Sodium Bicarbonate → HCID 58065495, compound

(5S)-2-(5-{3-[4-(Azetidin-1-ylcarbonyl)-2-fluorophenoxy]-5-[(1S)-2-methoxy-1-methylethoxy]phenyl}-1H-pyrrol-2-yl)-5-methyl-4,5-dihydro-1,3-oxazole (337.8 mg, 0.666 mmol) synthesized in Example (69b) was dissolved in dichloromethane (10 mL), and a boron tribromide/dichloromethane solution (1M, 1 mL, 1 mmol) was added at −78° C. under nitrogen atmosphere, followed by stirring at room temperature for 1 hour. To the reaction solution, a saturated aqueous sodium hydrogencarbonate solution was added, and extraction was carried out with ethyl acetate. The organic layer was washed with saturated brine, and subsequently dried over sodium sulfate. The solvent was distilled off under reduced pressure, and the resulting residue was purified using silica gel column chromatography (elution solvent: methanol/dichloromethane=2%-8%) to afford the desired compound (93.7 mg, yield 29%) as a pale yellow solid.