Intramolecular Cyclopropanation of Alkene-Tethered CF₃-Imidoyl Sulfoxonium Ylides: Synthesis of Cyclopropane-Fused Quinolines

A metal-free intramolecular cyclopropanation of CF₃-imidoyl sulfoxonium ylides with styrenes was developed, affording cyclopropane-fused quinolines. This strategy provides efficient access to diverse trifluoromethyl-substituted dihydro-1<i>H</i>-cyclopropa[<i>c</i>]quinolines under mild, transition-metal-free conditions. Notably, the sulfoxonium ylide generation and subsequent cyclopropanation could proceed in a one-pot fashion, affording the products in good yields.