH3), 102.30, 100.90 (2qc,
NC C C CONH2), 116.00 (CN), 136.20 (C N),
167.50 (CO); m/z(%) 150 [M+] (100), 124 (18), 100
(70), 90 (84), 80 (42), 64 (58), 52 (40), 38 (24), 28
(50), 18 (22). Found: C, 47.79; H, 3.89; N, 37.07.
C6H6N4O (150.14) requires C, 48.00; H, 4.03; N,
37.32%.
4-Cyano-2-(2-naphthyl)-1H-imidazole-5-carboxa-
mide 5f. Brown crystals, (0.21 g, 80%), mp
209–211◦C (from EtOH); v˜max (KBr) 3350 (NH),
3330–3300 (NH2), 3120 (CH), 2216 (CN), 1667
(CO), 1650 (C N) cm−1; δH (CDCl3): 7.30 (1H, d,
J = 1.2 Hz, Ar-H), 7.40–7.44 (1H, dd, J = 7.5, 1.2 Hz,
Ar-H), 7.50–7.54 (1H, dd, J = 7.8, 1.2 Hz, Ar-H),
7.60–7.66 (4H, m, Ar-H); δC (CDCl3): 107.40, 87.51
(2qc, NC C C CONH2), 117.20 (CN), 125.80 (2CH,
Ar-CH), 126.00 (CH, Ar-CH), 126.40 (CH, Ar-CH),
128.00 (2CH, Ar-CH), 130.30 (CH, Ar-CH), 133.70
(qc, Ar-C), 134.10 (qc, Ar-C), 136.20 (C N), 136.90
(qc, Ar-C), 167.50 (CO); m/z(%) 262 [M+] (20), 235
(10), 171 (100), 154 (60), 148 (32), 126 (74), 91
(12), 85 (8), 72 (94), 50 (16), 43 (84), 28 (30), 18
(40). Found: C, 68.34; H, 3.60; N, 21.10. C15H10N4O
requires C, 68.69; H, 3.84; N, 21.36%.
4-Cyano-2-phenyl-1H-imidazole-5-carboxamide
5b. Colorless crystals, (0.18 g 86%), mp 305–308◦C
(from CH3OH) (lit. [24] 306◦C).
4-Cyano-2-(4-methylphenyl)-1H-imidazole-5-car-
boxamide 5c. Brown crystals, (0.19 g, 82%), mp
239–240◦C (from EtOH); v˜max (KBr) = 3300 (NH),
3285–3210 (NH2), 3120 (CH), 2214 (CN), 1663 (CO),
1650 (C N) cm−1; δH (CDCl3): 2.50 (3H, s, CH3), 7.77–
7.80 (2H, m, Ar-H), 7.85–7.90 (2H, m, Ar-H), 10.80
(2H, br, s, NH2), 11.50 (1H, br, s, NH); δC (CDCl3):
20.90 (CH3), 99.76, 91.47 (2qc, NC C C CONH2),
117.20 (CN), 128.90 (2CH, Ar-CH), 129.30 (2CH,
Ar-CH), 134.70 (qc, Ar-C), 136.00 (C N), 140.10
(qc, Ar-C), 167.62 (CO); m/z (%) 226 [M+] (20), 182
(10), 148 (30), 135 (20), 118 (100), 107 (40), 90
(84), 80 (42), 64 (58), 52 (40), 38 (24), 28 (50), 18
(22). Found: C, 63.43; H, 4.30; N, 24.60. C12H10N4O
(226.24) requires C, 63.71; H, 4.46; N, 24.76%.
1,6-Dioxo-1,2,5,6-tetrahydro-2,5-benzodiazocine-
3,4-dicarbonitrile 10. Yellow crystals, (0.21 g, 90%),
mp 263–264◦C (from CH3CN); v˜max (KBr) 3350 (NH),
2230, 2220 (CN), 1705 (CO), 1620 (C C); δH (CDCl3):
7.60–7.73 (1H, m, Ar-H), 7.78 (1H, s, Ar-H), 7.91
(1H, d, J = 1.2 Hz, Ar-H), 8.00 (1H, d, J = 7.6 Hz,
Ar-H), 8.95 (2H, br, s, 2NH); δC (CDCl3): 102.60 (2qc,
NC C C CN), 117.23 (2CN), 127.40 (2CH, Ar-CH),
132.00 (2CH, Ar-CH), 132.30 (2qc, Ar-C), 165.00
(2CO); m/z(%) 238 [M+] (20), 220 [M+ − H2O] (30),
2-(4-Chlorophenyl)-4-cyano-1H-imidazole-5-car-
boxamide 5d. Yellow crystals, (0.20 g, 81%), mp
243–246◦C (from CH3OH); v˜max (KBr) = 3350 (NH),
3270–3199 (NH2), 3130 (CH), 2220 (CN), 1670 (CO),
1650 (C N) cm−1; δH (CDCl3): 7.60–7.67 (2H, m,
Ar-H), 7.72–7.83 (2H, m, Ar-H), 10.90 (2H, br, s,
NH2), 11.62 (1H, br, s, NH); δC (CDCl3): 112.24,
Heteroatom Chemistry DOI 10.1002/hc