A facial and convenient protocol for the synthesis of new thiazole, thiazolidinone and pyrazothiazole derivatives

Abstract: We have developed a facile method for the synthesis of a new series of thiazole, thiazolidinone and pyrazothiazole derivatives via the reaction 1,2- and 1,3-dicarbonyl compounds with ethyl bromoacetate, ethyl bromopyruvate or phenacyl bromide in ethanol as a solvent at ambient temperature or under reflux conditions. Major advantages of the present protocol include user friendly process, simple work-up, and inexpensive catalyst. Treatment of 1,3-dicarbonyl compounds (2, 6), isatin (9), or ninhydrine (12) and (15a-b) with thiosemicarbazide (1) in the presence of sodium acetate and HCl as a catalyst under heating or ambient temperature in ethanol as a solvent produced thiosemcarbazone derivatives (3, 7, 10, 13, 16a-b). These derivatives were utilized as key intermediates for synthesis of new thiazole, thiazolidinone and pyrazothiazole derivatives via the reaction with ethyl bromoacetate, ethyl bromopyruvate or phenacyl bromide in ethanol as a solvent at ambient temperature or under reflux conditions. The chemical structures of the newly synthesized compounds were characterized by FT-IR, 1H-NMR, 13C-NMR spectral and elemental analysis.