Condensation products derived from flavan-3-ol oak wood aldehydes reaction: 1. Structural investigation

In this first work, we report on a complete structural study of the condensation dimers formed in a wine like model solution (pH 3.5; H2O:EtOH, 88:12; 14 days of reaction in the dark) between a catechin and a representative oak wood aldehyde:furfuraldehyde. Of the four dimers expected, three were formed in sufficient quantity to be isolated by liquid chromatography. In this first study, the regio- and stereo-chemistry as well as the 3D structure of these compounds were obtained by using NMR and molecular modelling techniques.