Ir-Catalyzed Functionalization of C-H Bonds

The ability to selectively functionalize C-H bonds holds enormous potential value in virtually every sphere of organic chemistry, from fuels to pharmaceuticals. Transition metal complexes have shown great promise in this context. Iridium provided the first examples of oxidative addition of C-H bonds; this addition is key to iridium's leading role in alkane dehydrogenation and related reactions. Catalysts based on iridium have also proven highly effective for valuable borylations of C-H bonds and, to a lesser extent, for C-Si coupling. Compared with other platinum group metals, iridium chemistry has not been developed as extensively for the elaboration of C-C bonds from C-H bonds, but significant promise is indicated, particularly for coupling with simple hydrocarbons which lack functionalities that can act as directing groups.