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  • 1
    Electronic Resource
    Electronic Resource
    The systematic position of theHolarrheninae (Apocynaceae) (1990)
    Springer
    Plant systematics and evolution 171 (1990), S. 157-185 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Apocynaceae ; Plumerioideae ; Apocynoideae ; Holarrheninae ; Holarrhena ; Carruthersia ; Spirolobium ; Floral structure ; pollen morphology ; indole alkaloids ; steroidal alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genusHolarrhena, described byRobert Brown in 1811, has had a problematic taxonomic history, in part due to a suite of characters that does not conform with accepted concepts within theApocynaceae. In a number of important taxonomic charactersHolarrhena is typical of subfam.Apocynoideae. But due to the relatively unspecialized structure of the anthers most recent authors have placedHolarrheng, together withCarruthersia andSpirolobium, as the subtribeHolarrheninae in subfam.Plumerioideae. For the present investigation the floral structure and pollen morphology ofHolarrhena, Carruthersia andSpirolobium were analyzed. From the chemical literature reports of the occurrence of steroidal alkaloids in thePlumerioideae were evaluated. Our results indicate that the three genera belong to subfam.Apocynoideae in the tribeNerieae, but that the “Holarrheninae” is an unnatural group, and that the three genera should be accommodated individually within the tribe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00940603
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  • 2
    Electronic Resource
    Electronic Resource
    Synthese von Monomorin I, einem Spurpheromon der Pharao-Ameise (Monomorium pharaonis) (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 438-444 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Monomorin I, a Trail Pheromone of the Pharao Ant (Monomorium pharaonis)Katalytic hydrogenation of the 4-nitroalkanone 5 yielded the cis-pyrrolidine ester 6 (Scheme). The preparation of 5 was accomplished by ethanolysis of the nitrocyclohexanone derivative 4. Iodination at C(α) of 6, followed by cyclization, gave a nearly 5:6 mixture of the two C(5)-epimers 10/9 of octahydroindolizine. Epimerisation of the undesired 10 to 9 and subsequent transformation of the latter gave racemic monomorine I (1; 34% yield from 5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740221
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  • 3
    Electronic Resource
    Electronic Resource
    Biosynthesis of the Spermine Alkaloid Aphelandrine (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 565-571 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aphelandrine (1) is shown to be biosynthesized in the root cells of Aphelandra tetragona (VAHL) NEES from labelled putrescine (4), spermidine (5), and cinnamic acid (3). Whether spermine (6) and the (p-hydroxycinnamoyl)spermidine 8 are precursors of 1 is uncertain, since the latter is hydrolysed to a large extent before incorporation, and the former is metabolized to 4 and 5. Methionine (7) is the source of the 3-aminopropyl unit of 5 and 6.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740313
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoselektive Synthese von Pyrrolizidin-Alkaloiden aus NitroalkanonenHerrn Professor Dr. C. H. Eugster zurn 70. Geburtstag gewidmet (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 1352-1361 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Synthesis von Pyrrolizidin Alkaloids from NitroalkanonesReduction of 5-nitropentadecane-2,8-dione (11), synthesized by a Michael reaction from nitromethane, methyl vinyl ketone, and dec-1-en-3-one, gave, depending on the conditions, two epimeric 3-heptyl-2,3,5,6,7,7a-hexahydro-5-methyl-1H-pyrrolizines as the main products: Catalytic hydrogenation (Pd/C) afforded the expected 7aα-hydro epimer 1b with cis-orieted H-atoms at C(3), C(5), and C(7a). NaBH3CN/NH4OAc reduction of the nitrodione 11 yielded all four diastereoisomers with the 7aβ-hydro epimer 1a as the predominant component; 1a is a pheromone of the cryptic thief ant Solenopsis sp. The N-atom of the pyrrolizidine ring stems from NH4OAc exclusively as shown by reduction of 11 with NaBH3CN/(15N)H4OAc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740624
