Electroenzymatic Oxidative Desymmetrization by Engineered Thiamine-Dependent Enzymes for the Enantioselective Synthesis of Axially Chiral Biaryls

While biocatalysis and electrochemistry each offer unique advantages, such as enzyme selectivity and traceless electron use, their integration for unlocking new enzyme function remains limited. Here, we report a new-to-nature electroenzymatic desymmetrization strategy that enables the enantiodivergent synthesis of biaryls bearing axial chirality. By synergistically combining protein engineering and mediated electrolysis, we repurpose thiamine-dependent enzymes for the highly efficient biocatalytic desymmetrization of biaryl dialdehydes, achieving high enantioselectivity (up to >99% e.e., with enantiodivergence accessible in some cases), excellent yield (up to 99%), and low enzyme loading (down to 0.1 mol %, up to 930 TON). Mechanistic investigations confirm that electrochemically generated enzyme-bound radicals are key to this unnatural reactivity, and the engineered protein scaffolds provide precise enantiodiscrimination while preventing detrimental overoxidation. This work showcases the potential of synergistic electroenzymatic synthesis as a powerful platform for unlocking new enzyme reactivity, offering a compelling alternative to established methods such as photobiocatalysis and artificial enzymes.