Catalytic cathodic cyclodimerization of vinylarylsulfones

The cathodic cyclodimerization reaction of two vinylarylsulfones was investigated using cyclic voltammetry and UV-spectroelectrochemical techniques. The results indicate an E-CE sequence, where the chemical step is a dimerization anion radical-substrate. The proposed mechanism involved a catalytic cycle ((E) over right arrowT (E) over left arrow), based on the facts that (i) the reduction potential of the dimer is more negative than that of the monomer; (ii) cleavage rates of sulfone anion-radicals are slower than electron exchange rates. AM1-modeling of the reaction routes implying the anion radical-substrate dimerization that leads to the dimer anion radical supports the proposed reaction mechanism. (C) 2004 Elsevier B.V. All rights reserved.