ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    β-Ketocarbonsäureester mit trans-Enolisierung (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3382-3393 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: β-Ketocarboxylic Esters with trans-EnolizationOpen-chained β-ketocarboxylic esters 10/11, existing predominantly in the E-configuration 2 of the enol form, can be generated by the introduction of mesityl groups. The energy gain by the intramolecular hydrogen bridge in the Z-configurations 1 is compensated by the steric energy. Steric and electronic effects lead to energetically high-lying keto forms 10, 11, which do not play a role in the equilibrium. Besides the influence of the substituents R1, R2, and R3, the solvent dependency and the base-catalysed attainment of the equilibrium 1⇄2 are investigated. The high energy barrier for the E, Z-isomerization allows the isolation and storage of the E- and Z-forms in pure state.
    Notes: Durch die Einführung von Mesitylsubstituenten gelingt es, offenkettige β-Ketocarbonsäureester 10/11 herzustellen, die bevorzugt in der E-Konfiguration 2 der Enolform vorliegen. Der Energiegewinn der intramolekularen Wasserstoffbrücke in der Z-Konfiguration 1 wird durch die sterische Energie kompensiert. Sterische und elektronische Effekte bewirken, daß die Ketoformen 10/11 energetisch so hoch liegen, daß sie im Gleichgewicht keine Rolle spielen. Außer den Substituenteneinflüssen von R1, R2 und R3 werden die Solvensabhängigkeit und die basekatalysierte Einstellung der Gleichgewichte 1⇄2 untersucht. Die hohe Energiebarriere für die E,Z-Isomerisierung gestattet die Reindarstellung und Lagerung von E- und Z-Formen.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191115
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Konformation von 2-Diazo-1,3-diketonen (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 465-469 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation on the Conformation of 2-Diazo-1,3-diketonesConformational analyses of 2-diazo-1,3-diketones (2a-f) with bulky substituents are performed by applying 1H- and 13C-NMR measurements in solution (and in solid state).
    Notes: Mit Hilfe von 1H- und 13C-NMR-Messungen in Lösung (und im Festkörper) werden die Konformationen von 2-Diazo-1,3-diketonen (2a-f) mit sperrigen Resten untersucht.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210313
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Diastereoselektivität beim O-Angriff von Elektrophilen auf β-Ketocarbonsäureester-Enolate (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1719-1724 
    Details
    ISSN: 0009-2940
    Keywords: Enolates, ambidospecifity, Z/E-diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Diastereoselectivity of the O-Attack of Electrophiles on Enolates from β-KetocarboxylatesThe O-alkylated, -silylated or -acylated derivatives 4aa-ae, 4ba, bf, 4ca, cc, cf of the pure Z or E enoles 2a-c are generated via the enolates 3a-c. In contrast to the complete regioselectivity, the Z/E diastereoselectivity depends on the substituents in 2/3, the applied electrophile and the reaction conditions. Especially for soft electrophiles the Z/E ratio can change significantly during the reaction 3→4.
    Notes: Aus den in reiner Form eingesetzten Z- oder E-Enolen 2a-c werden über die Enolatstufe 3a-c die O-alkylierten, -silylierten oder -acylierten Produkte 4aa-ae, 4ba, bf und 4ca, cc, cf hergestellt. Im Gegensatz zu der vollständigen Regioselektivität hängt die Z/E-Diastereoselektivität dabei von den Substituenten in 2/3, dem verwendeten Elektrophil und den Reaktionsbedingungen ab. Insbesondere bei weichen Elektrophilen kann sich das Z/E-Verhältnis bei der Umsetzung 3→4 stark ändern.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220919
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Konfigurationsstabilität von Enolaten aus β-Ketocarbonsäureestern (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1109-1114 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Stability of the Configuration of Enolates from β-ketocarboxylic Acid EstersZ- and E-enoles of β-ketocarboxylic acid esters 1a-c are completely and irreversibly deprotonated yielding the enolates 2a-c under retention of the configuration (kinetic control). Depending on the counter ions (Li, Na, K), the medium (THF, HMPT), and the temperature a subsequent Z/E equilibration can occur. On this basis the syntheses of enol ethers and esters with the desired configuration can be performed.
    Notes: Z- und E-Enole von β-Ketocarbonsäurederivaten 1a-c werden vollständig und irreversibel deprotoniert, wobei unter Konfigurationserhalt (kinetische Kontrolle) die Enolate 2a-c entstehen. Abhängig von Gegenionen (Li, Na, K), Medium (THF, HMPT) und Temperatur kann anschließend eine Z/E-Äquilibrierung eintreten. Auf dieser Basis läßt sich die Synthese von Enolethern und Enolestern auf die gewünschte Konfiguration hinsteuern.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210614
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    facet.materialart.
    Unknown
    Organic acids, siderophores, enzymes and mechanical pressure for black slate bioweathering with the basidiomycete Schizophyllum commune (2019)
    Details
    Publication Date: 2019
    Description: Abstract Although many fungi are known to be able to perform bioweathering of rocks and minerals, little information is available concerning the role of basidiomycetes in this process. The wood‐rotting basidiomycete Schizophyllum commune was investigated for its ability to degrade black slate, a rock rich in organic carbon. Mechanical pressure of hyphae and extracellular polymeric substances was investigated for biophysical weathering. A mixed ß1‐3/ß1‐6 glucan, likely schizophyllan that is well known from S. commune, could be identified on black slate surfaces. Secretion of siderophores and organic acids as biochemical weathering agents was shown. Both may contribute to biochemical weathering in addition to enzymatic functions. Previously, the exoenzyme laccase was believed to attack organic matter within the black slate, and thereby releasing metals from the rock. Here, overexpression of laccase showed enhanced dissolution of quartz phases by etching and pitting. At the same time, the formation of a new secondary mineral phase, whewellite, could be demonstrated. Hence, a more comprehensive understanding of biophysical as well as biochemical weathering by S. commune could be reached and unexpected mechanisms like quartz dissolution linked to shale degradation. This article is protected by copyright. All rights reserved.
    Print ISSN: 1462-2912
    Electronic ISSN: 1462-2920
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Protein kinase N controls a lysosomal lipid switch to facilitate nutrient signalling via mTORC1 (2019)
    Springer Nature
    Details
    Publication Date: 2019
    Print ISSN: 1465-7392
    Electronic ISSN: 1476-4679
    Topics: Biology , Medicine
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Durch sterische effekte stabilisierte ß-ketocarbonsäuren (1989)
    Elsevier
    Details
    Publication Date: 1989-01-01
    Print ISSN: 0040-4039
    Electronic ISSN: 1873-3581
    Topics: Chemistry and Pharmacology
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...