Methanesulfonic Acid → 3-{4-[({2',6'-Dimethyl-4'-[2-(2-oxopyrrolidin-1-yl)ethoxy]biphenyl-3-yl}methyl)amino]-2-fluorophenyl}propanoic acid methanesulfonate

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Reaction Steps

To a solution of tert-butyl 3-{4-[({2′,6′-dimethyl-4′-[2-(2-oxopyrrolidin-1-yl)ethoxy]biphenyl-3-yl}methyl)amino]-2-fluorophenyl}propanoate (0.51 g, 0.91 mmol) in toluene (5 mL) was added trifluoroacetic acid (5 mL) under stirring at room temperature, and the mixture was stirred for 3 hr. The reaction mixture was concentrated under reduced pressure, and the residue was neutralized with saturated aqueous sodium hydrogencarbonate. The mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=1/1-ethyl acetate-ethyl acetate/methanol=10/1) to give a colorless amorphous powder. The obtained amorphous powder was dissolved in ethyl acetate, and methanesulfonic acid (0.82 mL) was added. The precipitated crystals were collected by filtration, washed, and dried to give the title compound (0.44 g, yield 88%) as colorless crystals.

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