Asymmetric Synthesis of Dihydropyranones via Gold(I)‐Catalyzed Intermolecular [4+2] Annulation of Propiolates and Alkenes

Intermolecular asymmetric gold catalysis involving alkyne activation presents a significant challenge due to its distinct mechanistic mode from other metals. Herein, we report a highly enantioselective synthesis of α,β‐unsaturated δ‐lactones from [4+2] annulation of propiolates and alkenes in upto 95 % ee. Notably, for the desired chiral recognition, the choice of 1,1,2,2‐tetrachloroethane as solvent was found to be crucial. Furthermore, an anionic surfactant (sodium dodecyl sulfate) improved the product selectivity in the divergence of the cyclopropyl gold carbene intermediate. The enantioselective [4+2] annulation of propiolates with alkenes led to the synthesis of dihydropyranones in upto 95 % enantiomeric excess. This one‐step protocol provides an efficient route to α,β‐unsaturated δ‐lactone scaffolds from di‐ and tri‐substituted alkenes as well as 1,3‐dienes.