Preparation of spirocyclic cyclopropyl ketones through condensation of epoxides with .beta.-keto phosphonates

Abstract

The β-keto phosphonate derivatives of several cyclic ketones have been shown to undergo condensation with epoxides upon treatment with base, affording spirocyclic cyclopropyl ketones. Moderate to resonable yields were obtained under sealed tube conditions with ethylene oxide, propylene oxide, and styrene oxide, and the substituted epoxides gave a single diastereomer in each case. The process can be viewed as an example of regiospecific geminal dialkylation, and cleavage of the cyclopropyl ring allows access to additional α,α-dialkylated ketones