Light energy is used by chemists to make small molecular rings

Single-crystal X-ray structures of two products arising from the cycloaddition reaction. In particular, on the left a unique five-four-three membered condensed ring system is visible. On the right, a four-six membered framework can be recognized. Carbon atoms are shown in grey, hydrogen atoms in white, nitrogen atoms in blue, oxygen atoms in red and chlorine atoms in green. Credit: University of Münster – Peter Bellotti

Molecules whose atoms are linked in rings are becoming more and more important in the search for new medicines. These ring systems have properties that make them great for making these active agents, and they are driving the development of new ways to treat cancer, neurodegenerative diseases, and infectious diseases. Now, a group of chemists from the University of Münster led by Prof. Frank Glorius has made new small molecular rings that have important medical uses but are hard to make because they are very sensitive. The work of the team was written up in the journal Nature Catalysis.

Chemists think it is hard to make small ring systems from so-called aromatic compounds. Also, the process requires a very large amount of energy. Another problem is that the energy has to be sent only to the source materials and not to the products that can’t handle heat. Now, Frank Glorius’s team has come up with a plan in which visible light, which is a cheap source of energy, turns on a photocatalyst that drives the reaction. The light is taken in by the photocatalyst, which sends its energy to the source materials. So, it makes it possible for synthesis to happen that is both very effective and gentle, with few or no unwanted side effects.

“We think our study is a big step forward in synthesis chemistry,” says Dr. Jiajia Ma, who is the study’s lead author. “It shows that light energy can be used to make small ring systems when it is directed in a certain way. Because we can make different ring systems by using different reaction partners, this gives us a lot of ways to make active agents.” The chemists only used raw materials that were easy to find and didn’t cost much.

Further information: Jiajia Ma et al, Facile access to fused 2D/3D rings via intermolecular cascade dearomative [2 + 2] cycloaddition/rearrangement reactions of quinolines with alkenes, Nature Catalysis (2022). DOI: 10.1038/s41929-022-00784-5

Journal information: Nature Catalysis

Source: University of Münste