Photoredox Cyclization of N-Arylacrylamides for Synthesis of Dihydroquinolinones

Metal- and additive-free photoredox cyclization of N-arylacrylamides is herein reported that provides a concise access to the formation of dihydroquinolinones. In this protocol, sustainable visible light was used as the energy source, and the organic light-emitting molecule 4CzIPN served as the efficient photocatalyst. This reaction system features exclusive 6-endo-trig cyclization selectivity with a generally good yield of a range of functionalized dihydroquinolinones and dihydrobenzoquinolinones. Mechanistical studies reveal the feasibility of both 1,3-H shift and intersystem crossing of the diradical intermediate.

Automated summary

A metal- and additive-free photoredox cyclization of N-arylacrylamides for the concise formation of dihydroquinolinones was reported, using sustainable visible light and the organic light-emitting molecule 4CzIPN as the efficient photocatalyst. The reaction system showed exclusive 6-endo-trig cyclization selectivity with generally good yields of functionalized dihydroquinolinones and dihydrobenzoquinolinones, with mechanistical studies supporting the feasibility of 1,3-H shift and intersystem crossing of the diradical intermediate.