Scientists of the ZIOC performed a complex investigation of photochemical properties of ortho-halogen-substituted diarylethenes

Diarylethenes are an important class of organic compounds due to their unique photochemical properties. Photocyclizations of diarylethenes are actively used in full synthesis, as well as in the design of drugs and photoresponsive materials. Products of diarylethenes photoreactions are often quite problematic to obtain by other methods, as well as have promising optical and biological properties.

Researchers of the Laboratory of Heterocyclic Compounds of the Zelinsky Institute carried out complex photochemical studies of ortho-halogen-substituted diarylethenes. It was found that, depending on the type of the halogen substituent and the solvent, the reaction proceeded with the formation of bi- or tricyclic compounds. Photocyclization with removal of the bromide cation, resulting in bicyclic fused aromatic structures, is preferred for bromodiarylethenes in tetrahydrofuran. The unusual ability to release the bromide cation made it possible to use them both as brominating agents and as Lewis acids to catalyze electrophilic reactions. Chlorine-substituted diarylethenes also undergo skeletal photorearrangement in THF with chlorine abstraction, while in chloroform, photocyclization proceeds through a tandem 6π-electrocyclization / sigmatropic shift reaction with the formation of a tricyclic framework.

Source:

Alexey V. Zakharov, Anton V. Yadykov, Elena B. Gaeva, Anatoly V. Metelitsa, Valerii Z. Shirinian Photoinduced Skeletal Rearrangement of Diarylethenes: Photorelease of Lewis Acid and Synthetic Applications J. Org. Chem. 2021, accepted manuscript. DOI: 10.1021/acs.joc.1c02033.