Gold Catalysis for Heterocyclic Chemistry: A Representative Case Study on Pyrone Natural Products

Abstract 2‐Pyrones and 4‐pyrones are common structural motifs in bioactive natural products. However, traditional methods for their synthesis, which try to emulate the biosynthetic pathway of cyclization of a 1,3,5‐tricarbonyl precursor, are often harsh and, therefore, not particularly suitable for applications to polyfunctionalized and/or sensitive target compounds. π‐Acid catalysis, in contrast, has proved to be better for a systematic exploration of the pyrone estate. To this end, alkynes are used as stable ketone surrogates, which can be activated under exceedingly mild conditions due to the pronounced carbophilicity of [LAu] + fragments (L=two electron donor ligand); attack of a tethered ester carbonyl group onto the transient alkyne–gold complex then forges the pyrone ring in a fully regiocontrolled manner.