Synthesis
General procedure for the synthesis of (1-methyl-1H-indazol-4-yl)methanol from 1-methyl-1H-indazole-4-carboxaldehyde: To a solution of 1-methyl-1H-indazole-4-carboxaldehyde (180 mg, 1.12 mmol) in tetrahydrofuran (THF, 10 mL) was added sodium borohydride (NaBH4, 85 mg, 2.24 mmol) in batches at room temperature. The reaction mixture was stirred at room temperature for 1 hour. After completion of the reaction, it was acidified to pH 3 with dilute hydrochloric acid and extracted with ethyl acetate (EtOAc). The organic layers were combined, washed sequentially with saturated sodium bicarbonate solution and brine, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to afford the crude product (1-methyl-1H-indazol-4-yl)methanol (191 mg), which could be used for the next reaction without further purification.
References
[1] Patent: WO2013/102142, 2013, A1. Location in patent: Paragraph 0159
[2] Patent: WO2013/102145, 2013, A1. Location in patent: Paragraph 0213
[3] Patent: US2015/344483, 2015, A1. Location in patent: Paragraph 0416; 0417
