Electro-carboxylation of 2-bromoisobutyramides. A useful synthetic way to ester-amides of 2,2-dimethylmalonic acid

The electroreduction of protic 2-bromoisobutyramides was studied in acetonitrile in the presence of carbon dioxide by means of cyclic voltammetry and controlled-potential electrolysis. The electrogeneration of the ?-carbanion is followed by a fast and quantitative carboxylation at the tertiary carbon, despite the N-H acidity of the starting compounds. The carboxylate anion was trapped both after and during the electrolysis procedure by alkylating reagents. High yields of ester-amides of 2,2-dimethylmalonic acid were obtained at both mercury and platinum cathodes.