In 40 ml of N,N-dimethylformamide were dissolved 5.39 g (21.6 mmol) of 4-dibutylamino-2-hydroxybenzaldehyde and 4.08 g (60.0 mmol) of imidazole. Next, 6.13 g (22.3 mmol) of tert-butylchlorodiphenylsilane was added dropwise thereto with stirring at room temperature. The mixture was stirred for 3.5 hours. After the reaction mixture was poured into water, extraction with ethyl acetate, washing with a saturated saline solution, drying over anhydrous sodium sulfate, and concentration were performed. The residue was purified by silica gel column chromatography to give 10.3 g of a colorless oily matter (yield: 97.7%).
