METHOD FOR PREPARING AN OPTICALLY PURE BENZOFURAN CARBOXYLIC ACID AND USE THEREOF FOR PREPARING EFAROXAN

摘要

A novel method for preparing an optically pure 2-ethyl-2,3-dihydro-benzofurancarboxylic acid derivative of general formula (II) is described, wherein R is a hydrogen atom, a halogen, a lower alkyl, lower alkoxy or hydroxy radical. The method comprises separating the racemic mixture by selective crystallisation with the suitable optically pure enantiomer of 2-phenylglycinol, in a suitable solvent, whereafter the optically pure, crystallised acid of formula (II) is isolated and recovered. The invention also provides the optically pure 2-ethyl-2,3-dihydro-benzofurancarboxylic acid derivative thus obtained and the use thereof for the preparation of an optically pure derivative of efaroxan.