Chelation-Assisted Nickel-Catalyzed C-H Functionalizations

Use of a directing group in C-H functionalizations, often referred to as chelation assistance, is one of the most reliable methods for achieving highly efficient and highly site-selective reactions. Although a variety of transition metals can be used in directed C-H functionalization reactions, Ni-catalyzed directed C-H functionalization reactions have remained a relatively underdeveloped area of research. Recently, interest in these reactions has been renewed due to the development of a combination of a Ni catalyst and an N,N'- bidentate group; the method is now emerging as a powerful tool for Ni-catalyzed C-H functionalization reactions. However, Ni- catalyzed C-H functionalizations that do not require the use of a specific directing group (e.g., N,N'-bidentate groups) have recently been reported. Thus, Ni-catalyzed C-H functionalizations have now reached a new and interesting stage.