Synthesis
GENERAL STEPS: To an anhydrous THF solution of N-methoxy-N-methyl-1H-indazole-3-carboxamide (950 mg, 4.63 mmol, 1.1 eq.), the mixture was cooled to 0 °C. Methylmagnesium bromide (7.7 mL, 23.17 mmol, 5.0 eq.) was slowly added dropwise at 0 °C. After the dropwise addition, the reaction mixture was stirred at room temperature for 12 hours. Upon completion of the reaction, the reaction was quenched by the addition of NH4Cl solution (5 mL). Subsequently, the solvent was removed by distillation under reduced pressure and the obtained residue was purified by column chromatography (eluent: ethyl acetate/petroleum ether = 1/2) to afford 1-(1H-indazol-3-yl)ethanone (610 mg, 82.3% yield) as a yellow solid.
References
[1] Tetrahedron, 2007, vol. 63, # 2, p. 419 - 428
[2] Patent: WO2018/15818, 2018, A2. Location in patent: Paragraph 00237
[3] Patent: WO2018/64135, 2018, A1. Location in patent: Paragraph 0275-0278
[4] Patent: US2011/65700, 2011, A1. Location in patent: Page/Page column 17
[5] European Journal of Medicinal Chemistry, 2011, vol. 46, # 10, p. 5138 - 5145
