To a solution of (R)-1-[(3R,5R)-5-(3,4,5-trifluorophenyl)morpholine-3-yl]ethanol (2 g) in tetrahydrofuran (20 mL) was added saturated sodium bicarbonate water (20 mL) and benzyl chloroformate (1.31 mL). After stirring the reaction solution at room temperature for 16 hours, benzyl chloroformate (1.33 mL) was further added thereto, and the mixture was then stirred for another 20 hours. The resultant solution was diluted with water and ethyl acetate. The organic layer was partitioned, washed with brine, and then dried over anhydrous magnesium sulfate. Solvent was removed by distillation under reduced pressure, and the resulting residue was purified by silica gel column chromatography (heptane/ethyl acetate), to thereby obtain the titled compound (880 mg). The physical properties of this crude product were as follows.
