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  • Articles  (10)
  • Chemistry  (8)
  • Computational Chemistry and Molecular Modeling  (2)
  • Pyrazolo-pyridazine, derivative  (1)
  • General Chemistry
  • Wiley-Blackwell  (10)
  • 1990-1994  (10)
  • 1980-1984
  • 1975-1979
  • 1991  (3)
  • 1990  (7)
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  • Articles  (10)
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  • Wiley-Blackwell  (10)
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  • 1990-1994  (10)
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  • 1975-1979
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  • 1
    Electronic Resource
    Electronic Resource
    Enkephalin analogues containing β-naphthylalanine at the fourth position (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 179-196 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To examine the importance of the aromatic side chains of enkephalin on opiate activity, we report the synthesis and conformational analysis of a series of analogues related to enkephalin with β-naphthylalanine in place of phenylalanine at the fourth position. Three linear analogues (Tyr-D-Ala-Gly-(L and D)-β Nal(1)-Leu-NH2 and Tyr-D-Ala-Gly-β Nal(2)-Leu-NH2) were initially synthesized to examine the effect of the substitution on biological activity. The increased activity of these peptides at the μ-opiate receptor, compared to native Leu-enkephalin, prompted us to examine the more conformational constrained analogues, Tr-c[D-A2bu-Gly-(L and D)-β Nal(1)-Leu], incorporating a α,γ-diaminobutyric acid at the second position and cyclization to the carboxylic end of the leucine. These two cyclic analogues provide insight into the necessity for the L chirality of the aromatic residue at position 4. The Tyr-c[D-A2bu-Gly-L-β Nal(1)-Leu] analogue is highly potent and displays a slight preference for the μ receptor. The conformational analysis indicates that despite the high flexibility of the tyrosine side chain, the aromatic rings of the tyrosine and naphthylalanine are relatively distant from each other. The presence of two intramolecular hydrogen bonds help maintain the conformation of the 14-membered backbone ring that keeps the side chains directed away from each other. These findings are in agreement with our model of an extended structure required for μ selectivity and a folded form with close aromatic ring placement for δ selectivity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290123
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  • 2
    Electronic Resource
    Electronic Resource
    Sur une tentative d'unification des théaories quantiques de la cancèrisation par les polyacènes: I. Thèorie des règions M, L, et B (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 461-486 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study is a unified approach to quantum theories of polyacen carcinogenesis. Part I discusses the M, L, and B regions theory. Although the M region of polyacens is much less reactive than is the K region, the chemical reactivity of these two regions parallels each other. Consequently, the K-L Pullman's theory may be reformulated by replacing the K region by the M region. The M-L regions theory improves all the quantum structure-carcinogenic activity relationships obtained previously in the K-L framework. Moreover, it would appear that in these correlations, the most important role is played by nonconcerted electrophilic reactions. We suggest that the M-L modified Pullman's theory and the Bay (B) region theory, proposed by Jerina et al., are related to different steps of the metabolic activation mechanism leading to ultimate carcinogen: the first step for the Pullman's theory and the carbocation step for the theory of the Bay region. We have termed the “M, L and B regions theory” as this unified approach to the problem of polyacens carcinogenesis.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560380308
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular-weight distributions in the thermally initiated emulsion polymerization of styrene (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 405-414 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In both thermal emulsion polymerization of styrene in the temperature range 60-80 °C, and peroxodisulfate-initiated polymerization at 60 °C, weight-average to number-average molecular-weight ratios (M̄w/M̄n) approach 1,5 when potassium octadecanoate is used as emulsifier. A low activation energy for thermal initiation (≈66,0 kJ/mol) was deduced which may indicate a catalytic effect of the emulsifier during the thermal initiation process. Participation of the emulsifier is probably attributed to a transfer of one of two monomer radicals, produced thermally, to the emulsifier, with subsequent desorption to the aqueous phase, leaving one radical in the polymerization locus.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920220
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  • 4
    Electronic Resource
    Electronic Resource
    Competitive hydrodesulfurization and hydrogenation in a monolithic reactor (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 746-752 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Competitive liquid-phase hydrodesulfurization of thiophene and hydrogenation of cyclohexene on a monolithic CoMo/γ-Al2O3 catalyst were studied. The flow pattern in the monolithic catalyst reactor was segmented gas-liquid flow (slug flow). The hydrogen pressure and the temperature were varied between 30-40 bar and 509-523 K, respectively. The experimental data are consistent with rate expressions of the Langmuir-Hinshelwood type where the reactions proceed on two different types of active sites. This kinetic model is based on hydrogenation of the thiophene ring prior to sulfur elimination.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360511
