[Br:1][C:2]1[CH:10]=[CH:9][C:5]2[NH:6][CH:7]=[N:8][C:4]=2[CH:3]=1.[H-].[Na+].[N+:13]([C:16]1[CH:21]=[CH:20][C:19]([S:22](Cl)(=[O:24])=[O:23])=[CH:18][CH:17]=1)([O-:15])=[O:14].O>CN(C=O)C.C(Cl)Cl.CO.C(OCC)(=O)C>[Br:1][C:2]1[CH:10]=[CH:9][C:5]2[N:6]=[CH:7][N:8]([S:22]([C:19]3[CH:18]=[CH:17][C:16]([N+:13]([O-:15])=[O:14])=[CH:21][CH:20]=3)(=[O:23])=[O:24])[C:4]=2[CH:3]=1
5-Bromo-1H-benzimidazole (756 mg) was dissolved in anhydrous DMF (3 ml) and cooled in an ice bath. Sodium hydride (60% in mineral oil) (153 mg) was added in one portion. The reaction was stirred for 1 h, before addition of 4-nitrobenzenesulfonyl chloride (850 mg) in DMF (2 ml) to the reaction. The reaction was stirred for a further hour before warming to RT and addition of water (10 ml). The reaction was stirred vigorously then left at RT overnight. Ethyl acetate (ca. 10 ml) was added to the reaction mixture and was then vigorously stirred. The reaction was dissolved in DCM:methanol and passed through a 1 g SAX cartridge. The residue was purified on silica cartridge using cyclohexane:ethyl acetate with a 50-100% gradient. Fractions containing the product were combined and evaporated to dryness to afford the title compound, 401 mg.
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