Tributyltin Chloride → 6-fluoro-3-(tributylstannyl)-1H-indazole

Participants

Reaction Steps

To a solution of 6-fluoro-3-iodo-1H-indazole (8.6 g, 32.8 mmol) in THF (200 mL) at 0° C. was slowly added portionwise sodium hydride (60% in mineral oil, 1.58 g, 39.4 mmol). The reaction mixture was stirred at room temperature for 10 min then cooled to −10° C. and isopropylmagnesium chloride (2.0 M in THF, 19.7 mL, 39.4 mmol) was added. The reaction mixture was stirred at −10° C. for 30 min then additional isopropylmagnesium chloride (2.0 M in THF, 8.2 mL, 16.4 mmol) was added. The reaction mixture was stirred at −10° C. for 30 min then tributylchlorostannane (11.6 mL, 42.7 mmol) was slowly added. Stirring was continued at −10° C. for 20 min then at room temperature for 3 h. The reaction mixture was quenched with saturated aqueous NH4Cl then diluted with water and extracted with EtOAc (2×). The combined organics were washed with brine then dried over MgSO4 and concentrated. The residue was purified by silica gel chromatography with 10% to 20% EtOAc/heptane (0.5% Et3N) to afford 6.53 g (47%) of 6-fluoro-3-tributylstannanyl-1H-indazole as a light brown viscous oil. 1H NMR (CDCl3, 300 MHz): δ (ppm) 7.65 (dd, J=8.7, 5.3 Hz, 1H), 7.20 (dd, J=9.3, 2.1 Hz, 1H), 6.92 (td, J=9.0, 2.1 Hz, 1H), 1.53-1.67 (m, 6H), 1.28-1.43 (m, 6H), 1.20-1.28 (m, 6H), 0.89 (t, J=7.4 Hz, 9H).

Provenance & Evidence