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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and X-Ray Diffraction Analysis of Bis(phenylsulphonyl)semibullvalenes. Lifting of the Degeneracy of Semibullvalenes in the Crystal Lattice[1] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 955-968 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalenes ; [n.3.3] Propellanes, derivatives of ; Vinyl sulphides and sulphones ; Bromination, allylic ; Debromination ; Zinc-copper couple ; Cope rearrangement in the solid state ; Valence tautomers, non-equivalent ; Equilibrium constants from atomic distances ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bicyclo[3.3.0]octanediones 4 and 9a, b and the [n.3.3]-propellanediones 9c, d, f, h react with thiophenol in the presence of titanium(IV) chloride and triethylamine to afford high yields of the vinyl sulphides 5 and mixtures of the vinyl sulphides 10/11. Sodium perborate oxidizes the vinyl sulphides 5 and 10/11 to the corresponding vinyl sulphones 6 and 12/13. N-Bromosuccinimide converts 6 into the dibromodisulfones 7. The exo,exo configuration of 7b is established by X-ray crystallography. The mixtures of disulphones 12/13 are brominated by N-bromosuccinimide to yield complex mixtures of uncharacterized dibromodisulphones 14. Debromination of the dibromodisulphones 7, and the mixtures of 14 as well, by the zinc-copper couple results in the formation of crystalline semibullvalenes 8 and 15 in moderate to high yields. - X-ray diffraction analyses of 8a, b and 15a-d reveal large variations of the apparent atomic distances in the cyclopropane rings (C2-C8) and at the open ends of the molecules (C4…C6). This result is interpreted in terms of equilibrating, non-degenerate valence tautomers resulting in averaged atomic distances. The equilibrium constants are calculated from the atomic distances on the basis of a limiting value of 157.8 pm for the C2-C8 bonds of the non-rearranging valence tautomers. The results are compared to those obtained from X-ray diffraction analyses of other substituted semibullvalenes. The lifting of the degeneracy of semibullvalenes in the solid state is attributed to subtle intermolecular interactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250430
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  • 2
    Electronic Resource
    Electronic Resource
    2,6-Dicyansemibullvalen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 969-973 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalenedicarbonitrile ; Bicyclo[3.3.0]octanes, derivatives of ; Cyanohydrins, O-trimethylsilyl ; Hydrogen fluoride-phosphorus oxychloride-pyridine, elimination by ; Bromination, N-bromosuccinimide ; Zinc-copper couple ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,6-Dicyanosemibullvalene[1]Bicyclo[3.3.0]octane-2,6-dione (2) adds trimethylsilyl cyanide under catalysis by zinc iodide to afford a mixture of the diastereomeric O-trimethylsilyl cyanohydrins exo,endo- and exo,exo-3 (3:7). Treatment of this mixture with the hydrogen fluoride-pyridine complex in phosphorus oxychloride as solvent and subsequent heating with an excess of pyridine yield 70% of a 1:1 mixture of the unsaturated dinitriles 4 and 5, which is separated by medium-pressure liquid chromatography. Allylic bromination of 4 by N-bromosuccinimide results in the formation of the Y,Y'-dibromodinitrile 6, the configuration of which is elucidated by means of an X-ray diffraction analysis. Reduction of 6 with the zinc-copper couple in tetrahydrofuran under ultrasonic irradiation leads to dilute solutions of the title compound 1 a. Attempts at the isolation of 1 a were frustrated by its tendency to polymerize. The structure of 1 a is based on IR, UV, 1H- and 13C-NMR spectra and a comparison with the known 1,5-dimethylsemibullvalenedicarbonitrile (1 b).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250431
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  • 3
    Electronic Resource
    Electronic Resource
    Ring Expansion of Heterocyclic Ketene N,X-Acetals and 2-Alkylidenedihydroindoles with Methanesulphonyl Azide by [3 + 2] Cycloaddition and Subsequent Extrusion of Molecular Nitrogen (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1541-1549 
