Universal Metal-Free Deborylation-Deuteration via Redox-Decoupled Tandem Flow Electrosynthesis

Flow electrochemical synthesis is a promising platform for constructing value-added targets such as d-labeled compounds. However, its efficiency and broader application are limited by the unproductive or kinetically mismatched counter half-reactions and architectural constraints of conventional flow cell architectures. Here, we report a redox-decoupled strategy within a single-cell tandem flow reactor that separates a classical substitutive deborylation-deuteration into sequential electrochemical steps. This approach enables the universal, metal-free deuteration of diverse organoboron species, including boronic acids, borate esters, and borates, across alkyl, (heterocyclic) aryl, alkenyl, and other derivatives (>100 examples). Using D2O as a cost-effective d-source, the system achieves excellent yields, d-incorporation, tolerance to the labile functional groups, and significantly improved Faradaic efficiency. The platform demonstrates industrial-grade durability with continuous operation for over 1200 h and enables scalable, unprotected synthesis of deuterated drug d-mexiletine. Overall, this strategy significantly expands the design space of flow electrochemistry, paving an exciting path toward green, economic, and efficient electrosynthesis.