Enantioselective synthesis of orthogonally protected (2R,3R)-(−)-epicatechin derivatives, key intermediates in the de novo chemical synthesis of (−)-epicatechin glucuronides and sulfates

Abstract Ten orthogonally protected (−)-epicatechin and 3′- or 4′- O -methyl-(−)-epicatechin derivatives were prepared in a regiospecific and enantioselective manner. For each orthogonally protected (−)-epicatechin derivative, one specific phenolic hydroxyl was protected with a methoxymethyl (MOM) or p -methoxybenyzl (PMB) group and the remainder were protected as benzyl ethers. These uniquely protected (−)-epicatechin derivatives were designed to facilitate the regiospecific installation of a glucuronic acid or sulfate unit onto (−)-epicatechin after selective removal of the MOM or PMB protecting group to provide authentic standards of (−)-epicatechin glucuronides and sulfates.