Density functional theory study for the cycloaddition of 1,3-butadienes with dimethyl acetylenedicarboxylate. Polar stepwise vs concerted mechanisms

Luis R. Domingo, Manuel Arnó, Renato Contreras, Patricia Pérez

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

83 Citas (Scopus)

Resumen

The molecular mechanisms for the cycloaddition reactions of four low activated 1,3-butadiene systems (1,3-butadiene, (E)-1,3-pentadiene, (Z)-1,3-pentadiene, and 4-methyl-1,3-pentadiene) with dimethyl acetylenedicarboxylate (DMAD) have been studied using density functional theory methods. For these cycloadditions, two competitive mechanisms have been characterized: the first one corresponds to a concerted C-C bond-formation where the asynchronicity depends on the methyl substitution. The second one corresponds to a stepwise process with a larger polar character where first a C-C bond is formed along the nucleophilic attack of 1,3-butadiene system to a conjugate position of the electron-poor substituted acetylene. Although the nonactivated 1,3-butadiene prefers the concerted process, substitution of hydrogen atoms by electron-releasing methyl groups favors the stepwise mechanism along with an increase of the charge-transfer process. A conformational analysis for DMAD reveals that both planar and perpendicular arrangements of the two-carboxylate groups have a decisive role on the dienophile/electrophile nature of this acetylene derivative. Thus, although the planar arrangement is preferred along the concerted process, the perpendicular favors the polar one along an increase of the electrophilicity of DMAD. The global and local electrophilicity power of these 1,3-butadienes and DMAD have been evaluated in order to rationalize these results. The study is completed with an analysis of the electrophilic/nucleophilic site activation, by probing the variations in local properties of DMAD perturbed by a model nucleophile with reference to a model transition structure. Inclusion of solvent effects, by means of a Polarizable continuum model, does not modify these gas-phase results.

Idioma originalInglés
Páginas (desde-hasta)952-961
Número de páginas10
PublicaciónJournal of Physical Chemistry A
Volumen106
N.º6
DOI
EstadoPublicada - 14 feb 2002

Áreas temáticas de ASJC Scopus

  • Química física y teórica

Huella

Profundice en los temas de investigación de 'Density functional theory study for the cycloaddition of 1,3-butadienes with dimethyl acetylenedicarboxylate. Polar stepwise vs concerted mechanisms'. En conjunto forman una huella única.

Citar esto