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  • 1
    Electronic Resource
    Electronic Resource
    Nucleophilic Substitution of 4H-Imidazolesby Thioles: New Starting Materials for Tetraazafulvalenes and Fused Heterocycles (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 1181-1190 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Fused heterocycles; 4H-Imidazoles; Nucleophilic substitution; 1 ; 3 ; 5 ; 7-Tetraazafulvalenes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  Different reactivities towards the 4H-imidazoles 1 depending on the nature of the sulfur containing nucleophile were observed. Whereas H2S and aromatic thioles led to 4,5-diaminoimidazoles in the course of a reduction process, treatment with aliphatic mercaptanes resulted in a substitution-reduction-dimerization cascade which finally gave bis-imidazoles. Their oxidative modification in presence of m-chloroperbenzoic acid then allowed new 1,3,5,7-tetraazafulvalenes to be easily obtained. Treatment of the bis-imidazoles with acetylene dimethyldicarboxylate caused cleavage of the central bond, thus leading to the formation of derivatives which are of interest for the transformation into fused heterocycles such as imidazo[4,5-b]azepines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060070026
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  • 2
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Derivaten des Thiosemicarbazids mit Bisimidchloriden der Oxalsäure (1989)
    Springer
    Monatshefte für Chemie 120 (1989), S. 1125-1137 
    Details
    ISSN: 1434-4475
    Keywords: 13C-NMR, Derivatives of oxalic acid ; DSP-Analysis ; NS-Heterocycles ; Thiosemicarbazones ; X-Ray crystallography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Arylsubstituted oxalic bis-imidochlorides1 react with thiosemicarbazones of type5 as well as13 to give five-membered-ring heterocycles8,11, and16.13C-NMR spectroscopy, chemical methods and X-ray crystallography have been used to investigate the nature of the structures obtained. The13C-chemical shifts of13 and imidazolidines16 are correlated with Hammett σ p constants and dual substituent parameters to evaluate the transmission of theX substitutent electronic effects via the side-chain iminyl carbon atom into the heterocyclic ring and its neighbouring phenyl groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809296
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  • 3
    Electronic Resource
    Electronic Resource
    On the reaction of dithiocarbamates with nitrogen-containing derivates of oxalic acid (1989)
    Springer
    Monatshefte für Chemie 120 (1989), S. 561-569 
    Details
    ISSN: 1434-4475
    Keywords: Derivatives of oxalic acid ; Dithiocarbamates ; MNDO-Calculation ; NS-Heterocycles ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei der Einwirkung von Bisimidchloriden der Oxalsäure auf Dithiocarbaminate entstehen durch Cycloacylierung 2-Thioxo-3-aryl(alkyl)-4,5-diiminothiazolidine. Die Molekülstruktur von 2-Thioxo-3-(4-methoxyphenyl)-4,5-bis(phenylimino)thiazolidin wird durch Röntgenkristallstrukturanalyse bestätigt.
    Notes: Summary The action of bisimidochlorides of oxalic acid on dithiocarbamates produces 2-thioxo-3-aryl(alkyl)-4,5-diiminothiazolidines by cycloacylation. The molecular structure of 2-thioxo-3-(4-methoxyphenyl)-4,5-bis(phenylimino)-thiazolidine is confirmed by X-ray crystal structure analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810842
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  • 4
    Electronic Resource
    Electronic Resource
    New Indigoid Compounds by Reduction of Bis-Imidoylchlorides of Oxalic Acid – A Further Evidence for Dimeric Isocyanides? (1999)
    Springer
    Monatshefte für Chemie 130 (1999), S. 1373-1382 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Dimeric isocyanides; Indigodianil; 1 ; 5-Naphthyridine; Spectroscopic properties.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Bis-imidoylchloride der Oxalsäure reagieren mit Magnesiumspänen in trockenem THF und unter Ultraschallbedingungen zu den 1,5-Naphthyridinderivaten und den isomeren Indigodianilen. Durch Untersuchungen des Reaktionsmechanismus konnten Hinweise auf radikalische C2-Schlüsselintermediate vom Typ dimerer Isocyanide erbracht werden.
