[N+](=[C:3]([C:8]([O:10][CH:11]([C:16]([Cl:19])([Cl:18])[Cl:17])[CH:12]=[C:13]([CH3:15])[CH3:14])=[O:9])[C:4]([O:6][CH3:7])=[O:5])=[N-]>CCCCCCCC.C(OCC)(=O)C.[Cu]>[Cl:17][C:16]([Cl:19])([Cl:18])[CH:11]1[CH:12]2[C:3]([C:4]([O:6][CH3:7])=[O:5])([C:13]2([CH3:15])[CH3:14])[C:8](=[O:9])[O:10]1To a refluxing suspension of copper powder (6.6 g, 0.104 mole) in 320 ml of n-octane was added dropwise in one hour a solution of methyl (±)-3-methyl-1-trichloromethyl-2-butenyl diazomalonate (6.6 g, 0.02 mole, prepared as described above for the ethyl ester) in 80 ml of n-octane. The reaction mixture was heated for 21/2 hours under reflux and then filtered while hot. The n-octane was evaporated from the filtrate under vacuum to produce a residue which was dissolved in ethyl acetate. The solution was washed successively with aqueous 1 N hydrochloric acid, aqueous sodium bicarbonate, and aqueous sodium chloride. After drying the solution over magnesium sulfate, the ethyl acetate was removed by evaporation, yielding methyl (±)-4-trichloromethyl-6,6-dimethyl-2-oxo-3-oxabicyclo[3.1.0]-hexane-1-carboxylate (5.77 g, 96% yield) as an oil. Trituration of the oil with ether afforded the crystalline lactone; mp, 118°-120°.
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