Cobalt(II)-Catalyzed [5+2] C?H Annulation of o-Arylanilines with Alkynes: An Expedient Route to Dibenzo-[b,d]azepines

Article abstract of DOI:10.1002/adsc.201900261

The first example of CoCl₂-catalyzed formal [5+2] oxidative annulation of o-arylanilines with alkynes was developed, giving access to various important imine-containing dibenzo-[b,d]azepine scaffolds through sequential C?C/C?N bond formation. The reaction employs catalytic amount of manganese and oxygen as cooxidants, and features a broad substrate scope. Preliminary mechanistic studies suggested that C?H activation is involved in the rate-determining step. Moreover, both internal and terminal alkynes are well tolerated in this transformation. Besides, a regioselective migratory insertion was observed when using terminal alkynes as substrates. (Figure presented.).