Synthesis and antimicrobial study of novel heterocyclic compounds from hydroxybenzophenones

The triazolothiadiazine analogues 6a–e were obtained via a multistep synthesis sequences beginning with the hydroxybenzophenones 1a–e. Hydroxybenzophenones on reaction with ethyl chloroacetate affords ethyl (2-aroylaryloxy)acetates 2a–e which on treatment with hydrazine hydrate yields 2-(2-aroylaryloxy)acetohydrazides 3a–e. Intramolecular cyclization of 3a–e with carbon disulfide affords 5-(2-aroylaryloxy)methyl-1,3,4-oxadiazole-2-(3H)thiones 4a–e, which on treatment with hydrazine hydrate yields 4-amino-5-(2-aroyl aryloxy)methyl-1,2,4-triazole-3-(2H)thiones 5a–e. Condensation of 5a–e with α-halocarbonyl compound results in 3-(2-aroylaryloxy)methyl-6-phenyl-1,2,4-triazolo[3,4-b][1,3,4] thiadiazine 6a–e analogues. The compounds 4a–e, 5a–e and 6a–e were tested against variety of fungal and bacterial strains in comparison to fluconazole and chloramphenicol, respectively.