Cobalt-Catalyzed Aerobic Oxidative C-H/C-H Cross-Coupling of Unactivated Arenes for the Synthesis of Biaryls.

A mild and efficient protocol for the synthesis of 2,2'-difunctional biaryls from readily available benzamides and oximes by Co(OAc)2·4H2O catalysis has been developed. The catalytic cycle that includes aerobic oxidation of Co(I) to Co(III) is successfully achieved for the first time through dual-chelation-assisted C-H/C-H coupling with the assistance of catalytic Mn(acac)3. The catalytic system exhibits powerful reactivity and tolerates a large number of sensitive functional groups.