ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2878-2894 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleotides, III. Synthesis and Properties of O′-Benzyl-substituted DiurdylphosphatesA series of differently interconnected diuridylphosphates 12, 15, 18, 21, 26 and 32 has been synthesised from 2′-O′-benzyl- (2) or 3′-O-benzyl-5′-O-trityluridine (3) and mono-O′-acetyl-mono-O′-benzyluridines (7, 8) via the phosphotriester method. Partial deblocking of protecting groups leads to interesting new derivatives of which various phosphotriesters could be separated into two diastereoisomers. The O′-benzyl protecting group shows some advantages due to its inert character in basic and acidic hydrolyses but creates problems on cleavage by hydrogenolysis.
    Notes: Ausgehend von 2′-O-Benzyl- (2) bzw. 3′-O-Benzyl-5′-O-trityluridin (3) und Mono-O′-acetyl-mono-O′-benzyluridinen (7, 8) werden nach der Phosphorsäure-triester-Methode verschiedenartig verknüpfte Diuridylphosphate 12, 15, 18, 21, 26 und 32 dargestellt. Durch partielle Schutzgruppenabspaltung werden eine Reihe interessanter Derivate erhalten, wobei es in einzelnen Fällen gelang, die Phosphorsäuretriester in zwei diastereomere Verbindungen aufzutrennen. Die O′-Benzyl-Schutzgruppe bewährt sich als säure- und alkalistabile Funktion, bereitet aber bei der hydrogenolytischen Abspaltung noch gewisse Schwierigkeiten.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2857-2871 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleotides, I. Synthesis and Properties of Thymidylyl-(3′→3′)-, (3′→5′)-, and -(5′→5′)-thymidineThe three isomeric thymidylyl-thymidines 7, 13, und 19 containing 3′ → 5′-, 3′ → 3′-, and 5′ → 5′-, internucleotid linkages are synthesised by the triester method via the corresponding blocked phenyl esters 10, 11, and 18. Alkaline hydrolysis of the unblocked phenyl triesters 9, 12, and 17 revealed that the absence of alkaline-stable blocking groups at the sugar hydroxyls gives rise to a partial isomerization of the internucleotidic linkage. The newly synthesized compounds are characterized by u. v. spectra and elementary analyses. C. d. spectra are less informative.
    Notes: Die drei isomeren Thymidylyl-thymidine 7, 13 und 19 mit 3′ → 5′-, 3′ → 3′- und 5′ → 5′-verknüpfender Internucleotidbindung werden nach dem Triester-Verfahren über die entsprechend blockierten Phenylester 10, 11 und 18 dargestellt. Die alkalische Hydrolyse der ungeschützten Phenyltriester 9, 12 und 17 lehrte, daß das Fehlen von alkalistabilen Schutzgruppen an den Zuckerhydroxylgruppen von einer partiellen Isomerisierung der Internucleotidbindung begleitet ist. Sämtliche synthetisierten Verbindungen werden durch UV-Spektren und Elementaranalysen charakterisiert. CD-Spektren sind wenig informativ.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mechanism of the Fritsch-Buttenberg-Wiechell Rearrangement.  -  The Stereochemistry of the Thermolysis of Potassium 3.3-Diaryl-2-chloroacrylates and of Lithiated 2.2-Diaryl-1-chloroethylenes3)The α-fragmentation of the stereoisomeric potassium 3-(4-biphenylyl)-2-chloro-3-phenyl-[2-14C]acrylates (10) at 160-190° in HMPT, and the thermolysis of the corresponding carbenoids, 2-(4-biphenylyl)-1-chloro-2-phenylvinyllithium (8), into (4-biphenylyl)phenyl-acetylene at low temperature both proceed stereospecifically with migration of the aryl substituent in trans-position of the halogen atom. The „trans-selectivity“ is lower for the acrylates (81% for trans- 10, 77% for cis-10) than for the carbenoids (97% for trans-84), 95% for cis-8). An „apparent cis-rearrangement“, consisting in the stereoisomerization of the halocarbanion intermediate 2 with a consecutive trans-migration, is excluded for the α-fragmentation by experimental evidence. In conclusion, a „true cis-rearrangement“ is postulated, which, like the trans-rearrangement, either starts at a late stage of the C-halogen bond breaking or after the formation of the carbene salt complex 22.
