Photoredox-catalyzed cascade annulation of N-propargylindoles with sulfonyl chlorides: access to 2-sulfonated 9H-pyrrolo[1,2-a]indoles

A photoredox-catalyzed cascade radical reaction of N-propargylindoles and sulfonyl chlorides to 2-sulfonated 9H-pyrrolo[1,2-a]indoles was described. By the direct use of commercially available sulfonyl chlorides as radical precursors, this transformation proceeded smoothly to afford the corresponding products in moderate to good yields under external oxidant-free conditions at room temperature.