Hydroxylation of ring A of flavan-3-ols: Influence of the ring A substitution pattern on the oxidative rearrangement of 6-hydroxyflavan-3-ols

Article abstract of DOI:10.1055/s-2006-950224

A general procedure for the oxidation of catechin derivatives is described, leading to the introduction of a new hydroxyl group at C-6. This procedure has been used for the synthesis of a number of 6-hydroxy flavan-3-ols, including elephantorrhizol, a natural flavan-3-ol exhibiting a fully substituted A ring. The substitution at C-8, albeit of poor influence on the course of this oxidation reaction, has been demonstrated to be preponderant for the further spontaneous oxidation and rearrangement of 6-hydroxy-flavan-3-ols into p-benzoquinones. The whole procedure allows the preparation of 6-alkyl substituted benzoquinones derived from catechin. Georg Thieme Verlag Stuttgart.