Synthesis of Selectively Substitutedortho-Vinylbiphenyls by Palladium-Catalysed Reaction ofortho-Substituted Aryl Iodides with Olefins

In the presence of Pd(OAc) 2 and norbornene as catalysts, ortho-substituted aryl iodides and terminal olefins react to afford selectively substituted ortho-vinylbiphenyl derivatives in good yields. The reaction proceeds through a series of steps including norbornene insertion and C-H activation with formation of pallada-cycles able to promote arylation of their aromatic part. Norbornene deinsertion then leads to the selective formation of a palladium-bonded biphenylyl group able to react with terminal olefins.