To an ice-cold suspension of Dess-Martin periodinane (50.0 g, 118 mmol) in anhydrous CH2Cl2 (350 mL) under argon (Ar) was added a solution of the compound from Step A (36.2 g, 75 mmol) in anhydrous CH2Cl2 (200 mL) dropwise over 0.5 h. The reaction mixture was stirred at 0° C. for 0.5 h and then at room temperature for 3 days. The mixture was diluted with anhydrous Et2O (600 mL) and poured into an ice-cold mixture of Na2S2O3.5H2O (180 g) in saturated aqueous NaHCO3 (1400 mL). The layers were separated, and the organic layer was washed with saturated aqueous NaHCO3 (600 mL), water (800 mL) and brine (600 mL), dried (MgSO4), filtered and evaporated to give the title compound (34.2 g) as a colorless oil, which was used without further purification in Step C below.
