New mode of sulfur ylides reactivity: stereoelectronic control provides C–C bond insertion before cyclopropanation/epoxidation directly affording homologated three-membered rings

Abstract

Ylides are versatile reagents known for their dual electrophilic and nucleophilic reactivity, mimicking carbenes in many reactions. In this study, we uncover a previously unreported reactivity pathway for ylides: a methylene insertion into C–C bonds. We show that sulfur ylides can achieve homologation of alkenes and aldehydes before proceeding through the classical Corey–Chaykovsky reaction. This process allows for the dual transfer of CH₂ groups to both substrates, yielding benzylcyclopropanes and benzyloxiranes, valuable intermediates in organic synthesis. Remarkably, the same sulfur ylide reagent participates in two distinct carbene-like transformations within this cascade. Mechanistic studies reveal the role of a tightly coordinated stereoelectronic network playing a crucial role in facilitating anionic 1,2-aryl shifts.