Transition-Metal-Catalyzed C-H Functionalization Reactions of π-Deficient Heterocycles

Electron-deficient aromatic heterocycles, such as pyridine, quinoline, and isoquinoline, occupy a vast and rapidly expanding area of chemistry because of the obvious application of their derivatives in medicine, agriculture, polymers, and other fields. These heterocycles are rather poorly reactive towards electrophilic metalation by C-H activation and oxidative C-H activation mechanisms. The catalytic C-H functionalization of electron-deficient heterocycles remains a challenge for the synthetic chemistry community. This Focus Review highlights significant developments made in the area of transition-metal-catalyzed C-H functionalization of pi-deficient heterocycles.