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Updated: Sep 27, 2025

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Published on: June 21, 2017

Understanding the different reactivity of (Z)- and (E)-β-nitrostyrenes in [3+2] cycloaddition reactions. An MEDT

Mar Ríos-Gutiérrez¹, Luis R Domingo¹, Radomir Jasiński²

¹Department of Organic Chemistry, University of Valencia Dr Moliner 50, 46100 Burjassot Valencia Spain rios@utopia.uv.es.

|April 15, 2022

Abstract:

The experimental reactivity of isomeric (Z)- and (E)-β-nitrostyrenes participating in [3+2] cycloaddition (32CA) reactions has been analysed on the basis of molecular electron density theory (MEDT) at the HF/6-311G(d,p), B3LYP/6-311G(d,p) and ωB97X-D/6-311G(d,p) computational levels. It was found that the polar zw-type 32CA reactions with 5,5-dimethylpyrroline-N-oxide proceed via a one-step mechanism, characterised by the attack of the nucleophilic oxygen centre of the nitrone on the electrophilically activated β-position of these nitrostyrenes. This behaviour is completely understood by means of the analysis of the conceptual DFT reactivity indices. These 32CA reactions present low activation enthalpies of 4.4 (Z) and 5.0 (E) kcal mol^-1, and are exo (Z) and endo (E) stereoselective (B3LYP), as well as completely meta regioselective (ωB97X-D, B3LYP). The less stable (Z)-β-nitrostyrene is more reactive than the (E)-one (HF). ELF and AIM topological analyses of the reagents and TSs show the great similitude between their electronic structures. Finally, NCI allows explaining the exo stereoselectivity found in the reaction of (Z)-β-nitrostyrene. The present MEDT study explains the different reactivity, selectivity and competitiveness in the title reactions.

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