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese von selektiv N- funktionalisierten Polyamin-Derivaten (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1511-1519 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Selectively N-Functionalized Polyamine DerivativesA threefold differently protected derivative 8 of the triamine spermidine (2) has been prepared in three steps starting from propane-1,3-diamine (1). The protected spermidine derivative 8 was converted to its spermine analogue 12, a useful polyamine intermediate. In a convergent way, the fourfold differently protected derivative 18 of the tetraamine spermine (3) has been obtained by coupling the two different and separately prepared propane-1,3-diamine units 15 and 17. Spermidine derivative 19 and spermine derivative 20, both selectively protected at both primary amino groups, have been Prepared from the free polyamines 2 and 3, respectively, in a direct approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760412
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  • 6
    Electronic Resource
    Electronic Resource
    Die massenspektrometrische Wasserabspaltung aus makrocyclischen Amino-ketonenHerrn Prof.Max Viscontini zum 80. Geburtstag gewidmet (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1636-1648 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Mass Spectral Loss of Water from Macrocyclic Amino-ketonesMacrocyclic oxo-lactams containing an N-alkylamino side chain are stable natural products. Their electron-impact mass spectra are characterized by intensive [M - H2O]+ signals, the molecular ion signal itself is missing. Under electrospray ionization conditions, on the other hand, the [M + 1]+ ion is the only detected signal. The loss of water is explained in terms of an internal (thermal) Schiff-base formation, leading to a e.g. bicyclo[11.9.4]-system. The alcohol corresponding to the macrocyclic ketones and/or lactams show an expected mass-spectral behavior following well known rules.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760421
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  • 7
    Electronic Resource
    Electronic Resource
    Synthetische Analoga von niedermolekularen Spinnentoxinen mit Acyl-polyamin-Struktur (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1167-1181 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic Analogues of Low-Molecular-Weight Acyl-polyamine Spider ToxinsLow-molecular-weight spider and wasp toxins are selective inhibitors of glutamate receptors of the central nervous system and consist of a polyamine backbone and one or several carboxylic acids and/or amino acids linked by a peptide-like bond. The syntheses of twelve analogues of spider and wasp toxins are described (10a-c, 15a-c, 20a-c, 25a-c) having the general structure of acyl, arylacyl, or heteroarylacyl → DL-alanyl → ω-aminoacyl → N1-spermidine, with variation in the acyl and the ω-aminoacyl part.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760304
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  • 8
    Electronic Resource
    Electronic Resource
    Cycloalkylations of N-(ω-Halogenoalkyl)-substituted Macrocyclic Imides (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 272-276 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With ω-halogenoalkyl isocyanates, 2-oxocyclododecane-l-carbonitrile is transformed under ring enlargement to 1-(ω-halogenoalkyl)-2,14-dioxo-1-azacyclotetradecane-3-carbonitriles. In the presence of base, these products undergo O- or C-alkylation leading to bicyclic compounds. The C-alkylation product 7 undergoes solvolysis to form a sixteen-membered ring compound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730205
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  • 9
    Electronic Resource
    Electronic Resource
    A New Synthesis of (2S,3R,4R)-2-(Hydroxymethyl)pyrrolidine-3,4-diol (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 445-450 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 6 was synthesized from 2,3,5-tri-O-benzyl-D-arabinofuranose (7) in three steps and 48% overall yield. Moreover, it was shown, in the case of γ-hydroxy amide 9, that the Mitsunobu reaction is not suitable for the preparation of γ-lactams, because O-alkylation is predominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740222
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of 1H,2,3-Triazoles from 2-Substituted Cyclododecanones and Phenyl AzideDedicated to Prof. Dr. Burchard Franck on the occasion of his 65th birthday (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 899-903 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By reaction with phenyl azide, 2-cyano- and 2-(ethoxycarbonyl)-substituted cyclododecanones are converted into 5-amino- and 5-hydroxy-1H-1,2,3-triazoles, respectively. The possible reaction mechanism is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740421
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