Synthesis of various fused pyrimidine rings and their pharmacological and antimicrobial evaluation

Various fused pyrimidines, such as furo[2,3-d]pyrimidine, triazolo[1,5-a]pyrimidine and tetrazolo[1,5-a]pyrimidine, were synthesized in the reactions of thioxopyrimidine-6(1H)-ones with ethyl chloroacetate (under different reaction conditions), thiourea and sodium nitrite. Pyrimidine thiones reacted with POCl3/PCl5 to give the chloro derivatives which reacted with sodium azide and thiourea to give tetrazolo[1,5-c]pyrimidines, and pyrimido pyrimidines. Thioxopyrimidine-6(1H)-ones reacted with benzylamine to give pyrrolo[2,3-d]pyrimidinethiones. Theoretical calculation using MIDO/3, Fukui indices and the heat of formation of some compounds were carried out. The pharmacological and antimicrobial activities of some of the synthesized products were also evaluated.