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Structure of silylated benzohydroxamic acids
Author(s) -
Schraml Jan,
Kvíčalová Magdalena,
Soukupová Ludmila,
Blechta Vratislav
Publication year - 1999
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/(sici)1097-458x(199906)37:6<427::aid-mrc481>3.0.co;2-0
Subject(s) - chemistry , moiety , tautomer , trimethylsilyl , carbon 13 nmr , stereochemistry , chemical shift , organic chemistry
NMR spectra ( 13 C, 15 N and 29 Si) of the products of trimethylsilylation and tert ‐butyldimethylsilylation of benzohydroxamic acid and model derivatives of benzohydroximic acid were studied in solutions. The products are shown to have the structure of ( Z )( syn )‐ O , O ′‐bis(trimethylsilyl) and ‐ O , O ′‐di( tert ‐butyldimethylsilyl) derivatives of benzohydroximic acid [i.e. ( Z )‐trimethylsilyl ester of N ‐(trimethylsiloxy)benzoimidic acid and ( Z )‐ tert ‐butyldimethylsilyl ester of N ‐( tert ‐butyldimethylsilyl)benzoimidic acid, respectively]. Whereas 15 N NMR chemical shifts are the most useful NMR parameter for differentiation between derivatives of hydroxamic and hydroximic tautomers, differentiation between Z and E stereoisomers of hydroximic acid derivatives is more reliable on the basis of 1 J ( 13 C, 13 C) coupling within the C—CN moiety. Copyright © 1999 John Wiley & Sons, Ltd.