Visible-Light-Promoted C3-Sulfenylindoles with Arylsulfonyl Chlorides via Electron Donor–Acceptor Complex

In this study, we present an efficient approach for the synthesis of 3-sulfenyl indoles through an electron donor–acceptor (EDA) complex-promoted photoreaction. This sulfenylation reaction leverages sulfonyl chlorides as the sulfur source and employs PPh₃ as the reductant without the need for any transition-metal catalyst or photocatalyst. At the same time, the relaxation process of the excited EDA complex was theoretically investigated at the method and multiconfiguration second-order perturbation//complete active space self-consistent field/PCM level of theory, which involves the π bond of indoles injecting an electron to the antibonding orbital of the S–Cl bond in arylsulfonyl chlorides.