Synthesis and Reactivity of Palladium Complexes Featuring a Diphosphinoborane Ligand

Synthetic access to the zerovalent palladium complexes {[(o-Ph2PC6H4)(2)BPh]Pd(L)} (L = pyridine (8a), 2,6-lutidine (813)) is reported. Structural characterization and DFT analysis of 8a revealed a strong Pd -> B interaction, which appears to inhibit oxidative addition reactions. Activation of allyl acetate is possible by reversible transfer of the acetate leaving group to the ligand's borane functionality. Catalytic activity in the allylic substitution of allyl acetate with HNEt2 is sensitive to the presence of free acetate, which reduces borane inhibition by reversible borate formation.