Overcoming Back Electron Transfer in the Electron Donor-Acceptor Complex-Mediated Visible Light-Driven Generation of ?-Aminoalkyl Radicals from Secondary Anilines

An additive-free, visible light-driven annulation between N-aryl amino acids and maleimide to form tetrahydroquinolines (THQs) is disclosed. Photochemical activation of an electron donor-acceptor (EDA) complex between amino acids and maleimides drives the reaction, and aerobic oxygen acts as the terminal oxidant in the net oxidative process. A range of N-aryl amino acids and maleimides have been investigated as substrates to furnish the target THQ in good to excellent yield. Mechanistic investigations, including titration and UV-vis studies, demonstrate the key role of the EDA complex as the photoactive species.

Automated summary

An additive-free, visible light-driven annulation between N-aryl amino acids and maleimide to form tetrahydroquinolines (THQs) is reported, where the photochemical activation of an electron donor-acceptor (EDA) complex drives the reaction. Aerobic oxygen acts as the terminal oxidant in the net oxidative process. Various N-aryl amino acids and maleimides have been investigated as substrates, leading to good to excellent yields of the target THQ. Mechanistic investigations using titration and UV-vis studies confirm the crucial role of the EDA complex as the photoactive species.