A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

The generation of aryl radicals from the corresponding halides by redox chemistry is generally considered a difficult task due to their highly negative reduction potentials. Here we demonstrate that α-aminoalkyl radicals can be used as both initiators and chain-carriers for the radical coupling of aryl halides with pyrrole derivatives, a transformation often employed to evaluate new highly reducing photocatalysts. This mode of reactivity obviates for the use of strong reducing species and was also competent in the formation of sp 2 C-P bonds. Mechanistic studies have delineated some of the key features operating that trigger aryl radical generation and also propagate the chain process. Aminoalkyl radicals can be used as both initiators and chain-carriers for the conversion of aryl halides into the corresponding radicals. This approach by-passes the requirement for strongly reducing photocatalysts.