Catalytic Performance of a Phosphapalladacycle Bearing a Biphenyl Moiety, Possessing an sp3 C-Pd Bond, toward the Heck Coupling Reaction

A new palladacycle, in which the palladium is bonded both to the phosphorus and to an SP3- carbon, has been used for the Heck reaction of mono- and disubstituted olefins with aryl bromides. The S-shaped kinetic curve in the reaction between alpha-methylstyrene and bromobenzene in the presence of amine as base shows that the reactions probably follow a conventional Pd(0)/Pd(II) cycle rather than a Pd(II)/Pd(IV) cycle.