Total synthesis of (−)-bis-8,8′-catechinylmethane isolated from cocoa liquor

An efficient synthesis of bis-8,8′-catechinylmethane, a dimeric flavanol linked through a methylene bridge, is described. Our strategy involved a regioselective coupling via a trifluoroacetic anhydride condensation reaction followed by ketone reduction to the methylene employing new conditions (lithium aluminum hydride and hexafluorophosphoric acid).