The reaction between secondary amines, benzoyl isothiocyanate, and dialkyl acetylene dicarboxylates (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 these products were confirmed by their IR, 1H and13CNMR, and mass spectra determination. All compounds have been screened for antimicrobial activity against Mycobacterium smegmatis by broth dilution and agar well diffusion methods. All the synthesized derivatives exhibited remarkable activity against this bacterium.