Rhenium-Catalyzed Decarboxylative Coupling of Cyclic Enol Carbonates with Silyl Enol Ethers and Ketene Silyl Acetals.

The Lewis acid-catalyzed decarboxylative coupling of cyclic enol carbonates, prepared by the fixation of carbon dioxide onto propargyl alcohols, with silyl enol ethers including ketene silyl acetals, was developed to afford 1,4-dicarbonyl compounds in good-to-high yields. As the plausible reaction mechanism, it was proposed that the decarboxylative formation of an oxyallyl cation intermediate or its equivalent and the sequential nucleophilic addition of silyl enol ethers proceeded to afford 1,4-dicarbonyl products. In addition, the synthetic utility of the obtained-1,4-dicarbonyl compounds was also demonstrated by applying them to the construction of multisubstituted heterocycles.