Molecules 2011, 16
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2H, Ar-H), 10.73 (br, 1H, NH, D2O exchangeable); 13C-NMR (DMSO): δ, ppm 166.29, 162.08, 152.30
(2C), 134.31, 128.69 (2C), 127.69, 125.89 (2C), 107.48, 87.97. MS: m/z (%) 257 (M+, 100), 226 (10),
200 (5), 134 (35), 128 (10), 90 (10).
4-(4-Methylthiazol-2-yl)-1H-pyrazole-3,5-diamine (5b). Yield 76%; m.p. 330–332 °C; Anal. calcd. for
C7H9N5S (195.24): C, 43.06; H, 4.65; N, 35.87; S, 16.42. Found: C, 42.89; H, 4.73; N; 35.60; S, 15.98;
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IR (KBr): υmax 3371, 3275 (NH2), 3255, 3180 (NH2), 3118 (NH); H-NMR (DMSO): δ, ppm 2.23 (s,
3H, CH3), 5.62 (br, 4H, 2NH2, D2O exchangeable), 6.86 (s, 1H, CH), 10.67 (br, 1H, NH, D2O
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exchangeable); C-NMR (DMSO): δ, ppm 164.33, 161.56, 150.03 (2C), 106.88, 87.68, 16.84. MS:
m/z (%) 195 (M+, 100), 164 (20), 138 (10), 123 (15), 112 (5), 72 (15).
3.4. Synthesis of 2,7-diamino-5-phenyl-3-(4-phenylthiazol-2-yl)pyrazolo[1,5-a]pyrimidine-6-
carbonitrile (11)
A mixture of 5a (2.57 g, 0.01 mol) and benzylidenemalononitrile (8, 1.54 g, 0.01 mol) in DMF
(10 mL) was stirred at reflux for 10 h (completion assessed by TLC analysis using ethyl acetate-
petroleum ether 1:1 as eluent). The reaction mixture was cooled and poured into ice-water giving a
solid which was collected by filtration and crystallized from DMF to give a the product as yellow
crystals in a yield of 75%; m.p. 298–300 °C; Anal. calcd. for C22H15N7S (409.47): C, 64.53; H, 3.69;
N, 23.94; S, 7.83. Found: C, 64.61; H, 3.69; N; 23.79; S, 7.59; IR (KBr): υmax 3430, 3318 (NH2), 3429,
3315 (NH2), 2211 (CN); 1H-NMR (DMSO): δ, ppm 6.85 (br, 2H, NH2, D2O exchangeable), 7.35–8.03
(m, 11H, Ar-H, thiazole-H), 8.57 (br, 2H, NH2, D2O exchangeable); 13C-NMR (DMSO): δ, ppm
195.47, 159.46, 157.98, 152.59, 148.91, 145.21, 137.10, 133.97, 130.37 (2C), 128.77 (2C), 128.70
(2C), 128.38 (2C), 127.89, 125.93, 116.48, 111.39, 92.24, 73.15. MS: m/z (%) 409 (M+, 100), 333 (5),
204 (15), 195 (5), 134 (30), 90(5).
3.5. Synthesis of 3-(4-phenylthiazol-2-yl)pyrazolo[1,5-a]pyrimidine-2,7-diamine (17)
A mixture of 5a (2.57 g, 0.01 mol) and 3-(piperidin-1-yl)acrylonitrile (15, 1.36 g, 0.01 mol) in
DMF (10 mL) was stirred at reflux for 10 h (completion assessed by TLC analysis using ethyl acetate-
petroleum ether 1:1 as eluent). The reaction mixture was cooled and poured into ice-water giving a
solid which was collected by filtration and crystallized from DMF to give a the product as yellow
crystals in a yield of 70%; m.p. 329–330 °C; Anal. calcd. for C15H12N6S (308.36): C, 58.43; H, 3.92;
N, 27.25; S, 10.40. Found: C, 58.33; H, 3.79; N; 27.20; S, 10.37; IR (KBr): υmax 3443, 3305 (NH2),
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3355, 3263 (NH2); H-NMR (DMSO): δ, ppm 6.13 (d, 1H, J = 6 Hz, CH), 6.62 (br, 2H, NH2, D2O
exchangeable), 7.33–7.47 (m, 3H, Ar-Hs), 7.61 (br, 2H, NH2, D2O exchangeable), 7.85 (s, 1H,
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thiazole-H), 8.01 (m, 2H, Ar-Hs), 8.07 (d, 1H, J = 6 Hz, CH); C-NMR (DMSO): δ, ppm 160.59,
156.98, 152.22, 149.36, 147.14, 146.94, 134.31, 128.75 (2C), 127.72, 125.90 (2C), 109.66, 89.99,
88.59. MS: m/z (%) 308 (M+, 100), 268 (30), 175 (5), 154 (5), 134 (30), 102 (5), 89(5), 77 (5).