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  • 1
    Electronic Resource
    Electronic Resource
    The Revised Structure of the Norditerpenoid Alkaloid Peregrine (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1768-1772 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of peregrine (1), a norditerpenoid alkaloid isolated from Delphinium peregrinum var. elongatum BOISS., was revised on the basis of the 1H-COSY, HMQC, HMBC, and ROESY NMR spectra and of the X-ray analysis of its parent alcohol 2. Some of the 13C-NMR resonances of 1 and the related alkaloids peregrine alcohol (2), 14-O-acetylperegrine (3), bicoloridine (4), bicoloridine alcohol (5), 6-O-acetylbicolorine (6), bicolorine (7), and 14-O-acetylbicolorine (8), were also reassigned.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770708
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  • 2
    Electronic Resource
    Electronic Resource
    An Efficient Enantioselective Synthesis of ( - )-SerricorolePresented at the Annual Autumn Meeting of the New Swiss Chemical Society, Bern, October 1992. (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1275-1281 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cigarette beetle pheromone (-)-serricorole (1) has been synthesized in 23% overall yield by an eight-step sequence starting from N-propionylsultam 3. The synthesis features asymmetric anti- and syn-aldolizations 3 → 4 and 8 → 9, a non-destructive N-acylsultam cleavage with lithiated ethylphenylsulfone (10 → 12), and the smooth, Ti-mediated cyclization of β-acyloxy-ketone 2 to dihydropyranone 14.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760314
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  • 3
    Electronic Resource
    Electronic Resource
    Stereocontrolled Syntheses of Polysubstituted 2,3-Dihydro-4H-pyran-4-ones by cyclocondensation of β- acyloxy-ketones (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1282-1291 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: syn-β-Acyloxy-ketones 6 and an anti-β-acyloxy-ketone 17 undergo smooth intramolecular enolate/ester condensations 6 → 18 and 17 → 19 when treated with TiCl4/EtN(i-Pr)2. Thus, tri- and tetrasubstituted cis- or trans-2,3-dihydro-4H-pyran-4-ones are easily prepared in a stereoselective manner.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760315
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  • 4
    Electronic Resource
    Electronic Resource
    Nitration of a Crude 9,10-Dihydrophenanthrene (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 63-66 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360112
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetic study of the formation and rupture of stable tetrahedral intermediates. C—O, C—N and C—S bond formation (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 80-89 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measured pseudo-first-order rate constants for intramolecular formation of tetrahedral intermediates from N-2-hydroxyethylphthalimide, N-2-aminoethylphthalimide and N-2-thioethylphthalimide at pH 〉 6 are reported. The reaction is specific and general base catalysed, with β(Brønsted) values 0·44, 0·52 and 0·52 respectively. From a plot of log kb (general base rate constants) vs γ′ [the affinities of EtXH (X = O, NH, S) toward the carbonylic carbon], β′nuc values of 0·01 (with OH- as specific base), 0·25 (with imdidazole as general base) and 0·27 (with HPO42- as general base were obtained). The observed relationships pxy = ϑβ′/ - ϑpKa = -ϑ(Brønsted)/ϑγ′ = 0·03 is supported by the predictions of an energy contour diagram, which, on extrapolation to a non-stable tetrahedral intermediate, predicts a late and slightly protonated transition state for the cleavage process. At pH 〈 3, these intermediates cleave to yield only the corresponding diacylimides. These reactions are general base and acid catalysed with β 〉 0·3 and α 〈 0·1. A fast equilibrium between the intermediate and its N-protonated (amide) form is reached. The general base rupture of the latter is faster than that of the corresponding non-protonated intermediate by a factor of ca 109 - 1010-fold.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070205
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  • 6
    Electronic Resource
    Electronic Resource
    Gas phase thermolysis of N-(tert-butylthio)allylamine and N-(tert-butylthio)diethylamine (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 585-590 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The title sulphenamides were pyrolysed in a stirred-flow reactor at temperatures of 310-410°C, pressures of 8-15 Torr and residence times of 0·4-2 s using toluene as the carrier gas. N-(tert-Butylthio)allylamine formed 73 ± 4% isobutene, 23 ± 3% propene and N-allylthiohydroxylamine. The first-order rate coefficients for the formation of isobutene and propene, respectively, followed the Arrhenius equations kC4(s-1) = 1012·52 ± 0·36 exp(-163 ± 5 kJ mol-1 RT) and kC3(s-1) = 1010·99 ± 0·29 exp(-151 ± 4 kJ mol-1 RT) N-(tert-Butylthio)diethylamine gave 97 ± 1% isobutene, 1·9 ± 0·4% isobutane and N,N-diethylthiohydroxylamine. The first-order rate coefficients for isobutene elimination followed the Arrhenius equation k(s-1) = 1013·45 ± 0·24 exp(-164 ± 3 kJ mol-1 RT). The formation of the products is interpreted in terms of an elimination reaction with a unimolecular, four-centered, cyclic transition state. The reactivity of these sulphenamides was found to be much higher than that of previously studied alkyl or aryl tert-butyl sulphides and disulphides.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610071102
