Total Synthesis of Cercidinin A

An ellagitannin, cercidinin A, was synthesized through both intramolecular coupling of gallates on a glucose moiety and double esterification of protected hexahydroxydiphenic acid to a diol. The total synthesis confirmed the revised structure of cercidinin A as 1,2,6‐tri‐ O ‐galloyl‐3,4‐( R )‐hexahydroxydiphenoyl (HHDP) β‐ D ‐glucose. This is the first synthesis of 3,4‐HHDP‐bridged ellagitannins and was achieved after overcoming two challenges: (1) full galloylation of β‐glucose hindered the formation of the 3,4‐HHDP group, and (2) the fully benzylated galloyl group, which is a routine component in ellagitannin synthesis, was not always appropriate. The solutions to these problems can be used to form a strategy for the synthesis of complex ellagitannins.