Photocatalytic Thio/Selenosulfonylation–Bicyclization of Indole-Tethered 1,6-Enynes Leading to Substituted Benzo[<i>c</i>]pyrrolo[1,2,3-<i>lm</i>]carbazoles

Abstract

The photocatalyzed radical-triggered thio/selenosulfonylation-bicyclization of indole-tethered 1,6-enynes has been established for the first time, enabling the synthesis of various previously unreported thio/selenosulfonylated benzo[<i>c</i>]pyrrolo[1,2,3-<i>lm</i>]carbazoles with moderate to good yields under mild conditions. The reaction pathway was proposed, consisting of energy transfer, homolytic cleavage, radical addition, 5-<i>exo</i>-<i>dig</i>, radical coupling, and a Mallory reaction cascade. This approach exhibits a wide substrate compatibility and excellent tolerability toward various functional groups and is characterized by its remarkable efficiency in both bond formation and annulation.