(2S,3R,4S,5S,6R)-2-[4-chloro-3-[[4-(2,2-difluoroethoxy)phenyl]methyl]phenyl]-6-(hydroxymethyl)-2-methoxy-tetrahydropyran-3,4,5-triol 12e (4 g, 8.43 mmol) was dissolved in 40 mL dichloromethane, followed by addition of DMAP (103 mg, 0.84 mmol), TBSCl (1.4 g, 9.27 mmol) and imidazole (1.72 g, 25.3 mmol) in turn. The reaction mixture was stirred for 16 hours. 40 mL saturated sodium bicarbonate were added before the reaction mixture was stirred and partitioned. Thereafter, the organic extract was washed with 0.1 N hydrochloric acid (20 mL) and saturated sodium chloride solution (40 mL), dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated under reduced pressure to obtain the title compound (2S,3R,4S,5S,6R)-6-[(tert-butyl(dimethyl)silyl)oxymethyl]-2-[4-chloro-3-[[4-(2,2-difluoroethoxy)phenyl]methyl]phenyl]-2-methoxy-tetrahydropyran-3,4,5-triol 12f (4.96 g, pale yellow solid), yield: 100%.
