Despite the increasing demand for efficient and sustainable chemical processes, the development of scalable systems using biocatalysis for fine chemical production remains a significant challenge. We have developed a scalable flow system using immobilized enzymes to facilitate flavin-dependent biocatalysis, targeting as a proof-of-concept asymmetric alkene reduction. The system integrates a flavin-dependent Old Yellow Enzyme (OYE) and a soluble hydrogenase to enable H2-driven regeneration of the OYE cofactor FMNH2. Molecular hydrogen was produced by water electrolysis using a proton exchange membrane (PEM) electrolyzer and introduced into the flow system via a designed gas membrane addition module at a high diffusion rate. The flow system shows remarkable stability and reusability, consistently achieving >99% conversion of ketoisophorone to levodione. It also demonstrates versatility and selectivity in reducing various cyclic enones and can be extended to further flavin-based biocatalytic approaches and gas-dependent reactions. This electro-driven continuous flow system, therefore, has significant potential for advancing sustainable processes in fine chemical synthesis.@en

Peroxygenases offer an attractive means to address challenges in selective oxyfunctionalization chemistry. Despite this, their application in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant H₂O₂. Often atom-inefficient peroxide generation systems are required, which show little potential for large-scale implementation. Here, we show that visible-light-driven, catalytic water oxidation can be used for in situ generation of H₂O₂ from water, rendering the peroxygenase catalytically active. In this way, the stereoselective oxyfunctionalization of hydrocarbons can be achieved by simply using the catalytic system, water and visible light.

@en