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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3128-3140 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospecific Cyclization of 2-(3-Hexenyl)-1,3-dimethyl-2-cyclohexen-1-ol with Z- and E-ConfigurationCyclization of 4a (Z) with formic acid leads selectively to the products with trans-configurated side chain: 5a (byproduct), 6a, and 7a. Starting from 4b (E), the products with cis-configurated side chain are exclusively formed: 5b (byproduct), 6b, and 7b. The constitution of the cyclization products was demonstrated by degradation to the diketones 10, 11. The elucidation of the relative configuration at C-7 was achieved by oxidation of 5a and 6a to 12a (trans), 5b and 6b to 12b (cis), 7a to 13a (trans), and 7b to 13b (cis). By alkaline equilibration of 12a/12b and 13a/13b the correlation between the stereochemical series was delineated. Reduction of the ketones gave 5a (from 12a), 5b (from 12b), 14a (from 13a), and 14b (from 13b). By this, all the diastereomeric racemates, which are possible in these series, were prepared and the relative configurations, given above, could be demonstrated.
    Notes: Die Cyclisierung von 4a (Z) mit Ameisensäure verläuft stereospezifisch zu den Produkten mit trans-konfigurierter Seitenkette: 5a (Nebenprodukt), 6a und 7a. Aus 4b (E) entstehen ausschließlich die Produkte mit cis-konfigurierter Seitenkette: 5b (Nebenprodukt), 6b und 7b. Die Konstitutionen der Cyclisierungsprodukte wurden durch Abbau zu den Diketonen 10, 11 bewiesen. Für die Aufklärung der relativen Konfiguration an C-7 wurden 5a und 6a zu 12a (trans), 5b und 6b zu 12b (cis), 7a zu 13a (trans) und 7b zu 13b (cis) oxidiert. Durch alkalische Äquilibrierung von 12a/12b und 13a/13b wurde die Verknüpfung der stereochemischen Reihen aufgezeigt. Reduktion der Ketone ergab 5a (aus 12a), 5b (aus 12b), 14a (aus 13a) und 14b (aus 13b). Damit lagen alle hier möglichen diastereomeren Racemate vor, so daß die angegebenen relativen Konfigurationen zugeordnet werden konnten.
    Additional Material: 1 Tab.
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclopropane Ring Cleavage in the α-Santal Series, I.  -  The Absolute Configurations of (-)-β-Santalol, (+)-epi-β-Santalol, and (E)-(-)-β-SantalolCyclopropane cleavage of (+)-α-santalyl acetate (1b) by treatment firstly with HCL/CHCl3 at -50°C and secondly with basic alumina resulted in (-)-β-santalyl acetate (2b) and (+)-epi-β-santalyl acetate (3b). The identity with 2b, 3b, isolated from east indian sandalwood oil, was demonstrated by 1H-, 13C-NMR, and ORD spectra. This result defines the absolute configurations of the β-santalols 2a, 3a, and 4a.
    Notes: Die Cyclopropan-Ringöffnung von (+)-α-Santalylacetat (1b) durch Einwirkung von 1. HCl/CHCl3 bei -50°C und 2. basischem Al2O3 führte zu (-)-β-Santalylacetat (2b) und (+)-epi-β-Santalylacetat (3b), die nach 1H- und 13C-NMR- sowie ORD-Spektren identisch mit den aus ostindischem Sandelholzöl isolierten Verbindungen 2b, 3b sind. Hierdurch werden die absoluten Konfigurationen der β-Santalole 2a, 3a und 4a festgelegt.
    Additional Material: 2 Tab.
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  • 3
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Apoterpenes and Aposesquiterpenes by Cooligomerization of Methyl Methacrylate with Isoprene and Myrcene Promoted by a Homogeneous Nickel Catalyst. An Example of Product-Control by Perturbation of CyclesThe cooligomerization of isoprene and methyl methacrylate in the presence of a homogeneous nickel catalyst leads in 64% yield to the formation of [2:l]-adducts, the sesquiterpenes 3, 4,5 and of a [1:]-adduct, the apoterpene 6. Methyl methacrylate and myrcene react with formation of the aposesquiterpene 10 in 7.5% yield. The course of the catalytic reaction is discussed. An example of product-control by perturbation of reaction cycles is presented. The catalytically formed compounds were converted into alcohols and aldehydes.  -  The odours and flavours of all compounds were critically examined.
    Notes: Die Cooligomerisation von Isopren und Methacrylsäure-methylester am homogenen Nickel-Katalysator fuhrt in 64 proz. Ausbeute zu [2:1]-Addukten, den Aposesquiterpenen 3, 4 und 5 sowie zu einem [1:1]-Addukt, dem Apoterpen 6. Methacrylsäure-methylester und Myrcen setzen sich zu 7.5% zum Aposesquiterpen 10 um. Der katalytische Reaktionsablauf wird diskutiert. Ein Beispiel der Produktsteuerung über Störung von Reaktionszyklen wird vorgestellt. Die katalytisch hergestellten Verbindungen wurden in Alkohole und Aldehyde umgewandelt.  -  Sämtliche Verbindungen wurden geruchlich und geschmacklich beurteilt.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1973 (1973), S. 1797-1815 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Prins Reaction with Cyclic Olefins, I.  -  The Reaction of Cyclododecene with ParaformaldehydeThe reaction of cyclododecene with paraformaldehyde leads in a highly stereoselective manner to the formation of trans-14-oxabicyclo[10.3.0]-trans-2-pentadecene (1) as the main product. Some of the 14-oxabicyclo[10.3.0]pentadecenes, 13-oxabicyclo[9.3.1]pentadecenes, and 2-cyclododecen-1-ylmethyl acetates, formed by this reaction, have been separated in pure form while the others have been obtained after saponification or hydrogenation. The structures of the isolated products have been established by chemical degradation and synthesis. A mechanism for the formation of the 14-oxabicyclo[10.3.0]pentadecenes and 13-oxabicyclo[9.3.1]-pentadecenes in the Prins reaction is proposed.
    Notes: Bei der Reaktion von Cyclododecen mit Paraformaldehyd wird trans-14-Oxabicyclo-[10.3.0]-trans-2-pentadecen (1) in hoch stereoselektiver Weise als Hauptprodukt gebildet. Einige der bei dieser Reaktion entstandenen 14-Oxabicyclo[10.3.0]pentadecene, 13-Oxabicyclo[9.3.1]pentadecene und (2-Cyclododecen-1-ylmethyl)acetate konnten in reiner Form abgetrennt werden, während die anderen nur in Form ihrer Verseifungs- oder Hydrierungs-produkte erhalten wurden. Die Strukturen der isolierten Verbindungen wurden durch Abbau und Synthese aufgeklärt. Es wird ein Mechanismus für die Bildung der 14-Oxabicyclo[10.3.0]-pentadecene und 13-Oxabicyclo[9.3.1]pentadecene bei der Prins-Reaktion vorgeschlagen.
    Additional Material: 3 Ill.
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  • 5
    Publication Date: 1979-01-01
    Print ISSN: 0040-4039
    Electronic ISSN: 1873-3581
    Topics: Chemistry and Pharmacology
    Published by Elsevier
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  • 6
    Publication Date: 1980-01-01
    Print ISSN: 0040-4039
    Electronic ISSN: 1873-3581
    Topics: Chemistry and Pharmacology
    Published by Elsevier
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