Access to Stable C(sp3)-Substituted Sulfonium Salts through Sulfoxide Activation and Investigation of Their Reactivity

We explored the synthesis and reactivity of C(sp³)-substituted sulfonium salts derived from sulfoxides and silyl enol ethers. We successfully isolated sulfonium salts as stable solids by modifying sulfoxide substituents and exchanging counterions. The reactivity of these sulfonium salts was demonstrated through α-halogenation and carbon–carbon bond formation reactions. These reactions represent Umpolung processes mediated by sulfonium groups, enabling the coupling of two nucleophiles. Notably, the characteristic reactivity of enone-containing sulfonium salt was demonstrated by the generation of an oxyallyl cation intermediate through the addition of β-dicarbonyl compounds under basic conditions.