6-Bromo-3-fluoro-4-nitro-1-(phenylsulfonyl)-1H-indazole → 6-Bromo-3-fluoro-1-(phenylsulfonyl)-1H-indazol-4-amine

Reaction equation

[Br:1][C:2]1[CH:10]=[C:9]2[C:5]([C:6]([F:20])=[N:7][N:8]2[S:11]([C:14]2[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=2)(=[O:13])=[O:12])=[C:4]([N+:21]([O-])=O)[CH:3]=1>C(O)(=O)C.C(OCC)(=O)C.[Fe]>[Br:1][C:2]1[CH:3]=[C:4]([NH2:21])[C:5]2[C:6]([F:20])=[N:7][N:8]([S:11]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)(=[O:12])=[O:13])[C:9]=2[CH:10]=1

Participants

Procedure

6-Bromo-3-fluoro-4-nitro-1-(phenylsulfonyl)-1H-indazole (5.9 g) was suspended in acetic acid (60 ml) and iron powder (4.12 g) was added. The suspension was heated to reflux. After 2 h the reaction mixture was diluted with ethyl acetate (100 ml) and filtered through celite. The filter cake was washed well with ethyl acetate then the filtrate basified to pH 8-9. The biphasic system was then stirred for ˜5 min. The layers were then separated, the aq washed with ethyl acetate and the combined organics washed with brine, dried (magnesium sulphate), filtered and concentrated in vacuum to yield a crude loaded onto a 330 g silica cartridge, purified on a 0-100% ethyl acetate:cyclohexane gradient and the relevant fractions combined and concentrated to yield the title compound, 2.4 g as a yellow solid.