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Measurement of long‐range heteronuclear selective 13 {1H} NOE enhancements: 4‐ (α‐arylethylidene)‐2‐phenyl‐5(4 H )‐oxazolones
Author(s) -
Cativiela Carlos,
SánchezFerrando Francisco
Publication year - 1985
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.1260231209
Subject(s) - heteronuclear molecule , chemistry , protonation , yield (engineering) , nuclear overhauser effect , stereochemistry , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , organic chemistry , physics , ion , thermodynamics
Abstract The technique previously described as two‐bond heteronuclear selective NOE difference was improved to yield quantitative data on NOE enhancement factors by recording separately the unperturbed and the perturbed FIDs. In this way the E and Z stereoisomers of 4(α‐arylethylidene)‐2‐phenyl‐5(4 H )‐oxazolones were easily distinguished. The latter showed positive NOE ehancements on quaternary carbons placed two, three and four bonds away from the irradiated methyl protons, as well as a negative NOE on a nearby protonated carbon.