ABSTRACT
A new series of 5,7-dimethyI-3-substituted[l,2,4]triazolo[4,3-cj,]pyrimidines[3-8] has been synthesized by reacting the triazolopyrimidinethiol with ethyl chloroacetate followed by treatment of the obtained ethyl ester with hydrazine hydrate to yield the corresponding hydrazide. Reaction of the hydrazide derivative with aryl sulfonyl chlorides afforded the corresponding sulfonyl hydrazides while its reaction with ethyl or phenyl isothiocyanates resulted in the formation of 1,2,4-triazolomethyl sulfide derivatives. A series of 5-aryl-7-phenyl-5,6-dihydro-[l,2,4]triazolo[4,3-alpha]pyrimidines [13-20] and their tricyclic pyridotriazolopyrimidine analogues [26-33] were prepared by interaction of different alpha,beta-unsaturated ketones with 3-amino-4H-[I,2,4]triazole-5-thiol followed by benzylation of the obtained 3-thiol derivative to afford the corresponding thioethers. The prepared compounds were screened for their antimicrobial, antiviral and cytotoxic activities. Some of the tested compounds showed promising activity. The detailed syntheses, spectroscopic and biological data are reported