Methanol → (1R)-2-bromo-1-phenylethanol

Participants

Reaction Steps

A 0.25 M tetrahydrofuran solution of (R)-4-cyclohexyl-5,5-diphenyl-2-methyl-1,3,2-oxazaborolidine (0.4 mL) (prepared as in example 12) was added to a dry flask containing borane dimethylsulfide complex (0.05 mL, 0.5 mmol) under nitrogen. The mixture was stirred at room temperature for I hour and then, a solution of bromoacetophenone (99.5 mg, 0.5 mmol) in dry tetrahydrofuran (3 mL) was added to the borane/(R)-4-cyclohexyl-5,5-diphenyl-2-methyl-1,3,2-oxazaborolidine complex over 20 minutes via a syringe pump. The reaction was stirred at room temperature for 2 hours. Methanol was added to quench the reaction and then the solvents were removed by evaporation. The residue obtained was dissolved in ethyl acetate, washed with 1M hydrochloric acid and filtered through a silica gel plug. The filtrate was concentrated to provide (R)-2-bromo-1-phenylethanol. The enantiomeric excess=96.2% and was measured by HPLC (Chiralcel OD-H column, mobile phase, hexane/isopropyl alcohol 9:1, flow rate=0.6 mL/min).

Provenance & Evidence