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  • 1995-1999  (29)
  • 1955-1959  (4)
  • 1935-1939  (1)
  • General Chemistry  (34)
  • 1
    Electronic Resource
    Electronic Resource
    Enantioselective Lithiation and Substitution of (E)-Cinnamyl N,N-Diisopropylcarbamate through Use of (-)-Sparteine Complexes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2397-2403 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Chiral allylic anions ; (-)-Sparteine ; Enantioselective deprotonation ; Stereochemistry of electrophilic allylic substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction leads to diastereomeric lithium carbanion pairs that are configurationally unstable and equilibrate even at temperatures below -50 °C. The initially formed epimer (1S)-epi-10 is rapidly converted to the thermodynamically more stable (1R)-10 (in toluene solution). Carboxylation, acylation with acid chlorides, stannylation, and silylation take place at the α-position with stereoinversion (79-86% ee). Methylating agents attack the γ-position; here, the stereochemical course depends on the leaving group, anti-SE′ for the iodide (50% ee) and syn-SE′ (48% ee) for the tosylate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Electrosynthesis of Aromatic Aldehydes by Palladium-Catalyzed Carbonylation of Aryl Iodides in the Presence of Formic Acid (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1471-1473 
    Details
    ISSN: 1434-193X
    Keywords: Palladium ; Homogeneous catalysis ; Carbon monoxide ; Aromatic aldehyde ; Formic acid ; Carbonylation ; Electrochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The palladium-catalyzed electrocarbonylation of aryl halides performed in the presence of formic acid under one atmosphere of carbon monoxide affords aromatic aldehydes in good to high yields.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Vinyl- and Divinylcyclopentadienes by Rhodium-Catalyzed Condensation of Alkynes with Cross-Conjugated Amino Metallahexatrienes [= (1-Amino-1,3-butadien-2-yl)carbene Complexes] (M = Cr, W) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2545-2561 
    Details
    ISSN: 1434-193X
    Keywords: Carbene complexes ; Catalysis ; Metallahexatrienes ; Vinyl cyclopentadienes ; Transmetallation ; Rhodium ; Tungsten ; Chromium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report on the first example of a transition metal-catalyzed cyclization reaction of a Fischer carbene complex. It comprises the generation of vinyl- and divinyl cyclopentadienes under exceedingly mild conditions at 20 °C by condensation of (1-amino-1,3-butadien-2-yl)carbene complexes (= cross-conjugated metallahexatrienes) (CO)5M=C(OEt)C(=CHNR2)CR1=CHR23 (M = Cr, W) with alkynes R3C≡CH 4 (R3 = Ph, cyclohex-1-enyl, isopropenyl, methoxymethyl, 1-trimethylsiloxycyclohex-1-yl) in the presence of catalytic amounts of [(COD)RhCl]2. The starting compounds 3 are accessible in high yields by addition of enamines (E)-R2NCH=CHR22 to (1-alkynyl)carbene complexes (CO)5M=C(OEt)C≡CR11 (M = Cr, W; R1 = Ph, cyclohex-1-enyl).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Clusters on Clusters: closo-Dodecaborate as a Ligand for Au55 Clusters (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2051-2055 
    Details
    ISSN: 1434-1948
    Keywords: Gold clusters ; closo-Dodecaborate ; Conductivity ; Charging energy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The exchange of PPh3 in Au55(PPh3)12Cl6 by Na2[B12H11SH] using a phase-transfer reaction from CH2Cl2 to water needs 6 weeks for reaction, but finally results in the quantitative formation of Au55[(B12H11SH)Na2]12Cl6 (2). Cluster 2, which is of considerable stability in aqueous solution, has been characterized by 1H-NMR, 11B-NMR, and IR spectroscopy as well as by transmission electron microscopy (TEM). The Na+ cations can be exchanged by (octyl)4N+ making the resulting cluster 4 soluble in polar organic solvents. The electrical properties of 2 and 4 are compared with those of Au55[Ph2PC6H4SO3N(octyl)4]12Cl6 (3), the ammonium derivative of the sodium salt. Cluster 3 shows the expected increase of activation energy in the temperature range of 130-250 K owing to the increase of cluster spacing compared with the sodium derivative. However, clusters 2 and 4, show electromigration in the electric field, caused by the huge amount of ionic charges in the ligand shell.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Borane Insertion into Group-4 Metal-to-Carbon Bonds: The Reaction of HB(C6F5)2 with (η2-Formaldehyde)zirconocene Dimer and with (Butadiene)zirconocene (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2243-2247 
