SCIENTIFIC EDUCATIONAL CENTER science idea

Scientists of St. Petersburg State University have discovered a new type of reactions, as a result of which it is possible to synthesize complex polycyclic organic molecules. The source code is unsaturated compounds, that is, with double or triple inter-carbon bonds, which in their structure resemble a Rubik's snake. This reaction allowed scientists to transform easily accessible and widely used in chemistry heteroaromatic 2D molecules into exotic and previously unknown 3D bridge structures in just one step.

Pericyclic reactions in organic chemistry make it possible to synthesize complex cyclic and polycyclic molecules from simpler ones in just one stage with complete preservation of all atoms. A research group from St. Petersburg State University has shown that conjugated azapolyenes — organic compounds with alternating single and double carbon-carbon bonds, in which part of the carbon atoms are replaced by nitrogen atoms, are very actively involved in such reactions. At the same time, the molecule of nitrogen — containing polyene, in contrast to its completely carbon analog, becomes similar to the famous Rubik's snake puzzle, from which you can assemble the most bizarre 2D and 3D structures.

Scientists have found a simple way to chemically obtain such nitrogen-containing polyenes from simple and affordable heteroaromatic compounds: pyrazoles and triazoles. The "Rubik's snakes" synthesized in this way spontaneously "fit" into highly unsaturated (having several double bonds) bicyclic bridge structures, that is, with two cycles. These compounds resemble alkaloids in structure, so they can potentially have biological activity and be used in medical chemistry. In addition, it turned out that even more complex cyclic molecules can be synthesized on their basis, which have boron and zinc atoms in their composition.

"We have discovered the process of self-assembly of fully conjugated nitrogen-containing polyenes. At the same time, highly unsaturated bicyclic bridge structures are formed — this is obviously just the beginning of the amazing chemistry of these molecules. In subsequent experiments, we showed that by varying the heteroatoms, that is, the nitrogen and oxygen atoms, as well as the substituents in azapolyene, it is possible to "lay" it not only in a bi -, but also in a tricyclic bridge structure. Unfortunately, such molecules are unstable, but we assume that their stability can be achieved if the carbon chain of the initial azapolyene is slightly lengthened. There is no doubt that the chemical "Rubik's snake" will still surprise us with its ability to form a whole world of amazing molecules in structure, " says Mikhail Sergeevich Novikov, head of the RNF grant, Doctor of Chemical Sciences, Professor at the Institute of Chemistry of St. Petersburg State University, head of the laboratory of azapolyene and ylide intermediates.

The results of the study, supported by a grant from the Russian Science Foundation (RPF), are published in the journal Organic Letters
Image: Reactions of synthesis of cyclic compounds based on chemical "Rubik's snakes" © Nikolay Rostovsky

Source: scientificrussia.ru, sci-dig.ru