The regioselective synthesis of 2,5- and 4,5-disubstituted thiazoles via the cyclization of 2-oxo-2-(amino)ethanedithioates with isocyanides.

The regioselective synthesis of 2-(methylthio)- N -aryl/alkylthiazole-5-carboxamides and ethyl-5-(aryl/alkyl carbamoyl)thiazole-4-carboxylates was carried out via the base-induced cyclization of methyl-2-oxo-2-(amino)ethanedithioates with TosMIC and ethyl isocyanoacetate, respectively, with high yields. The regioisomeric products were confirmed based on X-ray diffraction studies. An advantage of the present method is the wide-ranging isocyanide reactivity compared to earlier protocols, while the catalyst-free nature and rapid reaction times are noteworthy features.