Aromatic arylation via palladacycles: interception of reaction intermediates

The palladium-catalysed reaction of iodobenzene with norbornene was carried out in the presence of an excess of methyl acrylate in order to intercept palladium-bonded aryl groups. Species of this kind result from a complex sequence of norbornene insertion into arylpalladium bonds, aromatic substitution and arylation of the palladacycle thus formed, followed by a variety of steps including new norbornene insertion and its eventual expulsion when steric hindrance is generated by the process.