Recent Advances and Strategies for the Transition-Metal-Catalyzed C-H Functionalization of N-Nitrosoanilines

The challenges faced in the activation and functionalization of C-H bonds while producing high-value aromatic intermediates are significant for synthetic organic chemistry. This review summarizes the advancements made toward the C-H functionalization of N-nitrosoanilines in the past decade, in which the nitroso group coordinates to a transition metal, such as rhodium, palladium, cobalt, iridium, and ruthenium, acting as a directing group to allow the activation of the ortho C-H bond. The versatility of this synthetic approach has led to the regio- and chemoselective introduction of various functional groups giving rise to aromatic congeners with diverse functional and structural properties. C-H functionalized nitroso compounds can be further transformed into valuable synthetic intermediates and unique heterocyclic compounds. A description of the mechanism underlying each reaction is also included. This review includes the following sections: 1. Introduction 2. Rhodium-Catalyzed C-H Functionalization 3. Miscellaneous Catalysis 4.1 Cobalt-Catalyzed C-H Functionalization 4.2. Ruthenium-Catalyzed C-H Functionlization 4.3 Iridium-Catalyzed C-H Functionlization 5. Summary and Conclusions