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  • 1
    Electronic Resource
    Electronic Resource
    Electron-Transfer Chemistry and Redox-Switching of Stilbene-Like Heteroaromatic Compounds  -  Syntheses, Optoelectrochemical and ESR/ENDOR StudiesDedicated to Prof. M. Hanack on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2069-2077 
    Details
    ISSN: 0947-3440
    Keywords: Stilbenes ; Push-pull substitution ; Electron transfer ; (Z)/(E) Isomerisation ; Radical ions ; Cyclic voltammetry ; Spectroelectrochemistry ; ESR / ENDOR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Redox-active compounds, in which the electron donor and the acceptor subunits are covalently linked by a vinylene spacer group were synthesised and their properties were investigated by cyclovoltammetry, spectroelectrochemistry, and ESR/ENDOR spectroscopy.  -  10-Methylphenothiazinyl, 10-methylphenoxazinyl, and phenoxathiinyl were used as electron-donating groups whereas 9,10-anthraquinon-2-yl and phenyl groups were employed as acceptors. The synthesis of the push-pull-substituted stilbenes 1a, 1b, 1c, 2a, 2b and 2c was achieved by Wittig coupling of the heterocyclic aldehydes with the anthraquinoyl or phenyl phosphonium salts. The diastereoisomers were separated either by chromatography or by crystallization.  -  The redox potentials of the (Z) and (E) isomers differ only slightly. Spectroelectrochemical measurements indicate that the radical cations of the phenothiazine and phenoxazine derivatives undergo rearrangement from the (Z) to the (E) isomers. On the other hand, electron attachment leads to configurationally stable radical anions. This behaviour is rationalised in terms of the electron distribution reflected by the hyperfine data established by ESR/ENDOR spectroscopy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961218
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  • 2
    Electronic Resource
    Electronic Resource
    Ein erstes Beispiel eines porphyrinoiden Fulvalens: Synthese, Struktur, ESR- und elektrochemische UntersuchungenProf. Dr. Fabian Gerson in Anerkennung seiner Beiträge zum Verständnis von π-Systemen gewidmet (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2456-2476 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A First Example of a Porphyrinoid Fulvalene: Synthesis, Structure, ESR and Electrochemical InvestigationsThe macrocyclic tetraepoxy-1H-[21]annulen-1-one 4 can by synthesized by the cyclizing Wittig reaction of 5,5′-carbonylbis[furan-2-carboxaldehyde] (11) and the bisphosphonium salt 12, obtained from 2,2′-bifuran-5,5′-dicarboxaldehyde (13). According to an X-ray structure analysis, the annulenone 4 is not planar in the crystal; the 1H-NMR spectra of 4 reveal an averaged planarity with respect to the NMR timescale. The McMurry reaction of 4 yields fulvalene 3 in 43% yield as the most expanded fulvalene hithertoo known. The X-ray structure analyses of 3 surprising establishes a ‘syn’-orientation of the two rings with respect to the central C=C bond, thus forming a basket-like molecule. The 1H-NMR spectrum confirms the averaged planarity of both macrocycles in 3. CV and spectroelectrochemical measurements of 3 suggest a reversible two-electron reduction producing dianion 15 with two aromatic, anionic 5a,15a-didehydro-10H-21,22,23,24-tetraoxa-5a,15a-dihomocorrole (= tetraoxa[22]porphyrin(2.1.2.0)) ring systems containing 22π electrons each. The formation of 15 can also be achieved chemically by reaction of 3 with metallic potassium. The dication 16 of 3 may be antiaromatic, but the exact electronic structure is dubious. ESR and ENDOR investigations on the radical cation and the radical anion of 3 indicate that the free electron is delocalized in the entire molecule.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800814
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  • 3
    Electronic Resource
    Electronic Resource
    Selektive Reaktionen von Hydroazulenen: Chirale Norcaranderivate über die Umsetzung eines Dihydroazulens mit Singulettsauerstoff (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 773-782 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Selective Reactions of Hydroazulenes: Chiral Norcarane Derivatives by the Reaction of a Dihydroazulene with Singlet OxygenPhotosensitized oxygenation of the dihydroazulene 6 affords the two peroxides 7 and 8 in good overall yield. The major product is derived from the “norcaradiene” of 6. The cycloaddition with singlet oxygen occurs stereospecifically. Consecutive reaction of 7 yield chiral norcarane derivatives in stereospecific ways. Thus, by thermolysis of 7 the bisepoxide 10 is formed; reaction of 7 with triethylamine leads to the hydroxyketone 11 with MnO2 the homoquinone 13 is formed. The structures are established by spectroscopic methods.
