Synthesis of -aryl amines enabled by photocatalytic dehydrogenation.

Catalytic dehydrogenation (CD) visible-light photoredox catalysis provides an efficient route for the synthesis of aromatic compounds. However, access to -aryl amines, which are widely utilized synthetic moieties, visible-light-induced CD remains a significant challenge, because of the difficulty in controlling the reactivity of amines under photocatalytic conditions. Here, the visible-light-induced photocatalytic synthesis of -aryl amines was achieved by the CD of allylic amines. The unusual strategy using CFI as an hydrogen-atom acceptor enables the mild and controlled CD of amines bearing various functional groups and activated C-H bonds, suppressing side-reaction of the reactive -aryl amine products. Thorough mechanistic studies suggest the involvement of single-electron and hydrogen-atom transfers in a well-defined order to provide a synergistic effect in the control of the reactivity. Notably, the back-electron transfer process prevents the desired product from further reacting under oxidative conditions.