Sulfonium triggered one-pot synthesis of dihydrofurans via [3+2] annulation of alkenes and active methylene compounds†

A base-promoted, one-pot reaction of alkenes and active methylene compounds mediated by sulfonium salts was successfully developed. This approach enables the regioselective synthesis of a range of 2,3-dihydrofurans, demonstrating a broad substrate scope and good functional group compatibility. Importantly, the nucleophilic [3+2] annulation strategy avoids the use of transition-metal catalysts, strong oxidants and high-temperature conditions, aligning well with green and sustainable chemistry.