Recent Developments in Cobalt Catalyzed Carbon–Carbon and Carbon–Heteroatom Bond Formation via C–H Bond Functionalization

Cobalt catalysts have evolved to be seen as versatile eco-compatible and economical catalysts in organic synthesis in recent years. Cobalt-catalyzed reactions are undoubtedly a classic in synthetic chemistry for the formation of carbon–carbon and carbon–heteroatom bonds. Another important aspect in this field is catalyst variants, such as low-valent and high-valent cobalt catalysts. This review summarizes the recent progress and synthetic utility of low-valent and high-valent cobalt catalysts towards C–H functionalization processes achieving C–C, C–O, C–N and C–B bond formation. Mechanistic insight is also discussed, with the goal of serving as a stepping stone for further development in this field. In addition, Csp 3 –H bond functionalization reactions provide many opportunities for novel synthesis approaches. 1 Introduction 2 Carbon–Carbon Bond Formation 2.1 Csp 2 –Csp 3 Bond Formation 2.2 Csp 2 –Csp 2 Bond Formation 3 Carbon–Nitrogen Bond Formation 4 Csp 3 –H Bond Functionalization 5 Carbon–Oxygen Bond Formation 6 Carbon–Boron Bond Formation 7 Conclusion