A general and practical bifunctional cobalt catalytic system for N-heterocycle assembly via acceptorless dehydrogenation

A novel and highly-efficient N-heterocycle assembly methodology catalyzed by a cobalt- N , N -bidentate complex has been established. The cobalt complex is unprecedented, phosphine-free and easily-prepared, and is used in the synthesis of pyrimidines, quinolines, imidazoles, quinoxalines and indoles from readily available alcohols and amines via acceptorless dehydrogenation. More importantly, all N-heterocycles were obtained under nearly identical reaction conditions, which further demonstrated the generality and practicability of the catalytic system. Mechanistically, this cobalt complex forms a catalytic active species upon base treatment and is capable of realizing the alcohol AD process via metal–ligand cooperation.