Mechanistic switch via subtle ligand modulation: Palladium-catalyzed synthesis of α,β-substituted styrenes via C-H bond functionalization

A new catalyst system able to efficiently perform the synthesis of styrenes via C-H bond functionalization and a subtle ligand modification are described. The high level of activity achieved allows for the synthesis of highly functionalized α,β-substituted styrenes, even the elusive E-configured trisubstituted olefins, in a regio- and stereoselective manner. Mechanistic expts. allowed for the identification of the corresponding synthetic intermediates.