A 25 mL round bottom flask equipped with a magnetic stir bar was charged with 1.980 g (5.00 mmol) of the product of Step B dissolved in 9.0 mL acetone. To the reaction mixture was added 0.702 g (5.99 mmol) of 4-methylmorpholine N-oxide dissolved in 2 mL water followed by 1.6 mL (0.26 mmol) of an osmium tetroxide solution (4 wt % in water). The reaction mixture was stirred 1.5 h at room temperature at which point TLC analysis (25% ethyl acetate-hexanes) indicated complete consumption of the starting material. The reaction mixture was quenched with excess 10% aqueous sodium bisulfite, then partitioned between water and ethyl acetate in a separatory funnel. The organic layer was washed with water, separated, then dried (MgSO4), filtered and evaporated in vacuo. The residual oil was redissolved in 12 mL of 1:1 tetrahydrofuran-water in a 25 mL round bottom flask. To this solution was added 1.282 g (5.99 mmol) of sodium periodate and an aditional 3 mL of tetrahydrofuran. After stirring for approximately 30 min at room temperature, a precipitate formed. Stirring was continued for 1.5 h, at which point TLC analysis (50% ethyl acetate-hexanes) revealed a new less polar product spot. The mixture was suspended between ethyl acetate and water and extracted. The organic layer was separated, dried (MgSO4), filtered and evaporated in vacuo. The residual clear oil was used in the next step without further purification.