    Details
    ISSN: 1434-1948
    Keywords: Metallaoxirane ; HBR2 addition ; (Formaldehyde)zirconocene ; (Butadiene)zirconocene ; Heterocycles ; Boron ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (η2-Formaldehyde)zirconocene dimer (8) cleanly adds one or two molar equivalents of the borane HB(C6F5)2 by insertion of the H-[B] unit into the zirconium-carbon bond of the metallaoxirane moieties to form the mono- and bis-insertion products 16 and 17, respectively. These systems contain five-membered heterocyclic rings that are built up by connecting five different elements, namely H, B, C, O, and Zr. The bis(borane) insertion product 17 was characterized by an X-ray crystal structure analysis. (Butadiene)zirconocene reacts with HB(C6F5)2 in a similar way by insertion of the H-[B] unit into the (butadiene)C4-Zr linkage to form the metallacycle 18.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Novel μ3-Coordination of Urea at a Nickel(II) Site: Structure, Reactivity and Ferromagnetic Superexchange (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1851-1854 
    Details
    ISSN: 1434-1948
    Keywords: Urea ; Nickel ; Coordination modes ; Cooperative effects ; Magnetic properties ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A tetranuclear mixed-spin nickel(II) complex featuring two urea molecules in an unprecedented μ3-ĸN:ĸN′:ĸO coordination mode has been structurally characterized. The two central high-spin nickel(II) ions exhibit ferromagnetic coupling (J = +3.4 cm-1) mediated by the NH2-C-O linkages of the bridging urea. In solution the temperature dependence of the UV/Vis optical absorption and of the magnetic moment indicate that, upon cooling, additional solvent molecules bind to the terminal low-spin metal ions and a concomitant spin change occurs. In the solid state the coordinated urea ligands can be thermally degraded to cyanate within the grip of the multimetallic nickel(II) site.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Vinyl- and Divinylcyclopentadienes by Rhodium-Catalyzed Condensation of Alkynes with Cross-Conjugated Amino Metallahexatrienes [= (1-Amino-1,3-butadien-2-yl)carbene Complexes] (M = Cr, W) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3209-3209 
    Details
    ISSN: 1434-193X
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    The Formal Total Synthesis of Epothilone A (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2817-2823 
    Details
    ISSN: 1434-193X
    Keywords: Epothilone A ; Ring-closing metathesis ; Aldol reactions ; Lactones ; Diastereoselective alkylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formal total synthesis of epothilone A is described. The key steps in the synthesis of the northern hemisphere are a Z-selective ten-membered ring-closing metathesis reaction (RCM) and the diastereoselective alkylation at C8. Aldehyde 3 is formed by introduction of the thiazole moiety by a Wittig reaction and subsequent functional group transformation. An efficient route to keto acid 5 is described.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Frage der Existenz monomerer 1,2-Peroxyde, insbes. zur Konstitution des monomeren Allo-ocimen-peroxyds (1956)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 68 (1956), S. 304-305 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19560680810
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  • 10
    Electronic Resource
    Electronic Resource
    Die Synthese des Diamanten II (1957)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 69 (1957), S. 551-557 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In Fortsetzung einer früheren Behandlung des Problems der Diamantsynthese werden die neuesten Arbeiten auf diesem Gebiet besprochen, unter ihnen insbesondere die Synthesen der General Electric Comp. und der ASEA nebst ihren theoretischen und verfahrenstechnischen Grundlagen. Es wird gezeigt, daß das Gelingen der Diamantsynthesen nur durch die erstaunlichen neueren Entwicklungen auf dem Gebiet der Hochdruck-Hochtemperatur-Autoklaventechnik möglich wurde, und darauf hingewiesen, daß diese neuen Verfahrenstechniken sowohl eine ganz neue „Chemie der hohen Drucke und Temperaturen“ eröffnen, wie auch erstmals die Möglichkeit einer experimentellen petrologischen bzw. geochemischen Erforschung der tieferer (100-400 km) Magmenschichten der Erde bieten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19570691702
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