The intermolecular, rhodium-catalyzed silylation of arenes that we report here occurs under mild conditions, with arene as the limiting reagent and with regioselectivities that complement or surpass those of other arene functionalizations. Several factors lead to the selectivity and synthetic utility of the silylation reaction. First, the silicon reagent is sterically demanding. Assuming the intermediate that cleaves the aryl C–H bond contains a silyl group on the metal, the size of the silane reagent, along with the size of the ancillary ligands, control the degree of regioselectivity. Second, two of the substituents on the silane are bound to silicon through oxygen, and a siliconheteroatom bond is typically required for many of the transformations of arylsilanes at the C–Si bond. The origin of the remote selectivity remains to be defined. However, results suggest that a wide scope of functionalization reactions with remote regiocontrol should be achievable through judicious choice of ancillary ligands and reagents with appropriate steric bulk.

Link: http://www.sciencemag.org/content/343/6173/853.full.pdf

Chen Cheng and John F. Hartwig Science 2014, 343, 853.