16234-14-3

16233-51-5

16234-14-3

General procedure for the synthesis of 2,4-dichlorothieno[3,2-d]pyrimidine from thieno[3,2-d]pyrimidine-2,4-dione: To a suspension of thieno[3,2-d]pyrimidine-2,4-dione (5 g, 29 mmol) in POCl3 (40 mL) was added diisopropylethylamine (13 mL, 74 mmol), and the reaction mixture was heated refluxed for 2 hours. Upon completion of the reaction, the excess POCl3 and diisopropylethylamine were removed by distillation under reduced pressure. The resulting brown solid was dissolved in chloroform followed by aqueous phase partitioning. The aqueous phase was adjusted to alkaline by adding 5 M NaOH solution and extracted twice with chloroform. The organic phases were combined, washed sequentially with water and brine, dried over anhydrous Na2SO4 and filtered, and concentrated to afford the target product 2,4-dichlorothieno[3,2-d]pyrimidine as a light brown solid (6.05 g, quantitative yield).1H NMR (CDCl3, 300 MHz): δ 8.16 (d, J = 5.4 Hz, 1H), 7.56 (d, J = 5.7 Hz, 1H); LRMS (ESI): m/z calculated values [M + H]+ 204.94, 206.94, measured values 205.1, 207.0.