A mixture of ethyl 3-[3-ethoxy-1-[4-(2-phenyl-4-oxazolylmethoxy)benzyl]-1H-pyrazol-4-yl]propionate (523 mg), 1 N aqueous sodium hydroxide solution (2.5 ml), tetrahydrofuran (5 ml), and ethanol (5 ml) was stirred at room temperature for 3 hours, diluted with 1 N hydrochloric acid (2.5 ml), and extracted with ethyl acetate. The ethyl acetate layer was washed with saturated aqueous sodium chloride solution, dried (MgSO4), and concentrated. The obtained colorless crystals were collected by filtration, and 3-[3-ethoxy-1-[4-(2-phenyl-4-oxazolylmethoxy)benzyl]-1H-pyrazol-4-yl]propionic acid (456 mg, yield: 93%) was obtained. This was recrystallized from ethanol-hexane. Melting point: 135–136° C.
