Remote C(sp3) gamma- and epsilon-Arylation of Dienones and Trienones via a Co(II)-Catalyzed C–H Functionalization

Herein, we report the development of a methodology that provides a rapid access to gamma-arylated enones and epsilon-arylated dienones via a CC bond formation using a sustainable transition metal catalyst that enhances step and atom efficiency. This cobalt-catalyzed C-H bond activation process constitutes a rare report of a direct coupling between an arene and electron-rich silyldienol- and silyltrienol ethers to achieve the distal gamma- and epsilon-arylation of enones. A wide range of functional groups were successfully tested, resulting in arylation at the distal position with high regioselectivity. Mechanistic studies reveal valuable information regarding the pathway of the transformation, including a C-H activation and the generation of enone/dienone radicals from silyldienol and silyltrienol ethers, leading to a Co(IV) intermediate in the catalytic cycle. Successful removal of the directing group adds additional advantages to the methodology.