Hydrochloric Acid → 7-Amino-2-chlorothiazolo[4,5-d]pyrimidine

Participants

Reaction Conditions

Reaction Steps

To a suspension of 2,7-diaminothiazolo[4,5-d]pyrimidine (27: 16.3 g, 97.3 mmol) in water (200 mL) at 55° C. was added enough 1N NaOH (about 100 mL) to dissolve the starting material and sodium nitrite (8.0 g) was then added. This solution was then added dropwise over 30 min. to a solution containing con HCl (400 mL), water (100 mL) and LiCl (60 g) at 30° C. The resulting mixture was warmed to 45° C. for 15 min. and then hot water (1 L, 90°) was added. The reaction mixture was stirred overnight at room temperature, filtered to remove unreacted starting material and the filtrate was neutralized with solid NaOH to pH 4. The resulting solid was filtered off, washed with water and dried to yield 28: 5.38 g, 34%: recrystallization from water gave an analytical sample- mp >234° C. decomp.: UV λmax (pH 1) 228 nm (ε), 296 (): UV λmax (pH 7) 232 nm (ε), 298 (): UV λmax (pH 119 227 nm (ε), 300 (): 1H NMR (DMSO-d6) δ7.82 (b, 2H, NH2, exchanges with D2O), 8.41 (s, 1H, C5H). Anal. Calcd. for C5H3N4SCl.0.1H2O: C, 31.87: H, 1.71: N, 29.74: S, 17.02: Cl, 18.82. Found: C, 31.71: H, 1.50: N, 29.35: S, 16.92: Cl, 19.54.

Provenance & Evidence