4-Amino-2-chlorothieno[3,2-d]pyrimidine

16234-14-3

16234-40-5

General procedure for the synthesis of 4-amino-2-chlorothieno[3,2-d]pyrimidines from 2,4-dichlorothieno[3,2-d]pyrimidines: in a glass tube, 2,4-dichlorothieno[3,2-d]pyrimidines (800 mg, 3.90 mmol) were suspended in methanol (10 mL) and the suspension was cooled to -60 to -70 °C. Ammonia was passed into the cooled suspension. After sealing the glass tube, the reaction mixture was stirred at room temperature overnight until a clarified solution was formed. Subsequently, the solvent was removed by evaporation, and the resulting crude product was purified by column chromatography, sequentially using 9:1 hexane/ethyl acetate and 8:2 hexane/ethyl acetate as eluent, to afford 4-amino-2-chlorothieno[3,2-d]pyrimidine as an off-white solid (575 mg, 3.10 mmol, 80% yield). Thin layer chromatography (TLC) analysis showed an Rf value of 0.2 (unfolding agent was 3:1 hexane/ethyl acetate). The melting point of the compound was 272.3-274.2 °C. Nuclear magnetic resonance hydrogen spectrum (1H NMR, 400 MHz, DMSO-d6): δ 7.73 (d, 1H, J = 5.0 Hz), 8.38 (br s, 2H, NH2), 8.60 (d, 1H, J = 5.5 Hz). Nuclear magnetic resonance carbon spectrum (13C NMR, 100 MHz, DMSO-d6): δ 114.2, 124.7, 136.6, 157.7, 160.6, 162.4. Fast atom bombardment mass spectrometry (FAB-MS) analysis showed that the molecular ions peaks [M + H]+ had a calculated value of 185.9887, and the measured values were 185.9895 (35Cl ) and 187.9861 (37Cl), consistent with the molecular formula C6H4ClN3S.