[Br:1][C:2]1[CH:10]=[CH:9][C:8]([C:11](=[O:13])[NH2:12])=[C:7]2[C:3]=1[C:4]([CH2:14][CH:15]([N+:21]([O-])=O)[C:16]([O:18][CH2:19][CH3:20])=[O:17])=[CH:5][NH:6]2.Cl.[OH-].[Na+]>C(O)(C)C.C1COCC1.CCOC(C)=O.[Zn]>[NH2:21][CH:15]([CH2:14][C:4]1[C:3]2[C:7](=[C:8]([C:11](=[O:13])[NH2:12])[CH:9]=[CH:10][C:2]=2[Br:1])[NH:6][CH:5]=1)[C:16]([O:18][CH2:19][CH3:20])=[O:17]A solution of ethyl 3-(4-bromo-7-carbamoyl-1H-indol-3-yl)-2-nitropropanoate (4.6 g, 11.97 mmol) in isopropanol (200 mL) and THF (100 mL) was cooled in an ice bath and treated portionwise with zinc dust (8.85 g, 135 mmol), followed by 1 M aqueous HCl (150 mL) in portions. The mixture was stirred at room temperature for 3 h, then treated with NaOH pellets and 1 M aqueous NaOH to pH 9-10. The mixture was diluted with THF and EtOAc, stirred for 15 min and filtered through a CELITE® pad. The solids were rinsed with EtOAc, THF, and NaHCO3 (aq). The filtrates were concentrated to remove most of the organic solvents, and the aqueous residue was extracted with EtOAc. The combined extracts were washed with brine, dried and concentrated to provide the desired product as an off-white solid (3.65 g, 86% yield). LCMS (M+H)+ m/z 353.8, 355.8.
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