Electrochemical promoted defluorinative sulfoximination and fluorosulfonylation of non-activated aryl fluorides at room temperature

Abstract

Due to the high bond dissociation energy and kinetic inertness of the C–F bond, direct activation of inert aryl fluorides for new transformations under mild conditions remains a significant challenge. Although it has been known that single electron reduction can be applied for the activation of inert aryl fluorides at room temperature, the need for very strong reduction conditions along with the competitive side reactions during the reduction process limits the synthetic applications. Herein, by leveraging the advantages of electrosynthesis and the versatile transformation nature of aryl radicals, two types of challenging defluorinative transformations of non-activated aryl fluorides which include the sulfoximination via cheap nickel catalysis and the transition metal catalyst-free fluorosulfonylation at room temperature have been disclosed for the first time. These reactions show good functional group tolerance and can be applied for the late-stage modifications of bioactive derivatives. As for the practical nickel-catalyzed defluorinative sulfoximination, detailed mechanistic studies reveal that after the cathodic reduction of aryl fluorides to form the key aryl radical, a subsequent nickel-promoted C–N bond formation via paired electrolysis is responsible for the success.