Asymmetric Allylic Oxidation with Biarylbisoxazoline-Copper(I) Catalysis

Eight new bi-o-tolyl bisoxazolines were made and used as ligands in the copper catalyzed asymmetric allylic oxidation reaction. Three benzoyl tert-butyl peresters, p-nitro, o-iodo, and 2,4,6-trichloro were made and used with cyclohexene and cyclopentene with the ligands complexed to copper(I) hexafluorophosphate (10 mol%). High selectivities (73% ee, 78% yield) were obtained with the nitroperester and 1a (S,S,S R=Ph) and cyclohexene. For the cyclopentene, 1c (R=Bn) was best at 72% ee, 63% yield.