Tributyltin Chloride → 5-(difluoromethoxy)-3-(tributylstannyl)-1H-indazole

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In a flask, 5-(difluoromethoxy)-3-iodo-1H-indazole (1.2 g, 2.93 mmol) was dissolved in THF (30 mL). The solution was cooled to −25° C. Isopropylmagnesium chloride (8.8 mL, 8.8 mmol, 1M in THF) was added drop-wise at −25° C. The reaction mixture was stirred at −25° C. for 20 min. Then chlorotributyltin (1.6 mL, 5.86 mmol) was added slowly. The reaction mixture was allowed to warm to room temperature and stirred for 1.5 h. The reaction mixture was quenched with saturated NH4Cl solution and then extracted with EtOAc (3×20 mL), organics were washed with water (10 mL), brine (2×10 mL) and dried over Na2SO4 and concentrated. The residue was purified by column chromatography on silica gel eluting with petroleum ether/EtOAc (8:1) to give 5-(difluoromethoxy)-3-(tributylstannyl)-1H-indazole (1.1 g, 79%) as an oil. 1H NMR (300 MHz, CDCl3): δ 7.52-7.46 (m, 2H), 7.19 (d, 1H, J=7.9 Hz), 6.51 (t, 1H, J=88.6 Hz), 1.68-1.57 (m, 6H), 1.45-1.14 (m, 12H), 0.93-0.84 (m, 9H).

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