Bromine → N-{3-[(2-amino-1,3-benzothiazol-6-yl)oxy]phenyl}-2,2,2-trifluoroacetamide

To a solution of potassium thiocyanate (17.5 g, 180.0 mmol) in acetic acid (130 mL) was added a solution of N-[3-(4-aminophenoxy)phenyl]-2,2,2-trifluoroacetamide (13.0 g, 43.9 mmol) in acetic acid (20 mL), and the mixture was stirred at room temperature for 15 min. To the obtained solution was added dropwise a solution of bromine (7.71 g, 48.2 mmol) in acetic acid (30 mL) at room temperature over 30 min or longer and, after the completion of the dropwise addition, the mixture was stirred at room temperature for 13 hr. The resulting yellow solid was filtered off, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate (200 mL), and basified with 8N aqueous sodium hydroxide solution. The aqueous layer was separated, and the organic layer was washed with saturated aqueous sodium hydrogencarbonate solution (200 mL) and saturated brine (50 mL), and dried over anhydrous magnesium sulfate. The insoluble material was filtered off, and the filtrate was concentrated under reduced pressure to give the title compound (10.3 g, 66%) as a yellow amorphous substance. The obtained compound was used in the next reaction without a further purification.