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  • Wiley-Blackwell  (31)
  • 1975-1979  (31)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 337-356 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrogenolysis of Small Cycloalkanes, II. hydrogenation Basketane- and Snoutane-Derivativescis- and both trans-dimethyl twistane-4,5-dicarboxylates (9 and 11, 13) are formed via the dihydro intermediates 4-7 by hydrogenation of cis- and trans-dimethyl basketane-9,10-dicarboxylates (1 and 3) over Pd/C under normal conditions. During the uptake of the first mole-equivalent of hydrogen all the basketane derivatives were rearranged to snoutane derivatives (22 and 24) to some extent. The second C—C bond is cleaved on that side of the basketane skeleton, which is opposite to the first hydrogenated one. cis- and trans-dimethyl snoutane-9,10-dicarboxylates (22 and 24) were hydrogenated under the same conditions but more slowly via the dihydro derivatives (25, 27 and 29, 31) to yield cis- and trans-dimethyl isotwistanedicarboxylates (33 and 35). In snoutane derivatives the second cyclopropane ring is cleaved exclusively from the same side of the molecule as the first one. This is shown by separate hydrogenations of dihydro snoutane derivatives (27, 37 and 38). Hydrogenation of basketene (21) provides a mixture containing 70-75% of twistane (17) and 25-30% of isotwistane (39). The reasons for the different ways of hydrogenation in both systems are discussed. The configurations of all dihydro intermediates and endproducts have been established.
    Notes: cis- und trans-Basketan-9,10-dicarbonsäure-dimethylester (1 und 3) werden unter Normal-bedingungen mit Pd/C in Methanol über die isomeren Dihydrozwischenstufen (4-7) zu cis- und den beiden trans-Twistan-4,5-dicarbonsäure-dimethylestern (9 und 11, 13) hydriert. Bei der Hydrogenolyse der ersten C—C-Bindung erfolgt teilweise Umlagerung zu Snoutanderivaten (22 und 24). Die Öffnung der zweiten Bindung am Basketangerüst geschieht ausschließlich an der zur ersten hydrierten Bindung gegenüberliegenden Molekülseite. cis- und trans-Snoutan-9,10-dicarbonsäure-dimethylester (22 und 24) reagieren unter den gleichen Bedingungen ebenfalls, aber langsamer, über die Zwischenstufen (25, 27 und 29, 31) zu cis- und trans-Isotwistan-dicarbonsäure-dimethylester (33 und 35). An den getrennt untersuchten Zwischenstufen 27, 37 und 38 wird gezeigt, daß im Snoutangerüst beide Cyclopropanringe ausschließlich von der gleichen Molekülseite angegriffen werden. Aus Basketen (21) erhält man bei der Hydrierung ein Gemisch von 70-75% Twistan (17) und 25-30% Isotwistan (39). Die Ursachen für den verschiedenen Hydrierungsverlauf in beiden Systemen werden erörtert, und die Konfiguration aller Zwischenstufen und Endprodukte wird aufgeklärt.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1184-1194 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anisotropy Effects of Conjugated Cyclic Systems, I: N.M.R. Spectra of Mesityl- and (9-Anthryl)-substituted Aromatic CompoundsThe chemical shift differences Δδ of the n. m. r. signals of o-and p-methyl-groups in mesityl-substituted ring system are a measure of the magnetic anisotropy of aromatic systems. The same applies to the Δδ of the 1-H and 4-H signals of (9-anthryl)-substituents, but to a greater extent. The Δδ values for benzene, mesitylene, and anthracene as well as for pyrimidine, pyrazole, and isoxazole are reported and discussed.
    Notes: Die Differenz der chemischen Verschiebung Δδ von o-und p-Methylgruppen-Signalen in den NMR-Spektren mesitylsubstituierter Ringsysteme ist ein brauchbares Maß für die magnetische Anisotropie aromatischer Verbindungen. Das gleiche gilt noch verstärkt für die 1-H- und 4-H-Signale eines (9-Anthryl)-Substituenten. Δδ-Werte für Benzol, Mesitylen und Anthracen sowie Pyrimidin, Pyrazol und isoxazol werden mitgeteilt und besprochen.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1204-1207 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3636-3648 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asteranes, XIV. Experiments about Proof and Stability of the Triasteryl CationReactions of triasteranol 5 to give the bis(triasteryl) ether 12 and the azide 9 as well as the rearranged alcohol 17 and azide 20 are interpreted to proceed via the triasteryl cation 15. The tosylhydrazone 3, the alcohols 5 and 17, and the ether 12 lead to barbaralane (21). The solvolysis rates of the esters 7 and 8 together with the rapid DDQ oxidation of 5 to give 2 support the stabilisation of the positive charge on the α-carbon atom by both cyclopropane rings. The stability of the cation 15 and its re-formation from the rearranged cation 16 is unambiguously demonstrated by NMR spectra in super acids at -30°C.
    Notes: Reaktionen des Triasteranols 5 zum Bis(triasteryl)ether 12 und zum Azid 9 sowie zum umgelagerten Alkohol 17 und Azid 20 werden über das Triasteryl-Kation 15 gedeutet. Aus dem Tosylhydrazon 3 und den Alkoholen 5 und 17 sowie dem Ether 12 wird Barbaralan (21) erhalten. Solvolysegeschwindigkeiten der Triasterylester 7 und 8 und die rasche Oxidation von 5 zu 2 mit DDC bestätigen die Stabilisierung der positiven Ladung am α-C-Atom durch beide Cyclopropanringe. NMR-Spektren in Supersäuren demonstrieren die Beständigkeit des Kations 15 bei -30°C einwandfrei und zeigen die Rückbildung von 15 aus dem umgelagerten Kation 16 an.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1497-1502 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asteranes, XIV: trans-Photo Adducts from 3,6-Dihydrophtalic AnhydrideTwo [2 + 2]-trans-photo adducts 9a and 10a from the title compound 2 have been isolated. The structures are determined by NMR shift experiments and X-ray analysis of the ester 9b.