    Notes: Summary.  Bis-imidoylchlorides of oxalic acid react rapidly with magnesium shreds in dry THF under ultrasonic conditions to give 1,5-naphthyridine derivatives and the isomeric indigodianiles. Using a cross-over experiment the existence of key intermediates corresponding to dimeric isocyanides could be verified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010197
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  • 5
    Electronic Resource
    Electronic Resource
    Fixation of Carbon Dioxide by Oxalic Amidinato Magnesium Complexes: Structures and Reactions of Trimetallic Magnesium Carbamato and Related Complexes (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 1055-1064 
    Details
    ISSN: 1434-1948
    Keywords: Carbon dioxide fixation ; Magnesium ; N ligands ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of oxalic amidines R1-N=C(NHR2)-C(NHR2)=N-R1 with CH3MgX followed by uptake of CO2 results in the formation of the trimeric carbamato complexes [R1-N=C(NR2-COO)-C(NR2COO)=N-R1]3Mg3(THF)6 (2a: R1 = R2 = Ph; 2b: R1 = R2 = p-tolyl) as the thermodynamically stable final products of the reaction. Their X-ray crystal structures show that the three metal centres are in a linear arrangement. The central magnesium ion is octahedrally surrounded by six O-donor atoms of the μ2-carbamato bridges, while both peripheral magnesium ions are facially coordinated by three O-donor atoms of the carbamato groups and three THF molecules. This coordination sphere can be considered as a structural model for the active centre in the ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme. Compound 2a reacts with ZnCl2 or CoBr2, with CO2 elimination, to form dimeric complexes of the type [X2M(oxalamidinato)MX2][Mg(DMF)6] (M = Zn, Co; X = Cl, Br). X-ray crystal structure analyses show that the d-metals are tetrahedrally coordinated. The magnesium-bromide-containing intermediates in the formation of 2a and 2b are able to transfer CO2 to acetophenone, thus simulating the CO2 activation step in enzymatic biotin-dependent carboxylation reactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Fünfring-Cycloamidine - Neue farbige Heterocyclen mit ungewöhnlichen Eigenschaften. I. Synthese und spektrale Besonderheiten (1997)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 339 (1997), S. 729-734 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Ring-Cycloamidines - Deeply Coloured Heterocycles with Unusual Properties. I. Synthesis and Spectral FeaturesThe cycloacylation reaction of benzamidines with bis-imidoylchlorides 1 derived from oxalic acid was investigated. For example, treatment of benzamidine with 1 gives the new 4H-imidazoles (3a-l) in yields up to 92%. Because of rapid H-transfer processes in solution, the NMR-spectra of 3a-l show only a single signal set. Apart from prototropism, 3c shows interesting properties as an amphoteric heterocycle. The protonation of 3c is accompanied by a change of color from orange to blue. Probably, protonation takes place on the exocyclic imino nitrogen to give a cyanine type chromophor. The resulting cation can also be regarded as an antiaromatic 1,3-diazacyclopentadienylium system. In order to investigate the influence of exocyclic substituents at nitrogen on the UV/VIS absorption, compounds 3d-h were synthesized. Whereas electron withdrawing groups cause hypsochromic shifts of the first UV/VIS absorption band, the dimethylamino group shifts this band bathochromically as exemplified by 3e. This novel cycloamidine shows strong acidochromism with bathochromic shifts of more than Δλmax = 150 nm.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.199733901132
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  • 7
    Electronic Resource
    Electronic Resource
