Methyl (+/-)-3-methyl-1-trichloromethyl-2-butenyl diazomalonate → Methyl 4-trichloromethyl-6,6-dimethyl-2-oxo-3-oxabicyclo[3.1.0]hexane-1-carboxylate

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Reaction Steps

To 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 1N 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°.

Provenance & Evidence