Synthesis
Under nitrogen protection, 4-bromo-2-fluorobenzonitrile (5 g, 25.13 mmol) was dissolved in 20 mL of n-butanol, followed by hydrazine hydrate (1.04 mL, 50.26 mmol). The reaction mixture was heated to reflux and kept for 4 hours. Upon completion of the reaction, it was cooled to room temperature and a large amount of solid was observed to precipitate. The solid product was collected by diafiltration and the filter cake was washed with petroleum ether to remove impurities. Finally, the resulting white solid was dried to give 4.759 g of the target product 6-bromo-1H-indazol-3-amine in 85.7% yield.
References
[1] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 14, p. 4579 - 4584
[2] Bioorganic and Medicinal Chemistry Letters, 2010, vol. 20, # 6, p. 1985 - 1989
[3] Patent: CN106032359, 2016, A. Location in patent: Paragraph 0044; 0045; 0046
[4] Bioorganic and Medicinal Chemistry, 2018, vol. 26, # 3, p. 747 - 757
[5] Patent: CN106146493, 2016, A. Location in patent: Paragraph 0452; 0453; 0454; 0455
