Enantioselective Cyclization of 4-Alkenoic Acids via an Oxidative Allylic C-H Esterification

An enantioselective intramolecular oxidative cyclization of 4-alkenoic acids was developed. The reaction proceeded via a pi-allyl Pd intermediate generated by an allylic C-H activation to give gamma-lactone derivatives with moderate to good enantioselectivity. Spiro bis(isoxazoline) ligand, SPRIX, was indispensable for this asymmetric transformation.