1-acetylvinyl acrylates: new captodative olefins bearing an internal probe for the evaluation of the relative reactivity of captodative against electron-deficient double bonds in Diels-Alder and Friedel-Crafts reactions

Journal of the Brazilian Chemical Society

Rafael Herrera²  Hugo A. Jiménez-vázquez²  Francisco Delgado²  Björn C. G. Söderberg¹  Joaquín Tamariz² 

[1] ,Instituto Politécnico Nacional Escuela Nacional de Ciencias Biológicas Departamento de Química OrgánicaMéxico D.F. ,Mexico

关键词: captodative olefins;    Friedel-Crafts;    Diels-Alder cycloaddition;    transition state calculations;   

DOI  :  10.1590/S0103-50532005000300021

来源: SciELO

【 摘 要 】

The captodative olefins 1-acetylvinyl esters of methacrylic and trans-crotonic acids, 3a and 3b, have been prepared. The presence of a second double bond in the molecule, acting as an internal probe, allowed us to compare their relative reactivity in Diels-Alder and Friedel-Crafts reactions. The reactivity was evaluated with cyclopentadiene (6) as diene in Diels-Alder cycloadditions, and with furan (9) and thiophene (10) as heteroaromatic Friedel-Crafts substrates. In both processes, the captodative enone double bond proved to be more reactive than that in the acrylic moiety. FMO theory accounted for this chemoselectivity as a consequence of the major p contribution of the enone to the LUMO of these molecules. The slight exo stereoselectivity observed in the cycloaddition to 6 parallels the higher stability of the corresponding transition state, according to the results of B3LYP/6-311G(d,p) calculations.

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