[C:1]([O:5][C:6]([NH:8][C@@H:9]([C@@H:22]([O:25][C@@H:26]([CH2:28][CH2:29][CH:30]=[CH2:31])[CH3:27])[CH2:23][CH3:24])[C:10]([N:12]1[CH2:16][C@H:15]([OH:17])[CH2:14][C@H:13]1[C:18]([O:20]C)=[O:19])=[O:11])=[O:7])([CH3:4])([CH3:3])[CH3:2].C1COCC1.[OH-].[Li+]>CO>[C:1]([O:5][C:6]([NH:8][C@@H:9]([C@@H:22]([O:25][C@@H:26]([CH2:28][CH2:29][CH:30]=[CH2:31])[CH3:27])[CH2:23][CH3:24])[C:10]([N:12]1[CH2:16][C@H:15]([OH:17])[CH2:14][C@H:13]1[C:18]([OH:20])=[O:19])=[O:11])=[O:7])([CH3:2])([CH3:4])[CH3:3]To a round-bottom flask equipped with a stir bar was added (2S,4R)-methyl 1-((2S,3S)-2-((tert-butoxycarbonyl)amino)-3-((R)-hex-5-en-2-yloxy)pentanoyl)-4-hydroxypyrrolidine-2-carboxylate (all material from step 2, 1.39 mmol), THF (5 mL) and MeOH (5 mL). To the solution was added aq. lithium hydroxide (2.0 M, 4.51 mmol). The mixture was stirred at room temperature for 16 h; then was concentrated to afford an aqueous solution. This solution was acidified and then transferred to a separatory funnel. The solution was twice extracted with EtOAc. The combined organics were washed with brine; dried over MgSO4; filtered; then concentrated in vacuo to afford (2S,4R)-1-((2S,3S)-2-((tert-butoxycarbonyl)amino)-3-((R)-hex-5-en-2-yloxy)pentanoyl)-4-hydroxypyrrolidine-2-carboxylic acid as a white solid (489 mg).
Loading…