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NMR Study of the ( Z )‐Phenylhydrazones of 5‐Alkyl‐ and 5‐Aryl‐3‐benzoyl‐1,2,4‐oxadiazoles: Support for the Interpretation of Kinetic Results on the Rearrangement of 1,2,4‐Oxadiazoles to 1,2,3‐Triazoles
Author(s) -
Mezzina Elisabetta,
Spinelli Domenico,
Lamartina Liliana,
D’Anna Francesca,
Frenna Vincenzo,
Macaluso Gabriella
Publication year - 2005
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/ejoc.200500236
Subject(s) - chemistry , substituent , aryl , chemical shift , kinetic energy , alkyl , medicinal chemistry , computational chemistry , nitrogen , ring (chemistry) , carbon 13 nmr , stereochemistry , organic chemistry , physics , quantum mechanics
An analysis of the 1 H, 13 C, and 15 N NMR substituent chemical shifts (SCSs) of the title compounds in CDCl 3 solution has been carried out by using the SCSs of other classes of compounds (arenes, methyl esters or amides), Hammett substituent constants or kinetic data. The results obtained provide information concerning the ground‐state electronic distribution of the compounds examined. The results relevant to the carbon and nitrogen atoms of the 1,2,4‐oxadiazole ring can be considered of special interest, as the effects of the substituents on the chemical shifts of N‐4 and C‐5 appear in line with kinetic results collected in the study of the rearrangement (Boulton–Katritzky reaction) of the title compounds into the relevant 1,2,3‐triazoles, thereby strongly supporting the importance of the leaving‐group ability of the N‐4/C‐5/O‐1 system. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)