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

Highly selective and direct electroreductive ring-opening carboxylation of epoxides with CO 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 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.