Synthesis, characterization and in vitro antimicrobial activity of novel 2-thioxo-4-thiazolidinones and 4,4'-bis(2-thioxo-4-thiazolidinone-3-yl)diphenylsulfones.

2-Thioxo-4-thiazolidinones (3a,b) were achieved by cyclocondensation of isothiocyanatosulfonamides (1a,b) with sulfanylacetic acid at reflux temperature in dioxane in the presence of triethylamine. Compound (3a) was exploited to synthesize the versatile hitherto unknown 2-thioxo-4-thiazolidinones (5-10) via its reaction with some electrophiles. Cyclization of 4,4'-diisothiocyanate diphenylsulfone (11) with sulfanylacetic acid furnished 4,4'-bis(2-thioxo-4-thiazolidinone-3-yl)diphenylsulfone (12) which on treatment with excess 4-methoxybenzaldehyde in refluxing dioxane in the presence of piperidine yielded the bisbenzylidene derivative (13).