Effects of lithium ion-pairing on the electrochemical oxidation of 4-hydroxycinnamate derivatives

New insights into the electrochemical oxidative coupling of 4-hydroxycinnamate derivatives are delineated through the variation of the nature of the supporting electrolyte. In particular, replacement of a tetraethylammonium salt by a lithium salt markedly modified the outcome of the reaction, thus allowing the isolation of different coupling products. This effect could be ascribed to lithium ion-pairing phenomena, which affected both the starting materials and the bis-quinonemethide species generated during the oxidative coupling process.