Enantioselective Pd-Catalyzed Electrochemical Dearomative Allylation of Tropones: Construction of All-C Quaternary Stereocenters

A Pd-catalyzed electroreductive enantioselective dearomatization of tropones is documented. High levels of chemoselectivity toward the formation of seven-membered ring ketones featuring a stereochemically controlled all-carbon α-stereocenter are successfully accomplished by means of a Tsuji-Trost-like process (24 examples, regioselectivity >25:1, enantiomeric ratio of up to 96:4). Computational and electrochemical analyses allowed elucidation of the reaction manifold that involves initial reduction of the tropone motif and a subsequent chemo- and enantioselective allylation via an outer-sphere approach. In this way, a novel concept for the dearomatization of electron-poor scaffolds is disclosed by means of electrochemical reductive umpolung.