Work

On the Question of Zwitterionic Intermediates in the [3+2] Cycloaddition Reactions between Aryl Azides and Ethyl Propiolate

Year: 2023

Type: article

Abstract: The molecular mechanism of the [3+2] cycloaddition reactions between aryl azides and ethyl propiolate was evaluated in the framework of the Molecular Electron Density Theory. It was found that independently of the nature of the substituent within the azide molecule, the cycloaddition process is realized via a polar but single-step mechanism. All attempts of localization as postulated earlier by Abu-Orabi and coworkers' zwitterionic intermediates were not successful. At the same time, the formation of zwitterions with an "extended" conformation is possible on parallel reaction paths. The ELF analysis shows that the studied cycloaddition reaction leading to the 1,4-triazole proceeds by a two-stage one-step mechanism. It also revealed that both zwitterions are created by the donation of the nitrogen atom's nonbonding electron densities to carbon atoms of ethyl propiolate.

Source: Molecules

DOI: 10.3390/molecules28248152

Authors: Ewa Dresler, Przemysław Woliński, Aneta Wróblewska, Radomir Jasiński

Institutions: Łukasiewicz Research Network - Institute of Heavy Organic Synthesis "Blachownia", Cracow University of Technology, University of Łódź

Language: English

Topic: Organic Chemistry Cycloaddition Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,558

Funders: Infrastruktura PL-Grid, Academic Computer Centre Cyfronet, AGH University of Science and Technology