Light-Promoted Efficient Generation of Fe(I) to Initiate Amination

Iron-catalyzed cross-coupling reactions are difficult to achieve because they usually require a highly reactive, low-valent iron catalyst to undergo the oxidative addition process. Here, we report a method for light-promoted iron-catalyzed C-N coupling reactions between aryl bromides and amines in the presence of a catalytic amount of a bipyridine ligand under irradiation at 390-395 nm. This method, which does not require external photosensitizers, features a broad substrate scope (70 examples) and good functional group tolerance, providing a platform for the development of iron-catalyzed coupling reactions in organic synthesis. Mechanistic studies indicate that an organic base and light are crucial for the generation of an Fe(I) species and that the reaction involves an Fe(I)/Fe(III) catalytic cycle.