Triethylamine → ethyl N-(4-p-nitrophenyl-2-thiazolyl)carbamate

In 300 ml of tetrahydrofuran, was suspended 4.42 g of 2-amino-4-p-nitrophenylthiazole, followed by a further addition of 20 ml of triethylamine. The mixture was cooled to about 5° C., to which 10.5 ml of ethyl chloroformate was added dropwise. Then, the reaction mixture was stirred at room temperature for 3.5 days. Any insoluble matter was filtered off from the reaction mixture, and the filtrate was concentrated and then washed in ethyl acetate successively with water, dilute hydrochloric acid, and water. Then, the ethyl acetate solution was concentrated to about 50 ml and the resulting crystals were separated by filtration and then subjected to column chromatography on silica gel. The reaction product was eluted with a benzene/ethyl acetate mixed solvent. The resultant product was recrystallized from ethyl acetate to obtain 2.8 g of ethyl N-(4-p-nitrophenyl-2-thiazolyl)carbamate.