[NH:1]1[C:9]2[C:4](=[CH:5][C:6]([C:10]#[N:11])=[CH:7][CH:8]=2)[CH:3]=[N:2]1.CO.[Br:14]Br.Cl>[OH-].[Na+]>[Br:14][C:3]1[C:4]2[C:9](=[CH:8][CH:7]=[C:6]([C:10]#[N:11])[CH:5]=2)[NH:1][N:2]=1A 2-L round bottomed flask was charged with 1H-indazole-5-carbonitrile (17.6 g, 123 mmol), 333 mL methanol (MeOH), 333 mL of 2.0 M aq. NaOH, and a solution of bromine (Br2, 54.7 g, 344 mmol, 2.80 equiv.) in 166 mL of 2.0 M aq. NaOH. The mixture was warmed on an oil bath to 40° C. (external temperature) for 6 h, and then cooled to room temperature in a water bath. The pH of the solution adjusted to ca. 5.5 with 103 mL of 4.0 M aq. HCl. The resulting precipitate was collected by filtration, washed with 200 mL of H2O, and dried. The product was purified by chromatography on 265 g of silica gel using 30–40% EtOAc in hexanes. This afforded the title compound (12.83 g, 47% yield): ES-MS (m/z) 222 [M+1]+.
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