Selective Synthesis of 3-Substituted Pyrrolidinones by Enol-Passerini and Anomalous Enol-Passerini Condensations.

Enols are used for the first time in a condensation with aldehydes and isocyanides to selectively give three- or pseudo-four-component adducts, depending on the reaction conditions. These new transformations have proven to be a convenient alternative for the synthesis of biologically relevant pyrrolidinones containing peptidic or pseudo-peptidic groups on carbon 3. More importantly, this work attests to the utility of heterocyclic enols containing conjugated electron-withdrawing groups as useful reagents in isocyanide-based multicomponent reactions.