Subsequently, to a solution of (2-hydroxyethyl)carbamic acid benzyl ester (5.37 g, 27.5 mmol) in dimethylformamide (160 ml) were added t-butyldiphenylsilyl chloride (8.6 ml, 33.0 mmol) and imidazole (2.3 g, 33.8 mmol) in an ice bath, and the mixture was stirred at room temperature overnight. After checking the completion of the reaction, ethanol was added thereto and the reaction mixture was stirred for 2 hours. The reaction mixture was partitioned between ethyl acetate and saturated aqueous sodium hydrogencarbonate solution. The organic layer was washed with saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by chromatography on a silica gel column using hexane:ethyl acetate (5:1) as the eluant to afford [2-(t-butyldiphenylsilyloxy)ethyl]carbamic acid benzyl ester (11.93 g, yield 100%) as a colorless and transparent syrup.
