Synthesis of some New Dihydropyrimidines Derivatives by Cyclization of Polarized Unsaturated Systems

Reaction of benzylidene cyanoester 1 with thiosemicarbazide, cyanoacetamide, urea and thiourea was resulted in triazepine 2, pyridine 5, oxopyrimidine 6, and thiooxopyrimidine 8, respectively. Triazepine 2 was reacted with chloroacetic acid and/or chloroacetamide to give thiazolotriazepine 3 and acetamide 4. Reaction of thiopryrimidine 8 with hydrogeneperoxide affording pyrimidins 9 and with chloroacetic acid and chloroacetamide yielded thiazolopyrimidine benzylidene 10 and acetamide 11, while the reaction of 8 with benzylidene derivatives yielded pyrimidopyrimidine 16 and 17.