Visible light-induced cascade annulation of sulfoxonium ylides with azides for the synthesis of 2-trifluoromethyl indoles

Abstract

An efficient protocol was reported for the synthesis of 2-trifluoromethyl indoles through visible-light-promoted intermolecular cyclization of sulfoxonium ylides with azides, without the need for external photocatalysts, transition metals, or bases. The formation of 2-trifluoromethyl indoles involves an intriguing cascade process including azide rearrangement, intermolecular nucleophilic addition, and visible-light-promoted cyclization of a key intermediate. The protocol features high efficiency, mild conditions, excellent substrate compatibility and good regioselectivity. The practicality of this approach is demonstrated through scale-up reactions and further modifications of the synthesized indoles.