First regiocontrolled synthesis of procyanidin B6, a catechin dimer with rare connectivity: a halo-capping strategy for formation of 4,6-interflavan bonds.

The first regiocontrolled synthesis of procyanidin B6, a dimer with a rare 4,6-interflavan linkage, is described. Regioselective linking was achieved by the halo-capping strategy followed by removal of all the benzyl protecting groups and the halo-caps by one-pot hydrogenolysis.