Lithium triethylborohydride → (2R,3R)-3-(tert-Butyldimethylsilanyloxy)-2-hydroxymethylpyrrolidine-1-carboxylic acid tert-butyl ester

To (2S,3R)-3-(tert-Butyl-dimethyl-silanyloxy)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester (51A) (8.05 g, 22.39 mmol) in THF (90 mL) at −78° C. was added a 1 M solution of Super-Hydride® in THF (112 mL, 112 mmol) in five portions over 15 min The cold bath was removed and the reaction was allowed to warm to rt. After 3 h, the reaction was poured into a 1-L Erlenmeyer flask and was carefully quenched with ice while stirring and then diluted with EtOAc. The layers were separated and the organic layer washed with 1 M H3PO4, NaHCO3 and brine, dried (MgSO4), filtered and concentrated. The residue was diluted with CH2Cl2, stirred with silica gel overnight, then concentrated and purified via flash chromatography eluting with 30% EtOAc/hexane to obtain the title compound (6.70 g) as a clear oil.