Hydrogen chloride-ethyl acetate → methyl [(1S)-2-({6-[6-(cyclopropylmethoxy)-1,3-benzoxazol-2-yl]pyridin-3-yl}oxy)-1-methylethyl]carbamate

A mixture of tert-butyl [(1S)-2-({6-[6-(cyclopropylmethoxy)-1,3-benzoxazol-2-yl]pyridin-3-yl}oxy)-1-methylethyl]carbamate (84.6 mg), ethyl acetate (2 mL) and 4M hydrogen chloride/ethyl acetate (2 mL) was stirred at room temperature for 3 hr. The solvent was evaporated under reduced pressure, and the residue was mixed with triethylamine (0.5 mL), THF (2 mL) and methyl chloroformate (0.044 ml) at 0° C., and the obtained mixture was stirred at room temperature for 2 hr. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The combined organic layer was washed with saturated brine, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate) to give the title compound (17.5 mg).