Iridium-catalyzed borylation of arenes and heteroarenes via C-H activation

Direct C-H borylation of aromatic compounds catalyzed by a transition-metal complex was studied as an economical protocol for the synthesis of aromatic boron derivatives. Iridium complexes generated from Ir(l) precursors and 2,2'-bipyridine ligands efficiently catalyzed the reactions of arenes and heteroarenes with bis(pinacolato)diboron or pinacolborane to produce a variety of aryl- and heteroarylboron compounds. The catalytic cycle involves the formation of a tris(boryl)iridium(III) species and its oxidative addition to an aromatic C-H bond.