Zinc-Mediated Asymmetric Additions of Dialkylphosphine Oxides to α,β-Unsaturated Ketones and N-Sulfinylimines

A catalyst was synthesized on the basis of Trost’s dinuclear catalyst characterized by working well without pyridine in the present phospha-Michael reaction. Nevertheless, the presence of pyridine is still advantageous in the present system. The substrate scope was successfully extended to enones employing diallyl phosphine oxide as a nucleophile. Excellent yields and enantioselectivities (up to >99% ee) were achieved for a wide scope of enones employing the catalyst under mild conditions. The detailed reaction mechanism is also discussed herein. Finally, the unprecedented asymmetric additions of dialkylphosphine oxides to N-sulfinylimines were achieved by using Et2Zn as a base.