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  • Polymer and Materials Science  (8)
  • Inorganic Chemistry  (6)
  • 72.20.-i
  • 78.20.-e
  • Wiley-Blackwell  (14)
  • 1980-1984  (14)
Collection
Publisher
Year
  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational analysis of the CD spectrum is reported for the synthetic and membrane-modifying nonadecapeptide analog of alamethicin N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu(OBzl)- Gln-OMe. The CD data are evaluated according to three different methods and are discussed with respect to those obtained from natural alamethicin and suitable models such as N-t-Boc-(Aib-L-Ala)7-OPOE, fragments of the synthetic nonadecapeptide, and the hexadecapeptide N-t-Boc-(Aib-L-Ala)5-Pro-Ala-Aib-Aib-Glu(OBzl)-Gln-OMe. The synthetic nonadecapeptide with the longer helical region exhibits membrane activities comparable to those of alamethicin, whereas the hexadecapeptide with the shorter helix is inactive.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 241-246 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-, 1H-nmr, CD, and x-ray crystallography revealed β-turns of type III for Boc-Gly-L-Ala-Aib-OMe, Boc-L-Ala-Aib-L-Ala-OMe; the 310-helix for Boc-Aib-L-Ala-Aib-L-Ala-Aib-OMe; and antiparallel arranged α-helices for Boc-L-Ala-Aib-Ala-Aib-Ala-Glu(OBzl)-Ala-Aib-Ala-Aib-Ala-OMe. An N-terminal rigid α-helical segment is found in the polypeptide antibiotics alamethicin, suzukacillin, and trichotoxin. The α-helix dipole is essential for their voltage-dependent pore formation in lipid bilayer membranes, which is explained by a flip-flop gating mechanism based on dipole-dipole interactions of parallel and antiparallel arranged α-helices within oligomeric structures.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 804-807 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetylenedicarbonyl DichlorideIn situ prepared carbonyl chloride 2 can be used as „activated acetylenedicarboxylic acid“ in Diels-Alder syntheses.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1337-1382 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized and studied the CD spectra of five new double-stranded RNA polymers: poly[r(A-G)·r(C-U)], poly[r(A-U-C)·r(G-A-U)], poly[r(A-C-U)·r(A-G-U)], poly[r(A-A-C)·r(G-U-U)], and poly[r(A-C-C)·r(G-G-U)]. Together with previously published spectra of seven other RNA sequences, the spectra of these new sequences provide a library sufficient to approximate the spectra of all other RNA sequences by first-neighbor formulas and, in addition, give four spectra with which we may test the validity of first-neighbor approximations. (1) We find that the spectra of RNA sequence isomers are very different, but that the spectra essentially do obey first-neighbor relationships. (2) We have derived tentative first-neighbor assignments of negative bands at about 295 and 210 nm in the CD spectra. (3) A test of spectral independence shows that among the 12 polymer spectra there are at least seven significant independent spectral shapes, one less than the eight needed to give the most accurate spectral analysis of an unknown RNA sequence for its first-neighbor frequencies. (4) Spectra are calculated for RNAs of random base composition, approximating natural RNAs having complex sequences. (5) A T-matrix of spectral components assigned to the first-neighbor base pairs is derived from 10 of the spectra. This matrix allows an estimation of the CD spectrum of any other known RNA sequence or an analysis of the spectrum of an unknown sequence for its distribution of first-neighbor base-pair frequencies. (6) Test analyses of two of the synthetic polymers and of two natural RNAs set a probable limit on the accuracy of first-neighbor frequency determinations using this T-matrix. (7) Finally, we summarize in an appendix the melting temperatures for all the RNA and corresponding DNA sequences; it appears that the Tm values of both DNAs and RNAs approximately obey first-neighbor relationships.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2834-2843 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylhydrazines, 5. Synthesis of pyrazole-, Pyrazolo[3,4-d]pyrimidine-, and 1H-1,2,4-Triazol-Nucleoside 5′-amide Derivatives via Riburonamide HydrazonesIn a single step reaction the 3,5-dimethylpyrazole nucleoside-5′-amides 6a,c, the functionally substituted pyrazole nucleoside-5′-amides 9a and 10b, and the 1H-1,2,4-triazol-nucleoside-5′-amide 18 were obtained regio- and stereoselectively from the riburonamide hydrazones 4a-c.9a and 10b were transformed into the unprotected pyrazolo[3,4-d]pyrimidine nucleoside-5-amide 14a and 15b, derivatives of allopurinol riboside. likewise the ethylamide 20 of virazole-5′-acid was synthesized from 18.
