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Studies on Azole‐to‐Azole Interconversion − An Interesting Case of Absence of a “Primary Steric Effect” in the Ring‐Degenerate Equilibration between ortho ‐Substituted 3‐Aroylamino‐5‐methyl‐1,2,4‐oxadiazoles and 3‐Acetylamino‐5‐aryl‐1,2,4‐oxadiazoles in Methanol
Author(s) -
Buscemi Silvestre,
Frenna Vincenzo,
Pace Andrea,
Vivoicolò,
Cosimelli Barbara,
Spinelli Domenico
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200204)2002:8<1417::aid-ejoc1417>3.0.co;2-g
Subject(s) - chemistry , steric effects , substituent , ring (chemistry) , azole , reactivity (psychology) , stereochemistry , electronic effect , derivative (finance) , benzene , polar , computational chemistry , medicinal chemistry , organic chemistry , antifungal , medicine , physics , alternative medicine , pathology , dermatology , astronomy , financial economics , economics
The title reaction has been studied by 1 H NMR, both in CD 3 OD and in t BuOK/CD 3 OD. The components of the electronic effect of the substituent on the benzene ring show different contributions depending on whether the equilibrium between neutral (strong prevalence of the “proximity polar effect”) or anionic species (balance between “ordinary and proximity polar effects”) is considered. The “primary steric effect” does not significantly affect the reactivity, probably because of the importance of the internal amidic conjugation. For the ortho ‐methoxy derivative, interesting “special” proximity effects have been observed. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)