“…Sulfinate is a unique migrating group, which transforms into a sulfonyl group. The resulting zwitterion intermediate 8 was well stabilized on the anion part by the sulfonyl group, providing an opportunity to regulate the reactivity, leading to a series of sulfonyl-substituted cyclopropanes, dihydropyrroles, azepanes, and N , O -hetero bridge compounds (Scheme C) . Considering the powerful potential of enynone-derived carbene intermediates and the successful applications of the migration-annulation strategy of carbenes in organic synthesis, we report here a copper-catalyzed intramolecular cascade reaction of enynones 9 , involving a 1,4-sulfinate migration as a pivotal step, leading to the practical synthesis of furan-tethered benzocyclobutenes 12 (Scheme D).…”