4-{[2-(4-Chlorobutyrylamino)-4-pyridyl]oxy}aniline (100 mg), p-fluorophenyl isocyanate (0.037 ml) and tetrahydrofuran (3 ml) were stirred at room temperature for 25 minutes. Water and ethyl acetate were added to the reaction solution for extraction, NH type silica gel was added to the extract, the solvent was distilled off under reduced pressure and the reaction product was adsorbed onto the silica gel. The silica gel was charged into a dry column packed with NH type silica gel, and column purification was performed (hexane:ethyl acetate=1:1, followed by ethyl acetate and ethyl acetate:methanol=10:1). The solvent was distilled off under reduced pressure to obtain 56 mg of the target substance as a white solid.
