3034-22-8

7336-54-1

A. Preparation of 2-acetamido-5-bromothiazole Acetic anhydride (11 mL) was added slowly and dropwise to a mixed solution of dichloromethane (100 mL) and pyridine (60 mL) of 2-amino-5-bromothiazole (22.3 g, 85.9 mmol) while maintaining stirring. The reaction mixture was stirred at room temperature for 2.5 hours and then continued to stir for 4 hours to ensure complete reaction. Upon completion of the reaction, most of the solvent was removed by distillation under reduced pressure. The residue was washed sequentially with ethyl acetate and dilute aqueous hydrochloric acid to remove unreacted feedstock and by-products. The organic phase was subsequently washed to neutrality with water and dried with anhydrous magnesium sulfate. The dried organic solution was concentrated to give a crude product. The crude product was ground with ether, filtered, washed with ether and dried to give 2-acetamido-5-bromothiazole solid (15.1 g, 80% yield, molecular formula C5H5BrN2OS, mass spectrum m/e 222 (M + H)+).