N1-cyclopropyl-5-((2-amino-4-pyridyl)oxy)-1H-1-indolecarboxamide (400 mg, CAS No. 417722-12-4) described in WO02/32872, 2-chloroethyl isocyanate (150 mg) and tetrahydrofuran (5 ml) were stirred at 80° C. for 1.5 hours. The mixture was cooled to room temperature, silica gel was added, and the solvent was distilled off under reduced pressure. The silica gel was charged into a dry column packed with silica gel, and purification was performed by column chromatography (hexane:ethyl acetate=1:1, followed by ethyl acetate) to yield 280 mg of a colorless powder.
