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  • Articles  (17)
  • Organic Chemistry  (13)
  • Humans  (4)
  • 1990-1994  (17)
  • 1
    Electronic Resource
    Electronic Resource
    The kinetics of diastereomeric amino acids with o-phthaldialdehyde (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 471-475 
    Details
    ISSN: 0899-0042
    Keywords: amino acids ; kinetics ; epimers ; OPA ; postcolumn reaction detection ; fluorescence detection ; amino acid racemization ; dating methods ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reaction of the amino acid epimers L-isoleucine, D-alloisoleucine, L-threonine, and D-allo-threonine with o-phthaldialdehyde and mercaptoethanol were determined at 25°C. L-Isoleucine reacts faster than its D-epimer whereas L-threonine reacts slightly slower than its D-epimer. In the case of isoleucine, the consequence can be an allo/iso ratio which in the worst case is 25% too low if these amino acids are quantified by liquid chromatography and o-phthaldialdehyde fluorescence detection. The effect on dating of fossils by amino acid racemization is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030611
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  • 2
    Electronic Resource
    Electronic Resource
    A vivid model illustrating chiral recognition induced by achiral structures (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 208-210 
    Details
    ISSN: 0899-0042
    Keywords: enantioselectivity ; three-point model ; didactic model ; chiral separations ; ligand-exchange chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If diastereomeric complexes are adsorbed on a surface or if they include a molecule of solvent, two points of attractive interaction between the chiral species of the complex can be sufficient for mutual chiral recognition of these species. In special cases even one single point of interaction is sufficient. This extension of the three-point contact rule of Dalgliesh, first observed in chiral ligand-exchange chromatogrphy, can be demonstrated by using hands.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020403
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  • 3
    Electronic Resource
    Electronic Resource
    Reversed-Phase LC resolutions of chiral antiarrhythmic agents via derivatization with homochiral isothiocyanates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 43-51 
    Details
    ISSN: 0899-0042
    Keywords: mexiletine ; flecainide ; tocainide ; propafenone ; chirality ; enantiomers ; HPLC ; homochiral derivatization ; isothiocyanates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The search for new antiarrhythmic agents has been intense, because the established drugs for the treatment of cardiac arrhythmias are neither uniformly effective nor well-tolerated. Among the recently introduced new anti-arrhythmic agents are tocainide (TOC), mexiletine (MEX), flecainide (FLE), and propafenone (PRO). Each of these drugs is a chiral amine used clinically as the racemic mixture. We have examined the high-performance liquid chromatographic chiral resolution of the above four drugs via derivatization with homochiral derivatizing agents (HDAs). The amino functionality of the drugs was reacted with four homochiral isothiocyanates, 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (TAGIT), (R)-α-methylbenzyl isothiocyanate (RAMBI), (S)-1-(1-naphthyl)ethyl isothiocyanate (SNEIT), and (R)-1-(2-naphthyl)ethyl isothiocyanate (RBEIT). Complete separation of the two peaks (resolution factor R = 1.5) was achieved with all four HDAs for TOC, with TAGIT, RBEIT, and RAMBI for MEX, with TAGIT and SNEIT for PRO, and only with TAGIT for FLE. SNEIT was used to develop analytical procedures for the determination of the enantiomeric composition of TOC in human urine and blood serum. The four HDAs offer several advantages over many other HDAs and should be useful in studies of enantioselective drug action and disposition.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020107
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  • 4
    Electronic Resource
    Electronic Resource
    (Z)-1,1-dichloro-2-(4-benzyloxyphenyl)-2,3-bis(4-methoxyphenyl)cyclopropane: The synthesis and enantiomeric separation of an antitumor agent (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 41-45 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; Chiralpak AD ; amylose carbamate stationary phase ; antiestrogen ; breast cancer ; dichlorotriarylcyclopropane ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Z)-1,1-Dichloro-2-(4-benzyloxyphenyl)-2,3-bis(4-methoxyphenyl)cyclopropane (5), a potential antitumor agent designed to treat breast cancer, was prepared in three steps. A stereospecific palladium-catalyzed cross coupling reaction which provided the intermediate (Z)-triaryl alkene 4 was a crucial step in the synthesis. Makosza phase transfer reaction on 4 gave the enantiomeric (Z)-dichlorocyclopropane derivatives 5 which were resolved by semipreparative HPLC on a chiral stationary phase consisting of amylose tris-3,5-dimethylphenyl carbamate coated on silica gel. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060108
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  • 5
    Electronic Resource
    Electronic Resource
    Schwermetall- und chloridhaltige Filterstäube. I. Phasenanalysen und Modellversuche zum Recycling (1993)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 255-261 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flue Dusts Containing Heavy Metal Ions and Chloride.I. Phase Analysis, Model Experiments for RecyclingFour flue dusts from a cement factory, an electric-furnace steelmaking plant and a municipal waste plant were analyzed by powder diffraction methods. Chloride combines above all with alkali ions or heavy metal ions, especially yielding PbCl2 and KPb2Cl5. The controlled sublimation of these chloride compounds in open crucibles was developed and optimized in our laboratory. Between 850°C and 1150°C and at reaction times from 30 min up to 12 h, the chloride content decreases to below 0.1 wt-%. The sublimed phase mainly consists of alkali and lead chloride. Zinc is found in the flue dust as oxide and is enriched during this process. Recent investigations with a small waelz kiln give analogous results. With our procedure, the manufacturer by himself is able to exploit flue dusts containing a large amount of heavy metal elements and chloride which cannot be deposited. The remaining product contains mainly zinc oxide which can be recycled in the zinc industry or returned to the production process. The sublimed chloride compounds may be recycled in the potash industry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19933350307
