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  • 1980-1984  (7)
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  • 1
    Electronic Resource
    Electronic Resource
    Absolute Konfiguration von optisch aktivem 4,5-Diazatwist-4-en (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 748-753 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Absolute Configuration of Optically Active 4,5-Diazatwist-4-eneThe adduct 5 of diphenyl azodicarboxylate and 7,8-dibromobicyclo[4.2.0]octa-2,4-diene is transformed via 6 and 7 to the twistane derivative 8a, which is partially resolved on cellulose triacetate. Hydrogenation of (-)-4,5-Diazatwist-4-ene ((-)-1), obtained from (-)-8a, yields 2e, isolated as the hydrochloride (+)-2d. Since (+)-2d correlates with (+)-(2S, 5S)-bicyclo[2.2.2]octane-2,5-dicarboxylic acid ((+)-2a), M-helicity is attributed to (-)-1.
    Notes: Das Addukt 5 aus Azodicarbonsäure-diphenylester und 7,8-Dibrombicyclo[4.2.0]octa-2,4-dien liefert über 6 und 7 das Twistanderivat 8a, das sich an Triacetylcellulose partiell in die Enantiomeren trennen läßt. Hydrierung des aus (-)-8a zugänglichen (-)-4,5-Diazatwist-4-ens ((-)-1) ergibt 2e, das als Hydrochlorid (+)-2d isoliert wird. Da (+)-2d mit der (+)-(2S, 5S)-Bicyclo[2.2.2]octan-2,5-dicarbonsäure ((+)-2a) korreliert ist, wird (-)-1 die M-Helizität zugeordnet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150235
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  • 2
    Electronic Resource
    Electronic Resource
    Neuartige Bildung einer Azoverbindung mit dem C-Gerüst eines Secopentaprismans (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2366-2370 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Kind of Formation of an Azo Compound with a Secopentaprismane C-SkeletonDecarboxylating hydrolysis of 5a, which is generated by the reaction of 4 with tetrazine 2, followed by oxidation yields the hexacyclic azo compound 7a. Thermal denitrogenation of 7a leads to azo compound 14, while irridiation of both 7a and 14a yields the hexacyclic compound 15, which could not be transformed into the pentaprismane 16.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160625
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  • 3
    Electronic Resource
    Electronic Resource
    Versuche zur Darstellung von Derivaten des 2,3-Diazabicyclo[2.2.2]octa-5,7-diens (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2355-2365 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Attempts to Synthesize Derivatives of the 2,3-Diazabicyclo[2.2.2]octa-5,7-diene SystemThe 2,3-diazabicyclo[2.2.2]octa-5,7-diene derivatives 1a and b could neither be obtained by a photoaromatization reaction of 8 nor by an electrolytic oxidation of the dicarboxylic acids 13a, b. Cycloadditions to 21 lead to derivatives of the title system. At temperatures above -10°C these undergo a [4+2]-cycloreversion to produce the tetrahydrophthalazines 22. The thermal transformation of 21 to 22 is rationalized on the basis of a chain mechanism.
    Notes: Die 2,3-Diazabicyclo[2.2.2]octa-5,7-dien-Derivate 1a und b konnten weder über die Photoaromatisierung von 8 noch über die anodische Oxidation der Dicarbonsäure 13a, b erhalten werden. Cycloadditionen an 21 führten zu Derivaten des Titelsystems, die bereits oberhalb -10°C einer [4+2]-Cycloreversion unter Bildung der Tetrahydrophthalazine 22 unterliegen. Die thermische Umwandlung von 21 und 22 verläuft nach einem Kettenmechanismus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160624
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  • 4
    Electronic Resource
    Electronic Resource
    Valenzisomerisierungen, 16. Darstellung und dynamische Eigenschaften von Cyclooctatetraen-1,4-dicarbonsäure-Derivaten (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2214-2220 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Valence Isomerizations, 16. Preparation and Dynamic Properties of Cyclooctatetraene-1,4-dicarboxylic Acid DerivativesSynthesis and dynamic properties (ring inversion and bond shift) of dimethyl cyclooctatetraene-1,4-dicarboxylate (5) and its 2,3-dimethyl derivative 6 are described. Addition of optically active shift reagent causes a splitting of the NMR signals in the chiral d,l-pair as well in the achiral meso-bond shift isomer.