    Notes: Die Umsetzung des Dihydroazulens 6 mit Singulettsauerstoff ergibt die beiden Peroxide 7 und 8. Das Hauptprodukt 7 leitet sich vom “Norcaradien” des Hydroazulens 6 ab. Die 1O2-Addition erfolgt stereoselektiv. Folgereaktionen von 7 ergeben chirale Norcaranderivate: Thermolyse führt zum Bisepoxid 10, mit Triethylamin entsteht das Hydroxyketon 11 und Triphenylphosphan führt unter Sauerstoffabspaltung zu den Vinyloxiranen 12a und 12b. Bei diesen Reaktionen wird jeweils nur ein Diastereomeres gebildet. Die Oxidation von 11 mit Mangandioxid ergibt das Homochinon 13. Für sämtliche Reaktionsprodukte sind spektroskopische Daten angegeben.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840413
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  • 4
    Electronic Resource
    Electronic Resource
    Homobarrelene; Struktureigenschaften von Tricyclo[3.2.2.0 2,4]- nona-6,8-dienen und 8,9-Dimethylentricyclo[3.2.2.0 2,4]non-6-en; Synthese und Eigenschaften von Eisentricarbonylkomplexen (1977)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1977 (1977), S. 1730-1742 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Homobarrelenes; Structural Properties of Tricyclo [3.2.2.0 2,4]nona-6,8-dienes and 8,9-Dimethylenetricyclo[3.2.2.0 2,4]non-6-ene; Synthesis and Properties of Irontricarbonyl ComplexesSyntheses, spectroscopic properties and some reactions of tricyclo[3.2.2.0 2,4]nona-6,8-diene (2), 8,9-dimethylenetricyclo[3.2.2.0 2,4]non-6-ene (3) and 8-methylenetricyclo[3.2.2.0 2,4]non-6-ene (4) are described. The 13C-NMR spectra of 2, 3 and 4 give no indication of a longicyclic delocalization. Cycloadditions of dienophiles and 3 lead to the substituted homobarrelenes 20 - 23. Compounds 2 and 3 react with ironpentacarbonyl to give η-irontricarbonyl complexes 25 and 27. In 25 complexation occurs to the bishomocyclobutadiene unit. In 27, which is formed as a mixture of diastereomers, the cis-butadiene unit is complexed. - 1H-NMR, 13C-NMR and mass spectra are discussed.
    Notes: Synthese, spektroskopische Eigenschaften und einige Reaktionen sind für Tricyclo[3.2.2.0 2,4]-nona-6,8-dien (2), 8,9-Dimethylentricyclo[3.2.2.0 2,4]non-6-en (3) und 8-Methylentricyclo-[3.2.2.0 2,4]non-6-en (4) beschrieben. Aus den 13C-NMR-Spektren der Verbindungen 2, 3 und 4 kann keine Wechselwirkung zwischen Olefin- und Cyclopropanstrukturteilen abgeleitet werden. 3 cycloaddiert Dienophile zu den substituierten Homobarrelenen 20 - 23. Von 2 und 3 wurden mit Eisenpentacarbonyl die η-Eisentricarbonylkomplexe 25 und 27 hergestellt. Nach spektroskopischen Daten ist in 25 der Bis(homocyclobutadien)strukturteil komplexiert. In 27 (synthetisiert aus 3) ist der cis-Butadienstrukturteil komplexiert. 27 entsteht als Stereoisomerengemisch. - 1H-NMR, 13C-NMR und Massen-Spektren werden diskutiert.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197719771020
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  • 5
    Electronic Resource
    Electronic Resource
    Functional dyes for molecular switchingPreceding communication: Ref.. Dihydroazulene/vinylheptafulvene photochromism: Effect of π-arylenes on the switching behaviorDedicated to Prof. F. Effenberger on the occasion of his 65th birthday. (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1637-1641 
    Details
    ISSN: 0947-3440
    Keywords: Thermal and photochemical electrocyclization reactions ; Photochromism ; Molecular switching ; Luminescent properties ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reversible interconversion of dihydroazulene (DHA) and vinylheptafulvene (VHF) can be utilized to switch a number of physical properties. This communication reports on a fluorescent switch. By a multistep sequence involving an [8 + 2] cycloaddition route 9-anthracenyl-1,4-phenylene was covalently attached to C-2 of the DHA chromophore affording DHA-1 which undergoes complete and clean photochemical ring opening to vinylheptafulvene VHF-1. The latter is thermally reverted to DHA-1. The kinetics and the energetics of the thermal back reaction are discussed. On/off switching of luminescence was investigated: DHA-1 displays fluorescence whereas VHF-1 is nonfluorescent at ambient temperature.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199509227
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  • 6
    Electronic Resource
    Electronic Resource
