Cobalt-Catalyzed Chemoselective π–σ–π-Type Tandem Reductive Coupling to Access Isoquinolines via Carbocobaltation of Nitriles

Transition metal-catalyzed reductive coupling chemistry has been recognized as a powerful tool for the synthesis of diverse organic molecules. However, despite enormous progress in this field, there is no precedent for the tandem reductive coupling of widely accessible nitriles with electrophiles that contain σ- and π-type (σ/π-type) electrophilic functional groups simultaneously. Herein, we have established a unique cobalt catalysis system, enabling the chemoselective reductive coupling/tandem cyclization reaction of aryl halides (Br, Cl, I) bearing carbonyl moiety with a variety of aryl, alkenyl, and alkyl nitriles via the carbocobaltation of nitriles that is unknown yet. The protocol allows for the modular synthesis of structurally diverse isoquinolines with wide substrate scope (>60 examples), good functionalities tolerance, and good chemoselectivity.