Carbon dioxide in organic synthesis: Electrochemical carboxylation of α,β,γ,δ-unsaturated ketones

The use of carbon dioxide as a raw material is now an interesting strategy in the fields of renewables, organic synthesis and green chemistry. Carbon dioxide can be exploited as a single-carbon-atom building block by its fixation into organic scaffolds with the formation of new C-C bonds (carboxylation processes).This strategy requires a reductive activation of the organic substrate leading to the formation of carbanion species, capable of reacting with carbon dioxide. In this thesis work, we considered electrochemical carboxylation of α,β,γ,δ -unsaturated carbonyl compounds; despite retaining interest in the pharmaceutical field, these compounds have never been considered in their reactivity with CO2. Optimization of the electrosynthetic process allowed to obtain the corresponding carboxylic acids in good yields (up to 40%) and selectivity for the δ -position (up to 12:1 with respect to the β -position). A mechanistic investigation by conducting the experiments at different temperatures allowed to provide an estimation of the activation energies for the carboxylation step.