2-Fluoro-3-(2-hydroxyethoxymethyl)-5-methoxybenzaldehyde (305 mg) was dissolved in 3 ml of DMF, and 300 mg of imidazole and 283 mg of chlorotriisopropylsilane were added thereto. The resulting mixture was stirred at 50° C. for 2 hours, and then water was added thereto. The mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate. The desiccating agent was removed by filtration, and the filtrate was concentrated under reduced pressure to give a crude product of the title compound (533 mg).
