Boron tribromide → 5-Amino-2-fluorophenol

Participants

Reaction Steps

To a stirred solution of 4-fluoro-3-methoxyaniline (4.80 g, 34 mmol) in dichloromethane (50 mL), at −10° C., was added a 4.0 M solution of boron tribromide in dichloromethane (20 mL, 80 mmol). The reaction mixture was allowed to warm to rt and stirring was continued for a further 15 h. The reaction mixture was quenched via the addition of methanol. After concentration under reduced pressure, the residue was taken up in water, basified with saturated sodium hydrogen carbonate solution, and extracted with ethyl acetate. The combined ethyl acetate layers were washed with brine, dried over MgSO4, and concentrated under reduced pressure to afford 5-amino-2-fluorophenol (4.00 g, 93%) as a solid which was taken on without further purification. 1H NMR (400 MHz, CDCl3) δ 6.87 (dd, J=9.2, 9.2 Hz, 1H), 6.35 (m, 1H), 6.16 (m, 1H), 5.09 (brs, 1H), 3.56 (brs, 2H); LC-MS (ESI) m/z 128 (M+H)+.

Provenance & Evidence