Remote Catalytic C(sp<sup>3</sup>)–H Alkylation\nvia Relayed Carbenoid Transfer upon Olefin Chain Walking

Transition metal carbenes have emerged\nas versatile intermediates\nfor various types of alkylations. While reactions of metal carbene\nspecies with alkenes have been extensively studied, most examples\nfocus on cyclopropanation and allylic C–H insertion. Herein,\nwe present the first example of a catalytic strategy for the carbene-involved\nregioselective remote C–H alkylation of internal olefins by\nsynergistically combining two iridium-mediated reactivities of olefin\nchain walking and carbenoid migratory insertion. The present method,\nutilizing sulfoxonium ylides as a bench-stable robust carbene precursor,\nwas found to be effective for a series of olefins tethered with alkyl\nchains, heteroatom substituents, and complex biorelevant moieties.\nCombined experimental and computational studies revealed that reversible\niridium hydride-mediated olefin chain walking proceeds to lead to\na terminal alkyl-Ir intermediate, which then forms a carbenoid species\nfor the final migratory insertion, resulting in regioselective terminal-alkylated\nproducts.