[Br:1][C:2]1[CH:3]=[C:4]([N+:17]([O-])=O)[C:5]2[C:9]([CH:10]=1)=[N:8][N:7]([CH:11]1[CH2:16][CH2:15][CH2:14][CH2:13][O:12]1)[CH:6]=2.[Cl-].[NH4+].C(O)C>[Fe].O.C(OCC)(=O)C>[Br:1][C:2]1[CH:3]=[C:4]([NH2:17])[C:5]2[C:9]([CH:10]=1)=[N:8][N:7]([CH:11]1[CH2:16][CH2:15][CH2:14][CH2:13][O:12]1)[CH:6]=26-Bromo-4-nitro-2-(tetrahydro-2H-pyran-2-yl)-2H-indazole (6 g, 18.40 mmol), iron filings (3.29 g, 58.9 mmol) and ammonium chloride (0.492 g, 9.20 mmol) were weighed to a 250 ml round-bottomed flask and ethanol (60 ml) then water (18 ml) was added. The reaction was heated to 80° C. for 2.5 hr. The reaction mixture was cooled. 100 ml Ethyl acetate and 50 ml water was added. There was no visible separation of layers so the reaction was evaporated to remove the ethyl acetate and ethanol. 250 ml Ethyl acetate was then added and the organic layer was washed with a further 50 ml water, before passing through a hydrophobic frit. The organic layer was evaporated to dryness to give 6 g crude material. The aqueous layer was further extracted with DCM and then ethyl acetate. The DCM extract was evaporated to dryness to give a small amount of impure product that was discarded. The 6 g batch of crude material was purified by column chromatography on silica (120 g silica column, ISCO companion technology) eluting with a gradient of 1-2% methanol in DCM over 25 minutes. Fractions containing desired material were combined and evaporated to dryness to afford the title compound (3.95 g).
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