Hydrogen chloride-ethyl acetate → N-{(1S)-2-[(6-{6-[(3,3-difluorocyclobutyl)methoxy]-1,3-benzoxazol-2-yl}-5-fluoropyridin-3-yl)oxy]-1-methylethyl}acetamide

A mixture of tert-butyl {(1S)-2-[(6-{6-[(3,3-difluorocyclobutyl)methoxy]-1,3-benzoxazol-2-yl}-5-fluoropyridin-3-yl)oxy]-1-methylethyl}carbamate (390 mg), 4 M hydrogen chloride/ethyl acetate (3 mL), and ethyl acetate (3 mL) was stirred at room temperature for 4 hr. The mixture was concentrated under reduced pressure. The residue was mixed with pyridine (3 mL) and acetic anhydride (1 mL). The mixture was stirred at room temperature for 3 days. 1 M hydrochloric acid was added, and the mixture was extracted with ethyl is acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate/methanol) and recrystallization (ethyl acetate) to give the title compound (218 mg) as white crystals.