Intramolecular cyclopropanation reaction of β-γ-unsaturated epoxides yields highly strained tricyclo[4,1,0,01,5]heptane compounds whose hydrolysis affords α-keto spiro cyclopropanes. Both steps of this one-pot reaction are stereospecific.
The intramolecularcyclopropanation of β,γ-unsaturated metalated epoxides derived from 11 yielded the highly strained tricyclic intermediates 7. The facile hydrolysis of the latter species afforded the α-keto spirocyclopropanes 8 in a stereospecific fashion. Indeed, the stereochemistry of the starting alkenes 11d−e governs the relative configuration of the cyclopropanes 8d−e. Furthermore, these spiro