Enantioselective Reaction of N-Unprotected Activated Ketimines with Phosphine Oxides Catalyzed by Chiral Imidazoline-Phosphoric Acids.

The first enantioselective hydrophosphonylation of ketimines with phosphine oxides was developed. The reaction of unprotected ketimines with phosphine oxides using a bis(imidazoline)-phosphoric acid catalyst gave chiral α-quaternary aminophosphorous compounds having a primary amino group in excellent yields and enantioselectivities. Based on experimental results and DFT calculation, transition states were proposed to explain the stereoselectivity of the reaction.