Novel O,N,N,O-tetradentate ligand from tartaric acid

A new class of highly stable O,N,N,O-tetradentate bioxazoline ligands were synthesized from l-tartaric acid. Exploration of those ligands in Pd-catalyzed asymmetric allylic alkylation yielded alkylated product up to 96% ee. Necessity of additional chelation to obtain high enantioselectivity was also demonstrated. Structural modifications of this ligand might result in identification of a novel privileged chiral ligand from an inexpensive chiral pool.