Stepwise Mechanisms in the Ene Reaction of Alpha,Beta-Unsaturated Esters with N-Phenyl-1,2,4-Triazoline-3,5-Dione and Singlet Oxygen - Intermolecular Primary and Secondary Hydrogen Isotope Effects

 
This item is provided by the institution :
University of Ioannina
Repository :
Repository of UOI Olympias
see the original item page
in the repository's web site and access all digital files if the item*
share



1992 (EN)
Stepwise Mechanisms in the Ene Reaction of Alpha,Beta-Unsaturated Esters with N-Phenyl-1,2,4-Triazoline-3,5-Dione and Singlet Oxygen - Intermolecular Primary and Secondary Hydrogen Isotope Effects (EN)

Elemes, Y. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Elemes, Y. (EN)

Intermolecular primary and secondary isotope effects on the ene reaction of N-phenyl-1,2,4-triazoline-3,5-dione (PTAD) and singlet oxygen (O-1(2)) with deuterium-substituted (E)-2-methylbuten-2-oic (tiglic) acid methyl esters have been determined. In the case Of O-1(2), the primary isotope effect is 1.30-1.49 and the alpha and beta-secondary isotope effects are near unity, consistent with a stepwise reaction path via a perepoxide intermediate, where the allylic hydrogen-abstraction step is rate determining. On the other hand, the existence of both primary (1.44) and inverse alpha and beta-secondary isotope effects (0.91 and 0.77, respectively) in the PTAD reaction is consistent with either a concerted or a stepwise mechanism. Experiments in which both intermolecular primary and secondary isotope effects were measured at the same time suggest that, like singlet oxygen, PTAD reacts in a stepwise manner with the formation of the aziridinium imide intermediate (AI) in the rate-determining-step. (EN)

diels-alder reaction (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

J Am Chem Soc (EN)

English

1992

<Go to ISI>://A1992JE22500023

American Chemical Society (EN)



*Institutions are responsible for keeping their URLs functional (digital file, item page in repository site)