Phosphine-Catalyzed Alkyne-Ester Stitching for the Construction of Functionalized Cyclopentenones

We report a novel organophosphine-catalyzed cascade cyclization between alkynes and esters for the efficient synthesis of polysubstituted cyclopentenones. This transformation utilizes readily accessible starting materials to construct diverse, highly functionalized cyclopentenones bearing a quaternary carbon center. The reaction exhibits remarkable versatility, granting access to structurally complex spirocyclic architectures and cyclopentenones adorned with natural products and drug-like motifs. The broad substrate scope underscores the generality of this protocol, and the synthetic utility of the products is demonstrated through their straightforward derivatization into valuable synthons. Combined experimental and computational mechanistic studies support a plausible reaction pathway.