Chemical‐Reductant‐Free Electrochemical Deuteration Reaction using Deuterium Oxide

We report a method for the electrochemical deuteration of α,β‐unsaturated carbonyl compounds under catalyst‐ and external‐reductant‐free conditions, with deuteration rates as high as 99 % and yields up to 91 % in 2 h. The use of graphite felt for both the cathode and the anode was key to ensuring chemoselectivity and high deuterium incorporation under neutral conditions without the need for an external reductant. This method has a number of advantages over previously reported deuteration reactions that use stoichiometric metallic reductants. Mechanistic experiments showed that O2 evolution at the anode not only eliminates the need for an external reductant but also regulates the pH of the reaction mixture, keeping it approximately neutral. It's a D‐all! The first catalyst‐free and chemical‐reductant‐free deuteration of alkene and alkynes was achieved through an electrochemical approach with graphite felt electrodes and deuterated water in an undivided cell under neutral conditions. Up to 99 % D incorporation and 91 % yield can be obtained, and the method is compatible with electron‐rich alkenes, heterocycles, epoxides, and protecting groups. A series of deuterated pharmaceutical compounds was prepared.