To a mixed solution consisting of benzyl[(1R)-2-hydroxy-1-(1-hydroxycyclopropyl)ethyl]carbamate (900 mg) and 2,2,6,6-tetramethylpiperidine 1-oxyl (39.2 mg) in acetonitrile (5 mL) and phosphate buffer (pH 6.8, 5 mL) were simultaneously added dropwise 0.033M aqueous sodium hypochlorite solution (2.17 mL) and 2M aqueous sodium chlorite solution (3.58 mL) over 30 min. The reaction mixture was stirred at 35° C. for 2 days, and to the reaction mixture was added saturated aqueous sodium thiosulfate solution at room temperature. The mixture was adjusted with 8N aqueous sodium hydroxide solution to about pH at room temperature, and to the reaction mixture was added a small amount of diisopropyl ether. The reaction mixture was vigorously stirred at room temperature for 30 min, and the aqueous layer was separated and adjusted with 6N hydrochloric acid to about pH 2 at room temperature. The reaction mixture was added to water, and the mixture was extracted with ethyl acetate. The organic layer was separated, washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. To a solution of the residue, 50% aqueous dimethylamine solution (323 mg) and N-ethyl-N-(1-methylethyl)propan-2-amine (925 mg) in DMF (5 mL) was added O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (1361 mg) at room temperature. The reaction mixture was stirred at room temperature for 4 hr, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was separated, washed with water and saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (NH, ethyl acetate/hexane) to give the title compound (190 mg).
