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  • Analytical Chemistry and Spectroscopy  (3)
  • 3,4-dehydroretinal  (1)
  • 1
    ISSN: 0030-4921
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effects of protonation and hydrogen bonding in linear Schiff bases obtained from n-butylamine with butyraldehyde, crotonaldehyde, sorbaldehyde and all-trans-retinal were studied by means of 15N and 13C NMR. The protonation-induced chemical shifts (Δδ) are an order of magnitude larger for 15N than for 13C. For 15N, this effect was found to increase with the extent of conjugation, culminating in the retinylideneimine (Δδ = -146 ppm), which constitutes a model for the study of the structure of the Schiff base linkage in visual pigments and related systems. Theoretical calculations of protonation-induced Δδ values based on MINDO/ 3 are in agreement with experimental results.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 1040-1045 
    ISSN: 0749-1581
    Schlagwort(e): α-retinal ; α-ethyl retinoate ; α-retinol ; α-retinoic acid ; 3,4-dehydroretinal ; 3,4-dehydroretinol ; ethyl 3,4-dehydroretinoate ; 3,4-dehydroretinoic acid ; 2D heteronuclear-correlated spectroscopy ; APT ; empirical chemical shift calculations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 13C NMR assignments have been made for a series of 36 α- and 3,4-dehydroretinoids with different substituents (alcohol, ester, aldehyde and acid) and for their separated E and Z geometrical isomers. The assignments were made by using 2D heteronuclear-correlated NMR experiments. From the chemical shift data of 24 systematically related retinoids, empirical chemical shift changes due to four polar end groups (alcohol, aldehyde, carboxylic acids and esters), three chain configurations (all-E, 9Z and 13Z), and two ring substitutions (2,6,6-trimethyl-cyclohex-2-enyl and 2,6,6-trimethylcyclohexa-1,3-dienyl) were determined. All trends were found to be independent of each other, except for the dependence of the chemical shift change of the 13Z-isomers on the polar end groups. The chemical shift changes were used to predict the chemical shifts of other retinoids based on two different ring structures (2,6,6-trimethylcyclohexenyl and 4-methoxy-2,3,6-trimethylphenyl).
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 497-499 
    ISSN: 0749-1581
    Schlagwort(e): NMR ; 1H NMR ; 13C NMR ; 6-s-trans-retinoids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new class of vitamin A analogs (retinoids) was synthesized containing a dimethylene bridge to maintain a 6-s-trans conformation of the terminal double bonds. The 1H and 13C NMR spectra were assigned for 15 new compounds, including E-Z isomers (all-E, 13Z, 9Z and 9Z,13Z) of retinoids containing an ethyl ester and car-boxylic acid polar end groups, and also the (all-E)-isomer of the retinoids with an alcohol and aldehyde polar end-groups and five C15 intermediates. The assignments were based on long-range 1H—13C heteronuclear 2D experiments.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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