Synthesis
General procedure for the synthesis of 5-amino-N-tert-butoxycarbonylindazole from 5-nitroindazole: 10% Pd-C catalyst (0.054 g, 0.051 mmol in Pd) and the carbamate from Example 105 (2.647 g, 10.1 mmol) were suspended in 95% ethanol, and the system was degassed under reduced pressure and the reaction was carried out under hydrogen atmosphere. After 23 hours of reaction, the solvent was removed using a rotary evaporator. Ethyl acetate (20 mL) was added to the reaction mixture and after filtration, the filtrate was slowly concentrated on a rotary evaporator to give 2.335 g (100% yield) of brown solid product.LC-MS (ESI) m/z 134 [M-Boc + H]+.
References
[1] Patent: WO2006/135383, 2006, A2. Location in patent: Page/Page column 123-124
[2] Patent: WO2012/146724, 2012, A2
[3] Patent: US2014/57942, 2014, A1
[4] Patent: WO2014/68035, 2014, A1
[5] Asian Journal of Chemistry, 2014, vol. 26, # 22, p. 7539 - 7543
