Regioselective Synthesis of 2(1H)-Pyridinones from β-Aminoenones and Malononitrile. Reaction Mechanism

The identification of some intermediates of the reactions between β-aminoenones and malononitrile to give 2(1 H )-pyridinones has allowed us to obtain valuable information concerning its mechanism. These reactions begin with a conjugated addition of the nitrile to the enone followed by elimination. The compounds thus obtained cyclize to nonisolable 2 H -pyran-2-imine. This afforded 2(1 H )-pyridinones by ring opening to unsaturated aminoamides followed by cyclization (Dimroth-type rearrangement).