Issue 9, 1997

The role of cumulenic strain on the kinetic and thermodynamic control of the Diels–Alder reactions involving allenes as dienes

Abstract

Diels–Alder cycloaddition reactions of vinylallene and diallene with ethylene, acrylonitrile, maleic anhydride, p-benzoquinone and 1,4-naphthaquinone have been investigated at the semiempirical level and with limited ab initio and DFT calculations. Calculations predict that these reactions are concerted processes and these cumulated dienes are less reactive than the non-cumulated diene. With increase in cumulenic strain the reactivity decreases while the exothermicity of the reaction increases. This happens because the transition states occur ‘early’ and the cumulenic strain is therefore released only when the reaction proceeds from transition state to product. Deformation energy analysis explains that these cumulated dienes have to deform to a greater extent during the reaction and thus are responsible for the increase of the activation energy. Activation barriers predict the reactivity trends, regio- and stereo-selectivities reasonably.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 2, 1997, 1799-1804

The role of cumulenic strain on the kinetic and thermodynamic control of the Diels–Alder reactions involving allenes as dienes

M. Manoharan and P. Venuvanalingam, J. Chem. Soc., Perkin Trans. 2, 1997, 1799 DOI: 10.1039/A700250E

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