Imine-Oxazoline (ImOx): A ‑Symmetric ,‑Bidentate Ligand for Asymmetric Catalysis.

Asymmetric catalysis relies on the design of chiral ligands, but the variety of nitrogen-based ligands remains limited. To address this gap, we have developed a class of -symmetric ,-bidentate ligands, imine-oxazoline (ImOx), derived from amino acids through a four-step synthesis. ImOx features an imine moiety conjugated with a chiral oxazoline ring as a hybrid of α-diimine (ADI) and pyridine oxazoline (PyOx) ligands. Its low symmetry allows for independent optimization at both coordination sites. ImOx improves the enantioselectivity of palladium-catalyzed conjugate addition reactions, demonstrating a strong correlation between ee and the steric effects on both the imine and oxazoline sites. Studies on well-defined organopalladium intermediates reveal that the steric bulk of ImOx necessitates a cationic pathway to promote alkene insertion. Structural characterization of ImOx suggests a stronger -influence compared to PyOx. Moreover, ImOx demonstrates versatile redox activity, promoting the reduction of nickel complexes and stabilizing nickel radical complexes. We anticipate that ImOx will expand the toolkit of chiral N-ligands for asymmetric catalysis.