Acetoxyacetyl chloride → 3-(1-cyano-1-methylethyl)-N-(5-{[2-(glycoloylamino)-1,3-benzothiazol-6-yl]oxy}-2-methylphenyl)benzamide

To a solution of N-{5-[(2-amino-1,3-benzothiazol-6-yl)oxy]-2-methylphenyl}-3-(1-cyano-1-methylethyl)benzamide (200 mg, 0.452 mmol) produced in Example A7(vi) in pyridine (4.0 mL) was added 2-chloro-2-oxoethyl acetate (107 μL, 0.994 mmol), and the mixture was stirred at room temperature for 10 hr. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in methanol (4.0 mL). 1N Aqueous sodium hydroxide solution (4.0 mL) was added, and the mixture was stirred at room temperature for 1 hr. The reaction mixture was neutralized with 1N hydrochloric acid, and extracted with ethyl acetate (100 mL). The organic layer was washed with water (50 mL) and saturated brine (50 mL), successively, and dried over anhydrous sodium sulfate. The insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. The obtained residue was purified by basic silica gel column chromatography (ethyl acetate/methanol=100/0→80/20), and the obtained solution was concentrated under reduced pressure. The residue was triturated with ethyl acetate/diisopropyl ether to give the title compound (120 mg, 53%) as a colorless solid.