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Heterocyclic β‐enamino esters 43 —easy 13 C NMR distinction between aryl‐substituted dimroth isomers of the 1,2,3‐triazole series
Author(s) -
Wamhoff H.,
Bohlen J.,
Yang S. Y.
Publication year - 1986
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.1260240914
Subject(s) - chemistry , aryl , carbon 13 nmr , triazole , medicinal chemistry , stereochemistry , proton nmr , nmr spectra database , cis–trans isomerism , chemical shift , spectral line , organic chemistry , alkyl , physics , astronomy
Abstract 5‐Amino‐1‐aryl‐1,2,3‐triazoles and 5‐anilino‐1,2,3‐triazoles can be easily distinguished by their 13 C NMR spectra. Thus, C‐4 and C‐5 of some studied 5‐anilino isomers are deshielded by 2–5 ppm in comparison with the corresponding 5‐amino‐1‐aryl isomers. From the 13 C NMR signals of the aryl carbons in the same 5‐anilino isomers, C‐6 is shifted downfield ( ca 9 ppm; – I effect), whereas C‐7 and C‐9 are shifted upfield ( ca 7 and 10 ppm, respectively; + M effect). This allows a fast and easy assignment of both Dimroth isomers.