Synthesis
General procedure for the synthesis of 5-bromo-3-iodo-1H-indazole from 5-bromo-1H-indazole: To a solution of 5-bromo-1H-indazole (5.0 g, 25.4 mmol, 1.0 eq.) in anhydrous DMF (15.0 mL) was added sequentially, protected by nitrogen, KOH (4.3 g, 76.1 mmol, 3.0 eq.) and iodine (12.9 g, 50.75 mmol, 2.0 equiv). The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was diluted with ice water and then extracted with ethyl acetate (50 mL x 2). The organic layers were combined, washed sequentially with aqueous Na2S2O3 and brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure to afford the crude product 5-bromo-3-iodo-1H-indazole (8.0 g, 97.9% yield), which could be used for the next reaction without further purification.
References
[1] Molecules, 2018, vol. 23, # 8,
[2] Journal of Medicinal Chemistry, 2017, vol. 60, # 6, p. 2361 - 2372
[3] Patent: WO2017/98328, 2017, A2. Location in patent: Paragraph 00213
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[5] Letters in Drug Design and Discovery, 2013, vol. 10, # 7, p. 625 - 631
