Electron-transfer oxidation of Organo-cuprates with Benzophenone: Synthesis of Biaryls

A mild and simple way to synthesize Biaryls from aryl bromides via formation of organo-cuprate complexes has been developed. The Organo-cuprates {Ar2CuMgBr.Mg(I)Br}, generated from Arylmagnesium bromide and half equivalent of copper(I) iodide in dry THF at lower temperature under nitrogen, underwent electron-transfer oxidation with an aryl ketone benzophenone producing homo-coupled Biaryls in moderate yields. Aryl bromides either with electron-donating or with electron-withdrawing substituents were smoothly transformed into the corresponding Biaryls through formation of aryl Grignard reagents and Organo-cuprate complexes in a one pot reaction under this electron-transfer oxidation procedure.