Photoinduced Transformations with Diverse Maleimide Scaffolds.

Maleimides serve as crucial components in various synthetic processes and are of significant interest to researchers in bioorganic chemistry and biotechnology. Although thermal reactions involving maleimides have been studied extensively, light-mediated reactions with maleimides remain relatively underutilized. This review focuses on understanding the behavior of maleimides in their excited state, particularly their role as synthetic scaffolds for excited-state reactions.

Triple-Dearomative Photocycloaddition: A Strategy to Construct Caged Molecular Frameworks.

An unprecedented caged -benzo-dioxo-pentacycloundecane framework was serendipitously obtained in a single transformation via triple-dearomative photocycloaddition of chromone esters with furans. This caged structure was generated as part of an effort to access a tricyclic, oxygen-bridged intermediate enroute to the dihydroxanthone natural product nidulalin A. Reaction scope and limitations were thoroughly investigated, revealing the ability to access a multitude of synthetically challenging caged scaffolds in a two-step sequence.

The impact of UV light on synthetic photochemistry and photocatalysis.

During the past 15 years, an increasing number of research groups have embraced visible-light-mediated synthetic transformations as a powerful strategy for the construction and functionalization of organic molecules. This trend has followed the advent and development of photocatalysis, which often operates under mild visible-light irradiation. Nowadays, the general perception of UV-light photochemistry is often as an out-of-fashion approach that is difficult to perform and leads to unselective reaction pathways.

Photochemical [2+4]-Dimerization Reaction from the Excited State.

Aryl-maleimides undergo a novel [2+4]-photodimerization instead of the expected [2+2]-photodimerization under both direct irradiation with visible light and under sensitized energy transfer conditions. This new excited state reactivity in aryl-maleimides is deciphered through photochemical, photophysical, and spectroscopic studies. The stereochemistry of the photodimer depends on the type of non-bonding interactions prevalent during photodimerization which is in turn dictated by the substituents on the maleimide ring.

Chemoselective light-induced reactivity of β-enaminones.

The irradiation of β-enaminones, generated in situ from cyclic 1,3-diketones and activated alkenes leads to polyheterocyclic skeletons. The photoproduct chemoselectivity depends on the type of cyclic 1,3-diketones employed viz., 2-acetylcyclopentanone and 2-acetylcyclohexanone.