Boron tribromide → 2',6'-Dichlorobiphenyl-2-ol

Participants

Reaction Steps

To a solution of 2′,6′-dichloro-1,1′-biphenyl-2-yl methyl ether (5.83 g, 0.023 mol) in anhydrous dichloromethane (100 mL) at 0° C. under nitrogen was added a solution of boron tribromide (1.0 M in dichloromethane, 27.6 mL, 0.0276 mol) dropwise over 40 minutes via a syringe pump. The reaction mixture was then stirred at room temperature for 17 hours, then quenched by the addition of absolute ethanol (50 mL). The mixture was stirred at room temperature for 1.5 hours then concentrated under reduced pressure to afford a dark oil. The oil was dissolved in 2.0 M aqueous sodium hydroxide solution (200 mL) and the resulting milky suspension extracted with diethyl ether (200 mL). The separated aqueous phase was then cooled to 0° C. and acidified to pH 1 by the addition of concentrated hydrochloric acid. The resulting milky suspension was extracted with ethyl acetate (300 mL), the separated organic phase washed with water (200 mL) and saturated brine (200 mL), dried over magnesium sulfate and concentrated under reduced pressure to afford a yellow oil. Purification by flash chromatography using a solvent gradient of 3 to 15% ethyl acetate in hexane gave 4.99 g (91%) of 2′,6′-dichloro-1,1′-biphenyl-2-ol as a white solid. MS (EI) m/z 238 (M+).

Provenance & Evidence