Stereoselectivity in the epoxidation of βγ-unsaturated carboxylic acids

Abstract

Epoxidation of the βγ-unsaturated acids (VII)–(IX) by peroxy-acids over a range of reaction conditions has been investigated. In non-basic solvents there is a significant tendency for preferential epoxidation cis to carboxy-group, which is more marked for (IX) with pseudoaxial CO₂H. This preference, which disappears in more basic solvents, is explained in terms of H-bonding between CO₂H and peroxy-acid in the transition state (XVI).