Heterocyclic systems containing bridgehead nitrogen atom:: Synthesis and antimicrobial activity of thiazolo [3,2-b]-s-triazoles and isomeric thiazolo [2,3-c]-s-triazoles

Synthesis of 2,5-disubstituted thiazolo [3,2-b]-s-triazoles 5 has been achieved starting from the appropriate 5-mercapto-3-m-hydroxyphenyl-s-triazole 3. Compound 3 on condensation with alpha-haloketones gave the ketones 4 which on cyclization with PIPA afforded thiazolo [3,2-b]-s-triazoles 5 and not the isomeric thiazolo [2,3-c]-s-triazoles 7. This has been established by an unequivocal synthesis of 7 through POCI3 cyclization of 2-benzoylhydrazino-4-p-bromophenyl thiazole hydrobromide 6. The diuretic, antibacterial and antifungal activity of some of the compounds have also been evaluated.