Enantioselective synthesis of isoxazolines bearing allenes by palladium-catalyzed carboetherification of β,γ-unsaturated ketoximes with propargylic acetates†

Abstract

A highly efficient Pd-catalyzed enantioselective carboetherification reaction of β,γ-unsaturated ketoximes with propargylic acetates is demonstrated. This method provides various chiral isoxazolines bearing multisubstituted allene groups in good yields with excellent enantioselectivities. The sterically electron-rich BINOL-derived phosphoramidite ligand exhibits highly efficient control over both chemoselectivity and enantioselectivity. The salient features of this reaction include readily available starting materials, broad functional group tolerance, an easy scale-up, versatile transformations and promising photo-physical properties. DFT calculations were carried out to disclose the detailed mechanism and origins of the enantioselectivity.