EXPERIMENTAL
All products were characterized by IR, 1H NMR, MS and elemental analysis. Melting points were measured by using the capillary tubes on Büchi apparatus and are uncorrected. Each compound of the reactions was checked on thin-layer chromatography of Merck Kieselgel 60F254 and purified by column chromatography using Merck silica gel (70 - 230 mesh). IR spectra were recorded on the FT-IR Brucker Tensor 27. The 1H NMR spectra were recorded on Bruker DRX-300 FT-NMR spectrometer (300 MHz) with Me4Si as internal standard and chemical shifts are given in ppm (δ). Electron ionization mass spectra were recorded on a HP 59580 B spectrometer. Elemental analyses were performed on a Carlo Erba 1106 elemental analyzer.
General procedure for the preparation of 2-phenylthieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives (5). To a solution of each 3-phenylthieno[3,2-e][1,2,4]triazolo[4,3-c] pyrimidine 4 (1 mmol) in ethanol (30 mL) was added sodium acetate (0.164 g, 2 mmol) and the mixture was refluxed for 5 h and cooled. The precipitated solid was filtered, washed with water, dried and finally crystallized from ethanol to give the respective 2-phenylthieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine 5.
2-Phenylthieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5a). Yield 76%; mp 184 - 186 ℃; IR (KBr): 3062, 1631 cm-1; 1H NMR (CDCl3): δ 9.27 (s, 1H, pyrimidine-H), 8.37-8.33 (m, 2H, phenyl, H-2 and H-6), 7.88 (d, J = 5.9 Hz, 1H, thiophene), 7.70 (d, J = 5.9 Hz, thiophene), 7.56-7.52 (m, 3H, phenyl, H-3, H-4 and H-5); MS: (m/z) 252 (M+, 100), 149 (10), 134 (17), 118 (20), 95 (10), 77 (8). Anal. Calcd. for C13H8N4S: C, 61.89; H, 3.20; N, 22.21. Found: C, 61.71; H, 3.32; N, 22.05.
2-(4-Chlorophenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5b). Yield 78%; mp 265 - 267 ℃; IR (KBr): 3040, 1622 cm-1; 1H NMR (CDCl3): δ 9.26 (s, 1H, pyrimidine-H), 8.29 (d, 2H, phenyl, H-2 and H-6), 7.86 (d, J = 5.9 Hz, 1H, thiophene), 7.71 (d, J = 5.9 Hz, thiophene), 7.51 (d, 2H, phenyl, H-3 and H-5); MS: (m/z) 287 (M+, 100), 149 (22), 134 (15). Anal. Calcd. for C13H7ClN4S: C, 54.45; H, 2.46; N, 19.54. Found: C, 54.60; H, 2.30; N, 19.40.
2-p-Tolylthieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5c). Yield 62%; mp 217 - 218 ℃; IR (KBr): 3040, 2946, 1626, 1330 cm-1; 1H NMR (CDCl3): δ 9.25 (s, 1H, pyrimidine-H), 8.23 (d, 2H, phenyl, H-2 and H-6), 7.87 (d, J = 5.9 Hz, 1H, thiophene), 7.68 (d, J = 5.9 Hz, thiophene), 7.34 (d, 2H, phenyl, H-3 and H-5); MS: (m/z) 266 (M+, 100), 149 (25), 134 (10), 117 (10), 91 (9). Anal. Calcd. for C14H10N4S: C, 63.14; H, 3.78; N, 21.04. Found: C, 63.30; H, 3.70; N, 21.22.
2-(4-Methoxyphenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5d). Yield 60%; mp 236 - 238 ℃; IR (KBr): 3050, 2955, 1630, 1370 cm-1; 1H NMR (CDCl3): δ 9.24 (s, 1H, pyrimidine-H), 8.27 (d, 2H, phenyl, H-2 and H-6), 7.86 (d, J = 5.9 Hz, 1H, thiophene), 7.68 (d, J = 5.9 Hz, thiophene), 7.05 (d, 2H, phenyl, H-3 and H-5), 3.90 (s, 3H, Me); MS: (m/z) 282 (M+, 100), 149 (12), 134 (19). Anal. Calcd. for C14H10N4OS: C, 59.56; H, 3.57; N, 19.85. Found: C, 59.69; H, 3.43; N, 19.99.
