Enantiomerism in natural procyanidin polymers: use of epicatechin as a chiral resolution reagent

Abstract

Procyanidin polymers isolated from Palmae species contain 2,3-cis 5,7.3′,4′-tetrahydroxyflavan-3-ol units predominantly of the abnormal (2S,3S) configuration, but also containing about 25% of units with a (2R,3R) configuration; the proportion of each enantiomer was determined by the stereo- and regio-specific condensation of each unit's carbocation with (2S,3S)-(+)-or (2R,3R)-(–)-epicatechin and resolution of the diastero-isomeric C(4)–C(8) linked epicatechin dimers.