Potassium Hydroxide → tert-butyl 5-(difluoromethoxy)-3-iodo-1H-indazole-1-carboxylate

関与物質

反応手順

Diethyl bromodifluoromethylphosphonate (1.13 g, 4.22 mmol) was added in one portion to a cooled (−30° C.) solution of tert-butyl 5-hydroxy-3-iodo-1H-indazole-1-carboxylate and KOH (2.36 g, 42.2 mmol) in MeCN/H2O (20 mL/20 mL). The reaction mixture was allowed to warm to room temperature. After 20 min, the reaction mixture was diluted with EtOAc (15 mL), and the organic phase was separated. The water phase was extracted with EtOAc (10 mL). The combined organic layers were dried over Na2SO4. Evaporation of the solvent gave a crude product that was purified by column chromatography on silica gel eluting with petroleum ether/EtOAc (5:1) to give tert-butyl 5-(difluoromethoxy)-3-iodo-1H-indazole-1-carboxylate (0.41 g, 47% over two steps) as a white solid. 1H NMR (300 MHz, CDCl3): δ 8.13 (d, 1H, J=9.0 Hz), 7.39 (dd, 1H, J=9, 2.4 Hz), 7.23 (d, 1H, J=2.4 Hz), 6.57 (t, 1H, J=73.2 Hz), 1.73 (s, 9H).

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