    Notes: Aus den Riburonamid-hydrazonen 4a-c wurden in einer Eintopfreaktion regio- und stereoselektiv die 5′-Säureamid-Derivate des 3,5-Dimethylpyrazol-nucleosids 6a,c, der funktionell substituierten Pyrazol-nucleoside 9a) und 10n) und des 1H-1,2,4-Triazole-nucleosids 18 direkt aufgebaut. Als Allopurinolribosid-Derivate wurden aus 9a und 10b die ungeschützten pyrazolo[3,4-d]pyrimidin-nucleosid-5′-säureamide 14a und 15b hergestellt. Entsprechend wurde aus 18 das Ethylamid 20, der Virazol-5′-säure erhalten.
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1761-1767 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Acetals of L-Sorbose with n-Butyllithium2,3:4,6-Di-O-isopropylidene-α-L-sorbose (1a) gives with n-butyllithium the known 6-deoxy-2,3-O-isopropylidene-β-D-threo-hex-5-enulofuranose (2), while the corresponding benzylidene compound 4 yields the glycal derivative 2,5-anhydro-4,6-O-benzylidene-3-deoxy-L-threo-hex-2-enitol (5). The 1-benzyl ether 1b is converted into 3 by Wittig rearrangement. Under analogous conditions both possible Wittig rearrangement products 7a and b are obtained from methyl 6-O-benzyl-2,3,4-tri-O-methyl-α-D-glucopyranoside (6). Their configuration is established by 1H NMR spectroscopy.
    Notes: 2,3:4,6-Di-O-isopropyliden-α-L-sorbose (1a) ergibt mit n-Butyllithium die bekannte 6-Desoxy-2,3-O-isopropyliden-β-D-threo-hex-5-enulofuranose (2), während die entsprechende Benzylidenverbindung 4 das Glycal-Derivat 2,5-Anhydro-4,6-O-benzyliden-3-desoxy-L-threo-hex-2-enitol (5) liefert. Aus dem 1-Benzylether 1b entsteht u. a. durch Wittig-Umlagerung das Produkt 3. Unter den gleichen Bedingungen werden aus Methyl-6-O-benzyl-2,3,4-tri-O-methyl-α-D-glucopyranosid (6) beide möglichen Wittig-Umlagerungsprodukte 7a und 7b erhalten. Ihre Konfigurationszuordnung erfolgt aus dem 1H-NMR-Spektrum.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 740-745 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Acetals of L-Rhamnose with Lithium-organic Compounds New Syntheses of Mycaral, Olivomycal, and Methyl 2,3,6-Trideoxy-α-L-erythro-hex-2-enopyranosideMethyl α-L-mycaroside (6a) is obtained from the dideoxy-uloside 2) by Grignard addition. the benzylidene rhamnoside (1a) reacts with methyllithium to give in only one step mycaral (4) (21%) and olivomycal (5) (72%). With lithiumdiisopropylamide 1a yields the unsaturated sugar 3a.
