We have developed a mild, photoinduced, transition metal-free borylation at α-, β-, and γ- C(sp3)–H sites of amines. This general, selective, and operationally simple method features: (a) visible light-induced diboron reagent mediated aryl radical generation; (b) employment of commercially available and easily installable/removable reactive amide- or sulfonamide-based tether leading to the remote C–H activation; (c) a 1,n-hydrogen atom transfer (HAT) process (n = 5–7) for the generation of key alkyl radical intermediate; and (d) efficient radical addition to diboron reagents leading to the borylation product. The generality of this method is demonstrated by the employment of a wide range of acyclic and cyclic amines, including complex and pharmaceutically relevant molecules. Complementarity with existing approaches, as well as mechanistic studies and synthetic utility of this new method will be discussed.

Photoinduced metal-free radical C(sp3)–H borylation of amines

ACS Spring 2022

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