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  • 1
    Electronic Resource
    Electronic Resource
    Zur Kondensation von Acetonylaceton mit Cyanessigester (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 2594-2603 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensation of Acetonylacetone with Ethyl CyanoacetateKnoevenagel condensation of acetonylacetone and ethyl cyanoacetate in benzene catalysed by piperidine acetate leads to the formation of a mixture of products, which has been separated into 6 substances: the cyclopentene 5, the symmetrical bis-Knoevenagel product 3, the dihydrofulvene 2, the cyclopenta[b]pyran 1, and the pyrindinone 13 together with the corresponding saponification and decarboxylation product 6. A reaction scheme summarizing possible pathways is given on page 2599. By dilute acid catalysis the cyclopenta[b]pyran 1 rearranges to the pyrindinone 15, whereas conc. technical sulfuric acid cleaves the pyran ring to form the cyclopentenone 17.
    Notes: Bei der Knoevenagel-Kondensation von Acetonylaceton und Cyanessigsäure-äthylester mit Piperidinacetat in Benzol entsteht ein Produktgemisch, das in 6 Substanzen zerlegt werden konnte: in das Cyclopenten 5, das symmetrische Bis-Knoevenagel-Produkt 3, das Dihydrofulven 2, das Cyclopenta[b)pyran 1 und das Pyrindinon 13 sowie sein Verseifungs- und Decarboxylierungsprodukt 6. Ihre möglichen Bildungswege werden im Formelschema S. 2599 zusammengefaßt. Das Cyclopenta[b]pyran wird von verd. Säuren in das Pyrindinon 15 umgelagert, während konz. technische Schwefelsäure den Pyranring unter Bildung des Cyclopentenons 17 spaltet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050821
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  • 2
    Electronic Resource
    Electronic Resource
    Polycarbonylverbindungen, XVI. Darstellung und Struktur des Schwefelanalogons des Quadratsäure-Dianions K2[C4S4]·H2O (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2208-2215 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycarbonyls, XVI. Synthesis and Structure of the Sulfur Analogue of Squaric Acid Dianion K2[C4S4·H2O]Sulfhydrolysis of 1,2- or 1,3-dithiosquaric acid diamides yields the sulfur analogue 4 of squaric acid dianion, the first member of the „thioxocarbons“. Spectroscopic data and intramolecular distances determined by X-ray diffraction indicate a symmetrical, delocalised electron system with C—C- and C—S-bond orders of n - 1.25 and 1.5, resp.
    Notes: Durch Sulfhydrolyse von 1,2- bzw. 1,3-Dithioquadratsäure-bisamiden entsteht das Schwefelanalogon 4 des Quadratsäure-Dianions, der erste Vertreter der „Thioxokohlenstoffe“. Spektroskopische Daten und die aus einer röntgenographischen Strukturbestimmung erhaltenen innermolekularen Bindungslängen weisen auf ein symmetrisches, delokalisiertes Elektronensystem mit C — C- bzw. C — S-Bindungsordnungen von n = 1.25 bzw. 1.5 him.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090627
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen in der Isochroman- und Isothiochroman-Reihe, XIX. Dimere Isothiochroman- und Isochroman-1-carbonitrile (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3134-3138 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations in the Isochromane and Isothiochromane Series, XIX. Dimeric Isothiochromane- and Isochromane-1-carbonitrilesIsothiochromane-1-carbonitrile (1) and isochromane-1-carbonitrile (2) can be oxidized via the carbanions 3 and 4, resp., to give mixtures of racemic and meso-forms of the dimeric compounds 5A/B and 6A/B, respectively. The diastereomers are separated by fractionating crystallisation combined with preparative layer-chromatography. The structure assignment is made from spectroscopic results.
