A METHOD OF EPIMERIZATION OF ALKYL CHRYSANTHEMATE

摘要

Cis-chrysanthemate esters are isomerized by contact with a Lewis acid, to transform the cis-chrysanthemate ester into trans-chrysanthemate ester through epimerization at C3-position. The starting cis-chrysanthemate ester may be of any optical isomer ratio of (+)-form to (-)-form, including racemic form. The process is particularly suitable for use in the preparation of a (+)-trans-chrysanthemate ester from which (+)-trans-chrysanthemic acid can readily be prepared, the latter being an important acid component of pyrethroidal insecticides.