[OH:1][CH2:2][C@@H:3]1[CH2:7][C@H:6]([S:8][C:9]([C:22]2[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=2)([C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=2)[C:10]2[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=2)[CH2:5][N:4]1[C:28]([O:30][CH2:31][C:32]1[CH:37]=[CH:36][C:35]([N+:38]([O-:40])=[O:39])=[CH:34][CH:33]=1)=[O:29].[CH3:41][S:42](Cl)(=[O:44])=[O:43].C(N(CC)CC)C>ClCCl>[CH3:41][S:42]([O:1][CH2:2][C@@H:3]1[CH2:7][C@H:6]([S:8][C:9]([C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=2)([C:22]2[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=2)[C:10]2[CH:11]=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH2:5][N:4]1[C:28]([O:30][CH2:31][C:32]1[CH:37]=[CH:36][C:35]([N+:38]([O-:40])=[O:39])=[CH:34][CH:33]=1)=[O:29])(=[O:44])=[O:43]To a solution of (2S,4S)-2-hydroxymethyl-1-(4-nitrobenzyloxycarbonyl)-4-(triphenylmethylthio)pyrrolidine (10.7 g) in dichloromethane (100 ml) were added methanesulfonyl chloride (1.44 ml) and triethylamine (3.06 ml) under ice-cooling, and the mixture was stirred at the same temperature for 1 hour. The reaction mixture was washed with saturated aqueous sodium chloride, dried over magnesium sulfate and evaporated in vacuo to give a residue The residue was chromatographed on silica gel (150 g) eluting with a mixture of dichloromethane and acetone (40:1 V/V). The fractions containing the desired compound were collected and evaporated in vacuo to give (2S,4S)-2-(methanesulfonyloxy)methyl-1-(4-nitrobenzyloxycarbonyl)-4-(triphenylmethylthio)pyrrolidine (10.39 g).
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