Synthesis
General procedure for the synthesis of 6-bromo-3-methylindazole from 4-bromo-2-fluoroacetophenone: Hydrazine hydrate (1.65 ml, 34.09 mmol) was added to a 1,2-ethylene glycol (25 ml) solution of intermediate 94 (3.7 g, 17.04 mmol) at room temperature. After 12 hours of reaction, the reaction mixture was cooled to room temperature, quenched with water, the precipitated solid was filtered and dried under vacuum to afford 6-bromo-3-methylindazole as a colorless solid (2.5 g, 72% yield). The product was characterized by 1H-NMR (δppm, DMSO-d6, 400 MHz): δ12.74 (s, 1H), 7.67 (d, J=5.8 Hz, 1H), 7.65 (s, 1H), 7.19 (dd, J=8.6, 1.4 Hz, 1H), 2.46 (s, 3H).
References
[1] Patent: US2011/118257, 2011, A1. Location in patent: Page/Page column 98
[2] Patent: WO2010/54279, 2010, A1. Location in patent: Page/Page column 119-120
[3] Patent: WO2010/59658, 2010, A1. Location in patent: Page/Page column 200
[4] Patent: WO2012/37132, 2012, A1
[5] Patent: WO2015/42397, 2015, A1. Location in patent: Paragraph 0001196
