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  • Organic Chemistry  (14)
  • Azetes, 3,4-dihydro-  (1)
  • Biochemistry and Biotechnology  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Proteolytically stable peptides by incorporation of α-Tfm amino acids (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 3 (1997), S. 157-167 
    Details
    ISSN: 1075-2617
    Keywords: α-trifluoromethyl substituted amino acids ; α-chymotrypsin ; proteolytic stability ; Cα,α-disubstituted glycines ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of model peptides containing α-trifluoromethyl-substituted amino acids in five different positions relative to the predominant cleavage site of the serine protease α-chymotrypsin was synthesized by solution methods to investigate the influence of α-Tfm substitution on the proteolytic stability of peptides. Proteolysis studies demonstrated absolute stability of peptides substituted in the P1 position and still considerable proteolytic stability for peptides substituted at the P2 and P′2 positions compared with the corresponding unsubstituted model peptide. Comparison with peptides containing the fluorine-free disubstituted amino acid α-aminoisobutyric acid allowed to separate electronic from steric effects. Furthermore, the absolute configuration of the α-Tfm-substituted amino acid was found to exert considerable effects on the proteolytic stability, especially in P′1 substituted peptides. Investigations of this phenomenon using empirical force field calculations revealed that in the (S,R,S)-diasteromer the steric constraints exhibited by the α-Tfm group can be outweighed by an advantageous interaction of the fluorine atoms with the serine side chain of the enzyme. In contrast, a favourable interaction between substrate and enzyme is impossible for the (S,S,S)-diastereomer. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Base-induced reactions of isothiazolium salts with active 5-methyl or 5-methylene groups (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 175-183 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that N-phenyl-substituted isothiazolium salts 2/3a-e with active 5-methyl or 5-methylene groups can easily be obtained by reaction of β-thiocyanatovinylaldehydes 1 and substituted anilines. Based on a wide variety of isothiazolium salts accessible in that way, a study of their various reaction products, e.g. 1,6-diphenyl-substituted thiadiazapentalenes 4a-d, 5a-j and special spiro compounds 6, and the influence of donor and acceptor substituents becomes possible. The structure of the basic skeleton of the thiadiazapentalenes was confirmed by X-ray analysis and ab initio MO calculations. Some mechanistic aspects are supported by the MO results.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370140
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  • 3
    Electronic Resource
    Electronic Resource
    Neue Cyclosporine aus Tolypocladium inflatumAuszugsweise als Poster an der 24th Interscience Conference on Antimicrobial Agents and Chemotherapy präsentiert (Washington DC, 8.-10. Oktober 1984); Abstract No.900.. Die Cyclosporine K-Z (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 13-36 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel Cyclosporins from Tolypocladium inflatum. The Cyclosporins K-ZThe fungus T. inflatum produces a plethora of oligopeptides, the cyclosporins, which exhibit remarkable biological activities. Cyclosporin A, the main metabolite, represents a potent immunosuppressant which opened new ways in the immunotherapy of bone marrow and organ transplantations. In addition to the already described cyclosporins A-I, we report now the isolation of the cyclosporins K-Z. The structural assignments of these novel congeners are based on chemical degradation, correlation reactions, mass spectra, and extensive analysis of 1H- and 13C-NMR spectra. All cyclosporins are cyclic undecapeptides differing from each other by minor variations in the amino-acid sequence. Comparison of the immunosuppressive and antifungal effects furnished new information concerning structure-activity relationships.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700103
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  • 4
    Electronic Resource
    Electronic Resource