    Details
    ISSN: 0947-3440
    Keywords: [3 + 2] Cycloaddition ; Ketene N,X-acetals, cyclic ; Azides, electrophilic ; Amidines, cyclic N-sulphonyl- ; Ring expansion of heterocycles ; 1,2-Shift of carbon, nitrogen, sulphur, or selenium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methanesulphonyl azide (2) reacts readily with isolated cyclic ketene N,X-acetals of type 1, viz. 10a, d, 15b, d, and 22a-c, or those that are generated in situ by deprotonation of the corresponding 2-alkylbenzazolium tetrafluoroborates, i.e. 14a → 15a, 14b → 15b, and 18 → 19. Ring-expanded products are formed by extrusion of molecular nitrogen from intermediate labile [3 + 2] cycloadducts 3 with concomitant 1,2-shift of N (route A1 → 12, 24) or X (route A2 → 16, 20, 21). In addition, 3 may undergo [3 + 2] cycloreversion into N-sulphonylimine 5 and diazoalkane 6 (route B → 13, 17, 25). The configurations of the cyclic N-sulphonylamidines 16b and 21b, the N-sulphonylimine 24 and the N-sulphonylamine 27 are elucidated by means of X-ray diffraction analyses. The ratio of the (useful) ring-expansion reactions vs. the unwanted formation of 5 + 6 is hardly influenced by the solvent employed and temperature of the experiment but strongly by the nature of the potential migrating atom and the substituents at the α-carbon atom.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961008
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  • 4
    Electronic Resource
    Electronic Resource
    [3.3.3]Propelladiendicarbonitrile (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 503-513 
    Details
    ISSN: 0170-2041
    Keywords: [3.3.3]Propellanecarbonitriles ; Tricyclo[3.3.3.01.5]undecane-3,7-dione ; NBS Bromination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [3.3.3]Propelladienedicarbonitriles1)The 3,7-diketone 5 reacts with 4-chlorothiophenol in the presence of titanium tetrachloride/triethylamine to afford equal amounts of the vinyl sulfides C2/C5-6 in 95% yield. Equilibration of the 1:1 mixture of C2/C5-6 is catalyzed by trifluoroacetic acid and produces a 3:2 ratio of C2/C5-7 in almost quantitative yield. Potassium cyanide supported on aluminium oxide in boiling 2-methyl-2-butanol converts the latter into a mixture of the α,β-unsaturated dinitriles 1b, 11, 13, and 14, which are separated by chromatography. The intermediates 8 and 10 as well as the products 9 and 12 resulting from the addition of hydrogen cyanide to 1b and 11, respectively, are isolated in the same way. The dinitrile 1b is brominated by N-bromosuccinimide to afford a mixture of endo-15, exo-15, endo,endo-16, endo,exo-16, and 17, most of which are separated by chromatography. The endo-bromodinitrile endo-15 reacts with potassium methoxide in methanol to yield the exo-methoxydinitrile 18. The configuration of the dinitriles endo-15, endo,endo-16, and 18 is established by NOE difference spectroscopy and X-ray diffraction analyses.
    Notes: Das 3,7-Diketon 5 reagiert mit 4-Chlorthiophenol in Gegenwart von Titan(IV)-chlorid/Triethylamin zu gleichen Mengen der Bis(vinylsulfide) C2/C5-6 (65% Ausb.), die unter Trifluoressigsäure-Katalyse zu einem (3:2)-Gemisch äquilibriert werden. Oxidation von C2/C5-6 mit Natriumperborat-tetrahydrat in Essigsäure ergibt fast quantitativ die Bis(vinylsulfone) C2/C5-7. Diese liefern mit Kaliumcyanid auf Aluminiumoxid in siedendem 2-Methyl-2-butanol ein Gemisch der α,β-ungesättigten Dinitrile 1b, 11, 13 und 14, die chromatographisch getrennt werden So werden auch die Zwischenstufen 8 und 10 sowie Folgeprodukte von 1b und 11, nämlich die Trinitrile 9 und 12, isoliert. das Dinitril 1b wird mit N-Bromsuccinimed zu einem Gemisch von endo-15, exo-15, endo,endo-16, endo,exo-16 und 17 bromiert, das größtenteils chromatographisch getrennt wird. Das endo-Bromdinitril endo-15 reagiert mit Kaliummethanolat in Methanol zum exo-Methoxydinitril 18. Die Konfiguration der Dinitrile endo-15, endo,endo-16 und 18 wird durch NOE-Differenz-Spektren und Röntgenstrukturanalyse bewiesen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890190
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