反应详情

5.65 g (31.8 mmol) of N-bromosuccinimide are added portionwise while stirring to a solution of 5 g (31.6 mmol) of (R)-3,7-dimethyl-1-octanol and 9.05 g (34.5 mmol) of triphenylphosphine in 20 ml of methylene chloride. The temperature is held below 25° by occasional cooling of the reaction vessel. After 30-minutes stirring at room temperature, the solvent is removed on the rotary evaporator. The residue is washed out several times with n-hexane, then filtered and again rinsed with n-hexane. The combined n-hexane phases are concentrated on the rotary evaporator and the crude product is chromatographed on 200 g of silicagel with n-hexane. Distillation in the bulb-tube at 105°/15 Torr gives 6.1 g (87%) of (R)-1-bromo-3,7-dimethyloctane; [α]D20 =-5.0 (c=0.82, CHCl3).

1. customis held below 25°
2. temperatureby occasional cooling of the reaction vessel
3. customthe solvent is removed on the rotary evaporator
4. washThe residue is washed out several times with n-hexane
5. filtrationfiltered
6. washagain rinsed with n-hexane
7. concentrationThe combined n-hexane phases are concentrated on the rotary evaporator
8. customthe crude product is chromatographed on 200 g of silicagel with n-hexane
9. distillationDistillation in the bulb-tube at 105°/15 Torr