(R)-(-)-2-溴-1-苯基乙醇

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: The procedure as in Example 3 was repeated except that 7.5 g of 2-bromo-acetophenone was employed as a substrate in place of 7.5 g of 2-chloro-acetophenone to give 4.2 g of (S)-2-bromo-1-phenyl ethanol (b.p. 85° C./0.5 mmHg). The product had a specific rotatory power [α]D25 +48.7° (C=1, chloroform) and an optical purity of 97% enantiomer excess by an HPLC analysis.

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: (S)-2-amino-2-cyclohexyl-1,1-bis-(4-methoxyphenyl)ethanol (71.2 mg, 0.2 mmol), dry tetrahydrofuran (2 mL) and borane dimethylsulfide complex (1 00 μL, 1.0 mmol) were added to a dry flask under at atmosphere of nitrogen. The mixture was stirred at room temperature for 1.5 hours to form (R)-4-cyclohexyl-5,5-bis-(4-methoxy)phenyl-1,3,2-oxazaborolidine. A solution of bromoacetophenone (199 mg, 1.0 mmol) in dry tetrahydrofuran (4 mL) was added to the borane/(R)-4-cyclohexyl-5,5-bis-(4-methoxy)phenyl-1,3,2-oxazaborolidine complex at the rate of 9 mL/hr by means of a syringe pump. The resulting mixture was stirred at room temperature for an additional 1.5 hours. Methanol was added to quench the reaction and then the solvent was removed by evaporation. The resulting residue was chromatographed on silica gel (hexane/ethyl acetate, 25:1) and combination of the like fractions followed by removal of the solvent gave (S)-2-bromo-1-phenylethanol (170 mg, 96.6% ee). The enantiomeric excess was measured by HPLC (Chiralcel OD-H column, mobile phase, hexane/2-propanol 9:1, flow rate=0.7 mL/min). to quench the reaction the solvent was removed by evaporation The resulting residue was chromatographed on silica gel (hexane/ethyl acetate, 25:1) and combination of the like fractions followed by removal of the solvent