    Isolierung und Strukturermittlung der neuen Cyclosporine E, F, G, H und I (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 1655-1677 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation and Structure Determination of the New Cyclosporins E, F, G, H und IThe cyclosporins, a new group of biologically active metabolites, are produced by the fungus Tolypocladium inflatum GAMS (formerly designated as Trichoderma polysporum [LINK EX PERS.] RIFAI). They represent neutral cyclic oligopeptides composed of 11 amino acids. In addition to the already described cyclosporins A-D new minor compounds, cyclosporins E-I, have now been isolated from the crude cyclosporin-complex by applying extensive chromatographical separation procedures. The structures of the new compounds have been determined by spectroscopical evidence, hydrolytic cleavage and chemical correlation reactions as well as by X-ray analysis of suitable derivatives. Cyclosporins A, B, C, D and G differ from each other only in the nature of the amino acid no. 2. Cyclosporins E and I are N-demethylated congeners of cyclosporins A and D respectively, Cyclosporin F has been recognized as deoxycyclosporin A, whereas Cyclosporin H represents an epimeric form of cyclosporin A and contains N-methyl-D-valine in position 11.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650538
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  • 5
    Electronic Resource
    Electronic Resource
    Heterocyclische Siebenring-Verbindungen, XII1) Synthese 3,5-substituierter 4-Phenyl-1-benzoxepine über 2,3-Dihydro-Vorstufen (1974)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1974 (1974), S. 1301-1314 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-membered Ring Compounds XII1). - Synthesis of 3,5-Substituted 4-Phenyl-1-benzoxepins via 2,3-Dihydro PrimersThe 4-phenyl-2,3-dihydro-1-benzoxepin-3-ones 7 and 13 have been alkylated or acetylated to the 1-benzoxepins 8, 10, 17, and 19; synthesis of 16 was achieved by dehydrobromination of 15.
    Notes: Die 4-Phenyl-2,3-dihydro-1-benzoxepin-3-one 7 und 13 wurden zu den 1-Benzoxepinen 8, 10, 17 und 19 alkyliert oder acetyliert. Die Synthese von 16 gelang durch Bromwasserstoffabspaltung aus 15.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197419740817
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  • 6
    Electronic Resource
    Electronic Resource
    Heterocyclische Siebenring-Verbindungen, XV. Die thermische Umlagerung eines 2-Methyl-1-benzoxepins, ein Beitrag zur Frage der Zwischenprodukte der 1-Benzoxepin-Naphthol-Umlagerung (1975)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1975 (1975), S. 1797-1807 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-membered Ring Compounds, XV. - The Thermal Rearrangement of a 2-Methyl-l-benzoxepin, a Contribution to the Search for Intermediates in the 1-Benzoxepin- Naphthol RearrangementThermolysis of the 2-methyl-substituted 1-benzoxepin 4 yields 1,2-dihydronaphthalen-l-one 5, which on prolonged heating gives rise to the isomeric 1,4-dihydronaphthalen-l-one 7. Thermolysis of 4 in methanol however leads to the cis-addition product 9a, from which 5 subsequently regenerated. Thus intermediates B-D of I-benzoxepin rearrangements are verified. The rate of thermolysis of 4 in solution depends upon the ability of the solvent to act as a hydrogen-bond donor.
    Notes: Das 2-Methyl-1-benzoxepin 4 lagert sich beim Erhitzen zunächst in das 1,2-Dihydronaphthalin-1-on 5 um, das bei längerer Reaktionszeit in das isomere 1,4-Dihydronaphthalin-l-on 7 übergeht. Bei der Thermolyse von 4 in Methanol entsteht zunächst die cis-Additionsverbindung 9a und daraus dann wieder 5. Dadurch werden die Zwischenstufen B - D dieser Umlagerung bewiesen. Die Geschwindigkeit der Thermolyse von 4 hängt von der Fähigkeit des Lösungsmittels ab, als Wasserstoffbrückendonator zu wirken.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197519751008
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  • 7
    Electronic Resource
    Electronic Resource
    Heterocyclische Siebenring-Verbindungen, XXI. Photochemische Reaktionen substituierter 4-Phenyl-1-benzothiepine (1977)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1977 (1977), S. 1874-1887 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-Membered Ring Compounds, XXI. - Photochemical Reactions of Substituted 4-Phenyl-1-benzothiepinsOn photoisomerization substituted 4-phenyl-1-benzothiepins 2a-d undergo ring closure to give the expected 1-phenyl-2a,7b-dihydrocyclobuta[b][1]benzothiophenes 4a-d which are then transformed into the corresponding 2a-phenyl-2a,7b-dihydrocyclobuta[b][1]benzothiophenes 5a-d in a second photoreaction.
