Efficient One-Pot Synthesis of Alkyl 2-(Dialkylamino)-4-phenylthiazole-5-carboxylates and Single-Crystal X-Ray Structure of Methyl 2-(Diisopropylamino)-4-phenylthiazole-5-carboxylate

The reaction between secondary amines, benzoyl isothiocyanate, and dialkyl acetylenedicarboxylates (=dialkyl but-2-ynedioates) in the presence of silica gel (SiO2) led to alkyl 2-(dialkylamino)-4-phenylthiazole-5-carboxylates in fairly high yields. The structures of the products were confirmed by their IR, 1H- and 13C-NMR, and mass spectra, and by a single-crystal X-ray structure determination.