Asymmetric allylic oxidation of cycloalkenes using a tridentate tris(oxazoline) ligand as a chiral auxiliary

A tridentate tris(oxazoline) ligand (4b) was found to be an efficient chiral auxiliary for copper-mediated asymmetric allylic oxidation (Kharash–Sosnovsky reaction) of cycloalkenes. Regardless of the ring size of the substrate, the reaction examined showed good enantioselectivity higher than 81% ee.