N‐Heterocyclic Carbene‐Catalyzed [3+3] Annulation of Alkynyl Acyl Azolium with β‐Keto Ester for the Synthesis of Tri‐Substituted α‐Pyranones

Abstract The reactivity of N‐Heterocyclic carbene (NHC)‐bound alkynyl acyl azoliums is underexplored in chemistry. We herein reported an NHC‐catalyzed [3+3] annulation of alkynyl acyl azoliums with β ‐keto esters. The strategy features mild reaction conditions and exhibits broad substrates scope, delivering a wide range of tri‐substituted α ‐pyrones in moderate to excellent yields (up to 95%). This approach extends the reactivity of alkynyl acyl azoliums to β ‐keto esters binucleophiles.