Abstract

HERRERA, Rafael et al. 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. J. Mex. Chem. Soc [online]. 2005, vol.49, n.2, pp.218-228. ISSN 1870-249X.

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 n 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.

Keywords : captodative olefins; Friedel-Crafts; Diels-Alder cycloaddition; transition state calculations.

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