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1. 4-Bromo-2,6-difluorobenzonitrile (i-9a) (30 g, 138 mmol) was dissolved in anhydrous ethanol (300 mL) under nitrogen protection. 2. Hydrazine hydrate (NH2NH2-H2O) (27.6 g, 552 mmol) was slowly added dropwise with stirring at room temperature. 3. The reaction mixture was degassed, then heated to 90 °C and stirred to react for 2 hours. 4. Upon completion of the reaction, the mixture was cooled to room temperature and diluted with acetone (180 mL) and allowed to stand overnight. 5. The precipitated solid was collected by filtration and washed with dichloromethane (DCM) to afford the target compound, 6-bromo-4-fluoro-1H-indazol-3-amine (i-9b) (30 g, 94% yield), as a white solid. 6. The molecular ions were analyzed by LCMS (ESI), measuring the peak [M+H]+ was 230, which was consistent with the theoretically calculated value of C7H5BrFN3 .

[1] Patent: WO2014/28591, 2014, A2. Location in patent: Page/Page column 50
[2] Patent: US2015/210687, 2015, A1. Location in patent: Paragraph 0261
[3] Bioorganic and Medicinal Chemistry Letters, 2017, vol. 27, # 16, p. 3782 - 3786