Flow‐Enabled Direct Photochemical Functionalization of Aryl Fluorides

Direct functionalization of aryl fluorides remains challenging because of the exceptional strength of the CF bond and the reliance of existing methods on tailored catalysts or activated substrates. Here, we report a catalyst‐free photochemical strategy for the direct functionalization of electron‐rich fluoroarenes using UV irradiation in flow. A simple 3D‐printed microfluidic reactor paired with a commercially available UV source enables CF activation under operationally simple conditions, without the need for redox matching or external catalysts. The method accommodates a broad range of electron‐rich arenes and heteroarenes for CC bond formation and can be extended to CP bond formation using triethyl phosphite as a nucleophilic coupling partner. The continuous‐flow platform also enables direct scale‐up without re‐optimization. Mechanistic studies, including isotope‐labeling experiments, radical trapping studies, intramolecular cyclization probes, EPR spectroscopy, and DFT calculations, support a complex reaction manifold involving contributions from both heterolytic and homolytic CF cleavage pathways. This work establishes direct UV activation in flow as a simple and scalable platform for aryl fluoride diversification.