Computations Reveal That Electron-Withdrawing Leaving Groups Facilitate Intramolecular Conjugate Displacement Reactions by Negative Hyperconjugation.
J Org Chem
; 81(10): 4290-4, 2016 05 20.
Article
em En
| MEDLINE
| ID: mdl-27100519
ABSTRACT
Intramolecular conjugate displacement (ICD) reactions, developed by the Clive group, form carbocycles and polycyclic amines by intramolecular nucleophilic attack on a Michael acceptor with an allylic leaving group. Quantum mechanical investigations with density functional theory show that ICDs involve a stepwise addition, forming an intermediate stabilized carbanion, followed by elimination. The electron-withdrawing nature of the allylic leaving group facilitates the addition by negative hyperconjugation; the twist-boat conformation of the addition and intermediate is stabilized by this interaction. In the absence of an activating electron-withdrawing group as part of the Michael acceptor, a high energy concerted SN2' reaction occurs. The reactions of carbon nucleophiles have lower activation energies than those of amines.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2016
Tipo de documento:
Article