SilverCatalyzed Cascade Carboxylation and Cyclization of Trimethyl(2-methylenebut-3-yn-1-yl)silane Derivatives
摘要:
C-C bond forming carboxylation, and cyclization: of trimethyl(2-rnethylenbut-3,7yl)silaile derivatives and carbon dioxide was developed. Silver catalysts and CsF promoted the reaction to afford the:corresponding 2-furanone and 2-pyrone derivatives in good-to-high yields. The structure of the 2:furanone was confirmed by single-crystal X-ray crystallography, which revealed that the geometry of the exo-olefin was that of a Z-isomer. When an aromatic ring substituted alkyne was used, 2-furanone derivatives were selectively obtained via 5-exo-dig-cyclization, whereas the reaction of alkyl-substituted alkynes produced 2-pyrone derivatives with high selectivity.
Abstractmagnified imageA general and efficient copper(I)‐catalyzed cross‐coupling and heterocyclization reaction of terminal alkynes and β‐iodo‐α,β‐unsaturated acid derivatives has been developed under very mild conditions. This method provides easy access from good to excellent yields of a variety of 5‐ylidenebutenolides and 3‐substituted isocoumarins with excellent regio‐ and stereoselectivity. This procedure does not require the use of any expensive supplementary additives, and is palladium‐free.