Boron tribromide → 5-(3-[(1S)-2-Hydroxy-1-methylethoxy]-5-{5-[(5S)-5-methyl-4,5-dihydro-1,3-oxazol-2-yl]-1H-pyrrol-2-yl}phenoxy)-N-methylpyridine-2-sulfonamide

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Reaction Steps

5-(3-[(1S)-2-Methoxy-1-methylethoxy]-5-{5-[(5S)-5-methyl-4,5-dihydro-1,3-oxazol-2-yl]-1H-pyrrol-2-yl}phenoxy)-N-methylpyridine-2-sulfonamide (166 mg, 0.32 mmol) synthesized in Example (121d) was dissolved in methylene chloride (5 mL), and boron tribromide (1.0 mol/L methylene chloride solution, 0.34 mL, 0.34 mmol) was added at −78° C. under nitrogen atmosphere. Subsequently, the temperature was brought back to room temperature, followed by stirring for 1.5 hours. To the reaction solution, a saturated aqueous sodium hydrogencarbonate solution was added, and extraction was carried out with methylene chloride. 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/methylene chloride=0%-4%) to afford the desired compound (119 mg, yield 78%) as a white solid.

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