Regio- and stereoselective synthesis of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts via electrophilic heterocyclization of 3-S-propargylthio-4H-1,2,4-triazoles and their antimicrobial activity

Abstract

A procedure for the preparation of the title salts via regioselective halocyclization of 3-S-propargylthio-4H-1,2,4-triazoles is reported. Stereoselectivity of electrophilic heterocyclization depends on the nature of the electrophilic reagent: bromination is better than iodobromination and iodination. The heterocyclization with tellurium tetrahalogenides leads to the formation of a mixture of geometric isomers of the salts. Their structure was confirmed by 1H NMR, 13C NMR, HMBC and single crystal X-ray diffraction analysis.