C-H Functionalization via Photo-and Electrochemistry in Flow: A Review

Abstract

The direct activation and functionalization of C-H bonds represent a cornerstone of modern synthetic chemistry, aiming for step-and atom-economical routes to complex molecules. However, traditional methods often rely on stoichiometric oxidants or harsh conditions in terms of sustainability and selectivity challenges. Photo-and electrochemistry trigger a rapid surge of research interests as they supply light or electricity as traceless reagents, also possess the advantages of simple operation and tunable selectivity. Flow technology further enables the precise reaction control over multistep transformations, improved reaction reproducibility, enhanced safety, and the easy integration of photochemical and electrochemical steps. Taking advantages of continuous-flow photo-and electrochemistry can help chemists to expand the chemical space available for C-H functionalization. This review highlights the application of continuous-flow strategies in C-H functionalization, and showcases photo/electrochemical examples with different functional group transformations or reaction patterns for both C(sp 3 )-H/C(sp 2 )-H bonds in flow systems. By highlighting the enhanced performance, scalability, and mechanistic insights afforded by flow chemistry, we aim to illuminate the potential of this synergistic platform and inspire its broader application in the C-H functionalization field or even chemical synthesis and pharmaceutical manufacturing.