Synthesis of <i>N</i>-aryl amines enabled by photocatalytic dehydrogenation

Abstract

Catalytic dehydrogenation (CD) <i>via</i> visible-light photoredox catalysis provides an efficient route for the synthesis of aromatic compounds. However, access to <i>N</i>-aryl amines, which are widely utilized synthetic moieties, <i>via</i> 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 <i>N</i>-aryl amines was achieved by the CD of allylic amines. The unusual strategy using C₆F₅I 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 <i>N</i>-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.