Electrochemically Triggered Hole-Catalytic Benzylic Substitution Reaction at a Polymer Chain Containing β-O-4 Linkage

Abstract Organic electrosynthesis enables clean, sustainable, and unique molecular transformations; however, its application to polymeric materials is restricted by their sterically demanding nature, which hinders quantitative electron transfer at the electrode surface. Herein, we report, for the first time, a hole-catalytic reaction triggered via anodic oxidation as a key strategy for achieving a high degree of electrochemical transformation in polymeric materials. Careful molecular and reaction design enabled hole-catalytic benzylic substitution, with an 88% degree of substitution, in a sterically hindered polymer, via an electrolytically generated radical cation. Mechanistic studies revealed that through-space delocalization of holes between neighboring aromatic systems contributes significantly to the stabilization of the radical cation species and intra-chain hole transfer. Thus, this study establishes hole catalysis as an effective strategy for the electrochemical transformation of polymers, which may aid the design of sustainable electrosynthetic strategies for functional macromolecules.