Employing AC and DC Electrolysis to Modulate Electroenzymatic Pathways for Efficient and Stereoselective H-D Exchange

Stereoselective hydrogen isotope exchange (HIE) at chiral centers is an increasingly important strategy for preparing labeled molecules, yet its practical implementation depends on reliable control of nicotinamide cofactor regeneration. Here we introduce a redox-programmable electroenzymatic platform for stereoselective HIE based on electrode-controlled manipulation of the nicotinamide cofactor state. A wired ferredoxin-NADP⁺ reductase (FNR) electrode enables reversible electrochemical interconversion of NADP⁺ and its deuterated reduced form (NADPD) directly from D₂O. Coupling this cofactor cycling with enantioselective alcohol dehydrogenases (ADHs) establishes a reversible alcohol-ketone redox manifold that drives efficient and stereoselective H-D exchange at chiral alcohols. Stereochemical outcomes are programmed by the combined choice of paired electrolysis mode and enzyme configuration: direct-current electrolysis enables stereochemical editing with stereocomplementary ADHs, whereas alternating-current electrolysis supports rapid bidirectional cycling with a single ADH to achieve stereoretentive labeling. This strategy affords near-quantitative deuterium incorporation with high enantiopurity across a broad range of secondary alcohols.