Electrochemical reductive coupling reactions of aliphatic nitroalkenes

Abstract

We describe how to selectively affect either β-to-β coupling (electrohydrodimerization) or coupling between the α and β centers of aliphatic nitroalkenes, the latter in a catalytic process that can be initiated both with and without electrochemistry. Of particular significance is our discovery of conditions that allow electrohydrodimerization to be conducted using aliphatic nitroalkenes bearing acidic protons. Thus, one can affect at will, either a catalytic α-to-β coupling or an electrohydrodimerization using substrates that bear acidic protons, as well as those that do not. We also describe both voltammetric and ESR studies of the simple 1-nitro-3,3-dimethyl-1-butene, as well as the results of quantum mechanical calculations that shed light upon the nature of radial anions derived from electron deficient olefins. Both calculation and experiment suggest that the reluctance of these materials to undergo electrohydrodimerization can be correlated with the low electron density on carbon and the corresponding high value on oxygen, of the radical anion.