Aza-Diels-Alder addition of cyclopentadiene to propynyliminoglyoxylates

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Filipe Teixeira (Author) Other; Andre Melo (Author) FCUP; Natalia N D S Cordeiro (Author) FCUP

Journal

Title: Computational and Theoretical Chemistry

Vol. 1012

Pages: 54-59

ISSN: 2210-271X

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 4 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-005-0QJ

DOI: 10.1016/j.comptc.2013.02.014

Abstract (EN): The aza-Diels-Alder reaction of cyclopentadiene with protonated propynylimine of methyl (Me) and tert-butyl (t-Bu) carboxylate was studied, using density functional theory (DFT) at the X3LYP/6-31G (d) level, in order to elucidate the role of the ester group of the dienophile. Four independent reaction pathways were found for each diene/dienophile pair, all of them proceeding through a concerted, highly asynchronous, mechanism. Both systems exhibit a clear tendency for the formation of exo adducts and show the same overall behavior, despite steric hindrances. The exo cycloadducts are always favored relative to the endo analogs, both by kinetic and thermodynamic reasons. Gas-phase results showed that the exo/endo rate would be mostly controlled by the relative thermodynamic stability of the final products. However, the application of the polarizable continuum model (PCM) preferentially lowered the activation enthalpy of the reaction exo channels, stressing the importance of the kinetic over the thermodynamic aspects of the proposed mechanism. This resulted in a reaction model that satisfies the experimental evidence.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6