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 ecocompatible 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 CC, 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, Csp3-H bond functionalization reactions provide many opportunities for novel synthesis approaches. 1 Introduction 2 Carbon-Carbon Bond Formation 2.1 Csp2-Csp3 Bond Formation 2.2 Csp2-Csp2 Bond Formation 3 Carbon-Nitrogen Bond Formation 4 Csp3-H Bond Functionalization 5 Carbon-Oxygen Bond Formation 6 Carbon-Boron Bond Formation 7 Conclusion