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  • 6
    Electronic Resource
    Electronic Resource
    Structure elucidation of a Pyoverdin Produced by Pseudomonas aeruginosa ATCC 27 853 (1993)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 83-87 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The primary structure of a pyoverdin (Pa TII) isolated from an iron deficient culture medium of Pseudomonas aeruginosa ATCC 27 853 has been elucidated by spectroscopic methods and degradation studies. Total assignment of 1H and 13C resonances as well as sequential information were achieved by two-dimensional NMR techniques: HOHAHA1, NOESY, HSQC and HMBC. The structure consists of the common pyoverdin chromophore 5-amino-2,3-dihydro-8,9-dihydroxy-1H-pyrimido [1,2-a]quinoline-1-carboxylic acid with succinic acid bound amidically to its amino group and the carboxyl group linked to the N-terminus of D-Ser-D(CHO) OHOrn-L-Orn-Gly-D-aThr-L-Ser-L-cOHOrn. According to the short-hand nomenclature suggested in [2, 3] the pyoverdin may be described as pyoverdin-Q-so′ OGtaSo′*-SUC.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19933350113
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  • 7
    Electronic Resource
    Electronic Resource
    Syntheses and X-Ray Structures for Model Compounds of a Pyrimidinediyl-Based Rigid-Rod Aromatic Polyamide (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 184-189 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of model compounds for the pyrimidinediyl-based rigid-rod polyamide poly[imino-(pyrimidine-2,5-diyl)-imino-tetraphthaloyl] (PPYMT) was prepared, in order to compare their conformations to several model compounds of the related, fully aromatic polymer poly(p-phenyleneterephthalamide) (PPTA). In particular, the structures of N-(2-pyrimidyl)benzamide (PYMB) and its complexed form bis[(N-pyrimidin-2-yl)benzamide]nickel(II) dichloride (NiPYMB) were determined by X-ray diffraction. The molecular packing in these crystals provides us with a model for the possible ‘cross-linking’ of PPYMT fibers. The structures of the trimer model compounds N,N′ -bis(2-pyrimidyl)terephthalamide (PYTA) and N,N′ -bis(benzoyl)-2,5-diaminopyrimidine (BDAP) yield information about the conformation of PPYMT chains and are compared to analogous model compounds of PPTA.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750116
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis, Isolation, and NMR-Spectroscopic Characterization of Fourteen (Z)-Isomers of Lycopene and of Some Acetylenic Didehydro- and Tetradehydrolycopenes (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 1848-1865 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight (Z)-isomers of lycopene were prepared by stereocontrolled syntheses and fully characterized by 1H-NMR, 13C-NMR, mass, and UV/VIS spectroscopy: (5Z)-, (7Z)-, (15Z)-, (5Z,5′Z)-, (7Z,7′Z)-, (7Z,9Z)-, (9Z,9′Z)-, and (7Z,9Z,7′Z,9′Z)-lycopene. Six additional (Z)-isomers, namely (9Z)-, (13Z)-, (5Z,9′Z)-, (9Z,13′Z)-, (5Z,9Z,5′Z)-, and (5Z,13Z,5′Z)-lycopene, were isolated in small quantities from isomer mixtures by semiprep. HPLC and were identified by 1H-NMR spectroscopy.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750611
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  • 9
    Electronic Resource
    Electronic Resource
    Epoxidierung von Kohlenstoff-Kohlenstoff-Doppelbindungen in Terpenen durch Linolsäurehydroperoxide (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1253-1256 
    Details
    ISSN: 0170-2041
    Keywords: Terpenes ; Epoxides ; Linoleic acid derivatives ; Hydroperoxides ; Labeled compounds, 18O2 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Epoxidation of Carbon-Carbon Double Bonds in Terpenes by Linoleic Acid HydroperoxidesEpoxidation of C=C double bonds in terpenes is achieved by reaction with linoleic acid hydroperoxides (LOOH) exemplified with caryophyllene (3), methyl farnesoate (5) and squalene (8). Linoleic acid (9S)-hydroperoxide was obtained by reaction of linoleic acid (1) with lipoxygenase present in tomato homogenisate. When 18O2-labeled (9S)-LOOH (2) was used 18O was found in the terpene epoxide. While 3 is converted under physiological conditions regioselectively in high yiled into its 4,5-epoxide 4, the yield of epoxidized products from long-chain molecules, e.g. squalene (8), decreases strongly and no regioselectivity was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301204
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  • 10
    Electronic Resource
    Electronic Resource
    Enoletherepoxide und ihre Reaktionsprodukte mit Nucleophilen (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 17-21 
    Details
    ISSN: 0170-2041
    Keywords: Enol ethers ; Dioxirane, dimethyl ; Epoxides ; Acetals ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enol Ether Epoxides and Products Resulting from Their Reaction with Nucleophiles1,2-Epoxydecyl pentyl ether (9a) was synthesized by treatment of 1-decenyl pentyl ether (5) with diemthyldioxirane (8). The enol ether epoxide 9a, characterized by its mass, 1H- and 13C-NMR spectra, reacts readily with hydride, O-, S- and N-nucleophiles. Similar reactions are expected to take place in the organism after biological oxidation of plasmalogens to their epoxides. This hypothesis is verified by detection of mixed acetals after tissue workup.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930105
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