Visible-Light-Induced EDA Complex Activation of Thianthrenium Salts for the Synthesis of Nitrogen-Containing Heterocycles

A visible-light-driven photoredox method for the synthesis of nitrogen-containing heterocycles from thianthrenium salts and hydrazone aldehydes is described. Here, thianthrenium salts enable the formation of an electron donor–acceptor (EDA) complex to prompt the reaction. This enables efficient access to diverse N-heterocyclic scaffolds under mild conditions, with broad functional-group tolerance and readily available starting materials. This approach expands the utility of thianthrenium salts in photoredox chemistry and provides a practical platform for the synthesis of nitrogen-rich heterocycles and namely opens the road for the synthesis of sulfonyl derivatives of natural products and drug conjugates as a late-stage functionalization step.