All products were characterized by IR, ¹ H 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 60F ₂₅₄ and purified by column chromatography using Merck silica gel (70 - 230 mesh). IR spectra were recorded on the FT-IR Brucker Tensor 27. The ¹ H NMR spectra were recorded on Bruker DRX-300 FT-NMR spectrometer (300 MHz) with Me ₄ Si 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₃ H ₈ N ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₃ H ₇ ClN ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₄ H ₁₀ N ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₄ H ₁₀ N ₄ OS: 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 ; ¹ H 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 C ₁₃ H ₇ BrN ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₃ H ₇ ClN ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₄ H ₁₀ N ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₃ H ₇ BrN ₄ S: 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 ; ¹ H NMR (CDCl ₃ ): 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 C ₁₄ H ₁₀ N ₄ OS: C, 59.56; H, 3.57; N, 19.85. Found: C, 59.71; H, 3.66; N, 20.01.