Arylation of Secondary Phosphines with Diaryliodonium Salts under Metal‐Free and Non‐Photochemical Conditions

Abstract A metal‐ and irradiation‐free approach for the direct arylation of secondary phosphines has been developed. The reaction employs diaryliodonium salts as electrophilic aryl‐transfer reagents, effecting the P−Ar bond‐formation in a single step, under mild conditions, using t ‐BuOK as a base and DMSO as a solvent. The protocol furnishes expedient access to diverse unsymmetrical triarylphosphines and, upon a one‐pot oxidation, the corresponding triarylphosphine oxides. Experimental and computational studies support the inner sphere aryl‐transfer mechanism through a reductive coupling at the hypervalent iodine center. The calculations also point to a key role played by potassium ions, providing extra stabilization to the P−C bond‐forming transition state by binding the reactants via cation‐π interactions.