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  • 1
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie des Indols, XII. Synthesen eserinähnlicher Verbindungen, III; Neue an N-1 und N-8 substituierte Derivate des Desoxyeserolins sowie eine neue Synthese des Eserethols (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 927-943 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Indole, XII1). - Syntheses of Compounds Similar to Eserine, III; New Derivatives of Deoxyeseroline Substituted at N-1 and N-8 and a Novel Synthesis of EseretholeTreatment of the ethyl 3-methyl-4-phenylhydrazonobutanoates 1 with HCI/ethanol gives the furoindolones 2 in good yields. Reaction of 2 with primary amines furnishes the pyrroloindolones 3 without by-products. Furthermore, reactions of 2 with complex hydrides and with Grignard compounds are described. Eserethole (4e) has been obtained in quantitative yield by reaction of 2g with LiAIH4.
    Notes: Die Behandlung der 3-Methyl-4-phenylhydrazonobutansäure-ethylester 1 mit HCI/Ethanol liefert in guten Ausbeuten die Furoindolone 2. Die Reaktion von 2 mit primären Aminen ergibt ohne Nebenprodukte die Pyrroloindolone 3. Weiterhin werden Umsetzungen von 2 mit komplexen Hydriden und mit Grignard-Verbindungen beschrieben. Aus 2g erhält man mit LiAIH4 in quantitativer Ausbeute Eserethol (4e).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919790703
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  • 2
    Electronic Resource
    Electronic Resource
    Vomicin aus Strychnin (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 895-907 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vomicine from StrychnineVomicine (11) has been synthesized from strychnine in two different ways, each comprising seven steps, involving 9 and icajine (16), respectively, as key intermediates. The generation of phenol 9 from 4-diazostrychnine is an intramolecular reaction. The oxo-cyclo tautomerism of 11 and 16 depends upon the pH.
    Notes: Vomicin (11) wurde aus Strychnin auf zwei unterschiedlichen Wegen über 2-Brom-4-nitrostrychnin (7) bzw. Icajin (16) in jeweils 7 Stufen dargestellt. Die intermediäre Verkochung des 4-Diazostrychnins zum Phenol 9 ist eine intramolekulare Reaktion. Die Oxo-Cyclo-Tautomerie der Ringe V, VI in 11 und 16 ist pH-abhängig.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800610
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  • 3
    Electronic Resource
    Electronic Resource
    Allo-, Epiallo- und Pseudoyohimbane sowie Heteroyohimbane durch Reaktion eines tetracyclischen Aldehyds mit Acetessigester in verschiedenen Lösungsmitteln (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 233-238 
    Details
    ISSN: 0170-2041
    Keywords: Indolochinolizine ; Yohimbanes, pseudo-, epiallo-, and allo- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Allo-, Epiallo-, and Pseudoyohimbanes as well as Heteroyohimbanes by Reaction of a Tetracyclic Aldehyde with Acetoacetate in Different SolventsThe reaction of methyl acetoacetate with 4 in CH3OH/ CH3ONa leads to 11 and 12 with yohimbane skeleton but bicyclo ring E. In DMF/tBuOK, the epialloheteroyohimbane 13 is produced in fairly good yield, whereas in THF/NaH the allo-19-hydroxyyohimbinone 17 is formed, which undergoes thermal decomposition to the alloyohimb-18-enone 19. Finally, a full description of an early mentioned synthesis of rac-de-plancheine (7) is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900142
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  • 4
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie des Indols, XIII1) Synthesen in der β-Carbolinreihe, II; (±)-Yohimban und (±)-Epialloyohimban durch eine neue Indolsynthese (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 1643-1656 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Indole, XIII1). - Syntheses in the β-Carboline Series, II; (±)-Yohimban and (±)-Epialloyohimban by a Novel Indole SynthesisThe hydrindanone derivative 17 undergoes Schmidt rearrangement to yield selectively after reduction by LiAlH4 the perhydroisoquinolines 20, which have been alkylated at N-2′ by ethyl bromoacetate to give 21. Compound 21 has been cyclized by polyphosphoric anhydride via the acid 22 to yield the yohimban-6-ones 23 which on treatment with LiAlH4 give the title compounds 24a and b. To check the new synthesis the racemate of the natural substance 7 was synthesized.
    Notes: Durch Schmidt-Umlagerung des Hydrindanonderivats 17 und Reduktion mit LiAlH4 erhielt man selektiv die Perhydroisochinoline 20, welche am N-2′ mit Bromessigester zu 21 alkyliert und mittels Polyphosphorsäureanhydrid über die Säuren 22 zu den Yohimban-6-onen 23 cyclisiert werden konnten. Mit LiAlH4 entstanden daraus die Titelverbindungen 24a und b. Zuvor wurde zur Erprobung des neuen Syntheseweges das Racemat des Naturstoffs 7 dargestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919791103
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  • 5
    Electronic Resource
    Electronic Resource
    Stereoselektive Totalsynthese von rac-Yohimb-15-enon (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 857-862 
    Details
    ISSN: 0170-2041
    Keywords: Dieckmann cyclisation with sulfones ; Robinson annulation ; Aniline annulation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Synthesis of rac-Yohimb-15-enoneThe Robinson annulation of an octahydroindolo[2,3-α]quinolizin-2-one is a general concept for the synthesis of yohimbine alkaloids. Using the phenylsulfonyl group for activation, a diastereoselective synthesis of rac-yohimben-17-one 21 has been developed. A new synthesis of aromatic amines 23 and 24 has been discovered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001161
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  • 6
    Electronic Resource
    Electronic Resource
    Ein einfacher Zugang zu den tetracyclischen Vorläufern der Hetero- und Secoyohimbane, Strychnos- und Oxindolalkaloide (1994)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1994 (1994), S. 151-158 
    Details
    ISSN: 0170-2041
    Keywords: Indoles ; Alkaloids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Entry into the Series of Tetracyclic Hetero- and Secoyohimbanes, Strychnos and Oxindole AlkaloidsThe divinylogous urethane 4a reacts in diluted acetic acid to give the indolochinolizine 9 (yield 40%). The total amount grows up to 65%, if compound 14, prepared from 4a in nearly quantitative yield, is allowed to react with trifluoroacetic acid for a few minutes. Similarily, 4b and 4c give by treatment with SnCl2 and heat in an [4+2]-cycloaddition reaction the spiroindolines 17 and 18. Oxytryptamine reacts with 2 moles of 2 to give immediately the spirooxindole 21. This compound can be rearranged to give 23 (after treatment with acid, reduction and catalytic hydrogenation). 23 has the cis-configuration of rhyncophylline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199419940208
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