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  • 1
    Electronic Resource
    Electronic Resource
    Mechanistic aspects of the biogenesis of rose oxide in Pelargonium graveolens L'Héritier (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 229-237 
    Details
    ISSN: 0899-0042
    Keywords: deuterium labelling ; menthocitronellol ; citronellol ; enantioselective multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS) ; dynamic headspace analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanistic aspects of the biogenesis of the chiral monoterpenoid rose oxide in Pelargonium graveolens L'Héritier are investigated using deuterium-labelled precursors. After administration of the precursors using the cut-stem method, the dynamic headspace extracts of the plants are analysed using multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS). It is unequivocally shown that this plant is able to convert citronellol and menthocitronellol into cis-/trans-rose oxide. Menthocitronellol is converted into rose oxide with a clearly detectable enantiodiscrimination. These facts may be explained with the presence of an oxidase, which is able to oxidize citronellol and menthocitronellol in allylic position. A photooxygenation mechanism including singlet oxygen as the oxidizing agent is rather unlikely. Chirality 10:229-237, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chirality evaluation in flavour and essential oil analysis (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 50-55 
    Details
    ISSN: 0899-0042
    Keywords: simultaneous stereodifferentiation of γ(δ)-lactones ; chiral monoterpenes ; stereoselective analysis ; modified cyclodextrins ; genuineness of flavours and essential oils ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simultaneous stereodifferentiation of all aromarelevant 4(5) alkylsubstituted γ(δ)-lactones is described, using enantioselective multidimensional gas chromatography (MDG), and the column combination OV 1701/octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. The method is applicated to the lactone flavour compounds of fruits, indicating the advance to the analytical differentiation between “natural” and “nature-identical” aromas. Modified cyclodextrins are also proved to be powerful tools in the chirospecific CGC analysis of monoterpenoid constituents of essential oils. Optical purity control is discussed as an indicator for their natural origin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040111
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  • 3
    Electronic Resource
    Electronic Resource
    Stereoisomeric flavour compounds LXVII. 2-, 3-, and 4-Alkyl-branched acids, part 1: General approach to the synthesis of the enantiopure acids (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 420-426 
    Details
    ISSN: 0899-0042
    Keywords: synthesis of enantiopure 2-, 3-, and 4-alkyl-branched acids ; diastereomeric phenylglycinol amides ; chain elongation by Arndt-Eistert synthesis ; malonic ester synthesis or via 2-alkylated alkyl carbonitriles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general approach to the synthesis of 2-, 3-, and 4-alkyl-branched acids of high enantiomeric purity is described. The enantiopure 2-alkyl-branched acids are prepared via liquid chromatographic resolution of diastereomeric phenylglycinol amides and their absolute configuration is deduced from the 1H-NMR data of the separated diastereomers. Chain elongation methods, by Arndt-Eistert synthesis, via 2-alkylated alkyl carbonitrile or by malonic ester synthesis, are used to prepare 3- and 4-alkyl-branched acids of high configurational purity and known absolute configuration starting from the enantiomeric 2-alkyl-branched acids. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060510
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoisomeric flavour compounds LXVIII. 2-, 3-, and 4-Alkyl-branched acids, part 2: Chirospecific analysis and sensory evaluation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 427-434 
    Details
    ISSN: 0899-0042
    Keywords: 2-, 3-, and 4-alkyl-branched acids ; enantioselective analysis ; sensory evaluation ; heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin ; octakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-γ-cyclodextrin ; Chamaemelum nobile (L.) Allioni ; Parmesan cheese ; red meat flavour ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective GC analysis of 4-ethyloctanoic and 4-methylheptanoic acid, using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as the chiral stationary phase, is described and the sensory properties of several 4-alkyl-branched acids, using gas chromatography-olfactometry (GC-O) equipment and octakis(2,3-di-O-methyl-6-tert-butyldimethylsilyl)-γ-cyclodextrin as the stationary phase, are evaluated. The chirospecific analysis of various 2-, 3-, and 4-alkyl-branched acids from commercially available Roman chamomile (Chamaemelum nobile (L.) Allioni), Parmesan cheese, and subcutaneous mutton adipose tissue, using either GC-GC (MDGC) or GC-MS analytical methods, is described. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060511
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  • 5
    Electronic Resource
    Electronic Resource
    Stereoisomere Aromastoffe, XVI. Struktur und Eigenschaften optisch reiner 2-Methyl-4-propyl-1,3-oxathian-3-oxide (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 451-453 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoisomeric Flavor Compounds, XVI. - Structure and Properties of Optically Pure 2-Methyl-4-propyl-1,3-oxathiane 3-OxidesOxidation of cis-2-methyl-4-propyl-1,3-oxathiane (1) by NaIO4 yields diastereomeric sulfoxides (equatorial/axial relation 3:1), which were separated by liquid chromatography. From optically pure (2S,4R)-1 the sulfoxides 2 (75%) and 3 (25%) and from (2R,4S)-1 the sulfoxides 2′ (75%) and 3′ (25%) were generated. For 3 an X-ray structure analysis was performed.
