CC(OI1(OC(C)=O)(OC(C)=O)O[C:12](=O)[C:11]2[CH:10]=C[CH:8]=[CH:7][C:6]1=2)=O.[C:23]([O:27][C:28]([N:30]1[CH2:34][C@@H:33]([CH3:35])[C@H:32]([OH:36])[CH2:31]1)=[O:29])([CH3:26])([CH3:25])[CH3:24]>ClCCl>[CH3:10][CH:11]([CH2:6][CH2:7][CH3:8])[CH3:12].[C:23]([O:27][C:28]([N:30]1[CH2:31][C:32](=[O:36])[CH:33]([CH3:35])[CH2:34]1)=[O:29])([CH3:26])([CH3:24])[CH3:25]Cool down a suspension of Dess Martin periodinane (1.1 g, 2.6 mmol) in dry dichloromethane (5 mL) under nitrogen with an ice bath and add a solution of trans-3-hydroxy-4-methylpyrrolidine-1-carboxylic acid tert-butyl ester (350 mg, 1.73 mmol) in dry dichloromethane (2 mL). Stir under nitrogen and allow to warm up to room temperature overnight. Add saturated aqueous sodium hydrogen carbonate, then saturated aqueous sodium thiosulfate and extract with dichloromethane. Combine the organic layers and wash with saturated aqueous sodium chloride, dry (magnesium sulfate), concentrate and chromatograph on silica gel, eluting with 0:100 to 40:60 ethyl acetate:2-methylpentane to give 3-methyl-4-oxopyrrolidine-1-carboxylic acid tert-butyl ester (240 mg, 70%). 1H NMR (300 MHz, CDCl3) δ 4.06-4.19 (1H, m), 3.84-3.98 (1H, m), 3.61-3.72 (1H, m), 3.17 (1H, dd, J=11.11, 9.04 Hz), 2.56-2.70 (1H, m, J=7.72 Hz), 1.49 (9H, s), 1.18 (3H, d, J=7.16 Hz), MS (ES): m/z=222 [M+Na].
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