Deoxygenative Radical Boration of Inert Amides via a Combination of Relay and Cooperative Catalysis

One of the most challenging tasks in organic synthesis is to develop novel methodologies for rapid construction of complex molecules starting from easily available yet inert raw materials. In this context, multi-catalysis strategies have attracted great attention in the discovery of new reactivity profiles that may allow access to many difficult or unattainable transformations. So far the deoxygenative functionalization of ubiquitous amides is usually achieved by nucleophilic attack on the imine or iminium ion intermediate formed via activation of the C=O bond, and these functionalization reagents were often confined to C-based nucleophiles, which largely limited the diversity of the resultant amines. Herein, we disclose a combined strategy of relay and cooperative catalysis with a triple iridium-photoredox-organocatalysis system to achieve an unprecedented reductive boration of amides, affording valuable α-amino boron products which are viable building blocks. In this transformation, the Ir-catalyzed semi-reduction of amides is successfully incorporated with photo-organic catalyzed nucleophilic boryl radical addition, thus delivering the corresponding α-boryl amines in high efficiency.