Naphthyl-substituted bisoxazoline and pyridylbisoxazoline–copper(I) catalysts for asymmetric allylic oxidation

The synthesis of naphthyl substituted malonyl-derived and pyridine-based bisoxazolines and their applications in the asymmetric allylic oxidation of cyclohexene with t-butyl p-nitroperbenzoate have been performed with much improved reactivity (75% yield) while maintaining very good enantioselectivity (85% ee). A 1-naphthyl group as the side chain of the oxazoline ligand was found to be optimal. Correlations between the nature of the substituents on the bisoxazolines and the reactivity/selectivity have been established. Tridentate pyridylbisoxazoline ligands with naphthyl groups were also synthesized and employed.