Alkenylation of Unactivated Alkanes: Synthesis of Z-alkenes via Dual Co-TBADT Catalysis

Abstract

Alkenes serve as fundamental building blocks in organic synthesis. Hydroalkylation of terminal alkynes via C−H activation is arguably the simplest and most atom-economical method for the synthesis of alkenes, however, they remain confined to the use of C(sp2)−H or activated C(sp3)−H bonds. Although a chelating group facilitated the alkenylation of the C(sp3)−H bond, it produced E alkenes. Protocols by which unactivated C(sp3)−H bonds can be directly alkenylated via metal-hydride or radical pathway in the absence of a chelating group remain unknown. Despite a thorough evaluation of nickel-HAT catalysis yielding inadequate outcomes, our study showcases the potential of cobalt-HAT catalysis in achieving the desired Z alkene with excellent regio- and diastereoselectivity by reacting alkyne SOMOphiles with open-shell alkyl radicals generated in-situ. A mechanism has been devised based on the initial studies.