The Evolution of Pd⁰/PdII-Catalyzed Aromatic Fluorination

-filled glovebox, limiting the practicality of the method. Thus, a preformed wax capsule was designed to isolate the catalyst and reagents from the atmosphere and permit benchtop storage and setup. This new technology thus removes the requirement to employ a glovebox for the aromatic fluorination process and other air-sensitive protocols. In every catalyst system that we have studied to date, we observed the formation of regioisomeric fluoride side products. Through deuterium labeling studies it was found that they likely arise from a deprotonation event resulting in the formation of HF and a Pd-benzyne intermediate. Through an investigation of the mechanism of this undesired pathway, a new ligand was designed that substantially reduces the formation of the aryl fluoride regioisomer and even allows room-temperature Ar-F reductive elimination from a Pd(II) intermediate.