Original scientific paper

https://doi.org/10.5562/cca1825

Bioactive Phenylenediamine Derivatives of Dehydroacetic Acid: Synthesis, Structural Characterization and Deuterium Isotope Effects

Tomislav Jednačak ; Department of Chemistry, Faculty of Natural Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Predrag Novak ; Department of Chemistry, Faculty of Natural Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Krunoslav Užarević ; Department of Chemistry, Faculty of Natural Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Igor Bratoš ; PLIVA Croatia Ltd., TAPI Research & Development, Prilaz baruna Filipovića 25, HR-10000 Zagreb, Croatia
Jelena Marković ; Department of Chemistry, Faculty of Natural Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Marina Cindrić ; Department of Chemistry, Faculty of Natural Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia

Abstract

Several phenylenediamine derivatives of dehydroacetic acid, 3-acetyl-4-hydroxy-6-methyl-2Hpyran-
2-one have been synthesized and their structure elucidated by using NMR and IR spectroscopies
and mass spectrometry. Spectral analyses have pointed toward the localized keto-amine form as the predominant
tautomeric form in solution and solid-state which was in agreement with X-ray data. The relatively
broad N–H stretching bands observed in IR spectra and significant N–H proton down-field and keto
C=O up-field shifts in NMR spectra indicated the presence of intra-molecular hydrogen bonds in all studied
compounds. In order to gain further insights into nature of these interactions in solution deuterated
isotopomers have been prepared and deuterium isotope effects in 13C NMR spectra have been determined
and analyzed. The magnitude and sign of isotope effects have confirmed the existence of intra-molecular
hydrogen bonds. Observed differences in isotope effects reflected different hydrogen bond structure and
dynamics in studied compounds. The results presented in this paper might help in better understanding of
biological properties of the related compounds.(doi: 10.5562/cca1825)

Keywords

dehydroacetic acid; phenylenediamine derivatives; IR; NMR; MS; hydrogen Bonds; tautomerism; deuterium isotope effects

Hrčak ID:

71983

URI

https://hrcak.srce.hr/71983

Publication date:

3.10.2011.

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