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  • Organic Chemistry  (35)
  • Cyclodextrins  (2)
  • 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane
  • Wiley-Blackwell  (37)
  • 1
    Digitale Medien
    Digitale Medien
    New technique for the determination of interconversion processes based on capillary zone electrophoresis: Studies with axially chiral biphenyls (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 441-445 
    Details
    ISSN: 0899-0042
    Schlagwort(e): capillary zone electrophoresis ; axially chiral biphenyls ; energy barrier ; cyclodextrin derivatives ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new technique is presented for the investigation of the rotational energy barrier of axially chiral biphenyls, based on capillary zone electrophoresis using cyclodextrin derivatives as chiral selectors. Only minute amounts are required for the investigation of dynamic processes with energy barriers of 100-130 kJ/mol. The influence of the chiral selector on the conformational stability of atropisomers can be determined separately for each enantiomer. Additionally, segmentation of the capillary into different buffer zones allows us to exclude any influence of the chiral selector on the rotational energy barrier. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Enantioselective capillary gas chromatography in the investigation of stereochemical correlations of terpenoids (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 499-504 
    Details
    ISSN: 0899-0042
    Schlagwort(e): enantioselective capillary gas chromatography ; cyclodextrin derivatives ; stereochemistry of terpenes ; monoterpenes ; essential oils ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Capillary gas chromatography employing the unique selectivities of specifically substituted cyclodextrins is highly suited for stereochemical investigations of terpenoid compounds. The analysis of many essential oils have shown that monoterpene derivatives regularly occur as enantiomeric mixtures. In the case of sesquiterpene hydrocarbons, liverworts (Hepaticae) and other lower organisms usually biosynthesize compounds of opposite stereochemistry as compared to higher plants and enantiomeric mixtures occur only occasionally. The investigation of diterpene hydrocarbons has so far shown no indication of the presence of both enantiomers in the same plant. Chirality 10:499-504, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Enantioselective and nonenantioselective degradation of organic pollutants in the marine ecosystem (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 393-399 
    Details
    ISSN: 0899-0042
    Schlagwort(e): chiral capillary gas chromatography ; chiral high-performance liquid chromatography ; stationary cyclodextrin phases ; chiral pollutants ; enantioselective processes ; microbial degradation processes ; photochemical degradation processes ; enzymatic degradation processes ; blood-brain barrier ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Enantiomeric ratios of 11 chiral environmental pollutants determined in different compartments of the marine ecosystem by chiral capillary gas chromatography and chiral high-performance liquid chromatography allow discrimination between the following processes: enantioselective decomposition of both enantiomers with different velocities by marine microorganisms (α-HCH, β-PCCH, γ-PCCH); enantioselective decomposition of one enantiomer only by marine microorganisms (DCPP); enantioselective decomposition by enzymatic processes in marine biota (α-HCH, β-PCCH, trans-chlordane, cis-chlordane, octachlordane MC4, octachlordane MC5, octachlordane MC7, oxychlordane, heptachlor epoxide); enantioselective active transport through the “blood-brain barrier” (α-HCH); nonenantioselective photochemical degradation (α-HCH, β-PCCH). © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530050522
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  • 4
    Digitale Medien
    Digitale Medien
    Determination of the absolute configuration of secondary alcohols with Horeau's method including enantioselective gas chromatography (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 141-147 
