11C‐Cyanation of Aryl Fluorides via Nickel and Lithium Chloride‐Mediated C−F Bond Activation

Abstract

AbstractAryl fluorides are expected to be useful as radiolabeling precursors due to their chemical stability and ready availability. However, direct radiolabeling via carbon‐fluorine (C−F) bond cleavage is a challenging issue due to its significant inertness. Herein, we report a two‐phase radiosynthetic method for the ipso‐11C‐cyanation of aryl fluorides to obtain [11C]aryl nitriles via nickel‐mediated C−F bond activation. We also established a practical protocol that avoids the use of a glovebox, except for the initial preparation of a nickel/phosphine mixture, rendering the method applicable for general PET centers. This method enabled the efficient synthesis of diverse [11C]aryl nitriles from the corresponding aryl fluorides, including pharmaceutical drugs. Stoichiometric reactions and theoretical studies indicated a significant promotion effect of lithium chloride on the oxidative addition, affording an aryl(chloro)nickel(II) complex, which serves as a precursor for rapid 11C‐cyanation.