Fourteen novel 3-substituted-5-methyl-4-methylene-7-alkylsulfanyl-3,4-dihydro-pyrido[4,3-d]pyrimidine-8-carbonitriles, compounds 4a–n, were designed and synthesized via a facile regioselective cyclization process. The intermediate 2 reacted with triethyl orthoformate (molar ratio is 1:4) in the presence of acetic anhydride to give formamidate 3, which was cycled to 4 regioselectively upon addition of different amines at mild condition. The structures of compounds 4a–n were confirmed by IR, 1H NMR, MS and elemental analysis. The preliminary bi...
