A series of new 2-substituted 3-(4-chlorophenyl)-5,8,9- trimethylthieno[3′,2′:5,6]pyrido[4,3-d]pyrimidin-4(3H)-ones 8 were synthesized via an aza-Wittig reaction. Phosphoranylideneamino derivatives 6a or 6b reacted with 4-chlorophenyl isocyanate to give carbodiimide derivatives 7a or 7b, respectively, which were further treated with amines or phenols to give compounds 8 in the presence of a catalytic amount of EtONa or K 2CO3. The structure of 2-(4-chlorophenoxy)-3-(4- chlorophenyl)-5,8,9-trimethylthieno[3′,2′:5,6]pyrido[4,3-d] pyrimidin-4(3H)-one (8j) was comf...
