Preparation of dihydrotetrazolo[1,5-a]pyrimidine derivatives from Biginelli 3,4-dihydropyrimidine-2-thiones

Dihydropyrimidines (DHPM) with a fused tetrazole ring have been synthesized via a smooth and efficient three-step protocol involving N,S-dimethylated and 2-hydrazinyl-dihydropyrimidine intermediates, respectively. The described protocol is applicable to electron rich and electron poor DHPM precursors as well. The insertion of tetrazole ring in monastrol type dihydropyrimidines makes it interesting for pharmacological investigations.