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational studies of stereoisomeric 14-membered cyclic enkephalin analogues containing 1-naphthyialanine at the fourth position: Chirality effect of leucine at the fifth position on biological activity and receptor selectivity (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 877-898 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study structure-activity relationships of enkephalin-related analogues, we report the biological activity and conformational analysis of four 14-membered cyclic enkephalin analogues with β-(1-naphthyl)alanine in place of phenylalanine at the fourth position, Tyr-c[D-A2bu-Gly-(L and D)-βNal(1)-(L and D)-Leu]. The L-βNal(1)-containing analogues display higher activity at both the μ and δ receptors than the corresponding analogues with the L-Phe residue. In contrast to the linear enkephalins, the cyclic analogues with the D-βNal(1) residue are also active at the μ receptor since the relative spatial arrangement of functional groups required for biological activity is achieved by the constrained nature of the cyclic molecules. A comparison of the findings from the conformational analysis and biological assays establishes that relatively extended structures, in which the two aromatic side chains are oriented in opposite directions with a ∼ 14Å separation, is required for activity at the μ receptor. On the other hand, folded conformations with nearly parallel orientations and a close proximity ( 〈 10Å) of the aromatic rings of the Tyr and βNal(1) residues are required for activity at the δ receptor. It should be noted that the overall structures and thus the biological profiles of the 14-membered cyclic enkephalin analogues are strongly dependent on the conformation of the second residue. The folded conformations with parallel orientation of the two aromatic side chains of Tyr-c [D-A2bu-Gly-L-βNal (1)-D-Leu] is stabilized by an interaction between the Tyr phenolic OH proton and βNal(1) C*O groups. This analogue, which shows the highest activity at both the μ and δ receptors among the four stereoisomers studied, displays an increase of the fraction of the side-chain χ1 = t conformer for the βNal(1) residue. It is concluded that the incorporation of the D-Leu residue at the fifth position increases the relative fraction of the folded conformations with parallel orientation of the aromatic side chains, and hence enhances activity at the δ receptor as compared to the corresponding L-Leu containing analogue.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360310708
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of an amphoteric ion-exchange membrane (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 705-713 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An amphoteric ion-exchange membrane was prepared by chemical grafting of acrylic acid and dimethyl amino-2-ethyl methacrylate on ozonized polyethylene. The effects of the variation of external pH on the physicochemical properties of this membrane were studied (exchange capacity, electrical resistance, water and electrolyte content, and membrane potential). The determination of the mean activity coefficient of the NaCl in the membrane phase using the Donnan equilibrium equation reveals that this coefficient increases with the NaCl concentration in the external solution. Fundamental electrochemical properties of the amphoteric membrane are discussed on the basis of the variation of the membrane selectivity with the external electrolyte concentrations and the pH. The properties at neutral pH are accounted for by a mutual neutralization of some acidic and basic groups in the membrane phase.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290609
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  • 7
    Electronic Resource
    Electronic Resource
    Cyclocondensation of 4-Benzyl-1-hydrazinophthalazine (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1041-1048 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Hydrazino-4-benzylphthalazine 1 underwent closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride, trifluoroacetic anhydride, ortho esteres, aldehydes, urea or carbon disulphide to afford the N-formyl 3a, N-acyl 3b, and the appropriate 3-substituted-6-benzyl-s-triazolo [3,4-a] phthalazines 4a, c, 7, 8. Alkylation of the obtained s-triazolo[3,4-a]-phthalazine-3-thione 7 and s-triazolo [3,4-a] phthalazin-3-one 8 with N-substituted chloroacetamides gave the thioether 9 and N-substitution products 10, respectively. Likewise, applying Mannich conditions of the previously mentioned intermediates 7 and 8 yielded the N-Mannich bases (11 and 12). The new products were characterized by their elemental and spectral data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320622
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of polyfunctionally substituted pyridazines (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 293-296 
    Details
    ISSN: 0170-2041
    Keywords: Pyridazine, derivatives ; Pyrazolo-pyridazine, derivative ; Pyrido-pyridazine, derivative ; Isoxazolo-pyridazine, derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3-c]-pyridazine 6 was formed. The pyrido-pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo-pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900153
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of 2-alkyl-3-vinyloxaziridines as potential antitumor agents (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 461-464 
    Details
    ISSN: 0170-2041
    Keywords: Antitumor agents ; Oxaziridines ; Aldimines, unsaturated ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient method for the synthesis of previously unknown oxaziridines having unsaturated substituents at the 3-position (3a-k) is based on the selective oxidation of the imino group of α,β-unsaturated aldimines 2 with m-chloroperbenzoic acid. The title compounds and 2-tert-butyl-3-(phenylethynyl)oxaziridine (3k) exhibit potent activity against experimental tumor cells in vitro.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900187
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  • 10
    Electronic Resource
    Electronic Resource
    Sur une tentative d'unification des théaories quantiques de la cancérisation par les polyacènes. II: Le rôle de la rèagion K dans le processus d'activation metabolique conduisant au cancérogène ultime. Théorie des régions M, L, et BK (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 487-495 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study is a unified approach to quantum theories of polyacen carcinogenesis. Part II is on the role of the K-region in metabolic activation process leading to ultimate carcinogen and discusses the M, L, and BK theory. The saturation of the polyacen K-region, or the transformation into a quinoid one, deactivates the carcinogenic process going through a diol epoxyde, which results in Bay-region carbocation. K and B regions must be considered as two interdependent parts of the same structural entity, which may be termed the BK-region. The M, L, and BK theory achieves a complete unification of the Pullman and Jerina and other theories.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560380309
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