Synthesis
The general procedure for the synthesis of indazole-3-acetic acid from 3-amino-3-(2-nitrophenyl)propionic acid was as follows: 3-amino-3-(2-nitrophenyl)propionic acid (15 g, 71.4 mmol) was dissolved in a mixture of 5% sodium hydroxide solution (85 mL) and 85% hydrazine hydrate (5 mL). The reaction mixture was heated to 80°C, followed by the slow addition of nickel ruanne (25 mg in two portions). After the reaction was carried out for half an hour, the reaction mixture was cooled and the pH was adjusted to ≈2 with 6 N hydrochloric acid.The precipitated solid precipitate was collected by filtration and dried under vacuum to give 6.86 g of yellow solid product in 54.5% yield.
References
[1] Patent: EP2781508, 2014, A1. Location in patent: Paragraph 0099
[2] Patent: US2014/303186, 2014, A1. Location in patent: Paragraph 0224
[3] Journal of Medicinal Chemistry, 1992, vol. 35, # 12, p. 2155 - 2162
