Chiral Ferrocenyl N,N Ligands with Intramolecular Hydrogen Bonds for Highly Enantioselective Allylic Alkylations

Several novel ferrocene-derived bidentate nitrogen ligands, which were incorporated with multi-chiral factors, have been designed and synthesized by rational combination of oxazoline and pyridine. Their catalytic performances were preliminarily investigated in palladium-catalyzed asymmetric allylic alkylation, and excellent reactivities and enantioselectivities (up to 99% yield and 98% ee) were realized using the ligand with matched chirality. DFT calculations illustrated that an intramolecular hydrogen bond formed between the hydroxyl group and the oxazoline fragment of the ligand contributed to the optimal conformation of the ligand-Pd-allyl complex.