[CH2:1]([O:4][C:5]([N:7]1[CH2:11][C@H:10]([O:12][S:13]([CH3:16])(=[O:15])=[O:14])[CH2:9][C@H:8]1[CH2:17]OS(C1C=CC(Cl)=CC=1)(=O)=O)=[O:6])[CH:2]=[CH2:3].[C:29]1(=[O:39])[NH:33][C:32](=[O:34])[C:31]2=[CH:35][CH:36]=[CH:37][CH:38]=[C:30]12.[K].C(OCC)(=O)C>CN(C)C=O>[CH2:1]([O:4][C:5]([N:7]1[CH2:11][C@H:10]([O:12][S:13]([CH3:16])(=[O:14])=[O:15])[CH2:9][C@H:8]1[CH2:17][N:33]1[C:32](=[O:34])[C:31]2=[CH:35][CH:36]=[CH:37][CH:38]=[C:30]2[C:29]1=[O:39])=[O:6])[CH:2]=[CH2:3]To a solution of (2S,4R)-1-allyloxycarbonyl-2-p-chlorobenzenesulfonyloxymethyl-4-methanesulfonyloxypyrrolidine (23.7 g: ca. 50 mmole) in dimethylformamide (50 ml), potassium phthalimide (10.2 g: 55 mmole) is added in a nitrogen atmosphere, and the mixture is stirred at 60° C. for 3.5 hours. The reaction mixture is poured into a stirring mixture of ice water (500 ml) and ethyl acetate (500 ml). The organic layer is successively washed with water (4 times) and saturated brine, dried over magnesium sulfate, and concentrated in vacuo. The residue is recrystallized from a mixture of n-hexane and toluene. The solid is filtered off and the filtrate is purified by silica gel chromatography (toluene-ethyl acetate) to give crude (2S,4R)-1-allyloxycarbonyl-2-phthalimidomethyl-4-methanesulfonyloxypyrrolidine (12.41 g). Yield: 61%. Colorless oil.
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