    Notes: Methyl-α-L-mycarosid (6a) wird aus dem Didesoxy-ulosid 2 durch Grignard-Addition erhalten. Das Benzylidenrhamnosid 1a reagiert mit Methyllithium in einem schritt zu Mycaral (4) und Olivomycal (5). Mit Lithiumdiisopropylamid erhält man hingegen aus 1a den ungesättigten Zucker 3a.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1775-1789 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospecific Synthesis of Nucleoside-5′-carboxylic Acid Derivatives with Pyrimidines as Hetero-cyclic BasePyrimidine nucleoside-5′-carboxylic acid derivatives were synthesized by condensation of riburonic acid glycosyl halides with heterocyclic bases via different methods. According to the investigations, the benzoyl-protected riburonic acid glycosyl halides 3b and 16b are valuable starting materials for the synthesis of β-nucleosides. Silver perchlorate proved to be the best catalyst in these condensation reactions with respect to stereoselectivity and yield. The methyl esters and the ethyl amides of uridine-, cytidine-, and thymidine-5′-carboxylic acid 8b, 11b, 18b, 19b and 20b were synthesized by this method stereospecifically and in good yield.
    Notes: Pyrimidinnucleosid-5′-carbonsäure-Derivate wurden durch Kondensation von Riburonsäure-glycosylhalogeniden mit heterocyclischen Basen nach verschiedenen Methoden hergestellt. Nach den Untersuchungen eignen sich als Ausgangskomponenten zur Synthese der β-Nucleoside am besten die benzoyl-geschützten Riburonsäure-glycosylhalogenide 3b und 16b. Die Verwendung von Silberperchlorat als Katalysator für die Kondensation ergab insgesamt die besten Ergebnisse bezüglich Stereoselektivität und Ausbeute. Die Methylester bzw. Ethylamide 8b, 11b, 18b, 19b und 20b der Uridin-, Cytidin- und Thymidin-5′-carbonsäure wurden auf diese Weise stereospezifisch und mit guten Ausbeuten synthetisiert.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 1192-1195 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Acetals of Sugars with Organolithium Compounds A Simple Synthesis of 4,6-Dideoxy-α-D-erythro-hexopyranos-3-ulose1,2:3,4-Di-O-isopropylidene-β-L-arabinose (3) reacts with lithium diisopropylamide to give the 4-deoxy-4-eno sugar 4. After its oxidation a stereospecific 1,4-addition by methyllithium/copper (I) iodide yields the 4,6-dideoxy-3-ulose 6.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 174-177 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Based on known theoretical approaches on the stability and coagulation of disperse systems the agglomeration of an aqueous PVC microsuspension dispersion containing macromolecular dispersing agents has been investigated. In this tenside-stabilized systems different effects of ionogenic and non-ionogenic dispersing agents were established. Further, the behaviour of the agglomerates in this disperse PVC-plastiziser system (DPO) was investigated. Besides the particle size the layer thickness of the macromolecular dispersing agent and the constituents affecting the potential were found to act on the agglomeration and the reversible degradation to particles and thus the flow behaviour. The energy-distance functions of the aqueous and non-aqueous systems can be explained by the DLVO theory.
    Notes: Ausgehend von bekannten theoretischen Ansätzen zur Stabilität und Koagulation disperser Systeme wird die Agglomeration einer wäßrigen PVC-Mikrosuspension-Dispersion mit makromolekularen Dispergatoren untersucht. In diesem tensidstabilisierten System ist eine unterschiedliche Wirkung ionogener und nichtionogener Dispergatoren nachweisbar. Gleichzeitig wird das Verhalten der Agglomerate im dispersen System PVC/Weichmacher (DOP) untersucht. Es kann gezeigt werden, daß neben der Teilchengröße insbesondere die Schichtdicke des makromolekularen Dispergators und potentialbestimmende Inhaltsstoffe die Agglomeration oder den reversiblen Zerfall in die Teilchen und damit das Fließverhalten bestimmen. Mit Hilfe der DLVO-Theorie lassen sich die Energie-Abstands-Funktionen des wäßrigen und nichtwäßrigen Systems erklären.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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