[Si:1]([O:8][C@H:9]1[CH2:13][N:12]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[C@H:11]([CH2:21]OS(C2C=CC(C)=CC=2)(=O)=O)[CH2:10]1)([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2].C([BH-](CC)CC)C.[Li+]>C1COCC1.C([O-])(O)=O.[Na+].O>[Si:1]([O:8][C@H:9]1[CH2:13][N:12]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[C@H:11]([CH3:21])[CH2:10]1)([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2]tert-Butyl (2S,4R)-4-{[tert-butyl(dimethyl)silyl]oxy}-2-({[(4-methylphenyl)-sulfonyl]-oxy}methyl)pyrrolidine-1-carboxylate (6.32 g, 13.01 mmol) was dissolved in THF (50 mL) under nitrogen and cooled to 0° C. Lithium triethylborohydride solution (Super Hydride, 14.3 mL, 1.0 M in THF) was added dropwise and the mixture was then slowly warmed to room temperature. After 2 hours, TLC revealed half conversion. More lithium triethylborohydride solution (12.0 mL) was added and the solution stirred at room temperature overnight. Diluted with NaHCO3/H2O and extracted twice with ethyl acetate. Washed organic layer with NH4Cl/H2O and brine. Dried organic extracts over MgSO4, filtered and concentrated to give a colorless oil. Chromatographed on silica gel eluting with 10% ethyl acetate/hexane. Pure fractions were combined to give the desired product as a colorless oil, 3.74 g (91%). LC/MS (M+Na)+ m/z=338.2. 1H NMR (CDCl3) δ 4.34 (m, 1H), 3.95 (m, 1H), 3.35 (m, 2H), 1.98 (m, 1H), 1.65 (m, 1H), 1.47 (s, 9H), 1.20 (bs, 3H), 0.87 (s, 9H), 0.06 (s, 6H).
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