Dual Photoredox Cobalt Catalyzed [4+1] Annulation and C−H Alkoxylation

Herein, we developed two distinct pyridine N-oxide directed C-H activation protocols to achieve [4+1] annulation and alkoxylation of benzamide derivatives by merging Co-catalysis with visible-light photoredox catalysis. The protocols deliver the respective products in good yields under facile conditions at room temperature. The use of an inexpensive photocatalyst coupled with molecular oxygen bypassing the need of stoichiometric oxidants forms the chief highlight of the work. The protocols are scalable and the products could be further modified. Additionally, preliminary studies were carried out to probe the reaction mechanism.