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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 122-140 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectrometric study of acetylenic dialkylphosphonates (I) and of γ, δ-éthylenic-β-ketophosphonates (II) is characterised by rearrangement processes of the phosphorylated group and cleavage of the phosphorus-carbon bond. The fragmentation patterns of compounds II were identical to those found for I by loss of water.
    Notes: L'étude des processus de rupture en spectrométrie de masse de dialcoylphosphonates ényniques (I) et de β-cétophosphonates-γ, δ-éthylénique (II) sont caractérisés par des réarrangements au niveau du groupement phosphoré et des ruptures au niveau de la liaison phosphore-carbone. Les composés II conduisent à des schémas identiques à ceux de I par perte d'une molécule d'eau.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 514-524 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectrometric fragmentations of diethyl phosphates (1) and di-n-butyl phosphates (2) are influenced by the nature of the substituents R, R′ and R″ fixed on the double bond When R = H, the loss of ethylene or 1-butene is mainly observed. When R = CH3, the double rearrangement process occurs with alkyl group participation of the enolic chain.
    Notes: L'étude des fragmentation en spectrométrie de masse de phosphates diéthyliques (1) et di-n-butyliques (2) est grandement influencée par la nature des substituants R, R′, R″ fixés sur la double liaison Lorsque R = H on observe une perte prépondérante d'éthylène ou de butène-1. Dans le cas où R = CH3 le procesus de double réarrangement se produit avec participation des groupements alcoyles de l'enchaînement énolique.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 23-32 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NMR studies on E and Z enolic phosphates with no substituent on carbon 1 provided evidence for the existence of planar and gauche conformations. When no bulky substituents are present in the cisoid position of the phosphates two planar and two gauche forms are possible. The most stable conformation is the planar form having the phosphate group trans to the double bond. With a bulky substituent in the cisoïd position of the phosphates the planar form with the group cis to the double bond could not be observed. A close agreement is obtained between the values of dihedral angles determined from observed coupling constants and those calculated with the CNDO/2 method. Changes observed in cisoïd and transoïd 4J(POCCH) coupling constants with temperature variation and the reversal of magnitude of these constants when a bulky substituent is on carbon 158 are explained.
    Notes: L'analyse RMN des phosphates d'énols E et Z non substitués sur le carbone 1, nous a permis de mettre en évidence l'existence de conformations planes et gauches. Dans le cas de phosphates ne comportant pas de groupement volumineux en position cisoïde par rapport au groupement phosphate, il est possible d'envisager deux formes planes et deux formes gauches. La conformation la plus stable est la forme plane où le groupement phosphate est en trans par rapport à la double liaison. Dans le cas de phosphates comportant un groupement volumineux en position cisoïde, la forme plane où le groupement est en cis par rapport à la double liaison n'a pu être mise en évidence. Un bon accord est obtenu entre les valeurs des angles dièdres des formes gauches déterminées à partir des constantes de couplage et calculées en utilisant la méthode CNDO/2. La variation des constantes 4J(POCCH) cisoïde et transoïde en fonction de la température, a pu être justifiée et permettra d'expliquer le renversement apparent de la valeur de ces constantes lorsque l'on place un substituant sur le carbone 158.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 157-171 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectrometric study of a series of enolic phosphates of type A leades to fragmentation patterns influenced by the nature of the substituents (R, R′ and R″). It is generally observed that a simple or double hydrogen rearrangement occurs with the loss of the enolic groups. When R and R′ are alkyl groups, the migrating groups are the hydrogen atoms on the alkyl group at position 1. When there is no alkyl group at position 1, the hydrogen atoms of the alkyl group at position 2 induce the rearrangement process. Finally, if R, R′ and R″ are hydrogen atoms, the loss of the enolic chain occurs without any rearrangement.
    Notes: L'étude d'une série de phosphates énoliques du type A an spectrométrie de masse conduit à des schémas de rupture influencés par la nature des substituants R, R′ et R″, On observe généralement à côte de la perte du groupement énolique, des phénomènes des phénomènes de double ou simple réarrangement d'hydrogène. Lorsque R et R′ sont des groupements alcoyles, ce sont les atomes d'hydrogène du groupement fixé en 1 qui migrent. En l'absence de groupement alcoyle en 1, ce sont les atomes d'hydrogène du groupment en 2 qui provoquent le réarrangement. Enfin si R, R′ et R″ sont des atomes d'hydrogène, on a essentiellement perte de l'enchaînement éolique sans réarrangement.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 557-558 
    ISSN: 0749-1581
    Keywords: 17O NMR ; Methoxyflavones ; Steric effect ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 17O NMR spectra were recorded for ten methoxyflavones and one flavonol. The chemical shifts are discussed in terms of steric and conformational changes. They are related to previously reported 13C NMR data.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0749-1581
    Keywords: (+)-Aromadendrene ; (-)-Alloaromadendrene ; (+)-Ledene ; (-)-Dehydroaromadendrane ; (-)-Globulol ; (+)-Viridiflorol ; 2D Homonuclear and heteronuclear correlations ; 2D INADEQUATE ; 1H NMR ; 13C NMR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total assignment of the 1H and 13C NMR spectra of five aromadendrane derivatives, (+)-aromadendrene (1), (-)-alloaromadendrene (2), (+)-ledene (3), (-)-dehydroaromadendrane (4), (-)-globulol (5) and (+)-viridiflorol (6) has been performed. The 13C spectral assignment of globulol was achieved from DEPT and double quantum coherence measurements. The concerted application of 1H—1H homonuclear and 1H—13C heteronuclear two-dimensional chemical shift correlations provided other 13C and all 1H chemical shifts. Moreover, the 1H assignment for compounds 1—3 was reexamined from the high-field analysis of proton-proton coupling constants.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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