    Notes: Isothiochroman-1-carbonitril (1) und Isochroman-1-carbonitril (2) lassen sich über ihre Carbanionen 3 bzw. 4 zu Gemischen von Racem- und Mesoformen dimerer Verbindungen 5A und B bzw. 6A und B oxidieren. Durch eine Kombination von fraktionierender Kristallisation und präparativer Schichtchromatographie sind die Diastereomeren zu trennen, deren Strukturzuordnung aufgrund spektroskopischer Befunde erfolgt.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100918
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  • 4
    Electronic Resource
    Electronic Resource
    Zur Reaktion von 1,2-Diketonen mit Malononitril unter Piperidin-Katalyse (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 3247-3255 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of 1,2-Diketones with Malononitrile Catalysed by PiperidinePiperidine catalysis of the reaction between biacetyl and malononitrile leads to the formation of 2,6-diaza-cis-bicyclo[3.3.0]octanedione 6 and 2,10-dioxa-6-azatetracyclo[6.3.0.04,11.05,9]undecane 11a. Variation of the reaction conditions allows the isolation of 5 and 8a as intermediates. 6 is also formed by cyclisation of 8a with hydrogen chloride in ethanol; acid hydrolysis of 6 leads to the dicarboxylic acid 12 and its decarboxylation to 13. The structure 11a is deduced mainly from the reaction pathway 8a → 11a. By hydrolysis of the carbonimide group in 11a a lactone group is formed (e.g. 14a); methylation of the lactame nitrogen with diazomethane yields 15. Reaction of other 1,2-diketones with malononitrile also leads to the formation of 3-pyrrolin-2-ones 8, which may add another molecule of a 1,2-diketone to yield 11b-f.
    Notes: Die Umsetzung von Biacetyl mit Malononitril unter Piperidin-Katalyse führt zu dem 2,6-Diaza-cis-bicyclo[3.3.0]octandion 6 und dem 2,10-Dioxa-6-azatetracyclo[6.3.0.04,11.05,9]undecan 11a. Durch Variation der Reaktionsbedingungen können die Zwischenprodukte 5 bzw. 8a abgefangen werden. 6 entsteht ferner durch Cyclisierung von 8a mit Chlorwasserstoff in Äthanol; es läßt sich sauer zur Dicarbonsäure 12 verseifen und anschließend zu 13 decarboxylieren. Die Struktur von 11a ergibt sich vornehmlich aus seiner Bildung über 8a. Die Carbonimidgruppe in 11a kann zur Lactongruppe verseift (vgl. 14a), der Lactamstickstoff mit Diazomethan unter Bildung von 15 methyliert werden. Andere 1,2-Diketone reagieren ebenfalls mit Malononitril zu 3-Pyrrolin-2-onen 8; auch diese können eine weitere Molekel 1,2-Diketon unter Bildung von 11b-f addieren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751081014
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Biacetyl mit Malononitril unter Alkoholat-Katalyse (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 3256-3261 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Biacetyl with Malononitrile Catalysed by Sodium EthoxideReaction of biacetyl with malononitrile in the presence of sodium ethoxide leads to the formation of 1,5-dimethyl-3,7-dioxo-2,8-diaza-cis-bicyclo[3.3.0]octane-4,6-dicarbonitrile (6), which is also obtained by an alkali catalysed rearrangement of the isomeric 2,6-diaza compound 2. Hydrolysis of 6 by hydrochloric acid yields the corresponding dicarboxylic acid 9, decarboxylation 1,5-dimethyl-2,8-diaza-cis-bicyclo[3.3.0]octane-3,7-dione (10). Hydrolysis of 6 by hydrobromic acid leads to the formation of 1,5-dimethyl-2,8-dioxa-cis-bicyclo[3.3.0]octane-3,7-dione (8). The structure of 8 has been confirmed by some additional chemical transformations.
    Notes: Die Umsetzung von Biacetyl mit Malononitril unter Alkoholat-Katalyse führt zu 1,5-Dimethyl-3,7-dioxo-2,8-diaza-cis-bicyclo[3.3.0]octan-4,6-dicarbonitril (6), das ebenfalls durch alkalikatalysierte Umlagerung der isomeren 2,6-Diaza-Verbindung 2 entsteht. 6 läßt sich mit Salzsäure zu der entsprechenden Dicarbonsäure 9 hydrolysieren und zu 1,5-Dimethyl-2,8-diaza-cis-bicyclo-[3.3.0]octan-3,7-dion (10) decarboxylieren. Bromwasserstoffsäure überführt 6 in 1,5-Dimethyl-2,8-dioxa-cis-bicyclo[3.3.0]octan-3,7-dion (8), dessen Struktur durch einige zusätzliche Reaktionen abgesichert wird.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751081015
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  • 6
    Electronic Resource
    Electronic Resource
    1,1-Bis(tetrachlorcyclopentadienyl)cyclohexan und verwandte Produkte (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2593-2599 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,1-Bis(tetrachlorocyclopentadienyl)cyclohexane and Related ProductsThe bis-condensation products 10-13 are formed besides the expected fulvenes by the reaction of 1,2,3,4-tetrachlorocyclopentadiene (1) with azomethines (e. g. 2). In addition the spiro compound 8 has been obtained from 1 and N-cyclohexylidene-n-propylamine (2). During this reaction a common intermediate could be isolated in form of the ammonium salt 5. This decomposes in polar basic solvents to yield mainly fulvene 6, whereas in unpolar solvents 8 and 10 are formed exclusively after the addition of sodium hydride and 1. Dechlorination of 8 leads to the generation of the fulvalene 14.
