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Abstract
Three compounds were isolated from the base-catalyzed reaction products of (−)-epicatechin at pH 12 and 40°C. From the results of the NMR and CD measurements, these were revealed to be the enantiomers of catechinic acid, catechinic acid stereoisomer and diarylpropanol-catechinic acid dimer formed from the base-catalyzed reactions of (+)-catechin. Thus, it has been demonstrated that both rearrangement and dimerization reactions as well as epimerization take place in the base-catalyzed reaction of (−)-epicatechin, similar to that of (+)-catechin. These results support that the quinone methide intermediate is formed during the base-catalyzed reactions, and the configuration of the hydroxyl group at C-3 should influence significantly the stereoselectivity of the subsequent reactions.