Metal-free C(sp2)–H trifluoromethylation and perfluoroalkylation of enamines via aryl radical-mediated halogen atom transfer

Abstract

An efficient β-trifluoromethylation and perfluoroalkylation of enamide derivatives has been achieved under mild, transition metal-free conditions without requiring oxidants or photocatalysts. Using trifluoromethyl or perfluoroalkyl iodides via an aryl radical-mediated halogen atom transfer (XAT) strategy with aryl diazonium salts as radical precursors, the reaction proceeds with broad substrate scope and excellent functional group tolerance. Furthermore, the process is scalable and can be efficiently performed in a one-pot fashion without isolation of diazonium salts. Control experiments confirm that neither base nor light is essential for the reaction, whereas the presence of diazonium salts is crucial to sustain the reaction progress. Preliminary mechanistic studies suggest that a radical pathway is involved.