Phase-Transfer-Catalyzed Asymmetric Michael Addition of (Iminomethyl)phosphonates to α,β-Unsaturated Ketones: Access to α-Aminophosphonic Acid Derivatives.

A phase-transfer-catalyzed asymmetric Michael addition of (iminomethyl)phosphonates to α,β-unsaturated ketones is described. In the presence of 1 mol-% of a chiral dinuclear N-spiro ammonium salt, the addition reaction proceeded smoothly to afford the adducts in up to 97 % yield with up to 99:1 dr and 78 % ee. One of the products was readily converted into a cyclic α-aminophosphonic acid derivative without any erosion of the enantiopurity. [ABSTRACT FROM AUTHOR]