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  • 7
    Electronic Resource
    Electronic Resource
    Metal ion complexation by tetraester derivatives of bridged calix [4] arenes (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 471-481 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of bridged calix [4] arenes (5-10 methylene groups in the bridge) were synthesized and transformed into their tetraester derivatives by reaction with ethyl bromoacetate. The stability constants for complexes of the tetraester derivatives with sodium, potassium and silver cations, determined in methanol by spectroscopic or potentiometric techniques, show a drastic decrease (more than 105 for Na +) for the shorter methylene chains. 1H NMR studies demonstrate a conformational rearrangement of the calixarene part to fourfold symmetry to be necessary for the complexation of a cation, which is prevented by the shorter chains. This is further confirmed by the X-ray structure of a tetraester derivative with a CH2CH2COCH2CH2 bridge; crystals were monoclinic, space group P21/c,a = 11.847(2), b = 39.773(5), c = 12 · 127(2) Å, β = 109.24(1), V = 5395.1 Å3, Z = 4, Dx = 1.186 Mg m-3.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050809
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  • 8
    Electronic Resource
    Electronic Resource
    Mitrariosides, Five Bitter Labdane Glycosides from Mitraria coccinea (Gesneriaceae) (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 665-668 
    Details
    ISSN: 0170-2041
    Keywords: Mitraria coccinea ; Gesneriaceae ; Labdane glycosides, bitter ; Mitrariosides A  -  D ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From Mitraria coccinea Cav. (Gesneriaceae), five strongly bitter labdane glycosides named mitrariosides A1, A2, B, C and D (1  -  5) were obtained. The structures were deduced by chemical and spectroscopic evidence (COSY, 13C-1H CORR, NOESY and MS-FAB) and found to be: mitrarioside A1 (1): (6S)-19-(β-D-galactopyranosyloxy)-6-hydroxy-15-(α-Lrhamno-pyranosyloxy)labda-8(17),13-diene, mitrarioside A2 (2): (6S)-19-(β-D-glucopyranosyloxy)-6-hydroxy-15-(α-L-rhamnopyranosyloxy)labda-8(17),13-diene, mitrarioside B (3):(6S)-19-(β-D-glucopyranosyloxy)-6-hydroxy-15-(β-D-glucopyranosyloxy)-labda-8(17),13-diene, mitrarioside C (4): (6S)-19-(β-D-glucopyranosyloxy)-6,15-dihydroxylabda-8(17), 13-diene, and mitrarioside D (5): (6S)-19-(α-L-rhamnopyranosyloxy)-6,15-dihydroxy-labda-8(17),13-diene. The known compounds acteoside and calceolarioside C were also isolated.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201113
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  • 9
    Electronic Resource
    Electronic Resource
    Boussingoside D1, a new triterpenoid saponin from Boussingaultia baselloidesIn memory of Prof. Gavińa recently deceased. (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 291-293 
    Details
    ISSN: 0170-2041
    Keywords: Boussingaultia baselloides ; Basellaceae ; Hypoglucaemia ; Triterpenoid saponin ; Boussingoside ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four triterpenoid saponins have been isolated from the leaves of Boussingaultia baselloides by a combination of DCCC with HPLC. One is the new triterpenoid saponin boussingoside D1,3-O-[β-D-xylopyranosyl-(1→3)-O-β-D-glucoronopyranosyl]-30-noroleana-12,20(29)-dien-28-oic acid, the structure of which has been elucidated by 1H- and 13C-NMR spectroscopy, FAB-MS and chemical methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910149
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  • 10
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    Identification of a whitefly species by genomic and behavioral studies (1993)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1993-01-01
    Description: An introduced whitefly species, responsible for over a half billion dollars in damage to U.S. agricultural production in 1991, is morphologically indistinguishable from Bemisia tabaci (Gennadius). However, with the use of polymerase chain reaction-based DNA differentiation tests, allozymic frequency analyses, crossing experiments, and mating behavior studies, the introduced whitefly is found to be a distinct species. Recognition of this new species, the silverleaf whitefly, is critical in the search for management options.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Perring, T M -- Cooper, A D -- Rodriguez, R J -- Farrar, C A -- Bellows, T S Jr -- New York, N.Y. -- Science. 1993 Jan 1;259(5091):74-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Entomology, University of California, Riverside 92521.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8418497" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Base Sequence ; Crosses, Genetic ; DNA/genetics ; Diptera/*classification/genetics/*physiology ; Enzymes/genetics ; Female ; Genetic Linkage ; Male ; Molecular Sequence Data ; Oligodeoxyribonucleotides ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Sexual Behavior, Animal ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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