Regioselective C3-H Trifluoromethylation of 2H-Indazole Under Transition-Metal-Free Photoredox Catalysis

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a library of trifluoromethylated indazoles.