A Chiral Functionalized Salt-Catalyzed Asymmetric Michael Addition of Ketones to Nitroolefins

The chiral functionalized salt catalysis, which differs from the known enzyme‐ and transition metal‐based methods, has been successfully developed to carry out the Michael addition of ketones to nitroolefins. Chiral anion salt (type I), chiral cation salt (type II), or chiral anion‐chiral cation salt (type III) could be expected to be remarkably effective catalysts and afford the corresponding chemically and optically pure Michael addition adducts. A primary amine group activating the ketone during salt catalysis was their obvious and common property. Based on preliminary experimental investigations and previous reports on primary amine catalysis, a reaction pathway via imine, enamine, iminium ion to imine was proposed.