Copper-catalyzed asymmetric propargylation of imines enabled by a biphenol-based phosphoramidite ligand

Copper-catalyzed enantioselective propargylation of acyclic imines with electron-neutral protecting groups was established using a newly constructed phosphoramidite ligand, providing the corresponding homopropargyl amines in excellent yields and up to 95 : 5 er. The introduction of an ortho-substituent and high electron deficiency of imines are proven to be the key for achieving high enantioselectivity. In addition, this protocol features an easy-to-handle copper(ii) catalyst and diverse downstream transformations. Cu-catalyzed asymmetric propargylation of acyclic imines with electron-neutral protecting groups was established, providing the corresponding homopropargyl amines in excellent yields and high enantioselectivities.