New antiaromatic compounds were obtained at the Zelinsky Institute

The terms aromaticity and antiaromaticity are fundamental concepts of organic chemistry. Until recently, antiaromatic compounds were for the most part considered unstable; however, over the past decades, scientists have found ways to stabilize them. At present, antiaromatic compounds are considered as promising candidates for the creation of various functional materials based on them, such as field-effect transistors, solar cells, etc. For this reason, approaches to the synthesis of antiaromatic molecules are now becoming increasingly important in both fundamental and applied organic chemistry.

Researchers of the Laboratory of Chemistry of Diazo Compounds of the ZIOC have been actively engaged in the development of methods for the preparation and study of the chemical properties of antiaromatic compounds based on cycloheptatriene in recent years. In one of their latest works, they found that, as a result of the reaction of propylene derivatives containing two or three electron-withdrawing groups with di(methoxycarbonyl)vinylpyridinium, linear conjugated heptatrienyl anions were formed, which, as a result of conrotatory 8π-electrocyclization, were converted into cycloheptadienyl anions. Carrying out electrocyclization followed by leaving group elimination or oxidation with copper (II) salts leads to the formation of the corresponding cycloheptatrienes. Subsequent deprotonation, as well as the addition-oxidation cascade, give stable anionic or zwitterionic products containing formally 8π-antiaromatic cycloheptatrienyl anionic fragments. In the course of the study, the correlations between the UV-visible spectra of the obtained substances and the structure of the distorted fragment of the cycloheptatrienyl anion were also elucidated.
 

Source:

Matvey K. Ilyushchenko, Rinat F. Salikov, Alena D. Sokolova, Veronika V. Litvinenko, Alexander Yu. Belyy, Dmitry N. Platonov, Yury V. Tomilov Cascade Vinylation/8π-Electrocyclization and Cu(II)-Catalyzed Dehydrogenation toward Highly Stable Formally Antiaromatic Cycloheptatrienyl Anions // J. Org. Chem. 2023, 88, 5661–5670. DOI: 10.1021/acs.joc.3c00142.