Synergistic Action of Ascorbic Acid and Readily Accessible NHC^N Ligands for the Oxidation of Gold(I) With Electron‐Rich Aryldiazonium Salts

The synergistic action of ascorbic acid and NHC^N ligands enables the challenging oxidation of Au(I) with electron-rich aryldiazonium salts in the absence of a cocatalyst and/or irradiation. EPR, NMR, and x-ray analyses reveal the reaction to be triggered by a radical pathway facilitated by the ligand-assisted stabilization of the Au(III) center. The utility of this synergistic effect was demonstrated in a catalytic arylative carbocyclization, providing access to a 3,4-diaryl-2H-chromene containing two electron-rich aryl groups, a substitution pattern inaccessible by previous protocols.