Ellagitannin chemistry. First total synthesis of the 2,3- and 4,6-coupled ellagitannin pedunculagin

The biomimetic synthesis of pedunculagin (1) was accomplished through the sequential diastereoselective formation of two biphenyl C-C bonds. The synthesis strategy employed is predicated on extensive conformational modeling and involves initial oxidative coupling of the galloyl moieties at the O(2) and O(3) positions of an appropriately protected glucose-derived core, followed by installation and oxidative coupling of galloyl esters at the O(4) and O(6) positions.