SilverCatalyzed Cascade Carboxylation and Cyclization of Trimethyl(2-methylenebut-3-yn-1-yl)silane Derivatives

C–C bond-forming carboxylation
and cyclization of trimethyl­(2-methylenebut-3-yn-1-yl)­silane
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.