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).

Synthesis and antimicrobial evaluation of naphtho[2,1-b]pyrano[2,3-d]pyrimidine and pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives.

Several novel naphtho[2,1-b]pyrano[2,3-d]pyrimidines, pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines and their coumarin-3-yl derivatives were synthesized. Some of these derivatives exhibited pronounced antimicrobial activities.

Studies on thiazolopyridines--a novel synthesis of bis-thiazolopyridines as promising antimicrobial agents.

A variety of novel bis-thiazolopyridine derivatives 4a-e were synthesized via the reaction of bis-thiazolinone 3 with different arylcinnamonitrile derivatives (1:2 molar ratio), whereas the reaction of bis-compounds 7a-e with malononitrile in ethanol solution containing a few drops of piperidine afforded the novel bis-thiazolopyridines 8a-e. The structures of the synthesized compounds were established by elemental analyses and spectral data. Some of the newly synthesized compounds show moderate to high antimicrobial activity.