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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 287-291 
    ISSN: 0170-2041
    Keywords: Ginkgolide derivatives ; 14-Epiginkgolide derivatives ; Ginkgo biloba L. ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,14-Didehydro-10-hydroxyginkgolideOn the nomenclature: The skeleton of the ginkgolides A, B, C, M and J with the natural configuration is called “ginkgolide” since the systematic IUPAC nomenclature is too complicated. According to our nomenclature ginkgolide “A” is 3,10-dihydroxyginkgolide, ginkgolide “B” is 1,3,10-trihydroxyginkgolide etc. The numbering of the C atoms (formula 1) and the indexing of the H atoms (formula 2) are those proposed by Nakanishi[2]. (1) was prepared by reaction of 3,10-dihydroxyginkgolide (3) (ginkgolide “A”) by reaction with phosphoryl chloride in pyridine. Catalytic hydrogenation of 1 leads to 10-hydroxy-14-epiginkgolide (2a), which was epimerized with 4-(dimethylamino)pyridine (DMAP) in acetonitrile to give 10-hydroxyginkgolide (3a). 14-Epiginkgolide (2d) and ginkgolide (3d) were obtained from 2a and 3a via the 10-O-phenylthiocarbonyl derivatives 2c and 3c by means of a free-radical reduction with tri-n-butyltin hydride/α,α′-azobis(isobutyronitrile) (AIBN). By heating the 14-epiginkgolides 2a and 2b and the ginkgolides 3a and 3b in acetonitrile with DMAP an equilibrium on the side of the ginkgolides was established. The constitution and configuration of the compounds were proven by their 1H- and 13C-NMR spectra.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1023-1027 
    ISSN: 0170-2041
    Keywords: 1,10-Dihydroxyginkgolide ; 7-Deoxyginkgolide M ; 3-Deoxyginkgolide B ; 1,7,10-Trihydroxyginkgolide ; Ginkgolide M ; 14-Epiginkgolide ; Ginkgo biloba L. ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of the Ginkgolides, VI. - Preparation of 1,10-Dihydroxy- and 1,7,10-Trihydroxyginkgolide from 1,3,7,10-Tetrahydroxyginkgolide1,3,7,10-Tetrahydroxyginkgolide (“ginkgolide C”, 1) which can be isolated in large quantities from the terpene fraction of Ginkgo leaves, can be converted into 1-(tert-butyldiphenylsilyloxy)-3,7,10-trihydroxyginkgolide (2) in 95% yield. 2 was converted via straightforward reactions into 1,7,10-trihydroxyginkgolide (“ginkgolide M”, 9) and into the until now unknown 1,10-dihydroxyginkgolide (15). 15 can also be obtained from 1,3,10-trihydroxyginkgolide (“ginkgolide B”, 10). The intermediate products 14-epiginkgolides 8 and 14 were epimerized to the ginkgolides with natural configuration at C-14 by reaction with 4-(dimethylamino)pyridine in acetonitrile. The title compounds are of interest for their possible activity as antagonists of the platelet activating factor (PAF).
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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