A mixture of ethyl 3-[4-phenyl-1-[4-[3-(2-pyrazinyl)benzyloxy]benzyl]-3-pyrrolyl]propionate (647 mg), 1N aqueous sodium hydroxide solution (2.5 ml), tetrahydrofuran (5 ml), and ethanol (5 ml) was stirred at room temperature overnight, and 1N hydrochloric acid (2.5 ml) was added to the mixture, which was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated aqueous sodium chloride solution, dried (MgSO4), then concentrated. The colorless crystals obtained were collected by filtration to yield 3-[4-phenyl-1-[4-[3-(2-pyrazinyl)benzyloxy]benzyl]-3-pyrrolyl]propionic acid (470 mg, yield: 77%). This was recrystallized from ethyl acetate-hexane. Melting point: 91–92° C.
