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NMR study of E / Z isomerism in N ‐alkoxybenzoimidic acid derivatives
Author(s) -
Schraml Jan,
Blechta Vratislav,
Karban Jindřich,
Mindl Jaromir
Publication year - 2002
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1076
Subject(s) - chemistry , chemical shift , chloride , carbon atom , coupling constant , carbon 13 nmr , medicinal chemistry , stereochemistry , proton nmr , computational chemistry , organic chemistry , ring (chemistry) , physics , particle physics
Well defined E / Z isomers of N ‐methoxy‐ p ‐nitrobenzimidoyl chloride, N ‐methoxybenzimidoyl chloride, methyl N ‐methylbenzohydroximate and ethyl N ‐hydroxybenzimidate were prepared in order to provide model data for studies of benzhydroximic acid derivatives and related compounds. NMR parameters [ 1 H , 13 C and 15 N chemical shifts and 1 J ( 13 C , 13 C ) coupling constants] were determined. The results show that stereochemically most significant are the values of 1 J ( 13 C , 13 C ) couplings between aromatic C ipso and CN carbons and that the relationship, | J cis | > | J trans |, known for this coupling from oximes, is not affected by electronegative substituents at the CN carbon atom, but the values are. Copyright © 2002 John Wiley & Sons, Ltd.