From the viewpoint of synthetic accessibility and functional group compatibility, photoredox-catalyzed sulfur dioxide insertion strategy enables in situ generation of functionalized sulfonyl radicals from easily accessible starting materials under mild conditions, thereby conferring broader application potential. Here we present two complementary photoinduced sulfur dioxide insertion systems to trigger radical asymmetric Truce–Smiles rearrangements for preparing a variety of chiral sulfones that bear a quaternary carbon stereocenter. This protocol features broad substrate scope and excellent stereospecificity. Aside from scalability, the introduction of a quaternary carbon stereocenter at position β to bioactive molecule-derived sulfones further demonstrates the practicality and potential of this methodology.

Nitrogen heterocycles are of great medicinal importance, and the construction of nitrogen heterocyclic scaffolds has been one of the focuses in synthetic organic chemistry. Recently, the strategy of transition metal-catalyzed sp³ C–H activation and intramolecular C–N coupling to construct nitrogen heterocyclic scaffolds has been well developed. Palladium, copper, silver, nickel, cobalt, ruthenium and rhodium catalysis were successfully used for the construction of nitrogen heterocyclic scaffolds, aziridines, azetidines, pyrrolidines, pyrrolidine-2,5-diones, indolines, isoindolines, isoindolinones, tetrahydropyridines, oxazolidinones, oxazinanones, β-lactams, γ-lactams etc., which have been synthesized by the sp³ C–H activation strategy. Here, we summarize the progress of transition metal-catalyzed sp³ C–H activation/intramolecular C–N bond formation, and introduce both the reaction development and mechanisms in numerous synthetically useful intramolecular sp³ C–H catalytic aminations/amidations.