(Z)-γ-Alkylidenebutenolide Synthesis through Au(I)-Catalyzed 1,3-Acyloxy Migration and the Carbonyl-Ene Reaction

A bimetallic protocol has been developed to construct (Z)-gamma-alkylidenebutenolide compounds from readily available propargyl alpha-ketoesters. It involves a gold-catalyzed 1,3-acyloxy migration of propargyl alpha-ketoesters and a carbonyl-ene cyclization of in situ generated allenyl esters. DFT calculations suggest that the copper salt might play dual roles as both chloride abstractor facilitating the generation of highly active gold catalyst and Lewis acid promoting the stepwise intramolecular carbonyl-ene reaction.

Automated summary

A bimetallic protocol has been developed for the synthesis of (Z)-gamma-alkylidenebutenolide compounds from propargyl alpha-ketoesters. This method involves a gold-catalyzed acyloxy migration and a carbonyl-ene cyclization process, with DFT calculations suggesting a dual role for copper salt in facilitating the generation of active gold catalyst and promoting intramolecular carbonyl-ene reaction.