Direct and Selective Electrocarboxylation of Styrene Oxides with CO 2 for Accessing β-Hydroxy Acids.

Highly selective and direct electroreductive ring-opening carboxylation of epoxides with CO 2 in an undivided cell is reported. This reaction shows broad substrate scopes within styrene oxides under mild conditions, providing practical and scalable access to important synthetic intermediate β-hydroxy acids. Mechanistic studies show that CO 2 functions not only as a carboxylative reagent in this reaction but also as a promoter to enable efficient and chemoselective transformation of epoxides under additive-free electrochemical conditions. Cathodically generated α-radical and α-carbanion intermediates lead to the regioselective formation of α-carboxylation products.