    Zur Aminolyse von Bis-Imidoylchloriden der Oxalsäure. I. Umsetzung mit aromatischen und aliphatischen Aminen (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 143-152 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Aminolysis of Bis-Imidoylchlorides of Oxalic Acid. Part I. Reaction with Aromatic and Aliphatic AminesThe reaction between bis-imidoylchlorides 2 derived from oxalic acid and several aromatic and aliphatic amines was investigated. While primary aromatic amines need a thermical activation by refluxing, primary aliphatic amines give mainly at room temperature the amidines 3 in moderatly up to good yields.Proceeding from enantiomeric pure amines e.g. (R)- or (S)-1-phenethylamine the new homochiral oxalic amidines 3y and 3z with C2-symmetry were obtained. Several secondary amines react with the bis-imidoylchloride 2a to give via intramolecular cycloacylation derivatives of isatine. The new synthesized amidines 3 perform systems with a strong molecular dynamic like prototropie and E/Z-interconversion. All new compounds described were characterized by elemental analysis and spectroscopic methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370130
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  • 8
    Electronic Resource
    Electronic Resource
    Fünfring-Cycloamidine - Neue farbige Heterocyclen mit ungewöhnlichen Eigenschaften. II. Molekül- und Elektronenstruktur (1997)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 339 (1997), S. 735-741 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Ring-Cycloamidines - Deeply Colored Heterocycles with Unusual Properties. II. Molecular- and Electronic StructureThe crystal and molecular structure of two N,N′-aryl-5-amino-imidazole-4-imides were detected by X-ray analysis. The structural parameters are discussed in conjunction with theoretical data obtained by density functional and ab initio quantum theory. The interpretation of the molecular structures derived from the X-ray diffraction study is made more difficult by statistic disorder or by enclosure of water in the crystal. The theory predicts a planar 5-amino-imidazole-4-imide parent structure with an energy barrier to H-transfer of about 25 kcal/mol (DFT RB3LYP/6-311+G** and ab initio G2(MP2) calculations). The CC bond of the five-membered ring is exceedingly long. CC-bond length elongation is also reported for oxalbisamidine. The structure of the parent compound is discussed in terms of polymethinic and antiaromatic substructures. Weinholds's Natural Bond Orbital (NBO) scheme and Natural Resonance Theory (NRT) as well as Schleyer's criterion of the Nucleus Independent Chemical Shift (NICS) is consulted to reveal the very nature of the unique bond system.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.199733901133
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  • 9
    Electronic Resource
    Electronic Resource
    Eine unerwartete Reaktion zwischen Oxalylchlorid und atropisomeren Diaminen (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 199-201 
    Details
    ISSN: 0947-3440
    Keywords: Macrocyclic lactams ; Oxalamides ; Atropisomeric diamines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Unexpected Reaction between Oxalyl Chloride and Atropisomeric DiaminesChiral diamines like (S)-1,1′-binaphthalene-2,2′-diamine (3a) were acylated by oxalyl chloride to yield mainly a macrocyclic lactame 5, whereas the eight-membered oxamide 4 was formed only in small quantity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950128
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  • 10
    Electronic Resource
    Electronic Resource
    Umlagerung von 3-Thioxo-Δ1,4-steroiden, ein neuer Zugang zu Steroidthiolen (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1397-1399 
    Details
    ISSN: 0947-3440
    Keywords: 3-Thioxoandrosta-1,4-dien-17-one, rearrangement of ; Thioestratriene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangement of 3-Thioxo-Δ1,4-steroids, a New Approach of Steroid Thiols3-Thioxoandrosta-1,4-dien-17-one (1) is subjected to a dienthion-thiophenol rearrangement in aprotic and protic solvents in the presence of an acid catalyst resulting in the formation of 1-(acetylthio)-4-methylestra-1,3,5(10)-trien-17-one (2). 1-mercapto-4-methylestra-1,3,5(10)-trien-17-one (3), and the dimer 1,1′-(dithio)bis[4-methylestra-1,3,5(10)-trien-17-one] (4) as the reaction products. The mercapto compound 3 tends to be autoxidized to the sulfide 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199507189
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