NOVEL BRIDGEHEAD NITROGEN-HETEROCYCLES - SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF 5H-PYRAZOLO[3', 4'/4, 5]THIAZOLO[3, 2-A]-PYRIMIDINES

Synthesis of 2, 3-diaryl-6, 7-dihydro-5H-pyrazolo[3', 4': 4, 5]thiazolo[3, 2-a]pyrimidines (III) has been achieved in a single step by treating 2-arylidene-6, 7-dihydro-5H-thiazolo[3, 2-a]pyrimidin-3(2H)-ones (II) with hydrazines. Compounds II in turn have been obtained in a single step by condensing 3, 4, 5, 6-tetrahydropyrimidine-2-thione (I) with ethyl chloroacetate and aldehydes in the presence of pyridine and piperidine. Compounds III constitute a novel and hitherto unknown heterocyclic system. The antibacterial and antifungal activities of some of the compounds pertaining to this system have also been evaluated.