Catalyst-Free Photoredox Addition-Cyclisations: Exploitation of Natural Synergy between Aryl Acetic Acids and Maleimide

What is it about?

Certain carboxylic acids undergo a previously unknown photoredox reaction when irradiated with UVA in the presence of maleimide. Maleimide was found to synergistically act as a radical generating photoxidant and as a radical acceptor. Modest to excellent yields of ring-closed products chromenopyrroledione, thiochromenopyrroledione and pyrroloquinolinedione derivatives were obtained in thirteen preparative photolyses.

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Why is it important?

A simple and clean way of making pyrroledione and quinolinediones is described.