Journal of the American Chemical Society, Vol.116, No.8, 3357-3366, 1994
Ellagitannin Chemistry, Preparative and Mechanistic Studies of the Biomimetic Oxidative Coupling of Galloyl Esters
The construction of strictly the (S)-hexahydroxydiphenyl (HHDP) unit via biomimetic cyclization of suitably protected glucose-derived digalloyl esters has been achieved in good yield. Studies on substrates of increasing complexity utilizing a range of oxidants (Pb(OAc)(4), VOF3, Tl2O3) have helped define the scope and limitations of this approach to ellagitannin synthesis. Computer modeling of key cyclization precursors helped elucidate the molecular-level structural details which undergird the Haslam/Schmidt biosynthesis model for this class of naturally occurring secondary plant metabolites.