    Notes: Zwei [2 + 2]-trans-Photoaddukte 9a und 10a der Titelverbindung 2 werden isoliert und durch NMR-Verschiebungsversuche sowie Röntgenanalyse des Esters 9b in der Struktur aufgeklärt.
    Additional Material: 1 Ill.
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of muscaflavinA biomimetic type synthesis of the yellow dihydroazepine amino acid 5 isolated from fly agaric is achieved starting with carboxypyridyl alanine derivatives.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1195-1203 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Metal Complexes, XIII: Anisotropy Effects in the N. M. R. Spectra of metal Chelates of 3-Mesityl- and 3-(9-Anthryl)acetylacetone3-Mesityl- and 3-(9anthryl)-2,4-pentanedione (1 and 2) have been synthesized by heating tris[3-(bromo)acetylacetonato]chromium and iodomesitylene or 9-bromoanthracene with copper powder. Their complexes with Li, Na, K, Be, Al, Co, Pd, and Tl (1a-i) do not possess magnetic anisotropies in the chelate rings comparable with those of aromatic systems. This is shown in the n. m. r. spectra by means of the chemical shift differences of the o- and p- methyl signals (Δδ ≍ 0.1 ppm). Some boron chelates (7-9) have been investigated, too.
    Notes: Durch Erhitzen von Tris[3-(brom)acetylacetonato]chrom und jodmesitylen bzw. 9-Bromanthracen mit Kupferpulver werden 3-(Mesityl)- bzw. 3-(9-Anthryl)acetylaceton (1 and 2) dargestellt. Die NMR-Spektren der Chelatkomplexe mit Li, Na, K, Be, Al, Co, Pd und Tl (1a-i) zeigen an den Verschiebungsdifferenzen der o- und p-Methylsignale (Δδ ≍ 0.2 ppm) und für die Signale der 1-H und 4-H Atome am Anthrylrest (Δδ ≍ 0.1 ppm), daß diese Metallchelate keine mit aromatischen Systemen vergleichbare magnetische Anisotropie besitzen. Auch Borchelate (7-9) wurden untersucht.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 3781-3792 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asteranes, XIII Synthesis of Tetraasterane by Photodimerisation of 3,6-Dihydrophthalic AnhydrideThe cage dimeric tetraasteranetetracarboxylic dianhydride 8 as well as the open trans dimers 6 and 7 have been isolated among monomeric products (2-4) on irradiation 3,6-dihydrophthalic anhydride (1) in ether, acetone, and dioxane. Unsubstituted tetraasterane (pentacyclo-[6.4.0.02,7. 0.4,11 0.5,10]dodecane, 14, is obtained by degradation of tetraasterane-1,4,5,8-tetracarboxylic acid (12) with lead tetraacetate and N-chlorosuccinimide via the tetrachlorotetraasterane 13. The structures of 6 and 12 have been confirmed by X-ray analysis. The influence of substituents on fragmentation patterns of tetraasterane derivatives in the mass spectrometer is indicated.
    Notes: Bei der Belichtung von 3,6-Dihydrophthalsäure-anhydrid (1) in Äther, Aceton und dioxan werden neben monomeren Produkten (2-4) das käfigdimere Tetraasterantetracarbonsäure dianhydrid 8 sowie die offenen trans-Dimeren 6 und 7 isoliert. Der Abbau von Tetraasteran-1,4,5,8-tetracarbonsäure (12) mit Bleitetraacetat und N-Chlorsuccinimid ergibt über das Tetrachlortetraasteran 13, das unsubstituierte Tetraasteran (Pentacyclo[6.4.0.02,7 0.4, 110.5,10]dodecan,14, Die Strukturen von 6 und 12 wurden durch Röntgenanalyse bestätigt. Der Substituenteneinfluß auf den Zerfall von Tetraasteranderivaten im Massenspektrometer wird angedeutet.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3118-3125 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Bicyclo[3.3.1]nonane-2,4,7-trione by a New Method for β-Diketones from EstersBis(trimethylsilyl)acyloin enol ethers 7, available from esters by silylating acyloin condensation, react with phenyl(tribromomethyl)mercury to yield dibromocyclopropane derivatives 8. These are rearranged thermally into 2,3-Dibromo-1,3-bis(trimethylsilyloxy) olefins 9 from which 2-bromo-1,3-diketones 5 are obtained by hydrolysis. Dehalogenation is achieved with chromium(II) salts.
    Notes: Die aus Estern durch silylierende Acyloinkondensation zugänglichen Bis(trimethylsilyl)acyloin-enolether 7 reagieren mit Phenyl(tribrommethyl)quecksilber zu den Dibromcyclopropanderivaten 8. Diese lagern sich thermisch leicht in die 2,3-Dibrom-1,3-bis(trimethylsilyloxy)olefine 9 um, deren Hydrolyse zu 2-Brom-1,3-diketonen 5 führt. Die Enthalogenierung gelingt mit Chrom(II)-Salzen.
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