Sodium hydride (6.32 g, 0.158 mmol, 60% in oil) was loaded under argon circumstance in three-necked flask and hexane (100 ml) was added thereto. After stirring for a while, it was allowed to stand and the supernatant was removed by syringe. By repeating this procedure three times, the oil of sodium hydride was removed. After drying in vacuo anhydrous dimethyl sulfoxide (DMSO) (30 ml) was added and the solution was stirred at 60° C. for 1 hour. After cooling to room temperature, (S)-4-benzyloxy-1-trityloxy-2-butanol (55.89 g, 0.132 mol) in DMSO (40 ml) was gradually dropped at room temperature to the solution and then the solution was stirred for 30 minutes. To the solution was gradually dropped 2-benzyloxyethyl methanesulfonate (33.4 g, 0.145 mol) in DMSO (40 ml) at room temperature and then the solution was stirred for 12 hours. To the reaction mixture was added water (120 ml) and the solution was extracted with ethyl acetate. The extract was washed with water (150 ml) twice and with saturated brine once, dried on sodium sulfate, filtered and condensed in vacuo. The residue was subjected to silica gel chromatography to give (S)-4-benzyloxy-2-(2-benzyloxyethoxy)-1-trityloxybutane (70.8 g, yield 97%).
