Synthesis and biological evaluation of novel Indolyl 4-thiazolidinones bearing thiadiazine nucleus

A series of Ethyl 2-[2-(2,5-disubstituted-1H-indol-3-yl)-4-oxothiazolid-3-ylamino]-5,6-dihydro-5-oxo-4H-1,3,4-thiadiazine-6-carboxylates (4a-g) were synthesized from cyclocondensation of Ethyl 2-{(2E)-2-[(2,5-disubstituted-1H-indol-3-yl) methy leno] hydrazine}-5-oxo-5,6-dihydro-4H-1,3,4-thiadiazine-6-carboxylates (3a-g) with thioglycolic acid in the presence of the catalytic amount of zinc chloride. The compounds 3a-g were obtained from the reaction of Ethyl 2-hydrazinyl-5,6-dihydro-5-oxo-4H-1,3,4-thiadiazine-6-carboxylate (2) with various substituted indole-3-carboxaldehydes 1a-g. Newly synthesized compounds were characterized by using IR, 1H NMR, Mass spectral and analytical data. Title compounds were evaluated for their in vitro antimicrobial activities against various microbial strains and selected compounds were tested for their analgesic and anti-inflammatory activities. Some of the newly synthesized Indolyl 4-thiazolidinone analogues displayed significant activity towards antimicrobial, analgesic and anti-inflammatory activities.