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  • (-)-Menthone  (1)
  • 1,3-Dioxolan-4-one, (2S)-2(tert-butyl)-5-methylene-  (1)
  • Benzo[g,h,i]perylenes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Asymmetric Induction in the Diels-Alder Reaction of Chiral (2S)-2-(tert-Butyl)-5-methylene-1,3-dioxolan-4-one (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 327-330 
    Details
    ISSN: 0009-2940
    Keywords: Asymmetric induction ; Diels-Alder reaction ; 1,3-Dioxolan-4-one, (2S)-2(tert-butyl)-5-methylene- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetrische Induktion in der Diels-Alder-Reaktion von (2S)-2-tert-Butyl-5-methylen-1,3-dioxolan-4-onDie Diels-Alder-Reaktion der Methylenverbindung 3 mit Cyclopentadien bei Raumtemperatur führt zu den Addukten 4 und 5 mit mehr als 95proz. Seitendifferenzierung und 96proz. exo-Selektivität. Die Struktur der Produkte wurde sowohl durch chemische Folgeraktionen als auch durch eine Röntgenstrukturanalyse von 4 bestimmt. Eine Mischung aus 4 und 5 wurde zum optisch aktiven (+)-Norbornenon 12 abgebaut. Katalyse mit TiCl2(PrO)2 sowie AlEtCl2 bei niedrigen Temperaturen verringert dramatisch die Seitendifferenzierung.
    Notes: The Diels-Alder reaction of the cyclic methylene compound 3 with cyclopentadiene at ambient temperature leads to the adducts 4 and 5 with more than 95% face and more than 96% exo selectivity. The structure of the products has been verified by chemical correlation as well as by X-ray diffraction analysis of the Diels-Alder adduct 4. The mixture of 4 and 5 was converted to optically active (+)-norbornenone 12. face Selectivity was dramatically decreased by Lewis acid catalysis with TiCl2(iPrO)2 or AlEtCl2 at lower temperatures.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220220
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cycloadditions, 53. New spirocyclic chiral dienes  -  synthesis and diastereoselective Diels-Alder reactions with N-phenylmaleimide (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1455-1461 
    Details
    ISSN: 0947-3440
    Keywords: Dienes, chiral ; 1,3-Dioxin-4-ones ; (-)-Menthone ; Diels-Alder reactions, diastereoselective ; Cycloadditions, high-pressure ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and diastereoselective Diels-Alder reactions of new spirocyclic chiral dienes are reported. Starting with diketene and (-)-menthone (1), we prepared the diastereomeric diketene-menthone adducts 2 and 3. Further derivatization and olefination afforded four chiral dienes 12-15. Diastereoselective Diels-Alder reactions of these dienes with N-phenylmaleimide (NPM) under high-pressure conditions yielded the corresponding cycloadducts 16-19. Olefination of 6-diethylphosphonomethyl-2,2-dimethyl-1,3-dioxin-4-one 8 with formaldehyde led to unexpected compounds 9-11 resulting from the originally formed olefination product.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199508198
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and X-ray Analysis of New [5]Helicenes - HMO Calculations on the Photocyclization of the Stilbene Precursors (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1709-1718 
    Details
    ISSN: 1434-193X
    Keywords: Sum of free valence numbers ; Benzo[g,h,i]perylenes ; [5]Helicenes ; Photocyclization ; HMO calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of the new pentahelicenes 5, 11, 17, 21, and 28 with various substituents are described. In the case of 2,13-dicyano-[5]helicene (11) optical resolution was achieved by HPLC using a column packed with γ-cyclodextrin. However, the enantiomers racemized within a few hours. On the other hand, the enantiomers of 28 turned out to be stable after separation on triacetylcellulose using MPLC. The crystal structures of 11, 17, and 21 were solved and indicated the typical distortions which are expected for helicenes. The model of the sum of free valence numbers was applied in order to rationalize the reactivity pattern of the photochemical phenanthrene cyclization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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