ELECTROCHEMICAL AND PHOTOCATALYTIC C–H FUNCTIONALIZATION: A DECADE OF PROGRESS TOWARD ATOM-ECONOMIC LATE-STAGE MODIFICATION

The direct functionalization of C–H bonds represents one of the most powerful and atom-economical strategies in modern organic synthesis, enabling the conversion of ubiquitous, inert C–H bonds into valuable C–C and C–heteroatom bonds without requiring prefunctionalized substrates. Over the past decade, electrochemical and photocatalytic approaches have emerged as transformative platforms for C–H functionalization, offering sustainable alternatives to traditional methods that rely on stoichiometric oxidants, precious metal catalysts, and harsh reaction conditions. This review provides a comprehensive overview of the progress achieved in electrochemical and photocatalytic C–H functionalization from 2013 to 2023, with particular emphasis on the paradigm shift from precious metal catalysts (Pd, Rh, Ir, Ru) to earth-abundant 3d metals (Ni, Fe, Co, Cu). We critically examine the development of paired electrolysis strategies that simultaneously harness anodic oxidation and cathodic reduction, the integration of flow chemistry for scalable continuous-flow transformations, and the application of green chemistry metrics—including E-factor and atom economy—to evaluate the sustainability of these methodologies. The translational potential of these approaches for pharmaceutical and agrochemical late-stage functionalization is discussed, alongside current limitations and unresolved challenges. Finally, we offer perspectives on emerging trends, including electrophotocatalysis, artificial intelligence-driven reaction optimization, and the integration of renewable energy sources for sustainable chemical synthesis.