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  • cyclodextrin derivatives  (5)
  • Cyclodextrins  (2)
  • 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Andrena wilkella male bees discriminate between enantiomers of cephalic secretion components (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 429-441 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Enantiomer discrimination ; male patrolling ; odor marking ; Hymenoptera ; Apoidea ; Andrena wilkella ; bee ; EAG ; spiroacetal ; absolute configuration ; 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee,Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior inA. wilkella.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01021775
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  • 2
    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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  • 3
    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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  • 4
    Digitale Medien
    Digitale Medien
    Separation of basic drugs by capillary electrophoresis using selectively modified cyclodextrins as chiral selectors (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 355-363 
    Details
    ISSN: 1040-7685
    Schlagwort(e): basic drugs ; capillary electrophoresis ; cyclodextrin derivatives ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of seven differently methylated β-cyclodextrin derivatives and of pure β-cyclodextrin (β-CD) on the enantiomeric resolution by capillary electrophoresis of six basic chiral pharmaceuticals is investigated. The methyl substitution pattern affects enantioselectivity much more than other experimental parameters. The purity of the used cyclodextrin derivatives is analyzed by successive hydrolysis, reduction, acetylation, and GC/MS of each CD derivative and by MALDI-TOF mass spectrometry. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mcs.1220070408
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  • 5
    Digitale Medien
    Digitale Medien
    Diluted versus undiluted cyclodextrin derivates in capillary gas chromatography and the effect of linear carrier gas velocity, column temperature, and length on enantiomer separation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 35-40 
    Details
    ISSN: 1040-7685
    Schlagwort(e): Enantiomers ; gas chromatography ; cyclodextrin derivatives ; temperature dependence ; capillary columns ; selectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of dilution of the chiral stationary phase octakis (3-O-butyryl-2, 6-di-O-pentyl)-γ-cyclodextrin in the achiral polysiloxane OV-1701 on the separation factor was investigated over a wide concentration range. The loss in enantioselectivity was only negligible down to a dilution of 50% (w/w), since the separation factor vs. concentration curves levels off at higher concentrations. Because of the strong temperature dependence of the separation factors, the properties of short columns (10 m and 4.5 m) were evaluated. These short columns, which allow operation at low temperatures and lead to enhanced separation factors were found to be appropriate for the separations of simple mixtures, because the gain in selectivity exceeded the loss in separation efficiency. For complex mixtures, the higher efficiencies of columns of at least 25 m in length were still necessary. A plot of In α vs. 1/T did not yield straight lines, but showed a significant curvature, leading to considerable relative errors if thermodynamic data were derived from these plots.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mcs.1220050105
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  • 6
    Digitale Medien
    Digitale Medien
    Chloro-bis-propyl Ethers in the Elbe River - Isomeric Distribution and Enantioselective Degradation (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 113-120 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Enantioselective GC of chlorinated bis(propyl) ethers ; environmental analysis ; contamination of the Elbe River ; cyclodextrin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Cyclodextrin derivatives are evaluated as chiral stationary phases for the enantiomer separation of chlorinated bis(propyl) ethers (BPE). The enantiomeric composition of the 2,3,2′,3′- and 1,3,2′,3′-isomers of tetrachlorobis(propyl) ether in the Elbe River has been quantitatively determined by enantioselective gas chromatography and coupled gas chromatography/mass spectrometry in selected-ion-monitoring mode. Significant enantiomeric discriminations are observed in selected water samples, indicating that enantioselective bio-degradation mechanisms are at least partly responsible for the overall degradation processes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part VII: Cyclodextrins with an inverse substitution pattern - synthesis and enantioselectivityPart VI, see reference [6]. (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 702-707 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Enantioselective capillary gas chromatography ; Cyclodextrins ; Inverse substitution pattern ; Mechanism of chiral recognition ; Applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Transferring the site of specific substitution of dipentylated cyclodextrins with methyl or acyl residues from the secondary 3-hydroxyl group to the primary 6-hydroxyl group was expected to provide new information on the mechanism of chiral recognition. The 3-position points towards and the 6-position points away from the cyclodextrin cavity which via inclusion complex formation is supposed to play a major role in chiral separation. The “inverse” 6-O-acyl-2,3-di-O-pentyl-cyclodextrins displayed almost no enantioselectivity but the corresponding 6-O-methyl derivatives are a versatile supplement to the chiral capillary GC phases nowadays available. Among the compounds that could be enantiomerically resolved are alcohols, amino acids, alkyl halides, bicyclic ethers, acetals, olefins, other hydrocarbons and chiral pharmaceuticals.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240131010
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  • 8
    Digitale Medien
    Digitale Medien
    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 119-126 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Host-guest complexes ; Molecular-dynamics (MD) simulation ; Enantioselective gas chromatography ; Cyclodextrins ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The energies of complexation of methyl (R)/(S)-2-chloropropionate [(R)/(S)-2] with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular-dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)-2 and the closest H-H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270120
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