Electrochemically Promoted Regioselective C3─H Trifluoromethylation of 2H-Indazoles.

Abstract

Trifluoromethyl-substituted heterocyclic compounds are an essential class of organofluorocompounds with significant applications in agriculture, medicine, and organic synthesis. As a result, an array of techniques using a variety of radical, nucleophilic, and electrophilic trifluoromethylating agents have been devised. In previous methodologies, expensive transition metal catalysts were employed, along with the use of oxidants in stoichiometric amounts, and carried out at elevated temperatures. In this thesis, a green and sustainable approach having oxidant-free and transition metal-free conditions has been outlined for the electrochemically activated regioselective C3─H trifluoromethylation of 2H-indazoles, using CF3SO2Na as the trifluoromethyl source. A diverse library of trifluoromethylated products incorporating an array of functionalities has been successfully synthesized in moderate to good yields. A plausible reaction mechanism has been proposed based on control experiment and cyclic voltammetry experiment.