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  • 1
    Electronic Resource
    Electronic Resource
    Syntheses and conformations of persubstituted inverse calixarenes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1401-1408 
    Details
    ISSN: 0947-3440
    Keywords: Calix[n]arenes (n = 4-13) ; Macrocycles ; Calculations, force-field ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of ten inverse calix[n]arenes (2-11) bearing four to thirteen benzene units were prepared by starting from 3,4,5-trimethoxybenzaldehyde followed by LC separation on silica gel. In 2-11 the substitution pattern is interchanged compared with the usual calixarenes. The conformational analysis was undertaken by variable temperature 1H-NMR spectroscopy and by MM2 calculations. Calix[4]arene 2 is a rigid molecule and shows the 1,3-alternate conformation which in addition was proven by X-ray analysis. At low temperatures the calix[5]arene 3 adopts the uudod conformation, where a methyl group of one benzene unit residues in the cavity of the macrocycle. At low temperature calix[6]arene 4 forms an 1:2 equilibrium between the 1,3,5-alternate (ududud; 4E) and the uududu (4B) conformation. Conformation 4B can be regarded as an intramolecular combination of a cone and an alternate arrangement of the benzene units. The calix[8]-arene shows the highest ΔG* value of the series and adopts an uuududdd conformation at low temperature. The inverse calixarenes 5 and 7-11 bearing seven and nine to thirteen aromatic units, respectively, are conformationally highly flexible systems even at low temperatures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199508190
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  • 2
    Electronic Resource
    Electronic Resource
    Chemie und Stereochemie der Iridoide, IV. Synthese und Röntgenstrukturanalyse von 15-Methyl-12-epi-prostaglandin F2β (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 761-772 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, IV. - Synthesis and X-Ray Structure Analysis of 15-Methyl-12-epi-prostaglandin F2βCrystalline(15R)- and (15S)-15-methyl-12-epi-PGF2β [15R)-5b and 5b] are synthesized enantiomerically pure starting from (1S,6R,9R)-(+)-7,9-bis(p-phenylbenzoyloxy)-3-oxabicyclo- [4.3.0]nonan-2-ol (1), which is prepared from catalpol. Contrary to our described synthesis of 12-epi-PGF2β, the intermediate products 2-5a are crystalline by virtue of the introduction of the p-phenylbenzoyl protecting group. Thus, their physical constants could be determined unequivocally. The X-ray structure analysis of (15R)-15-epi-PGF2β proves the correctness of our earlier statements based on analytical and spectroscopical investigations.
    Notes: Ausgehend von dem aus Catalpol hergestellten (1S,6R,7R,9R)-(+)-7,9-Bis(p-phenylbenzoyloxy)-3-oxabicyclo[4.3.0]nonan-2-ol (1) werden (15R)- und (15S)-15-Methyl-12-epi-PGF2β [(15R)-5b und 5b] kristallin und enantiomerenrein synthetisiert. Im Gegensatz zu der von uns beschriebenen Synthese von 12-epi-PGF2β sind durch die Einführung der p-Phenylbenzoyl-Schutzgruppen auch die Zwischenprodukte 2-5a kristallin, so daß ihre physikalischen Konstanten eindeutig bestimmt werden konnten. Die Röntgenstrukturanalyse von (15R)-15-Methyl-12-epi-PGF2β beweist, daß die von uns aus den analytischen und spektroskopischen Untersuchungen gemachten Aussagen richtig sind.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840412
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  • 3
    Electronic Resource
    Electronic Resource
    Chemie und Stereochemie der Iridoide, IX. EPC-Synthese von (1R,2R,2″Z)-(-)-Methyl-jasmonat aus Catalpol - Kristall- und Molekularstruktur von Methyl-dehydrojasmonat-semicarbazon (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 361-366 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, IX1). - EPC Synthesis of (1R,2R,2″Z)-(-)-Methyl Jasmonate from Catalpol - Crystal and Molecular Structure of Methyl Dehydrojasmonate SemicarbazoneCatalpol is converted into the enantiomerically pure (1R,2R,2″Z)-(-)-methyl jasmonate (1) by a 16-step synthesis (yield about 7%). The R-configuration at C-1 of 1 results from the synthesis. The complete stereochemistry of 1 is confirmed by the X-ray analysis of methyl dehydrojasmonate semicarbazone (semicarbazone of 12).
    Notes: In einer 16stufigen Synthese wird aus Catalpol das enantiomerenreine (1R,2R,2″Z)-(-)-Methyl-jasmonat (1) hergestellt (Ausbeute ca. 7%). Durch die Synthese ist die R-Konfiguration an C-1 von 1 vorgegeben. Mit der Röntgenstrukturanalyse des Methyl-dehydrojasmonat-semicarbazons (Semicarbazon von 12) wird die vollständige Stereochemie von 1 bestätigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870335
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  • 4
    Electronic Resource
    Electronic Resource
    Chemie der Ginkgolide, I. 10-Acetyl-1-methoxycarbonyl-2,3,14,15,16-pentanorginkgolid A, ein Zwischenprodukt zur Herstellung von Bilobalid (1986)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1986 (1986), S. 1057-1066 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Ginkgolides, I. - 10-Acetyl-1-methoxycarbonyl-2,3,14,15,16-pentanorginkgolide A, an Intermediate for the Synthesis of BilobalideThe title compound 8b, an intermediate of the intended partial synthesis of bilobalide (10) is obtained by degradation of ginkgolide A (1). The X-ray structural analysis of 14,15,16-trinorginkgolide A (7) confirms the structure of the rings B - E of the ginkgolides.