    Notes: Die α-Fragmentierung der stereoisomeren Kalium-2-chlor-3-phenyl-3-[biphenylyl-(4)]-[2-14C]-acrylate (10) bei 160-190° in HMPT zu Phenyl-[biphenylyl-(4)]-acetylen (11) vollzieht sich ebenso wie die Thermolyse der strukturanalogen Carbenoide, 1-Chlor-2-phenyl-2-[biphenylyl-(4)]-vinyllithium (8), bei tiefer Temperatur stereospezifisch unter Wanderung der zum Halogen trans-ständigen Arylgruppe. Bei den Acrylaten ist die „trans-Selektivität“ (81% bei trans-10, 77% bei cis-10) geringer als bei den Carbenoiden (97% bei trans-84), 95% bei cis-8). Für den cis-spezifischen Anteil der α-Fragmentierung wird eine Stereoisomerisierung am intermediären Halogencarbanion 2 experimentell ausgeschlossen und daher eine „wahre cis-Umlagerung“ postuliert, die wie die trans-Umlagerung entweder im Spätstadium der Halogenablösung vom α-Kohlenstoff oder am Carben-Salzkomplex 22 einsetzt.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2895-2906 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleotides, IV. Stereochemistry of Diuridyl-phenylphosphatesThe stereochemistry of various substituted diuridyl-(2′ → 5′)-, -(3′ → 5′)-, -(2′ → 2′)-, -(3′ → 3′)- and -(5′ → 5′)-phenylphosphates is discussed on the basis of their spectroscopic properties and the differences in n.m.r. spectra of diastereomeric diuridyl-phenylphosphates as well as of corresponding compounds with two diastereotopic uridyl groups. The c.d. spectra of 2′-O-benzyl-substituted diuridylphosphates indicate a stacking-effect of the uracil- and benzyl-moiety.
    Notes: Die Stereochemie verschiedenartig substituierter Diuridyl-(2′ → 5′)-, -(3′ → 5′)-, -(2′ → 2′)-, -(3′ → 3′)- und -(5′ → 5′)-phenylphosphate wird anhand ihrer spektroskopischen Eigenschaften und der Unterschiede in den NMR-Spektren diastereomerer Diuridyl-phenylphosphate sowie entsprechender Verbindungen mit zwei zueinander diastereotopen Uridylgruppen diskutiert. Die CD-Spektren 2′-O′-benzyl-substituierter Diuridylphosphate deuten auf eine räumliche Überlagerung von Uracil- und Benzylgruppe im Sinne eines „stacking“-Effektes hin.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2019-06-14
    Description: The Radiation Assessment Detector (RAD) (Hassler et al., 2012) onboard the Mars Science Laboratory (MSL) Curiosity rover (Grotzinger et al., 2012) has been making detailed measurements of the radiation environment on the surface of Mars since landing on 6 August 2012 (Hassler et al., 2014; Zeitlin et al., 2016). These measurements are the first of their kind on the surface of another planet and are providing essential measurements of the radiation environment on Mars in preparation for a human mission in the coming decades. The objectives of RAD are; 1) to characterize the energetic particle spectrum on the surface of Mars as a function of time in the solar cycle, including direct (galactic cosmic rays and solar energetic particles) and indirect (neutrons, etc.) radiation created in the atmosphere and regolith, 2) to determine the dose and doseequivalent rates as a function of time in the solar cycle, and 3) to use these observations to test and validate space radiation transport models. Initial results of the charged particle spectra (Ehresmann et al., 2014) and neutral particle spectrum (Khler et al., 2014), as well as dose and doseequivalent during cruise (Zeitlin et al., 2013) and on the surface (Hassler et al., 2014) have been reported, and with almost five years of continuous measurements, RAD continues to characterize the radiation environment as solar minimum is approached.
    Keywords: Space Radiation; Lunar and Planetary Science and Exploration
    Type: NF1676L-27115 , Life Sciences in Space Research (ISSN 2214-5524) (e-ISSN 2214-5532); 14; 1-2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...