DABCO-directed EDA-complex mediated regioselective C4-sulfonylation of quinoline N-oxide

Abstract

A visible light-mediated, electron donor–acceptor (EDA) complex-enabled regioselective C4-sulfonylated quinoline N-oxide is presented. In this transformation, organic thiosulfonates serve as a sulfonyl radical (RSO2•) precursor, enabling the formation of either C4 sulfonylated quinoline N-oxide or C4 sulfonylated quinoline (deoxygenated) by slight variation of the solvent composition. The base DABCO acts as an electron donor, forming an EDA complex with the acceptor thiosulfonate, generating an RSO2•. DABCO also serves as a transient directing group in dictating the C4-regioselectivity by temporarily blocking the more reactive C2 site.