Synthesis
5-Fluoro-1H-indazole (2.0 g, 14.0 mmol) was used as raw material and dissolved in DIVIF (50 mL). To this solution, iodine (7.46 g, 28.0 mmol) and potassium hydroxide (2.4 g, 42 mmol) were added sequentially at 0 °C. The reaction mixture was stirred at 0 °C for 0.5 h and then gradually warmed up to room temperature. The reaction process was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was filtered and the filtrate was concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate=3/1) to afford 5-fluoro-3-iodo-1H-indazole (3.7 g, yield: 96.1%) as a white solid. The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ=13.64 (s, 1H), 7.63 (dd, J=4.8,4.4 Hz, 1H), 7.38-7.30 (m, 1H), 7.20 (dd, J=6.4,2.4 Hz, 1H).
References
[1] Patent: WO2018/132372, 2018, A1. Location in patent: Paragraph 01229
[2] Patent: WO2018/188590, 2018, A1. Location in patent: Paragraph 00437
[3] Synthesis, 2011, # 19, p. 3089 - 3098
[4] Journal of Medicinal Chemistry, 2014, vol. 57, # 12, p. 5419 - 5434
[5] Molecules, 2018, vol. 23, # 8,
