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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 49 (1984), S. 3766-3771 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1907-1919 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, XXI1).  -  Synthesis of 3-DemethoxyaranciamycinoneThe intramolecular Wittig reaction of the ylide 8b leads to the dihydronaphthacene 9b which can be transformed into the ketol 16 by cis-hydroxylation and pyridinium chlorochromate oxidation. A hydroxy group at C-4 can be introduced either by bromination followed by treatment with diluted alkali or by direct base catalysed hydroxylation leading to the 2,4-cis-diol 18 with high stereoselectivity. The reaction of the bromination products 17a/17b with silver trifluoromethane-sulfonate predominately yields the epimeric 2,4-trans-diol 19 (3-demethoxyaranciamycinone) besides minor amounts of 18 and the elimination product 20.
    Notes: Die intramolekulare Wittig-Reaktion des Ylids 8b führt zum Dihydronaphthacen 9b, das durch cis-Hydroxylierung und Pyridiniumchlorochromat-Oxidation zum Ketol 16 umgewandelt werden kann. Eine Hydroxygruppe an C-4 kann entweder durch Bromierung  -  gefolgt von Behandlung mit verdünntem Alkali  -  oder durch direkte basenkatalysierte Hydroxylierung eingeführt werden und liefert mit hoher Stereoselektivität das 2,4-cis-Diol 18. Die Reaktion der Bromierungsprodukte 17a/17b mit Silber-trifluormethansulfonat ergibt hauptsächlich das epimere 2,4-trans-Diol 19 (3-Desmethoxyaranciamycinon) neben geringeren Mengen 18 und dem Eliminierungsprodukt 20.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, 36.  -  Convergent Synthesis of Enantiomerically Pure Daunomycinone DerivativesThe ortho-quinoid vinylketenes 12 and 13 can be generated thermally or photochemically from the benzocyclobutenones 3 and 4. They undergo cycloaddition with the substituted benzoquinone 14 to yield the isomeric tetracyclic compounds 15, 16, 19, and 20 which can be oxidized to give the 10-deoxydaunomycinone derivatives 23 and 24. A similar cycloaddition of bisketenes obtained photolytically from the corresponding benzocyclobutenediones 9-11 with the enantiomerically pure AB building block 29 affords the symmetrically substituted daunomycinones 33-35 in only two steps.
    Notes: Die aus den Benzocyclobutenonen 3 und 4 thermisch oder photochemisch erzeugten ortho-chinoiden Vinylketene 12 und 13 gehen mit dem substituierten Benzochinon 14 eine Cycloaddition zu den isomeren Tetracyclen 15, 16, 19 und 20 ein, die zu den 10-Desoxydaunomycinon-Derivaten 23 und 24 oxidiert werden. Eine analoge Cycloaddition der aus den Benzocyclobutendionen 9-11 photochemisch erzeugten Bisketene mit dem enantiomerenreinen AB-Baustein 29 führt in nur zwei Schritten zu den optisch aktiven, symmetrisch substituierten Daunomycinonen 33-35.
    Type of Medium: Electronic Resource
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