Unveiling the Lewis Acid Catalyzed Diels–Alder Reactions Through the Molecular Electron Density Theory

Molecules

Patricia Pérez¹  Luis R. Domingo²  Mar Ríos-Gutiérrez² 

[1] Department of Chemistry, Computational and Theoretical Chemistry Group, Faculty of Sciences, University Andres Bello, Santiago 8370146, Chile;Department of Organic Chemistry, University of Valencia, 46100 Burjassot, Valencia, Spain;

关键词: Diels–Alder;    Lewis acid;    catalysis;    molecular electron density theory;    relation mechanism;   

DOI  :  10.3390/molecules25112535

来源: DOAJ

【 摘 要 】

The effects of metal-based Lewis acid (LA) catalysts on the reaction rate and regioselectivity in polar Diels–Alder (P-DA) reactions has been analyzed within the molecular electron density theory (MEDT). A clear linear correlation between the reduction of the activation energies and the increase of the polar character of the reactions measured by analysis of the global electron density transfer at the corresponding transition state structures (TS) is found, a behavior easily predictable by analysis of the electrophilicity ω and nucleophilicity N indices of the reagents. The presence of a strong electron-releasing group in the diene changes the mechanism of these P-DA reactions from a two-stage one-step to a two-step one via formation of a zwitterionic intermediate. However, this change in the reaction mechanism does not have any chemical relevance. This MEDT study makes it possible to establish that the more favorable nucleophilic/electrophilic interactions taking place at the TSs of LA catalyzed P-DA reactions are responsible for the high acceleration and complete regioselectivity experimentally observed.

【 授权许可】

Unknown