Cobalt-Catalyzed C–H Annulation of Aryl Sulfonamides and Benzamides with CaC2 as the Acetylene Source

We have developed a cobalt-catalyzed, aminoquinoline-directed C-H/N-H annulation reaction of benzamides and aryl sulfonamides, enabling access to 3,4-unsubstituted isoquinolinone and 3,4-unsubstituted benzothiazine dioxide derivatives. This method employs calcium carbide as an inexpensive, easy-to-handle, and solid acetylene source. The reaction conditions showed a broad functional group tolerance, which allowed the synthesis of various C-H/C-N annulation products in yields of up to 99%.