Yet Another C-H Activation - in Organic Synthesis

Reference: To, C.T., Chan, T.L., Li, B.Z., Hui, Y.Y., Kwok, T.Y., Lam, S.Y., Chan, K.S., C-H Arylation of Unactivated Arenes with Aryl Halides Catalyzed by Cobalt Porphyrin, Tetrahedron Letters (2010)

Professor Chan's work is impressive. It represents yet another scrupulous use of C-H activation in organic synthesis, this time using Cobalt as the catalyst. This coupling reaction enables an unactivated aromatic (benzene) to be stitched onto a functionalized aryl halide, and the result is an arylation to form useful biaryls. As they have suggested, this prevents the use of hard reagents such as Grignards and organolithiums in the reaction.

A personal observation: we can see from a number of recent publications that Cobalt is emerging as a good metal for a number of useful organic transformations, especially coupling reactions. Watch out, Copper!