Regioselective Radical Arene Amination for the Concise Synthesis of ortho-Phenylenediamines

The formation of arene C-N bonds directly from C-H bonds is of great importance and there has been rapid recent de-velopment of methods for achieving this through radical mechanisms, often involving reactive N-centered radicals. A major challenge associated with these advances is that of regiocontrol, with mixtures of regioisomeric products ob-tained in most protocols, limiting broader utility. We have designed a system that utilizes attractive non-covalent interactions between an anionic substrate and an incoming radical cation in order to guide it to the arene ortho posi-tion. The anionic substrate takes the form of a sulfamate-protected aniline and telescoped cleavage of the sulfamate group after amination leads directly to ortho-phenylenediamines, key building blocks for a range of medicinally-relevant diazoles. Our method can deliver both free amines and monoalkyl amines allowing access to unsymmetrical, selectively monoalkylated benzimidazoles and benzotriazoles. As well as providing concise access to valuable ortho-phenylenediamines, this work demonstrates the potential for utilizing non-covalent interactions to control positional selectivity in radical reactions.EPRSC European Research Council Royal Societ