Synthetic Studies of Proanthocyanidins. Highly Stereoselective Synthesis of the Catechin Dimer, Procyanidin-B3

Abstract

  A stereoselective synthesis of benzylated procyanidin-B3, a condensed catechin dimer, is described. Condensation of 5,7,3′,4′-tetrabenzylcatechin with (2R,3S,4S)-5,7,3′,4′-tetrabenzyloxy-3-acetoxy-4-methoxyflavan as an electrophile in the presence of TiCl₄ led to octabenzylated procyanidin-B3 stereoselectively.