Yield:404827-77-6 94%

Reaction Conditions:

with hydrazine hydrate in butan-1-ol at 120; for 4 h;

Steps:

1.3.1. Synthesis of 6-bromo-1H-indazole-3-amine (11)

A mixture of 4-bromo-2-fluorobenzonitrile 10 (6.00 g, 30.0 mmol) and 80% hydrazine hydrate (2.32 mL, 60.0 mmol) in n-butanol (25 mL) was heated at 120 for 4 h. After reactant consumed completely, the precipitate that formed was filtered, washed with appropriate n-heptane for twice, and dried in vacuum to obtain the desired product 11 as a white solid powder (5.93 g, 94%). ¹H NMR (600 MHz, DMSO-d6) δ 11.50 (s, 1 H), 7.65 (d, J = 9.0 Hz, 1 H), 7.42 (s, 1 H), 7.03 (d, J = 8.4 Hz, 1 H), 5.46 (s, 2 H).

References:

Wang, Xing-Rong;Wang, Shuai;Li, Wen-Bo;Xu, Kai-Yan;Qiao, Xue-Peng;Jing, Xue-Li;Wang, Zi-Xiao;Yang, Chang-jiang;Chen, Shi-Wu [European Journal of Medicinal Chemistry,2021,vol. 213,art. no. 113192] Location in patent:supporting information