Cobalt-catalyzed synthesis of quinolines from the redox-neutral annulation of anilides and alkynes

A new method of cobalt-catalyzed annulation of anilides and internal alkynes for the efficient synthesis of quinoline scaffolds was developed. The combination of cobalt catalyst with the Lewis acid Zn(OTf)(2) ensured the success of the annulation to give the quinoline heterocycles in high efficiency. The transformation is supposed to undergo ortho C-H activation and nucleophilic addition of C-Co species toward the amides. Attractive features of this system include the use of a low cost cobalt catalyst, the easy-handling operation, and readily available substrates.