Electrochemical Umpolung of Bromide: Transition-Metal-Free Bromination of Indole C–H Bond

A facile and sustainable electrochemical umpolung of bromide ion protocol was developed under mild reaction conditions. Transition metal catalysts and exogenous chemical oxidants were obviated for the bromination of C–H bond. Notably, graphite rod, which is commercially available at supermarkets and is inexpensive, was employed as the electrode material. This operationally easy and environmentally friendly approach accomplished the synthesis of 3-bromoindole in excellent yield and regioselectivity.