Electroreduction of methyl 2-bromo-2-phenylpropanoate on a vitreous carbon electrode: meso- and DL-dimethyl 2,3-dimethyl-2,3-diphenylsuccinate

Abstract

The electrochemical reduction of ethyl α-bromophenylacetate (1) and methyl 2-bromo-2-phenylpropanoate (5) in dry dimethylformamide on a vitreous carbon electrode has been studied. Dimeric products are formed as a consequence of controlled potential electrolysis of (1) and (5) on a reticulated vitreous carbon electrode. By this route, meso- and DL-diethyl 2,3-diphenylsuccinate and -dimethyl 2,3-dimethyl-2,3-diphenylsuccinate are obtained from ester (1) and (5), respectively. A triester is also obtained among the products. The spectral data (n.m.r., mass spectra) show the structure of this triester to be almost certainly MeO₂C·CMePh·C₆H₄·CMeCO₂Me·CMePh·CO₂Me (9). To explain the results, a mechanism is proposed, involving the formation of dimer (10) as an intermediate.