[Si]([O:8][C@@H:9]1[CH2:13][CH:12]([CH:14]2[CH2:16][CH2:15]2)[N:11]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[C@H:10]1[CH:24]1[CH2:26][CH2:25]1)(C(C)(C)C)(C)C.CCCC[N+](CCCC)(CCCC)CCCC.[F-].CC(OI1(OC(C)=O)(OC(C)=O)OC(=O)C2C=CC=CC1=2)=O>C1COCC1>[CH:24]1([C@H:10]2[C:9](=[O:8])[CH2:13][CH:12]([CH:14]3[CH2:16][CH2:15]3)[N:11]2[C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[CH2:25][CH2:26]1(2S,3R)-tert-Butyl 3-(tert-butyldimethylsilyloxy)-2,5-dicyclopropylpyrrolidine-1-carboxylate (19) (412 mg, 1.08 mmol) was dissolved in THF (1 mL) and placed under nitrogen. TBAF (IM THF, 1.29 mL) was added and the reaction stirred for 2 hr. The reaction was concentrated in vacuo and used without further purification. This material was dissolved in CH2Cl2 (2 mL) and placed under nitrogen. Dess-Martin reagent (788 mg, 1.86 mmol) was added and the reaction quenched with sat. aq. NaHCO3 (2 mL) followed by sat. Na2S2O3 (2 mL) when complete as indicated by TLC monitoring. The organic layer was isolated and concentrated in vacuo. The resulting crude product was purified by column chromatography using EtOAc/hexane gradients to yield (2S)-tert-butyl 2,5-dicyclopropyl-3-oxopyrrolidine-1-carboxylate (20) (128 mg, 45% over two steps) as a yellow oil.
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