Conformationally restricted arene intermediates in the intermolecular heck arylation of vinylarenes

The NMR observation of o-benzylpalladium intermediates at low temperature, formed by reaction of arylpalladium diphosphine cations with simple vinylarenes, indicates restricted rotation in the adjacent aryl ring. The stability of the intermediate is greater in the dppp than in the dppf series. By a combination of NMR, techniques, it was possible to characterise the intermediate, and to consider permissible structures.