    Details
    ISSN: 0899-0042
    Schlagwort(e): Horeau's method ; configuration of secondary alcohols ; enantioselective gas chromatography ; 2-phenylbutyric acid ; cyclodextrin derivative ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of optically active secondary alcohols with excess of racemic 2-phenylbutyric acid anhydride in pyridine proceeds at different rates to the diastereoisomeric esters (kinetic partial resolution). According to Horeau the (unknown) absolute configuration of the alcohol can be derived from the optical rotation of the remaining excess of 2-phenylbutyric acid in the reaction mixture. Measuring the optical rotation may be very difficult in cases of small absolute rotation values and may be inaccurate due to the necessity to completely remove all chiral impurities. The application of Horeau's method is greatly facilitated by gas chromatographic determination of the enantiomeric ratio of the remaining 2-phenylbutyric acid after methylation using a short capillary column with heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin as a chiral stationary phase. Baseline resolution of the enantiomers is achieved after approximately 10 min of retention time. Due to the high selectivity of capillary gas chromatography the probability of impurities in the mixture to interfere with the measurement of the enantiomeric ratio is extremely low. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530060215
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  • 5
    Digitale Medien
    Digitale Medien
    Determination of the enantiomeric composition of mexiletine and its four hydroxylated metabolites in urine by enantioselective capillary gas chromatography (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 30-34 
    Details
    ISSN: 0899-0042
    Schlagwort(e): gas chromatography ; modified β-cyclodextrin column ; chiral separation ; assay ; mexiletine ; hydroxylated metabolites ; urine ; conjugation/deconjugation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The enantiomers of mexiletine and four of its hydroxylated metabolites were directly separated by capillary gas chromatography using a heptakis(6-O-tert-butyl-dimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin column. The method was applied to the analysis of urine samples from cancer patients who were treated with racemic mexiletine as part of a study of the use of mexiletine in the relief of neuropathic pain. Samples analyzed before and after deconjugation of the urine with β-glucuronidase/arylsulfatase showed a high stereoselectivity in the formation and conjugation of these compounds. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Stoffwechselprodukte von Mikroorganismen. 253. Mitteilung252, Mitteilung. Hormaomycin, ein neues Peptid-lacton mit morphogener Aktivität auf Streptomyceten (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 426-437 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Hormaomycin, a Novel Peptide Lactone with Morphogenetic Activity on StreptomycesA culture identified as Streptomyces griseoflavus (strain W-384) has been found to produce a novel peptide-lactone antibiotic designated hormaomycin (6). The empirical molecular formula of the compound is established to be C55H69ClN10O14. The constituent amino acids of the antibiotic are suggested to be allothreonine (1; 1), isoleucine (2; 1), 3-methyl-phenylalanine (3; 2), and, for the first time identified from a natural source, 4-[(Z)-prop-1-enyl]-proline (4; 1) and 3-(2-nitrocyclopropyl)-alanine (5; 2). The amino acids were delivered by acidic hydrolysis and assigned by high-resolution- GC/MS analysis (after transformation to derivatives) in combination with extended 2D-NMR experiments of the antibiotic itself. From the latter, it became plausible that the N-terminus of the peptide chain is acylated by a Cl-containing derivative of 1H-pyrrol-2-carboxylic acid. Hormaomycin is active against some Gram-positive bacteria. In addition, the antibiotic exhibits potent aerial mycelium-inducing activity and effects the production of antibiotics.
