C([S:4][C@@H:5]1[CH2:9][N:8]([C:10]([O:12][CH2:13][C:14]2[CH:19]=[CH:18][C:17]([N+:20]([O-:22])=[O:21])=[CH:16][CH:15]=2)=[O:11])[C@H:7]([CH2:23][OH:24])[CH2:6]1)(=O)C.C[O-].[Na+].[C:28]1([C:34](Cl)([C:41]2[CH:46]=[CH:45][CH:44]=[CH:43][CH:42]=2)[C:35]2[CH:40]=[CH:39][CH:38]=[CH:37][CH:36]=2)[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1>CO.O1CCCC1.C(OCC)(=O)C>[OH:24][CH2:23][C@@H:7]1[CH2:6][C@H:5]([S:4][C:34]([C:41]2[CH:46]=[CH:45][CH:44]=[CH:43][CH:42]=2)([C:35]2[CH:40]=[CH:39][CH:38]=[CH:37][CH:36]=2)[C:28]2[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=2)[CH2:9][N:8]1[C:10]([O:12][CH2:13][C:14]1[CH:19]=[CH:18][C:17]([N+:20]([O-:22])=[O:21])=[CH:16][CH:15]=1)=[O:11]To a solution of (2S,4S)-4-acetylthio-2-hydroxymethyl-1-(4-nitrobenzyloxycarbonyl)pyrrolidine (15 g) in a mixture of methanol (150 ml) and tetrahydrofuran (150 ml) was added a 28% solution of sodium methoxide in methanol (8.95 ml) under ice-cooling and the mixture was stirred at the same temperature for 10 minutes. To the mixture was added triphenylmethyl chloride (12.39 g) on ice-bath, followed by stirring at the same temperature for 1 hour. The precipitates were filtered off and the filtrate was evaporated in vacuo to give a residue. The residue was dissolved in ethyl acetate (200 ml), washed with water, dried over magnesium sulfate, and concentrated under reduced pressure to give a syrup. The syrup was chromatographed on silica gel (200 g) eluting with a mixture of dichloromethane and acetone (9:1 V/V). The fractions containing the desired compound were collected and evaporated in vacuo to give (2S,4S)-2-hydroxymethyl-1-(4-nitrobenzyloxycarbonyl)-4-(triphenylmethylthio)pyrrolidine (22.24 g).
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