Cobalt-Catalyzed Secondary Alkylation of Arenes and Olefins with Alkyl Ethers through the Cleavage of C(sp²)–H and C(sp³)–O Bonds

A novel cobalt-catalyzed C–H alkylation of arenes and olefins is achieved with (pyridin-2-yl)­isopropyl amine as an N,N-bidentate directing group. Different linear, branched, and cyclic alkyl ethers were used as practical secondary alkylating reagents through cleavage of C­(sp³)–O bond, providing an efficient approach to the synthesis of verstile o-alkylated arylamides and tetrasubstituted acrylamides. Mechanistic studies indicate that cleavage of the inert C­(sp³)–O bond involves a cobalt-promoted radical process and that cleavage of the inert C­(sp²)–H bond by a cobalt catalyst is a rate-limiting step.