[C:1]([O:4][CH:5]1[CH:9]([N:10]2[C:14]3[CH:15]=[C:16]([Cl:20])[C:17]([Cl:19])=[CH:18][C:13]=3[N:12]=[CH:11]2)[CH2:8][CH:7]([CH2:21][O:22][C:23](=[O:25])[CH3:24])[CH:6]1[O:26][C:27](=[O:29])[CH3:28])(=[O:3])[CH3:2].[Br:30]N1C(=O)CCC1=O>O1CCOCC1>[C:1]([O:4][CH:5]1[CH:9]([N:10]2[C:14]3[CH:15]=[C:16]([Cl:20])[C:17]([Cl:19])=[CH:18][C:13]=3[N:12]=[C:11]2[Br:30])[CH2:8][CH:7]([CH2:21][O:22][C:23](=[O:25])[CH3:24])[CH:6]1[O:26][C:27](=[O:29])[CH3:28])(=[O:3])[CH3:2](±)(1R*, 2S*, 3S*, 5S*)-3-(Acetoxymethyl)-5-(5,6-dichloro-1H-benzimidazol-1-yl)-1,2-cyclopentanediyl diacetate (4.20 g, 9.48 mmol) was refluxed in dry dioxane (25 mL) while freshly recrystallized N-bromosuccinimide (3.37 g, 18.9 mmol) was added all at once. After 5 minutes of reflux, volatiles were removed in vacuo. The residue was partitioned between water and chloroform. The chloroform layer was dried (sodium sulfate), and evaporated to an oil which was chromatographed on silica gel with elution by 1:1 hexanes-ethyl acetate. Resolidification from ethanol-water gave title compound as white powder (3.10 g, 63%), m.p. 157°-158.5° C.; 1H-NMR(DMSO-d6) identical to that of the sample described in Example 3.
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