The Role of Supramolecular Intermediates in the Potential Energy Surface of the Diels-Alder Reaction

  • Karla Ramírez-Gualito Universidad Nacional Autónoma de México
  • Néstor López-Mora Universidad Nacional Autónoma de México
  • Hugo A. Jiménez-Vázquez Instituto Politécnico Nacional
  • Joaquín Tamariz Instituto Politécnico Nacional
  • Gabriel Cuevas Universidad Nacional Autónoma de México

Abstract

The potential energy surface of four stereoselective Diels-Alder reactions was studied, namely: cyclopentadiene-maleic anhydride, furan-maleic anhydride, the dimerization of cyclopentadiene, and cyclopentadiene-cyclopropene. For completeness, we also studied the reaction between ethylene and 2-hydroxy-6-methyl-1,4-benzoquinone, a [5+2] cycloaddition reaction. For all cases at least a stationary state of supramolecular nature a van der Waals complex, was determined. These stationary states are complexes formed by the interaction between the reagents, minima located in the paths between the non-interacting molecules and the transition states. The existence of these complexes makes it necessary to reconsider the role of Secondary Orbital Interactions in the selectivity of these reactions. As it is the case with other complexes, the stability of these supramolecular intermediates depends on electrostatic phenomena such as dispersion forces. The observation of [5+2] intramolecular complexes in solution is important since up to now, this kind of van der Waals complexes had only been described in the gas phase.

Author Biographies

Karla Ramírez-Gualito, Universidad Nacional Autónoma de México
Instituto de Química
Néstor López-Mora, Universidad Nacional Autónoma de México
Instituto de Química
Hugo A. Jiménez-Vázquez, Instituto Politécnico Nacional
Departamento de Química Orgánica. Escuela Nacional de Ciencias Biológicas
Joaquín Tamariz, Instituto Politécnico Nacional
Departamento de Química Orgánica. Escuela Nacional de Ciencias Biológicas
Gabriel Cuevas, Universidad Nacional Autónoma de México
Instituto de Química
Published
10-12-2017