(-CATECHIN-ACETALDEHYDE CONDENSATION PRODUCTS IN RELATION TO WINE-AGING())

Dimers resulting from acetaldehyde-flavanol condensation were studied in an acidic hydroalcoholic medium (12% ethanol pH 3.2) in order to si mulate the conditions of wine tannin-transformation during the wine-ag eing process. One of the dimers was isolated after hemisynthesis and s tudied by mass spectrometry, NMR and molecular mechanics. Mass spectro metric analysis was in accordance with a dimeric structure with a CH-C H3 linkage. NMR showed the presence of a 6-8 (ethane-1,1-diyl)di(+)-ca techin. The carbon atoms, C-6 and C-8, involved in the linkage, have a n asymmetric conformation, with the two catechols in an equatorial pos ition. (C) 1997 Elsevier Science Ltd.