    Notizen: No abstract.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19890720303
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  • 7
    Digitale Medien
    Digitale Medien
    Unusual and Novel C11H16 Hydrocarbons from the Southern Australian Brown Alga Dictyopteris acrostichoides (Phaeophyceae) (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 734-744 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Unusual and novel C11H16 olefins with (E)- or (E,E)-configuration instead of the previously known (Z)- or (E,Z)-configuration at the double bond(s) within the longer side chain are the main products of the Australian phaeophyte Dictyopteris acrostichoides. This configuration anomaly refers to all four series of alicyclic C11H16 hydrocarbons, namely the disubstituted cyclopentenes and cyclopropanes, as well as the monosubstituted cycloheptadienes and cyclopentenes. Chiral compounds within the above series have the same absolute configuration. The two (cyclopent-3-enyl)hexa-1, 3-dienes 11 and 13 are found for the first time. The absolute configuration and optical purity of the hydrocarbons are determined by gas chromatography on modified cyclodextrins as chiral stationary phases. The synthesis of chiral references via lipase-catalyzed resolutions is described.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19920750309
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  • 8
    Digitale Medien
    Digitale Medien
    Synthesis and Absolute Configuration of the C12-Terpenoid Dehydrogeosmin from the Flower Scents of Rebutia marsoneri and Dolichothele sphaerica (Cactaceae); a new approach to bis-angularly substituted trans-decalins (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1949-1955 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Optically pure(+)-(4S, 4aS, 8aS)-1,2,3,4,4a,5,8,8a-octahydro-4,8a-dimethylnaphthalen-4a-ol((+)-1; dehydrogeosmin) is released from flower heads of the two cactaceae Rebutia marsoneri and Dolichothele spharica. The absolute configuration of (+)-1 is identical with that of the known microbial metabolial geosmin (-)-2. The key reactions of the synthesis of 1 are the kinetically controlled transesterification of the primary alcohol 4 using a lipase from Candida cyclindracea and the stereo-and regiospecific angular alkylation of a cis-decalin skeleton by a Lewis-acid-assisted ring opening of the quaternary epoxy-alcohol 3 with MeMgBr/Cul. The sequence provides a new entry into the class of bis-angularly substituted trans-decalins.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19930760513
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  • 9
    Digitale Medien
    Digitale Medien
    Reaktionen von Aminosäuren und Peptiden, II. Darstellung von 2-Aminooxazolderivaten aus Peptidamiden mit Hexafluoracetanhydrid (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 973-985 
    Details
    ISSN: 0170-2041
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Reactions of Amino Acids and Peptides, II. - Preparation of 2-Aminooxazole Derivatives from Peptide Amides with Hexafluoroacetic AnhydrideC-Terminal amino acid amide residues of peptide amides react with hexafluoroacetic anhydride to form stable 5-(trifluoroacetylamino)oxazole derivatives. Several representatives of this class of compounds have been synthesized and their structures determined by 1H-NMR and mass spectrometry and by their chemical reactions. The heterocyclization reaction can be used for the formation of volatile derivatives in the analysis of peptide amides on a microgram scale and for the identification of the C-terminal amino acid residue in peptide amides.
    Notizen: C-Terminale Aminosäureamidreste von Peptidamiden reagieren mit Hexafluoracetanhydrid in guten Ausbeuten zu stabilen 5-(Trifluoracetylamino)oxazolderivaten. Verschiedene Vertreter dieser Verbindungen wurden dargestellt und ihre Struktur durch 1H-NMR-, Massenspektrometrie und chemische Reaktionen charakterisiert. Die Heterocyclisierungsreaktion kann im Mikrogramm-Maßstab zur Herstellung flüchtiger Derivate bei der Analytik von Peptidamiden und zur Identifizierung der C-terminalen Aminosäure von Peptidamiden benutzt werden.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.197919790708
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  • 10
    Digitale Medien
    Digitale Medien
    Synthese der N-terminalen Aminosäure der Nikkomycine I, J, X und Z (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1615-1622 
    Details
    ISSN: 0170-2041
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthesis of the N-Terminal Amino Acid of the Nikkomycins I, J, X, and ZA mixture of four stereoisomers of 2-amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbutanoic acid (14), the N-terminal amino acid of the nikkomycin antibiotics could be synthesized in a twelve-step procedure. By comparison of 1H NMR spectra, mass spectra and of the gas chromato-graphic behaviour of various derivatives the constitution and relative configuration of the natural compound has been confirmed.
    Notizen: Ein Gemisch aus vier Stereoisomeren von 2-Amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbuttersäure (14) der N-terminalen Aminosäure der Nikkomycin-Antibiotika konnte in einer zwölfstufigen Synthese dargestellt werden. Durch Vergleich der 1H-NMR-Spektren, Massenspektren und des gaschromatographischen Verhaltens verschiedener Derivate von Synthese- und Naturprodukt wird die Richtigkeit der angenommenen Konstitution und relativen Konfiguration bestätigt.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.198219820904
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