Resolution by diastereomeric salts: Access to both enantiomers of racemic acid using the same enantiomer of resolving base

Abstract

Racemic carboxylic acid, a Diels‐Alder cycloadduct derived from 5‐bromo‐3‐phenyl‐α‐pyrone and acrylate dienophile, was resolved into enantiomers by diastereomeric salt crystallization. Quinidine was used as a sole resolving base. The salt of (+)‐acid crystallized from aqueous acetonitrile solution. Once this salt was separated by filtration, quinidine salt with (−)‐acid crystallized from mother liquor. As a result, both enantiomers of Diels‐Alder cycloadduct were isolated in high enantiomeric purity.