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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of vinylcyclopropanes by intramolecular epoxide ring opening. Application for an enantioselective synthesis of dictyopterene A (1993)
    s.l. : American Chemical Society
    The @journal of organic chemistry 58 (1993), S. 626-632 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00055a014
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: 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
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050522
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  • 3
    Electronic Resource
    Electronic Resource
    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
    Keywords: Horeau's method ; configuration of secondary alcohols ; enantioselective gas chromatography ; 2-phenylbutyric acid ; cyclodextrin derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060215
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  • 4
    Electronic Resource
    Electronic Resource
    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
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760513
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of (3R,4R)-3-Amino-4-hydroxyhexahydroazepine, the Chiral Constituent of the Antibiotic Ophiocordin (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 651-655 
    Details
    ISSN: 0170-2041
    Keywords: 3-Amino-4-hydroxyhexahydroazepine ; Cordyceps ophioglossoides ; Antifungals ; Antibiotics ; Ophiocordin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (3R,4R)-3-Amino-4-hydroxyhexahydroazepine (2), the optically active constituent of the antifungal antibiotic ophiocordin (1), was prepared in a multistep synthesis starting from D-serine. The absolute configuration was unambigously assigned by a comparison of the synthesized stereoisomer 2 with its racemate and the chiral moiety of the antibiotic ophiocordin by enantioselective gas chromatography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301106
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  • 6
    Electronic Resource
    Electronic Resource
    Gas chromatographic enantiomer separation of agrochemicals and polychlorinated biphenyls (PCBs) using modified cyclodextrins (1994)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 859-864 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Polychlorinated pesticides ; Polychlorinated biphenyls (PCBs) ; Pyrethroid insecticides/Allethrin ; Organophosphorus pesticides/Acephate, Malaoxon ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of the polychlorinated polycyclic xenobiotics heptachlor, cis- and trans-chlordane, cis- and trans-heptachlorepoxide, oxychlordane, and bromocyclen have been resolved by gas chromatography with selectively substituted cyclodextrins. The order of elution of these compounds and of α-hexachlorocyclohexane (α-HCH) was determined by comparison with enantiomerically enriched reference compounds obtained by preparative enantioselective gas chromatography.A separation of the eight stereoisomers of the pyrethroid insecticide allethrin into seven peaks was achieved. Both trans-diastereomers were separated into their enantiomers and the order of elution could be determined by comparison with commercially available (S)-bioallethrin and trans-bioallethrin. Also one cis-diastereomer was separated, wheras the other cis-isomer could not be resolved. In addition 15 out of 19 stable atropisomeric polychlorinated biphenyls with 5, 6 and 7 chlorine substituents, some chiral organophosphorus pesticides, including acephate and malaoxon and the herbicide bromoacil were separated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240171209
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  • 7
    Electronic Resource
    Electronic Resource
    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
    Keywords: Enantiomers ; gas chromatography ; cyclodextrin derivatives ; temperature dependence ; capillary columns ; selectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050105
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  • 8
    Electronic Resource
    Electronic Resource
    Gas chromatographic enantiomer separation with modified cyclodextrins: Carboxylic acid esters and epoxides (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 175-181 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; 2,6-di-O-methyl-3-O-pentyl-β- and y-cyclodextrins ; α and β hydroxy acids ; Branched carboxylic acids ; Non-steroidal anti-inflammatory drugs ; Abscisic Acid ; Epoxides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The wide range of application of 2,6-di-O-methyl-3-O-pentyl-β-and y-cyclodextrins is demonstrated by the resolution of the enantiomers of the methyl esters of chiral carboxylic acids: α and β hydroxy acids with up to 18 carbon atoms, hydroxy di- and tricarboxylic acids, and alkyl/aryl-substituted carboxylic acid methyl esters, including the plant hormone abscisic acid, insect juvenile hormones, and some non-steroidal anti-inflammatory drugs can be resolved with generally large separation factors. The new cyclodextrin derivatives also exhibit high selectivity for epoxides.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160309
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  • 9
    Electronic Resource
    Electronic Resource
    Enantiomer separation by capillary SFC and GC on immobilized octakis(2,6-di-O-methyl-3-O-pentyl)-γ-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 779-783 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Enantioselective supercritical fluid chromatography ; Immobilized chiral stationary phases ; Modified cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heptakis(2,6-di-O-methyl-3-O-pentyl) (2-O-methyl-6-O-oct-1-enyl-3-O-pentyl)-γ-cyclodextrin was immobilized to narrow-bore fused silica capillaries after selective modification. One tert-butyldimethylsilyl group was introduced into octakis-(2-O-methyl-3-O-pentyl)-γ-cyclodextrin in order to get a pure monofunctionalized cyclodextrin derivative. During synthesis the tert-butyldimethylsilyl group was replaced by an anchoring group to bind the cyclodextrin to a polysiloxane. After thermal immobilization of the modified polysiloxane this new chiral stationary phase was applied in GC and SFC. High efficiency separations were obtained in GC. In SFC very polar compounds could be chromatographed at low temperatures resulting in higher separation factors as compared to GC.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240171110
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  • 10
    Electronic Resource
    Electronic Resource
    Gas chromatographic separation of atropisomeric alkylated and polychlorinated biphenyls using modified cyclodextrins (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 376-378 
    Details
    ISSN: 0935-6304
    Keywords: Resolution of atropisomers ; Alkylated biphenyls ; Polychlorinated biphenyls (PCBs) ; Dynamic gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectively alkylated cyclodextrins have been used to resolve the enantiomers of 2,2′ alkylated biphenyls. The configurational stability of 2,2′-dimethyl and 2,2′-diethyl biphenyls is insufficient for gas chromatographic separation even at ambient temperature. 2-Isopropyl-2′-t-butyl- and 2,2′-di-t-butylbiphenyl are configurationally stable under the conditions applied, whereas 2,2′-diisopropyl- and 2,2′-bis(trifluoromethyl)biphenyl show temperature-dependent interconversion of the enantiomers during chromatography. The gas chromatographic separation of the enantiomers of some ortho trichlorinated biphenyls carrying 4, 5, and 6 chlorine substituents has been demonstrated for the first time.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160609
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