[Si](O[CH2:9][C@H:10]([CH2:26][CH2:27][O:28]S(C)(=O)=O)[CH2:11][C@H:12]1[CH2:16][O:15][C:14]([CH3:18])([CH3:17])[N:13]1[C:19]([O:21][C:22]([CH3:25])([CH3:24])[CH3:23])=[O:20])(C(C)(C)C)(C)C.CCN(CC)CC.C(O)=O>C1COCC1.CC(=O)OCC>[CH3:18][C:14]1([CH3:17])[N:13]([C:19]([O:21][C:22]([CH3:23])([CH3:24])[CH3:25])=[O:20])[C@@H:12]([CH2:11][C@H:10]2[CH2:26][CH2:27][O:28][CH2:9]2)[CH2:16][O:15]1To a solution of (S)-tert-butyl 4-((S)-2-((tert-butyldimethylsilyloxy)methyl)-4-(methylsulfonyloxy)butyl)-2,2-dimethyloxazolidine-3-carboxylate (6.2 g) in 200 mL of THF was added TEAF. The reaction mixture was stirred for 12 h under reflux. The mixture was diluted with EA, washed with water back extracted EA. The combined organic layer was washed with brine, filtered, and concentrated. The crude product was purified by flash column to give the pure product (S)-tert-butyl 2,2-dimethyl-4-(((S)-tetrahydrofuran-3-yl)methyl)oxazolidine-3-carboxylate (2.4 g, 67%).
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