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  • 1995-1999  (2)
  • 1985-1989  (2)
  • Organic Chemistry  (3)
  • Crystal Structure  (1)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 113-124 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrogen abstraction of radical intermediates yielded by radical addition to the methylene compound 6, shows excellent facial selectivity. Conformational analyses of the radical intermediates were carried out by quantum chemical calculations and explain these results. The chiral radicals 7 and 8, yielded from the chiral bromides 3 and 4, lead with ethyl acrylate to the adducts 28 and 29 with more 96% de. The adduct 28 was converted to the optically active γ-valerolactone 30. The structures of the bromides 3, 4 and 31 as well as the radical adducts 19a, 24 and 25 have been verified by X-ray diffraction analysis.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 695-704 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereoselective Syntheses of rac-Slaframine and rac-6-epi-SlaframineIndolizidinones 8 have been obtained from thalidomide (5) and cyclopropylphosphonium salts 6 in good yields. Acid-catalyzed rearrangement of 8a gave the isomer 11. A regio- and stereoselective acetoxylation of 8a and 11 was achieved with lead tetraacetate: using standard conditions, acetates 15 and 16 were obtained; in the presence of triethylamine, however, 8a has been transformed into the acetoxy derivative 17. rac-6-epi-Slaframine (4) and rac-slaframine (1) were obtained from acetates 16 and 17 on conventional routes.
    Notes: Indolizidinone 8 wurden aus Thalidomid (5) und Cyclopropylphosphoniumsalzen 6 in guten Ausbeuten erhalten. 8a ließ sich mit Säuren zu 11 isomerisieren. Eine regio- und stereoselektive Acetoxylierung von 8a und 11 gelang mit Blei(IV)-acetat: unter den üblichen Bedingungen entstanden die Acetate 15 und 16; in Gegenwart von Triethylamin reagierte 8a jedoch zum Acetoxyderivat 17. rac-6-epi-Slaframin (4) und rac-Slaframin (1) wurden aus 16 und 17 auf konventionellen Wegen erhalten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1437-1447 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Synthesis of Mitomycins, 4.- Elucidation of the Configuration of Mitosane DerivativesThe configurations of the mitosane derivatives described in the previous communications1) were established by spectroscopic investigations and X-ray analysis of rac-1e.
    Notes: Die Konfigurationen der in den vorstehenden Arbeiten beschriebenen Mitosan-Derivate wurden durch spektroskopische Untersuchungen und eine Röntgenstrukturanalyse der Verbindung rac-1e bewiesen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 448-454 
    ISSN: 0044-2313
    Keywords: Dirhenium Heptoxide Dihydrate ; Perrhenic Acid ; Dioxane ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Rhenium(VII) Oxide with 1,4-Dioxane - Crystal Structure of Re2O7(OH2)2 · 2(1,4-Dioxane)By solvolysis of polymeric Re2O7 with 1,4-dioxane in the presence of small amounts of H2O two products of compositions Re2O6(OH)2 · 3(1,4-dioxane) (1) and Re2O7 · 2H2O · 2(1,4-dioxane) (2) are formed. From a complete X-ray single-crystal structure analysis 2 could now be characterized structurally (monoclinic, space group P21/c, a = 6.828(3) Å, b = 9.530(2) Å, c = 26.421(8) Å, β = 91.71(3)°, Z = 4). The compound is important as a convenient precursor for the preparation of pure rhenium trioxide. It is to be formulated as Re2O7(OH2)2 · 2(1,4-dioxane) and contains, contrary to 1, no 1,4-dioxane coordinated to Re. The crystalline phase consists of a supramolecular arrangement of Re2O7(OH2)2 units as in “solid perrhenic acid” and of 1,4-dioxane molecules associated through O—H … O hydrogen bridges. Analogous to dirhenium heptoxide and to solid perrhenic acid one of the rhenium atoms is in tetrahedral, the other is in distorted octahedral coordination.
    Notes: Durch Solvolyse des polymeren Re2O7 mit 1,4-Dioxan entstehen in Gegenwart von geringen Mengen H2O zwei Produkte mit den Zusammensetzungen Re2O6(OH)2 · 3(1,4-Dioxan) (1) und Re2O7 · 2H2O · 2(1,4-Dioxan) (2). Durch eine Röntgenstrukturanalyse konnte nun 2, das als Edukt zur Synthese von reinem ReO3 wichtig ist, strukturell charakterisiert werden. Die kristalline Phase ist als Re2O7(OH2)2 · 2(1,4-Dioxan) zu formulieren und enthält im Gegensatz zu 1 kein an Rhenium koordiniertes 1,4-Dioxan; sie besteht aus einer supramolekularen Anordnung von Re2O7(OH2)2-Einheiten wie in der „festen Perrheniumsäure“ und über O—H … O-Wasserstoffbrücken gebundenen 1,4-Dioxan-Molekülen. In Analogie zum Dirheniumheptoxid und der festen Perrheniumsäure ist eines der Rheniumatome tetraedrisch, das andere verzerrt-oktaedrisch koordiniert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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