[CH2:1]([O:3][C:4](=[O:28])[CH2:5][N:6]1[C:14]2[CH2:13][CH2:12][CH2:11][CH:10]([NH:15][S:16]([C:19]3[CH:24]=[CH:23][CH:22]=[C:21]([N+:25]([O-])=O)[CH:20]=3)(=[O:18])=[O:17])[C:9]=2[CH:8]=[N:7]1)[CH3:2]>C(O)(=O)C.C(O)C.ClCCl.[Zn]>[CH2:1]([O:3][C:4](=[O:28])[CH2:5][N:6]1[C:14]2[CH2:13][CH2:12][CH2:11][CH:10]([NH:15][S:16]([C:19]3[CH:24]=[CH:23][CH:22]=[C:21]([NH2:25])[CH:20]=3)(=[O:18])=[O:17])[C:9]=2[CH:8]=[N:7]1)[CH3:2]To a solution of [4-(3-nitro-benzenesulfonylamino)-4,5,6,7-tetrahydro-indazol-1-yl]-acetic acid ethyl ester (390 mg, 0.96 mmol) in acetic acid (3 mL) and ethanol (15 mL) was added zinc powder portionwise. After being heated at reflux for 2 hours, the mixture was cooled to room temperature, diluted with dichloromethane (30 mL), filtered through a glass funnel and concentrated in vacuo. The residue was purified by flash column (gradient elution, 0-5% methanol in dichloromethane) to afford [4-(3-amino-benzenesulfonylamino)-4,5,6,7-tetrahydro-indazol-1-yl]-acetic acid ethyl ester (300 mg, 83%) as a semisolid. MS cald. for C17H22N4O4S 378, obsd. (ESI+) [(M+H)+] 379.
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