General procedure for the synthesis of ethyl 4-cyclopropyl-2-thiazolecarboxylate from ethyl thiooxalate and 1-cyclopropyl-2-bromoacetophenone: 2-bromo-1-cyclopropylacetophenone (6.80 g, 42.0 mmol) and ethyl aminothioacetate (4.66 g, 35.0 mmol) were dissolved in ethanol (50 mL). The reaction mixture was heated to reflux for 1 hour. After completion of the reaction, the mixture was concentrated to dryness. The residue was purified by fast column chromatography (silica gel as stationary phase, eluent hexane/ethyl acetate = 4:1) to afford ethyl 4-cyclopropyl-2-thiazolecarboxylate (6.7 g, 98% yield). Mass spectrometry analysis: calculated value (C9H11NO2S + H)+: 198.06; measured value: (M+H)+ =198.05.
