Nitrogen centered radicals in visible-light promoted reactions

Nitrogen Centered Radicals (NCR) are known in literature since the first years of 1900, but only with the spread of photoredox catalysis, and in particular visible light-mediated radical processes, nitrogen radical chemistry became more accessible generating these kinds of radicals in situ employing mild conditions. In fact, unlike their carbon counterpart, nitrogen radicals have not historically spread in academia or industry due to a lack of an efficient strategy to produce them. Nowadays, NCR are more established, and this graphical review illustrates the key publications from the literature categorized them by both the type of NCR and the type of reaction. In fact, nitrogen radicals can be divided in four different categories according to their electronical configuration, orbital structure and chemical behaviour. The reactivity of all these radicals can be summarized into four main classes: they are mostly exploited into intramolecular cyclization; intramolecular hydrogen atom abstraction; Norrish type-I fragmentation and intermolecular addition to π systems.