Cobalt-Catalyzed Carbonylation of C(sp2)-H Bonds with Azodicarboxylate as the Carbonyl Source.

A novel and efficient approach for the C(sp2)-H bond carbonylation of benzamides has been developed using stable and inexpensive Co(OAc)2·4H2O as the catalyst and the commercially available and easily handling azodicarboxylates as the nontoxic carbonyl source. A broad range of substrates bearing diverse functional groups were tolerated. This is the first example where cobalt-catalyzed C(sp2)-H bond carbonylation occurs with azodicarboxylate as the carbonyl source.