Enantioselective Synthesis of Biphenols from 1,4-Diketones by Traceless Central-to-Axial Chirality Exchange

A method for the enantioselective synthesis of biphenols from readily prepared 1,4-diketones is reported. Key to the success of this method is the highly selective transfer of central to axial chirality during a double aromatization event triggered by BF(3)·OEt(2). On the basis of X-ray crystallographic data, a stereochemical model for this chirality exchange process is put forth.