    Notes: Synthese und dynamische Eigenschaften (Ringinversion und Bindungsverschiebung) von Cyclooctatetraen-1,4-dicarbonsäure-dimethylester (5) und seinem 2,3-Dimethyl-Derivat 6 werden beschrieben. Zugabe von optisch aktivem Verschiebungsreagenz führt nicht nur beim chiralen d,l-Paar, sondern auch beim achiralen meso-Bindungsisomeren von 5 zu einer Aufspaltung der NMR-Signale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150617
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  • 5
    Electronic Resource
    Electronic Resource
    Darstellung und Reaktionen von Verbindungen mit 5,6-Diazalumibullvalen-Gerüst (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2154-2174 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Reactions of Compounds of the 5,6-Diazalumibullvalene SeriesThe 9,10-diazasnoutane derivatives 3a und 16 can be rearranged to the 5,6-diazalumibullvalene derivatives 4a and 17 on treatment with acids.  -  The methyl-substituted diazasnoutane 16 is prepared by a new route. This compares favourably with an alternative procedure involving the bromination of methylcyclooctatetraene as a key step.  -  The thermal behaviour of the azo compounds 23 - 26  -  prepared from 4a  -  is investigated.  -  Some azoxy compounds of the 5,6-diazalumibullvalene series have been synthesized. The location of the oxygen atom can not be deduced from NMR spectroscopy and has been established by an X-ray analysis of 37.
    Notes: Die 9,10-Diazasnoutan-Derivate 3a und 16 lassen sich mit Säuren zu den 5,6-Diazalumibullvalen-Derivaten 4a und 17 umlagern.  -  Für die Darstellung des methyl-substituierten Diazasnoutan-Derivats 16 wird ein neuer Weg beschrieben, und es werden dessen Vorteile gegenüber einem alternativen Verfahren, das die Bromierung von Methylcyclooctatetraen beinhaltet, diskutiert.  -  Das thermische Verhalten der aus 4a zugänglichen Azoverbindungen 23 - 26 wird untersucht.  -  Die Position des Sauerstoffs in verschiedenen Azoxyverbindungen mit 5,6-Diazalumibullvalen-Gerüst läßt sich kernresonanzspektroskopisch nicht einwandfrei festlegen und wird über die Röntgenstrukturanalyse von 37 ermittelt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130611
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  • 6
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 36: Versuche zur Darstellung von Tetramethyltetrahedran aus alicyclischen Vorstufen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3935-3958 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 36: Attempts to Synthesize Tetramethyltetrahedrane from Alicyclic PrecursorsSynthesis as well as the thermal and photochemical behaviour of compounds with ring skeletons 1 and 3 are described. Whereas the former are accessible by standard procedures the approach to the bicyclobutane derivatives is based on the isomerization of diester 1b into valence isomer 3b which can be achieved in good yield by SiO2, or Al2O3. There are only minor differences in the cleavage of the pairs 1/3 provoked by heating or photochemical excitation. This is even true for irradiations in argon at 10 K. Under those conditions anhydrides la and 3a form the same charge transfer complex 28a between tetramethylcyclobutadiene and phthalic anhydride. A direct detection of tetramethyltetrahedrane using these means is not possible.
    Notes: Synthese sowie thermisches und photochemisches Verhalten von Verbindungen mit den Ringgerüsten 1 bzw. 3 werden beschrieben. Während erstere nach Standardverfahren zugänglich sind, fußt der präparative Zugang der Bicyclobutan-Derivate auf der mit SiO2 oder Al2O3 in guter Ausbeute erreichbaren Isomerisierung von Diester 1b zum Valenzisomeren 3b. Bei der durch Erhitzen oder Photoanregung bewirkten Spaltung unterscheiden sich die Paare 1/3 nur geringfügig. Dies gilt selbst für Bestrahlungen in Argon bei 10 K. Unter diesen Bedingungen liefern die Anhydride la und 3a den gleichen Charge-transfer-Komplex 28a zwischen Tetramethylcyclobutadien und Phthalsäureanhydrid. Ein direkter Nachweis von Tetramethyltetrahedran gelingt auf diese Weise nicht.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141216
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  • 7
    Electronic Resource
    Electronic Resource
    Isotopic perturbation of a degenerate valence isomerization. A 13C NMR study of deuterio-1,5-dimethylsemibullvalene (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 18 (1982), S. 176-177 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono deuterio-1,5-dimethylsemibullvalene is studied by the isotopic perturbation method with respect to the equilibrium of the valence isomerization. It emerges that deuterium prefers the cyclopropane position. From the temperature dependence of the splittings in the 13C NMR spectra the ground state enthalpy difference in mono deuterio-1,5-dimethylsemibullvalene is calculated to be 484 J mol-1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270180313
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