LAUSR

Utility of 4-oxo-6-styryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 1 in synthesis of a new series of fused pyrimidines was described. Pyrimido[2,1- b ][1,3]thiazines 6 – 9 were obtained via Michael addition of compound 1 to the polarized systems 2 – 5 in the presence of nanosized ZnO. S -alkylation of pyrimidine 1 followed by cyclization with phenacyl bromide, monochloroacetic acid, chloroacetonitrile and oxalyl chloride afforded the desired thiazolo[3,2- a ]pyrimidines 10 – 13 . Hydrazinolysis of compound 1 followed by addition cyclization with acetic anhydride, formic acid, carbon disulfide and benzoyl chloride afforded triazolo[4,3- a ]pyrimidines 15 – 18 . The antimicrobial screening showed high activity for thiazolo[3,2- a ]pyrimidines 11 and 12 against both Gram (+ ve) and Gram (− ve) bacteria.