Br[CH2:2][C:3]1[C:4]([CH2:9]Br)=[CH:5][CH:6]=[CH:7][CH:8]=1.[CH3:11][CH:12]1[CH2:16][CH2:15][CH:14]([CH3:17])[C:13]1=[O:18].N1CCCC1.O>C(#N)C>[CH3:11][C:12]12[C:13](=[O:18])[C:14]([CH3:17])([CH2:15][CH2:16]1)[CH2:9][C:4]1[CH:5]=[CH:6][CH:7]=[CH:8][C:3]=1[CH2:2]2
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.
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