[OH:1][C@@H:2]1[CH2:6][N:5]([C:7]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8])[C@H:4]([C:14]([O:16][CH3:17])=[O:15])[CH2:3]1.S(=O)(O)[O-].C([N+](CCCC)(CCCC)CCCC)CCC.[OH-].[Na+].O.[Br:42][CH2:43][CH2:44]Br>ClCCl>[Br:42][CH2:43][CH2:44][O:1][C@@H:2]1[CH2:6][N:5]([C:7]([O:9][C:10]([CH3:11])([CH3:12])[CH3:13])=[O:8])[C@H:4]([C:14]([O:16][CH3:17])=[O:15])[CH2:3]10.98 g (4 mmol) of 1-tert-butyl 2-methyl (2S,4S)-4-hydroxypyrrolidine-1,2-dioate (ALDRICH) was dissolved in 36 ml of 1,2-dibromoethane and cooled in an ice-bath. After addition of 1.36 g (4 mmol) of tetrabutylammonium bisulphite, 18 ml of 50% strength aqueous sodium hydroxide solution are added, and the mixture is stirred on ice for 2 hours and at room temperature overnight. After addition of 200 ml of water and 200 ml of dichloro-methane, the organic phase was washed once more with water, dried over sodium sulphate and filtered, and the filtrate was concentrated. The resulting crude product is chromatographed on silica gel using a dichloromethane/ethyl acetate gradient, and the appropriate fractions are combined and concentrated. Yield: 60 mg (4.3%)
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