A facile synthesis of 2-substituted thieno[3 ',2 '-5,6]-pyrido[4,3-d]pyrimidin-4(3H)-ones

摘要

The thienopyridine derivative 2, obtained from reaction of acetoacetic ester with 1 in the presence of tin tetrachloride, was treated with triphenylphosphine in hexachloroethane and Et3N to give iminophosphorane 3. Iminophosphorane 3 reacted with phenyl isocyanate to give carbodiimide 4, which was further treated with phenols or ethenol to produce 2-substituted 5,8,9-trimethyl-3-phenyl-thieno[3',2'-5,6]pyrido[4,3-dlpyrimidin-4(3H)-ones 5 in presence of catalytic amount of K2CO3 or EtONa. The structures of compounds 5 were confirmed by H-1 NMR, IR, MS, and elemental analysis.