    Notes: Die Photoisomerisierung der substituierten 4-Phenyl-1-benzothiepine 2a-d liefert zunächst unter Ringschluß die erwarteten 1-Phenyl-2a,7b-dihydrocyclobuta[b][1]benzothiophene 4a-d. Diese werden in einer nachfolgenden Photoumlagerung in die entsprechenden 2a-Phenyl-2a,7b-dihydrocyclobuta[b][1]benzothiophene 5a-d übergeführt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197719771109
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  • 8
    Electronic Resource
    Electronic Resource
    Chromane, XV. Synthese von (±)-Brasilin (1963)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 667 (1963), S. 116-125 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus racem. cis- und racem. trans-3.4-Dihydroxy-7-methoxy-3-[3.4-dimethoxybenzyl]-chroman entsteht in Eisessig mit 1% Perchlorsäure (±)-Brasilin-trimethyläther.  -  Aus den entsprechenden Benzyloxyverbindungen bildet sich in Eisessig mit 1% Perchlorsäure (±)-Brasilin-tribenzyläther, der bei katalytischer Hydrierung zu (±)-Brasilin entbenzyliert wird.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19636670114
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  • 9
    Electronic Resource
    Electronic Resource
    Heterocyclische Siebenring-Verbindungen, XIV. Diels-Alder-Reaktionen substituierter 1-Benzoxepine (1975)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1975 (1975), S. 1571-1575 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-membered Ring Compounds, XIV. - Diels-Alder Reactions of Substituted 1-BenzoxepinReaction of the 1-benzoxepins la - e with ethylenetetracarbonitrile yields the corresponding 3,4-benzo-2-oxabicyclo[3.2.2]non-3,8-dienes. The rate of the addition reaction is governed by position and donor strength of the substituents in the hetero-ring of la -e.
    Notes: Die I-Benzoxepine 1a- e reagieren mit Äthylentetracarbonitril zu Derivaten des 3,4-Benzo- 2-oxabicyclo[3.2.2]non-3,8-diens, wobei die Tendenz zur Diels-Alder-Reaktion durch Stellung und Donorstärke der Substituenten im Heteroring von la - e bestimmt wird.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197519750904
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  • 10
    Electronic Resource
    Electronic Resource
    Heterocyclische Siebenring-Verbindungen, XVIII. Einfluß der Substituenten auf die photochemische 1-Benzoxepin-Umlagerung (1977)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1977 (1977), S. 1597-1609 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-Membered Ring Compounds, XVIII. - The Influence of Different Substituents upon the Photorearrangement of 1-BenzoxepinsThe relative tendency of a series of 4-phenyl-1-benzoxepins 3 to undergo photochemical isomerizations yielding the corresponding 1-phenyl-2a,7b-dihydrocyclobuta[b]-1-benzo-furans 4 has been investigated experimentally with respect to different substitution patterns. It can be shown that effects of π-acceptor- and π-donor substituents, respectively, are explained well by a simple π MO model based upon perturbation theory.
    Notes: Die relative photochemische Umlagerungstendenz von gezielt substituierten 4-Phenyl-1-benzoxepinen 3 zu den entsprechenden 1-Phenyl-2a,7b-dihydrocyclobuta[b]-1-benzofuranen 4 wurde experimentell im Hinblick auf ihre Substituentenabhängigkeit untersucht. Es wird gezeigt, daß sich die gefundenen Effekte von π-Acceptor- oder π-Donorsubstituenten befriedigend auf der Basis eines einfachen störungstheoretischen π-MO-Modells deuten lassen.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197719771003
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