Manganese-Catalyzed Cycloalkene Ring Expansion Synthesis of Azaheterocycles

Radical chemistry is synthetically useful but can be plagued by the non-intuitive reaction course and indiscriminate reactivity profile. Herein, dynamic radical effect is revealed as a conceptual logic for the predictive achievement of radical reaction selectivity. The reversible bonding association/dissociation of two radicals serves as a synthetic handle for directing one radical to the target reaction recourse, without the participation of the other radical. A Mn catalytic protocol has been developed for cycloalkene ring expansion synthesis of azaheterocycles. An initial azidyl radical addition to alkene and subsequent reversible O2 occupation of C-radical site prevents further radical coupling and steers the reaction toward the intramolecular rearrangement pathway. A broad substrate scope has been established for the synthesis of pyridine and isoquinoline derivatives. This new radical synthetic perspective promises as an important guiding principle for empowering radical-based chemical transformations.