Site-selective Hydrogenation/Deuteration of Benzylic Olefins Enabled by Electroreduction Using Water

Abstract

We describe an operationally simple and user-friendly protocol that allows the site-selective hydrogenation and deuteration of di-, tri- and tetrasubstituted benzylic olefins by electroreduction while other groups prone to hydrogenation are present. The radical anionic intermediates react with the most inexpensive hydrogen/deuterium source H2O/D2O. Our method overcomes many limitations that arise from previously reported electroreductive hydrogenations. The applicability of this reaction is demonstrated by a broad substrate scope (>50 examples) that focuses on functional group tolerance and sites that are affected by metal-catalyzed hydrogenation (alkenes, alkynes, protecting groups).