In a dichloromethane/N,N-dimethylformamide (70 ml/70 ml) mixture were dissolved t-butyl N,N-bis(2-hydroxyethyl)carbamate (9.00 g, 43.8 mmol) and imidazole (2.60 g, 38.2 mmol), followed by the dropwise addition of t-butylchlorodiphenylsilane (8.1 ml, 31 mmol) at room temperature. After completion of the dropwise addition, the reaction mixture was stirred at room temperature for 14 hours. The residue obtained by concentrating the reaction mixture under reduced pressure was added with diethyl ether. The resulting mixture was washed with water and the organic layer was dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure. The residue thus obtained was subjected to flash silica gel chromatography, and the fraction obtained from the hexane:ethyl acetate=2:1 eluate was concentrated under reduced pressure, whereby the title compound (7.41 g, 16.7 mmol, 54%) was obtained as a colorless oil.
