Some recent advances in transition-metal-catalyzed ortho SP2 C-H functionalization using Ru, Rh, and Pd

In the past decade, transition-metal-catalyzed C-H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals. Two classes of weakly coordinating directing groups, commonly occurring functional groups, and easily removable auxiliaries, have been found to be efficient and practical for C-H activation reactions. This mini-review contains examples of recent research advances on transition-metal-catalyzed SP2 C-H functionalization via weak coordination, using Ru, Rh, and Pd. A number of weakly coordinating functional groups (e.g., ketone, ester, carbamate, tertiary amide, ether, thioether, alcohol, and some others) are covered. As the field of transition-metal-catalyzed C-H functionalization continues to develop and more synthetically useful chemo-, regio-, and enantioselective reactions catalyzed by transition metal via weak coordination are discovered, this promising and attractive strategy will play a more important role in modern organic synthesis.