Methods in synthesis of flavonoids.: Part 2: High yield access to both enantiomers of catechin

Resolution of racemic synthetic tetra-O-benzylcatechin 2 is described, through the formation of esters 5 and 6 derived from dibenzoyl-l-tartaric acid. The diastereoisomer of the natural series 6 was separated by crystallization, the other one being an oil. This process allowed us to prepare enantiomerically pure (+)-catechin 8 in high yield. The pure isomer in the ent-series 9 could be obtained, following the same scheme of reactions.