    Notes: Die Titelverbindung 8b, ein Zwischenprodukt der beabsichtigten Partialsynthese von Bilobalid (10), wird durch Abbau von Ginkgolid A (1) gewonnen. Durch Röntgenstrukturanalyse von 14,15,16-Trinorginkgolid A (7) wird die Struktur der Ringe B - E der Ginkgolide bestätigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198619860610
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  • 5
    Electronic Resource
    Electronic Resource
    Naturstoffe aus Arzneipflanzen, XXIV. Isolierung, Strukturaufklärung und Synthese von (Z,Z)-4,4′-(1,4-Pentadien-1,5-diyl)diphenol, einem ungewöhnlichen Naturstoff aus den Blättern des Ginkgo-Baumes (Ginkgo biloba L.) (1986)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1986 (1986), S. 1772-1778 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Natural Products from Medicinal Plants, XXIV. - Isolation, Structure Determination, and Synthesis of (Z,Z)-4,4′-(1,4-Pentadiene-1,5-diyl)diphenol, an Unusual Natural Product from the Leaves of the Ginkgo Tree (Ginkgo biloba L.)The title compound 1 was isolated from the leaves of the ginkgo tree by column chromatography. The structure of the new natural product was determined by synthesis starting from the bis(phosphorane) 3 und by X-ray analysis of its O,O′-bis(4-nitrobenzoyl) derivative 2.
    Notes: Die Titelverbindung 1 wird aus den Blättern des Ginkgo-Baumes säulenchromatographisch isoliert. Die Struktur des neuen Naturstoffs wird durch Synthese aus dem Bis(phosphoran) 3 und durch Röntgenstrukturanalyse seines O,O′-Bis(4-nitrobenzoyl)-Derivats 2 bewiesen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198619861010
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  • 6
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, V. Substratkontrollierte asymmetrische Synthese von (-)-Hirsuten und (-)-3-Hydroxyhirsuten aus (R)-(-)-Carvon (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 403-411 
    Details
    ISSN: 0170-2041
    Keywords: Hirsutene derivatives ; Cyclopenta[a]pentalenes ; Radicals ; Cyclizations ; Triquinanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, V. - Substrate-Controlled Asymmetric Synthesis of (-)-Hirsutene and (-)-3-Hydroxyhirsutene from (R)-(-)-Carvone(3aR,6aR)-(-)-6a-Methyl-3,3a,4,6a-tetrahydro-2H-cyclopenta- [b]furan-2-one (6) and (1R,4S)-(-)-3-[4-(but-3-inyl)-3-methyl-cyclopent-2-enyl]-2,2-dimethylpropan-1-ol (11) are key compounds in the synthesis reported in this paper. Enantiomerically pure 6 was obtained in five straightforward steps from the inexpensive precursor (R)-(-)-carvone (1). Compound 11 was prepared from 6 via an SN2′ reaction, by analogy with the synthesis reported by Curran et al. The linear triquinanes 13 and 15 were obtained in gram quantities in two additional steps. The utilisation of (S)-(+)-carvone (ent-1) allows access to the other enantiomeric forms. X-ray analysis of 15a confirmed the structure of 15 and, by correlation, that of 13.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930166
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  • 7
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, VI. Totalsynthese von (-)-Coriolin und (-)-Epicoriolin aus (S)-(+)-Carvon (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1133-1140 
    Details
    ISSN: 0170-2041
    Keywords: (-)-Coriolin ; (-)-Epicoriolin ; Radicals ; Cyclization ; Triquinans ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dines, VI. - Total Synthesis of (-)-Coriolin and (-)-Epicoriolin from (S)-(+)-Carvone(3aR,4S,6aS)-(+)-4-(4-Methoxybenzyloxy)-6a-methyl-3,3a,4,6a-tetrahydro-2H-cyclopenta[b]furan-2-one (10) and (3aR,3bR,4R,6aS,7S,7aS)-(-)-decahydro-4,7-dihydroxy-3a,5,5-trimethyl-3-methylene-2H-cyclopenta[a]pentalen-2-one (21) are the key intermediates in the synthesis of the title compounds 1 and 1a. Enantiomerically pure 10 is produced from (S)-(+)-carvone (4) in seven straightforward reactions. Compound 21 is produced from 10 by analogy with the method developed for the synthesis of (-)-hirsutene. Through the introduction of the double bond into 21 via the silylenolether 23 one arrives at precoriolin 25, which is converted into (-)-coriolin (1) and the C-3 epimer (-)-epicoriolin (1a) (63:37) with hydrogen peroxide. The structures of 1 and 1a were confirmed via X-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301181
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