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  • 1990-1994  (3)
  • Organic Chemistry  (2)
  • Bicyclo[3.2.1]octanes, stereoselective syntheses of  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Carbonylierende Ringerweiterung, 4. Diastereoselektive Synthesen von Bicyclo[3.2.1]oct-3-en-2,8-dionen durch doppelte Carbonylierung von (R)-(-)-α-Phellandren (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1079-1087 
    Details
    ISSN: 0009-2940
    Keywords: Ring enlargement ; Phellandrene ; Carbonylation ; Bicyclo[3.2.1]octanes, stereoselective syntheses of ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbonylating Ring Enlargement, 41). - Diastereoselective Syntheses of Bicyclo[3.2.l]oct-3-ene-2,8-diones by Double Carbonylation of (It)-(-)-α-PhellandreneIn order to clarify the stereochemistry of the carbonylating ring enlargement of cyclohexadiene complexes 1 to complexed seven-membered ring ketones 2 and the further carbonylation to bicyclo[3.2.1]oct-3-ene-2,8-diones 3 the exo and endo isomers of (R)-(-)-α-phellandrene complex 7 were synthesized in pure form and in various isomeric ratios and converted. The optically active ring-enlargement products 11 and 12 obtained therefrom, as well as the enantiomerically pure bicyclooctenes 20-22, implicate a stereospecific reaction course under retention of the configuration predetermined by the starting material 6 and its complexes 7. This was confirmed by an X-ray determination of the absolute configuration of exo-12. Thus, the method is suitable for the diastereoselective synthesis of bicyclo[3.2.1]oct-3-ene-2,8-diones 3 from 1,3-cyclohexadiene complexes 1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230522
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemische Studien, 62. Untersuchungen zur Photostabilität von Halometason und Prednicarbat in kristallinem Zustand sowie Kristallstruktur von Halometason (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 63-67 
    Details
    ISSN: 0170-2041
    Keywords: Prednicarbate ; Halometasone ; Photochemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Studies, 62.  -  Investigation on the Photostability of Halometasone and Prednicarbate in the Crystal State and Crystal Structure of HalometasoneUV irradiation of halometasone (1) in the crystal state yields three photoproducts: 2-chloro-6α,-9-difluoro-11β, 17α-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbaldehyde (3), 2-chloro-6α,9-difluoro-11β-hydroxy-16α-methylandrosta-1,4-diene-3,17-dione (4 and the dimerization product 2ξ-chloro-2ξ-(2-chloro-6α,9-difluoro-11β,2→-trihydroxy-16α-methyl-3,20-dioxopregna-1,4-dien-21-yl)-6α,9-difluoro-11β,17, 21-trihydroxy-16α-methylpregna-4-ene-3,20-dione (5). The structure of 5 is determined by the molecular packing of 1 in the crystal, as shown by an X-ray analysis of 1. Two photo-products are formed after irradiation of prednicarbate (2): 11β, 17-dihydroxy-21-propionyloxypregna-1,4-diene-3,20-dione (6) and 17-(ethoxycarbonyloxy)-11β,21-dihydroxypregna-1,4-diene-3,20-dione (7).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199219920112
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  • 3
    Electronic Resource
    Electronic Resource
    Derivate des Imidazols, VII. 2,3-Dihydro-1,3,4,5-tetramethyl-2-methylen-1H-imidazol als Kupplungsreagens. Die Kristallstruktur von Bis(1,3,4,5-tetramethyl-2-imidazolyl)methylium-iodid (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1149-1151 
    Details
    ISSN: 0170-2041
    Keywords: Imidazoles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Derivatives, VII. - 2,3-Dihydro-1,3,4,5-tetramethyl-2-methylen-1H-imidazole as Coupling Reagent. The X-ray Structure of Bis(1,3,4,5-tetramethyl-2-imidazolyl)methylium Iodide2,3-Dihydro-1,2,3,4-tetramethyl-2-methylen-1H-imidazole (1) reacts with 1,3,4,5-tetramethyl-2-(methylthio)imidazolium iodide (4) in the presence of pyridine to give bis(1,3,4,5-tetramethyl-2-imidazolyl)methylium iodide (5) which is also formed by the reaction of 4 and methyl lithium in the ratio 2:3. The X-ray structure of 5 is reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301184
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