Nucleophilic ring opening of epoxides by carbanions : Novel formation of cyclopropane derivatives in a non-polar solvent

Abstract

Nucleophilic ring-opening of epoxides 2( a-d) with carbanions of different steric requirements under refluxing benzene afforded a single stereoisomer of the cyclopropane derivatives 4. The same reaction under refluxing ethanol gave the normal products, i.e. the trans-lactones 6. Mechanism and high stereoselectivity observed in the novel cyelopropane formation, and regiospecific cleavage of the cyclopropane carboxylic acids (in 4) have also been discussed in detail.