Reactivity of nucleophiles toward a p-benzyne derived from an enediyne

Imagen de Gabriel J. Reyes-Rodríguez
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TítuloReactivity of nucleophiles toward a p-benzyne derived from an enediyne
Publication TypeJournal Article
Year of Publication2012
AutoresPerrin, CL, Reyes-Rodríguez, GJ
JournalJournal of Physical Organic Chemistry
Volume26
Issue2
Start Page206
Date Published07/2012
Palabras clavecycloaromatization, diradical, enediyne, nucleophilic addition, p-benzyne, selectivity, solvation
Abstract

Enediynes undergo cycloaromatization to p-benzyne diradicals.Anewreactionof p-benzynes isherepresented. Instead of their usual radical reactivity, they add nucleophiles, followed by protonation. Kinetic evidence showed that the rate-limiting step is the cycloaromatization, followed by rapid addition of a nucleophile. The unusual feature of nucleophilic addition to a radical center in a singlet diradical is discussed. Calculations that ignore solvation suggest that the addition has no activation barrier, but one is created by the necessity for desolvation of the anionic nucleophile. Relative reactivities of several nucleophiles have been measured under competition conditions. The observation of deuterium incorporation from DMSO-d6 or CD3CN shows that the species that is protonated is the aryl anion, not the p-benzyne. The extent of deuterium incorporation increases as the nucleophile is changed from iodide to bromide to chloride. This remarkable instance of selectivity is discussed. These studies of p-benzyne reactivity are exploring the nonradical chemistry of this diradical.

URLhttp://doi.wiley.com/10.1002/poc.2994
DOI10.1002/poc.2994

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