反应详情

154.65 g (0.65 mol) of racemic 6-cyclohexyl-2-isopropyl-4-hexenoic acid and 210.5 g (0.65 mol) of anhydrous quinine are dissolved in 1 liter of methanol. The mixture is concentrated by evaporation and the residue is recrystallised from ether hexane. The crystallisate is filtered with suction and thoroughly washed with cold hexane. The salt is treated with 1N HCl and the acid is extracted with ether. Concentration by evaporation yields 6-cyclohexyl-2(R)-isopropyl-4-hexenoic acid of 90% ee. If the quinine salt is recrystallised a second time from ether/hexane before the treatment with HCl, the (R)-acid obtainable therefrom has a purity of more than 95% ee.

1. concentrationThe mixture is concentrated by evaporation
2. customthe residue is recrystallised from ether hexane
3. filtrationThe crystallisate is filtered with suction
4. washthoroughly washed with cold hexane
5. additionThe salt is treated with 1N HCl
6. extractionthe acid is extracted with ether
7. concentrationConcentration
8. customby evaporation