Activation of Aryl and Vinyl Triflates by Palladium and Electron Transfer – Electrosynthesis of Aromatic and α,β-Unsaturated Carboxylic Acids from Carbon Dioxide

The electrochemical reduction of aryl and vinyl triflates in the presence of CO2 and a catalytic amount of palladium results in the formation of aromatic and α,β-unsaturated carboxylic acids. Aryl and vinyl triflates usually undergo palladium-catalysed cross-coupling reactions with nucleophiles. Their reactivity has been reversed in the presence of an electron source, so that they react with electrophiles such as CO2. The reaction proceeds through an activation of the C–O bond of the aryl or vinyl triflate by oxidative addition to a palladium(0) complex, followed by an activation by electron transfer of the thus formed aryl- or vinylpalladium(II) complexes.