    Notes: Durch Oxidation von cis-2-Methyl-4-propyl-1,3-oxathian (1) mit NaIO4 entstehen diastereomere Sulfoxide (äquatorial/axial-Verhältnis 3:1), die flüssigkeitschromatographisch rein erhalten werden. Aus optisch reinem (2S,4R)-1 werden die Sulfoxide 2 (75%) und 3 (25%), aus (2R,4S)-1 die Sulfoxide 2′ (75%) und 3′ (25%) erhalten. Für 3 wurde eine Röntgenstrukturanalyse durchgeführt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870352
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoisomere Aromastoffe, XXXI Tetrahydro-2-methylthiophen-3-ol - Struktur und Eigenschaften der Stereoisomeren (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 859-862 
    Details
    ISSN: 0170-2041
    Keywords: Thiophen-3-ol, tetrahydro-2-methyl- ; Flavor substances, chiral ; Chirality and odor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoisomeric Flavor Substances XXXI1). - Tetrahydro-2-methylthiophen-3-ol - Structure and Properties of the StereoisomersTetrahydro-2-methylthiophen-3-ol (6) has been synthesized and separated by liquid chromatography to yield cis (6a/6a′) and trans isomers (6b/6b′). Using (S)-tetrahydro-5-oxo-2-furancarboxylic acid chloride, 6a/6a′ and 6b/6b′ are transformed into the diastereomeric esters 7-10 which are separated by liquid chromatography. Hydrolysis of the esters yields the optically pure stereoisomers 6a, 6a′, 6b, and 6b′. Absolute configuration and sensory characteristics of these stereoisomers are given.
    Notes: Tetrahydro-2-methylthiophen-3-ol (6) wurde synthetisiert und flüssigkeitschromatographisch in cis- (6a/6a′) und trans-Isomere (6b/6b′) getrennt. Durch Umsetzung mit (S)-Tetrahydro-5-oxo-2-furancarbonsäurechlorid werden aus 6a/6a′ und 6b/6b′ die diastereomeren Ester 7-10 gebildet, deren flüssigkeitschromatographische Trennung und anschließende Hydrolyse zu den optisch reinen Stereoisomeren 6a, 6a′, 6b und 6b′ führt. Absolute Konfiguration und sensorische Bewertung der Stereoisomeren werden mitgeteilt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890237
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  • 7
    Electronic Resource
    Electronic Resource
    Stereoisomeric flavour compounds XXXV: Chiral aroma compounds of sherry I. Optically pure stereoisomers of solerone and solerole (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 293-300 
    Details
    ISSN: 0899-0042
    Keywords: optical isomers ; chirality and odour ; chiral flavour compound resolution ; enantiomer separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioseparation of the sherry aroma components 5-oxo-4-hydroxyhexanoic acid γ-lactone (solerone) and 4,5-dihydroxyhexanoic acid γ-lactone (solerole) is achieved, using Chiraspher (Merck) as the chiral HPLC phase and the optical purity ascertained directly by HRGC with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (Lipodex D) as the chiral stationary phase. The absolute configurations of 4,5-dihydroxyhexanoic acid γ-lactones are assigned by 1H-NMR spectral data of diastereomeric α-methoxy-α-trifluoromethylphenylacetic acid (MTPA) esters, according to Mosher's model. Sensory qualities of the isomers are given.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010408
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  • 8
    Electronic Resource
    Electronic Resource
    Stereoisomeric flavour compounds XLV: Structure analysis of 2-alkoxy-5-alkyl-tetrahydrofurans (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 76-83 
    Details
    ISSN: 0899-0042
    Keywords: chiral flavour compounds ; chiral cyclic acetals NMR data ; diastereoisomer/enantiomer separation ; crystal structure elucidation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of several 2-alkoxy-5-alkyl-tetrahydrofurans is of interest in our investigations of structure-function relationships of chiral flavour compounds. For the preparation of the enantiomeric acetals the unambiguous configurational assignment of the cis and trans series of these compounds is indispensable. By means of crystalline acetal derivatives the absolute structure of a model compound in the cis and the trans configuration is revealed by X-ray measurement and correlated with the corresponding cis and trans configurated aroma compounds. The first complete structure elucidation of the class of 2-alkoxy-5-alkyltetrahydrofurans has been carried out.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030113
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  • 9
    Electronic Resource
    Electronic Resource
    Diluted modified cyclodextrins as chiral stationary phases - influence of the polysiloxane solvent: Heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrinPresented at the 16th International Symposium on Capillary Chromatography, September 26-30, 1994, Riva del Garda, Italy (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 152-156 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Heptakis (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin ; Polysiloxanes ; Thermodynamic parameters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of different polysiloxane solvents on the efficiency and stereoselectivity of columns coated with mixtures of heptakis (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin and the polysiloxanes was investigated. Generally, the enantioselectivity increased with decreasing polarity of the silicone solvent and/or increasing cyclodextrin concentration, with some exceptions. Thermodynamic investigations showed that a change of the diluting phase or the cyclodextrin concentration affects entropy as well as enthalpy differences between the diastereomeric cyclodextrin/solute complexes. As a consequence, a certain cyclodextrin/polysiloxane combination is superior to another only at a particular temperature.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240180303
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  • 10
    Electronic Resource
    Electronic Resource
    Stereodifferentiation and simultaneous analysis of 2- and 3-hydroxyalkanoic acids from biomembranes by multidimensional gas chromatography (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 191-193 
    Details
    ISSN: 0935-6304
    Keywords: Enantio-MDGC analysis ; Chiral compounds of bacterial membranes ; Chiral hydroxy fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240180311
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