反应详情

α,α'-Dibromoxylene (30.3 g., 0.115 Mole) is dissolved in dry acetonitrile (250 ml.) and then, under nitrogen, the pyrrolidine enamine of 2,5-dimethylcyclopentanone (prepared from 2,5-dimethylcyclopentanone and pyrrolidine via the method of Stork) is added dropwise over one-half hour. The mixture is refluxed 2 days, cooled, water (100 ml.) is added; and the mixture is refluxed 1 hour, cooled, concentrated in vacuo, then extracted with ether (3×75 ml.). The combined extracts are washed with 10% HCl (50 ml.), brine (50 ml.), then dried and evaporated to yield 16 g. of solid, which recrystallized from dichloroethane-hexane gives pure title compound (9.7 g.). The mother liquors are chromatographed on silica gel (100 g.), eluting with ether-hexane (1:4) to give 5.8 g. more title compound, which yields 4.9 g. pure on crystallization from ether-hexane (64% total yield), m.p. 134°-135° C.

1. additionis added dropwise over one-half hour
2. temperatureThe mixture is refluxed 2 days
3. temperaturecooled
4. temperatureand the mixture is refluxed 1 hour
5. temperaturecooled
6. concentrationconcentrated in vacuo
7. extractionextracted with ether (3×75 ml.)
8. washThe combined extracts are washed with 10% HCl (50 ml.), brine (50 ml.)
9. customdried
10. customevaporated
11. customto yield 16 g
12. customof solid, which recrystallized from dichloroethane-hexane