    Tetracarbonylferrate aus Orthoameisensäurederivaten und PentacarbonyleisenHerrn Prof. Dr. H. Bredereck zum 75. Geburtstag gewidmet. (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 997-1015 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Group Transfer Reactions1).  -  Tetracarbonylferrates from Orthoformic Acid Derivatives and PentacarbonylironHerrn Prof. Dr. H. Bredereck zum 75. Geburtstag gewidmet.The nucleophilic leaving group X is transferred from orthoformic acid derivatives HC(NR2)2X (X = NR2, OR, CN) to Fe(CO)5. No such reactions were observed between 4 and amide acetals (HCX2NR2) or ortho ester derivatives HCX3 (X = OR, SR). The structures of the transition metal-acyl complexes obtained have been determined by IR and NMR spectra. In the case of the reaction of tris(dimethylamino)methane (3a) with 4 the equilibrium between the resulting amidinium-carbamoyltetracarbonylferrate complex 5a and the starting materials was investigated. The equilibrium is shifted completely in favor of the ionic compound 5a. However, 3a could be isolated by extraction of this solution with an apolar solvent. Alkylation of 5a with triethyloxonium tetrafluoroborate leads to the tetracarbonyliron-carbene complex 13. Reaction of 5a
    Notes: Orthoameisensäurederivate der Struktur HC(NR2)2X (X = NR2, OR, CN) übertragen die nukleophile Austrittsgruppe X auf Fe(CO)5. Mit Amidacetalen (HCNR2X2) und Verbindungen der Struktur HCX3 (X = OR, SR) konnten keine derartigen Reaktionen nachgewiesen werden. Die Strukturen der entstehenden Übergangsmetallacylkomplexe werden mittels IR- und NMR-Spektroskopie ermittelt. Bei der Umsetzung von Tris(dimethylamino)methan (3a) mit Fe(CO)5 ist das Gleichgewicht zwischen dem entstehenden Amidinium-Carbamoyltetracarbonylferrat-Komplex 5a und den Ausgangsverbindungen vollständig nach 5a verlagert; dennoch kann hieraus mit unpolaren Lösungsmitteln die Trisaminoverbindung 3a extrahiert werden. Die Alkylierung von 5a mit Triethyloxonium-tetrafluoroborat ergibt den Tetracarbonyleisencarben-Komplex 13. Die Umsetzung von 5a mit Acrylonitril oder Acrylsäure-methylester liefert nach Addition sowohl des Nukleophils “NR2⊕” als auch des Elektrophils [HC(NR2)2]⊖ und anschließenden Eliminierungen die β-Dimethylamino-Substitutionsprodukte 18 bzw. 21. Das Trisaminomethan 3a hingegen induziert eine Polymerisation des Acrylonitrils.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800702
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  • 7
    Electronic Resource
    Electronic Resource
    Fulvene mit inverser Ringpolarisation, 20. über die Regiochemie der [8 + 2]-Cycloaddition von 8-Methoxyheptafulven und Chinonen. Synthese und Eigenschaften substituierter Acenazulendione (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1346-1359 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fulvenes with Inverse Ring Polarisation, 20.- Regiochemistry of the [8 + 2] Cycloaddition of 8-Methoxyheptafulvene and Quinones. Syntheses and Properties of Substituted AcenazulenedionesThe reaction of 2,5-dimethylbenzoquinone (7a) with 8-methoxyheptafulvene (4) leads to the dihydroazulene 11, the stereochemistry of which was assigned by NMR spectroscopy (NOE). Mixtures of regioisomers were formed with varying selectivity by the reactions of 4 with the unsymmetrically substituted quinones 5, 7b, 8, and 9. The ratio of components in these mixtures was determined quantitatively. Some of the isomers were isolated and the structures were assigned by spectroscopic methods. The effects of the substituents of the quinones on the regioselectivity of the [8 + 2] cycloaddition is dependent on steric and electronic effects. Cyclic voltammetry shows for the electrochemical reduction of some of these novel quinoid acenazulenediones a normal two-step electron transfer, others follow a more complex mechanism.
    Notes: 2,5-Dimethylbenzochinon (7a) reagiert mit 8-Methoxyheptafulven (4) zum Dihydroazulen 11, dessen räumliche Struktur durch NMR-Spektroskopie (NOE) bewiesen wurde. Bei Umsetzungen von 4 mit den unsymmetrisch substituierten Chinonen 5, 7b, 8 und 9 werden mit unterschiedlicher Selektivität Gemische von Regioisomeren erhalten. Die quantitative Zusammensetzung dieser Gemische wurde bestimmt. Einige Regioisomere wurden isoliert und die Strukturen durch spektroskopische Methoden zugeordnet. Die Substituenteneffekte bei der [8 + 2]-Cycloaddition sind sowohl auf elektronische als auch auf sterische Effekte zurückzuführen. Cyclische Voltammetrie zeigt für die Reduktion dieser neuen chinoiden Acenazulendione teilweise ein normales zweistufiges, teilweise ein komplexes Elektronentransfer-Verhalten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850706
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