A new method for the preparation of unusual heterocyclic compounds was developed by the scientists of the ZIOC

Fused heterocycles containing a bridgehead nitrogen atom are of increasing interest in organic and medicinal chemistry. Among such structures, indolizines and their aza analogs are the most studied, while [5,5]-annulated heterocycles are much less investigated due to the lack of routes for their synthesis. However, such structures are quite attractive from the point of view of their biological properties, including anticancer and antitumor activities. That is why the development of simple methods for the preparation of a wide range of [5,5]-annelated heterocycles is an important task of modern organic synthesis.

Researchers from the Laboratory of Organic and Metal-Organic Nitrogen-Oxygen Systems of the Zelinsky Institute proposed an effective method for the preparation of interesting [5,5]-annelated N-fused heterocycles such as as pyrrolo[2,1-b]thiazoles and pyrrolo[1,2-b]indazoles. At the same time, the tricyclic system of pyrrolo[1,2-b]indazole, which does not contain additional annulated rings, has not been previously reported at all. The method is based on the oxidative [3+2]-annulation reaction between nitroalkenes and azolium ylides in the presence of copper(II) salts. The process is applicable to a wide range of the starting substrates and produces the desired fused heterocycles in moderate to high yields. A detailed study of the reactivity, as well as the biological properties of the obtained compounds, is a promising area of research for organic chemists and medical chemists.

Source:

Vladimir A. Motornov, Andrey A. Tabolin, Sema L. Ioffe Oxidative [3+2]-annulation of nitroalkenes and azolium ylides in the presence of Cu(II): efficient synthesis of [5,5]-annulated N-fused heterocycles. New J. Chem., 2022, 46, 4134-4141. DOI: 10.1039/d1nj05332a.