Visible-light-promoted EDA complex enables cascade annulation of 2-vinyloxydiphenylacetylene with thiols and 4-cyanopyridine: facile access to diverse 2,3-difunctionalized benzofurans.

Abstract

Herein, we report an electron donor-acceptor (EDA) complex-driven strategy for the three-component cascade annulation of 2-vinyloxydiphenylacetylene, thiols, and 4-cyanopyridine, enabling the regioselective synthesis of C-2 α-thiomethylated and C-3 pyridylmethylated benzofuran derivatives. This protocol features high efficiency, no requirement for an external photocatalyst, broad substrate scope with good functional group compatibility and mild reaction conditions. Mechanistic studies indicate a radical pathway featuring regiospecific addition, annulation, and cross-coupling of the in situ-formed radical intermediate, while sequential protonation and deprotonation ultimately drive aromatization.