2-(4-Bromophenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5e). Yield 70%; mp 244 - 246 ℃; IR (KBr): 3030, 1600 cm-1; 1H NMR (DMSO-d6): δ 9.73 (s, 1H, pyrimidine-H), 8.28 (d, 2H, phenyl, H-2 and H-6), 8.10 (d, J = 5.9 Hz, 1H, thiophene), 7.88 (d, J = 5.9 Hz, thiophene), 7.79 (d, 2H, phenyl, H-3 and H-5); MS: (m/z) 331 (M+). Anal. Calcd. for C13H7BrN4S: C, 47.14; H, 2.13; N, 16.92. Found: C, 47.29; H, 2.25; N, 16.80.
2-(3-Chlorophenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5f). Yield 74%; mp 247 - 249 ℃; IR (KBr): 3045, 1612 cm-1; 1H NMR (CDCl3): δ 9.26 (s, 1H, pyrimidine-H), 8.36 (s, 1H, phenyl, H-2), 8.23 (d, 1H, phenyl, H-6), 7.87 (d, J = 5.9 Hz, 1H, thiophene), 7.71 (d, J = 5.9 Hz, thiophene), 7.51-7.46 (m, 2H, phenyl, H-4 and H-5); MS: (m/z) 287 (M+, 100), 149 (15), 134 (20). Anal. Calcd. for C13H7ClN4S: C, 54.45; H, 2.46; N, 19.54. Found: C, 54.59; H, 2.57; N, 19.60.
2-m-Tolylthieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5g). Yield 63%; mp 193 - 195 ℃; IR (KBr): 3040, 1635, 1375 cm-1; 1H NMR (CDCl3): δ 9.33 (s, 1H, pyrimidine-H), 8.20 (d, 1H, phenyl, H-6), 7.89 (d, J = 5.9 Hz, 1H, thiophene), 7.68 (d, J = 5.9 Hz, thiophene), 7.53 (t, 1H, phenyl, H-5), 7.17-7.09 (m, 2H, phenyl, H-2 and H-4); MS: (m/z) 266 (M+, 100), 149 (15). Anal. Calcd. for C14H10N4S: C, 63.14; H, 3.78; N, 21.04. Found: C, 63.01; H, 3.67; N, 21.18.
2-(3-Bromophenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5h). Yield 69%; mp 246 - 248 ℃; IR (KBr): 3064, 1622 cm-1; 1H NMR (CDCl3): δ 9.27 (s, 1H, pyrimidine-H), 8.52 (s, 1H, phenyl, H-2), 8.28 (d, 1H, phenyl, H-6), 7.86 (d, J = 5.9 Hz, 1H, thiophene), 7.73 (d, J = 5.9 Hz, thiophene), 7.65 (d, 1H, phenyl, H-4), 7.41 (t, 1H, phenyl, H-5); MS: (m/z) 331 (M+, 100), 134 (20). Anal. Calcd. for C13H7BrN4S: C, 47.14; H, 2.13; N, 16.92. Found: C, 47.32; H, 2.02; N, 17.10.
2-(2-Methoxyphenyl)thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine (5i). Yield 56%; mp 220 - 222 ℃; IR (KBr): 3090, 2975, 1610, 1375 cm-1; 1H NMR (CDCl3): δ 9.26 (s, 1H, pyrimidine-H), 8.17-8.13 (m, 2H, phenyl, H-4 and H-6), 7.88 (d, J = 5.9 Hz, 1H, thiophene), 7.69 (d, J = 5.9 Hz, thiophene), 7.42 (t, 1H, phenyl, H-5), 7.34 (d, 1H, phenyl, H-3), 2.48 (s, 3H, Me); MS: (m/z) 282 (M+, 100), 149 (18), 134 (15). Anal. Calcd. for C14H10N4OS: C, 59.56; H, 3.57; N, 19.85. Found: C, 59.71; H, 3.66; N, 20.01.
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