Visible-light-induced cascade sulfonylation/cyclization of N-propargylindoles with aryldiazonium tetrafluoroborates via the insertion of sulfur dioxide

Abstract

A simple and efficient visible-light-catalyzed cascade sulfonylation/cyclization of N-propargylindoles with K₂S₂O₅ and aryldiazonium tetrafluoroborates for the construction of 2-sulfonyl-substituted 9H-pyrrolo[1,2-a]indoles is developed. In this transformation, K₂S₂O₅ as a simple and inexpensive sulfur dioxide source provides sulfur dioxide for accessing sulfonyl radicals. This method features excellent functional group tolerance and offers a convenient route for assembling a new C–C bond and two new C–S bonds in one step.