Nickel-Cobalt Bimetallic Strategy Enables Regioselective C8–H Alkylation of Polyaromatics with Inert Alkyl Chlorides

A regioselective C8−H alkylation of polyaromatics exampled with inert alkyl chloride is reported. The reaction proceeds via the synergistic participation of inexpensive transition metals nickel and cobalt. This approach enables the coupling of various substituted polyaromatic rings with a broad range of primary and secondary alkyl chlorides. Further synthetic applications provide a series of simple conversions to useful building blocks, suggesting its potency in the late-stage functionalization of complex molecules. Mechanistic investigation illustrates that the reaction goes through a radical process with an unusual Ni(II)→Ni(III)→Ni(I) cycle being responsible for the rate-determining C−H insertion of alkyl radicals, which are generated by the homolysis of chloroalkane with 2-electrons oxidative addition of Co(I).