Radical C‒N Borylation of Aromatic Amines Enabled by a Pyrylium Reagent

Herein, we report a radical borylation of aromatic amines through a homolytic C(sp2)‒N bond cleavage. This method capitalizes on a simple and mild activation via a pyrylium reagent (ScPyry-OTf) thus priming the amino group for reactivity. The combination of terpyridine and a diboron reagent triggers a radical reaction which cleaves the C(sp2)‒N bond and forges a new C(sp2)‒B bond. The unique non-planar structure of the pyridinium intermediate, provides the necessary driving force for the aryl radical formation. The method permits borylation of a wide variety of aromatic amines indistinctively of the electronic environment.