C-3 Functionalization of 2-Aryl-2H-indazoles under Photo/Electrocatalysis

2H-Indazole is a privileged scaffold widely existing in drugs and bioactive molecules. The C-H functionalization of 2H-indazole is the cutting edge in medicinal chemistry and organic chemistry. Compared with traditional synthetic methods, the visible light/electrochemical-promoted synthetic method has mild conditions and is an environmentally friendly synthetic strategy. The C-H functionalization of 2-aryl-2H-indazoles at the C-3 position catalyzed by photochemical/electrochemical strategies in recent years is summarized in terms of catalytic systems, with special emphasis on the corresponding reaction mechanism, which might inspire the further development of new catalytic methods.