    Notes: Bei der Umsetzung von 1,2,3,4-Tetrachlorcyclopentadien (1) mit Azomethinen (z. B. 2) entstehen neben den erwarteten Fulvenen die Bis-Kondensationsprodukte 10-13. Mit N-Cyclohexyliden-n-propylamin (2) bildet 1 zusätzlich die Spiroverbindung 8; außerdem ließ sich in diesem Fall eine gemeinsame Zwischenstufe in Form des Ammoniumsalzes 5 abfangen, die in polaren, basischen Lösungsmitteln hauptsächlich zum Fulven 6 weiterreagiert, in unpolaren Lösungsmitteln nach Zusatz von Natriumhydrid und 1 jedoch ausschließlich 8 und 10 bildet. Die Dechlorierung von 8 liefert das Fulvalen 14.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751080814
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  • 7
    Electronic Resource
    Electronic Resource
    Konkurrenz von Endoperoxid- und Hydroperoxid-Bildung bei der Umsetzung von Singulett-Sauerstoff mit cyclischen, konjugierten Dienen. Teil I (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 51-58 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition of Endoperoxide and Hydroperoxide Formation in the Reaction of Singlet Oxygen with Cyclic, Conjugated DienesRose-bengal-sensitized photooxygenation of (-)-(R)-α-phellandrene (1) in MeOH at room temperature yielded a complex mixture of products, contrary to previous reports describing cis-(3S, 6R)-epidioxy-p-menthene (2) and trans-(3R, 6S)-epidioxy-p-menthene (3) as the only products. The mixture was separated by prep. HPLC (silica gel, pentane/Et2O 9:1). Besides the known endoperoxides 2 (yield 39%) and 3 (26%), all those hydroper-oxides, which can be deduced from an ene reaction of 1O2 with 1, were isolated, i.e. 4β-p-mentha-2,5-dien-1β-yl hydroperoxide (4) (14%), 4β-p-mentha-2,5-dien-1α-yl hydroperoxide (5) (9%), (2R, 4R)-p-mentha-1(7), 5-dien-2-yl hydroperoxide (6) (2,1%), (2S, 4R)-p-mentha-1(7),5-dien-2-yl hydroperoxide (7) (1,5%) and (1R)-p-mentha-3,6-dien-yl hydroperoxide (8; 1,5%; Scheme 1). Furthermore, the constant cis/trans ratio for all diastereoisomeric pairs (2/2, 4/2, 6/2) was striking. With the help of the two possible conformers 1a and 1b of the starting material a model of a common first step for endoperoxide as well as for hydroperoxide formation is developed. A photooxygenation at -50° supports this model. The absolute value of the cis/trans ratio changes in the same way for the endoperoxides and the hydroperoxides.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720107
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  • 8
    Electronic Resource
    Electronic Resource
    Neuartige Triterpen-Lactone aus Helenium autumnale L. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 342-346 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel Triterpene Lactones of Helenium autumnale L.Three novel triterpene lactones 1-3 could be detected by investigating a pentane extraxt of the Helenium autumnale L. (Asteraceae) roots. The structures are especially elucidated by 1H- and 13C-NMR spectroscopy. The lactones 1-3 formally represent Diels-Alder products of a reaction between a sesquiterpene lactone and an α,β-unsaturated sequiterpene aldehyde.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700211
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  • 9
    Electronic Resource
    Electronic Resource
    Isolierung und Strukturaufklärung epimerer 1(5),6-Guaiadiene aus Tolubalsam (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1616-1622 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation and Structure Elucidation of Epimeric 1(5,)6-Guaiadienes from TolubalsamTwo epimeric 1(5),6-guaiadienes, which have very similar spectroscopic properties, were isolated from tolubalsam. Their structures were elucidated by NMR spectroscopy, acid-catalyzed isomerization of γ-gurjunene, and Diels-Alder reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700619
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  • 10
    Electronic Resource
    Electronic Resource
    A Novel Rearrangement Product of Podophyllotoxone - Ester Derivatives and in vitro cytotoxicity studies (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 771-777 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new rearrangement product of podophyllotoxone was obtained by reaction with strong bases. In vitro cytotoxities of this substance and some derivatives were determined using L-1210 and KB cell lines.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770318
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