At 0 °C, 1.50 g of (2R,3S,4S)-2-(hydroxymethyl)tetrahydrothiophene-3,4-diol was dissolved in 15 mL of N,N-dimethylformamide. To this solution, 2.00 g of 60% sodium hydride was added, the reaction temperature was kept at 5°C or lower and stirred for 1 hour. Subsequently, 4.50 mL of benzyl bromide was slowly added at 0°C. After addition, the reaction mixture was warmed to 25°C and stirring was continued for 3 hours. Upon completion of the reaction, the mixture was extracted by adding ethyl acetate and water to the mixture. The organic layer was separated, washed with saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure to give the crude product. The crude product was purified by column chromatography (eluent: hexane/ethyl acetate = 95/5 to 86/14) to give 2.31 g of (2R,3S,4S)-3,4-bis(benzyloxy)-2-((benzyloxy)methyl)tetrahydrothiophene.
