Ellagitannin Chemistry. The First Total Chemical Synthesis of an Ellagitannin Natural Product, Tellimagrandin I

Tellimagrandin I was synthesized by two different biogenetically patterned routes. One route featured diastereoselective galloyl ester coupling between the O(4) and O(6) galloyl moieties in a glucose-derived substrate bearing additional protected galloyl groups on O(2) and O(3). The second route relied on a completely diastereoselective and regioselective Pb(OAc)₄-based oxidative coupling exclusively between the O(4) and O(6) galloyl esters in a glucose-derived substrate featuring oxidation sensitive galloyl groups on O(2)-O(6). Molecular mechanics-based conformational analysis provides a rationale for the observed selectivity.