N-Heterocyclic carbene (NHC) palladium(II) complexes bearing chiral oxazoline ligands and their catalytic activities in allylic alkylation reactions

摘要

NHC--Pd(II) complexes bearing a chiral oxazoline ligand (IIIa--f) were synthesized by cleavage of dimeric palladium complexes with the oxazoline ligand. They were fully characterized by ^1H and ^{13}C NMR and elemental analyses. The catalytic activity of the complexes (IIIa--f) in allylic alkylation reactions was evaluated. The complex IIIa was found to be the most active catalyst. Very low ee values indicate that the oxazoline is dissociated from the active catalytic species.