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  • 1985-1989  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1-7 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: cyclo-Trimerisation of 1,4-Naphthoquinone; Cooperation of Phenol/Quinone Additions and Redox ReactionsThe reaction course2) postulated for the cyclo-trimerisation of 1,4-naphthoquinone (1a) to cyclo-tri-1,4-naphthoquinone (11a) is confirmed and supplemented by: (i) isolation of the red intermediate 1′,4′-dihydroxy-2,2′-binaphthyl-1,4-quinone (5a), (ii) synthesis of 11a starting from 5a or 2,2′-binaphthyl-1,4:1′,4′-diquinone (6a), and (iii) reduction of 5a and 6a by 1,4-naphthalenediol (2a) to 2,2′-binaphthyl-1,1′,4,4′-tetrol (4a). Requirement for the cyclo-trimerisation of 1a to 11a is a cooperation of phenol/quinone additions and redox reactions controlled by the permanent decreasing oxidation potential of the reaction mixture. As byproducts of the synthesis of 11a in acetic acid 9a, 10a, 12a, 12c, 13a, 13c, and 14a could be isolated as acetates.
    Notes: Der für die cyclo-Trimerisierung von 1,4-Naphthochinon (1a) zu cyclo-Tri-1,4-naphthochinon (11a, Triphthaloylbenzol) postulierte Reaktionsverlauf2) wurde bestätigt und ergänzt durch: 1. Isolierung des roten Zwischenproduktes 1′,4′-Dihydroxy-2,2′-binaphthyl-1,4-chinon (5a), 2. Synthese von 11a, ausgehend von 5a oder 2,2′-Binaphthyl-1,4:1′,4′-dichinon (6a). 3. Reduktion von 5a und 6a durch 1,4-Naphthalindiol (2a) zu 2,2′-Binaphthyl-1,1,′4,4′-tetrol (4a). Vorbedingung für die cyclo-Trimerisierung von 1a zu 11a ist ein Kooperieren, von Phenol/Chinon-Additionen und Redoxreaktionen, das gesteuert wird durch das laufend kleiner werdende Oxidationspotential der Reaktionslösung. Bei der Synthese von 11a in Eisessig wurden die Nebenprodukte 9a, 10a, 12a, 12c, 13a, 13c und 14a als Acetate isoliert.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 343-347 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bacteriochlorophyll f. - Partial Synthesis and the Behaviour of Some DerivativesStarting with chlorophyll a/b mixture 5/6 from green plants, we describe the partial synthesis of the bacteriophaeophorbide f methyl ester 7. This is a derivative of bacteriochlorophyll f (4). We postulate the existence of 4 as a natural product, though it has not yet been isolated. Methods for the separation of the epimeric compounds 7 are described.
    Notes: Wir beschreiben die Partialsynthese des Bacteriophäophorbid-f-methylesters 7 ausgehend vom Chlorophyll-a/b-Gemisch 5/6 aus grünen Pflanzen. 7 ist ein Derivat des von uns postulierten, in der Natur jedoch noch nicht entdeckten Bacteriochlorophylls f (4). Verfahren zur Epimerentrennung von 7 werden beschrieben.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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