Base and Nucleophilic Catalysis Enables Formal [3+2] Cycloaddition of Alkynyl Diazoketones and Aminomalonates: Access to γ,γ‐Disubstituted 3‐Pyrrolin‐2‐ones

A formal [3+2] cycloaddition of alkynyl diazoketones with aminomalonates has been developed, providing rapid access to highly substituted γ,γ-disubstituted 3-pyrrolin-2-ones. This transformation proceeds under mild conditions with broad substrate scope and good functional-group tolerance, providing a practical approach to synthetically valuable five-membered nitrogen heterocycles. Furthermore, the reaction can be readily performed on gram scale, and the obtained products undergo versatile downstream transformations, demonstrating the synthetic utility of this methodology.