反应详情

温度

0 °C

(1S, 2R)-(+)-Norephedrine (7.78 g, 51 mmol), toluene (150 mL), and trimethylboroxine (4.8 mL) were combined at ambient temperature and stirred for 5 days. Water, toluene and excess boroxine were distilled off until about 70 mL volume remained. The reaction was chased with toluene (3×90 mL), and the remainder of toluene removed under vacuum to afford the oxazaborolidine as a pale yellow oil (8.71 g, 98%). 1H NMR (C6D6) δ; 7.36-6.98 (m, 5H), 5.33(d, J=8 Hz, 1H), 3.43 (dq, J=8 Hz, J=6 Hz, 1H), 2.72 (bs, 1H, 0.37 (s, 3H), 0.36(d, J=6 Hz, 3H). To a solution of α-tetralone (2.92 g, 19.7 mmol), THF (80 mL), and the oxazaborolidine derived from norephedrine (218 mg, 1.2 mmol) under a nitrogen atmosphere was added borane methylsulfide complex (2M in THF, 7.0 mL, 14 mmol) over 75 min. After the addition was complete, the contents stirred for an additional 15 min, cooled to 0° C., and quenched with methanol (27 mL). After stirring the quenched reaction for 18 hrs the solvents were removed under vacuum, the residual oil was dissolved in methylene chloride (50 mL), washed with pH 4 phosphate buffer (50 mL), water (50 mL), treated with magnesium sulfate, and the solvent was removed under vacuum to give 3.16 g (80% ee) of the (S) tetralol as a colorless oil.

1. additionAfter the addition
2. customquenched with methanol (27 mL)
3. stirringAfter stirring
4. customthe quenched reaction for 18 hrs the solvents
5. customwere removed under vacuum
6. dissolutionthe residual oil was dissolved in methylene chloride (50 mL)
7. washwashed with pH 4 phosphate buffer (50 mL), water (50 mL)
8. additiontreated with magnesium sulfate
9. customthe solvent was removed under vacuum