Transition Metal-Free Regioselective C-3 Amidation of Indoles with N-Fluorobenzenesulfonimide

A direct transition metal-free regioselective C-3 amidation of indoles has been developed with the commercially available N-fluorobenzenesulfonimide (NFSI) as the amino source under external oxidant-free conditions. This amidation requires only a catalytic amount of base and exhibits excellent functional group tolerance and regioselectivity. The C-3 regioselectivity was proposed to realize by a free radical mechanism.