α-Functionalization of ethers with acridanes and amines via metal-free direct C(sp3)–H radical–radical cross-dehydrogenative coupling

Abstract

Metal-free, direct radical–radical cross-dehydrogenative coupling (CDC) of the relatively unactivated C(sp³)–H bond of ethers with the C(sp³)–H bond of acridanes and amines has been developed, enabling the construction of C9-etherified acridanes and α-etherified amines in moderate to excellent yields using tert-butyl hydroperoxide (TBHP) as the sole oxidant. Mechanistic investigations, including characterization of the TEMPO-adduct by single crystal X-ray analysis and isotope-labeling experiments, further substantiate the radical–radical coupling pathway.