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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 96 (1974), S. 5667-5668 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2635-2648 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal isomerisations, VII. The Gas Phase Pyrolysis of trans-and cis-1,2-DiethynylcyclobutanesGas phase pyrolysis of trans- and cis-1,2-diethynylcyclobutane (trans- and cis-8) in a flow system between 300 and 700°C affords 1,2-dihydropentalene (13) and bicyclo[4.2.0]octa-1,5,7-triene (14) as the main isomerisation products. Pyrolysis experiments with the methyl derivatives 20 and 21 indicate that in the first step of this reaction bisallenes (26) are formed by a [3,3]sigmatropic rearrangement of the 1,5-hexadiyne part of the molecule. These isomerise subsequently to 14 by a disrotatory process, and to 13 by 1,5-carbon bridging and insertion of the resulting carbene intermediates (24).
    Notes: Dis Gasphasenpyrolyse von trans- und cis-1,2-Diäthinylcyclobutan (trans- und cis-8) im Strömungsrohr zwischen 300 und 700°C liefert 1,2-Dihydropentalen (13) und Bicyclo[4.2.0]octa-1,5,7-trien (14) als Hauptisomerisierungsprodukte. Pyrolyseexperimente mit den Methylderivaten 20 und 21 sprechen dafür, daß bei dieser Reaktion durch eine [3,3]sigmatrope Umlagerung im 1,5-Hexadiin-Teil des Moleküls zunächst Bisallene 26 entstehen, die in den Folgeschritten entweder durch Disrotation zu 14 oder durch 1,5-C—C-Verknüpfung über Carbenzwischenstufen (24) und Einschiebung zu 13 reagieren.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 597-612 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkynes and Cumulenes, XVII. Photoaddition of Vinylacetylene to other Unsaturated HydrocarbonsOn irradiation in the presence of triplet sensitizers, vinylacetylene (1) may be added with its double bond to olefins [1,1-dichloroethene (4), (E)-1,2-dichloroethene (13)], dienes [1,3-butadiene (33a), 2-methyl-1,3-butadiene (33b), 2-chloro-1,3-butadiene (33c)], allenes [propadiene (40), 1,2-pentadien-4-yne (43), 1,2,4,5-hexatetraene (48)], and diynes [butadiyne (51)]. The resulting multifunctionalized cyclobutane derivatives are characterized by spectroscopic and chemical methods. Since the ethinyl group of these codimers may be hydrated to the acetyl function, 1 represents a photochemical equivalent of methyl vinyl ketone which itself does not undergo the described photoadditions. When benzene (56) is employed as addition partner the primary product of the codimerization, 54, isomerizes to vinylcyclooctatetraene (55).
    Notes: Vinylacetylen (1) läßt sich bei Bestrahlung in Gegenwart von Triplettsensibilisatoren mit seiner Doppelbindung an Olefine [1,1-Dichlorethen (4), (E)-1,2-Dichlorethen (13)], Diene [1,3-Butadien (33a), 2-Methyl-1,3-butadien (33b), 2-Chlor-1,3-butadien (33c)], Allene [Propadien (40), 1,2-Pentadien-4-in (43), 1,2,4,5-Hexatetraen (48)] und Diine [Butadiin (51)] addieren. Die resultierenden, mehrfach funktionalisierten Cyclobutan-Abkömmlinge werden durch spektroskopische und chemische Methoden charakterisiert. Da sich die Ethinylgruppe dieser Codimeren zur Acetylfunktion hydratisieren läßt, stellt 1 insgesamt ein photochemisches Äquivalent für Methylvinylketon dar, das entsprechende Photoadditionen nicht eingeht. Im Falle von Benzol (56) als Additionspartner isomerisiert das Primäraddukt der Codimerisierung, 54, zur Vinylcyclooctatetraen (55).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1105-1109 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkynes and Cumulenes, XVIII. On the Nieuwland Acetylene Oligomerization: Structure of the TetramersThe tetramers formed during the Nieuwland acetylene oligomerization are shown to be (E)- and (Z)-1,3,7-octatrien-5-yne [(E)- and (Z)-5] by their 1H and 13C NMR spectra as well as by chemical structure proof.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3772-3788 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkynes and Cumulenes, XV: On the Photodimerization of Conjugated EnynesOn irradiation in the presence of triplet sensitizers having a triplet energy 〉 250 KJ/mol, vinylacetylene (1a) dimerizes to cis-and trans-1,2-diethynylcyclobutane (cis and trans-2) as well as minor amounts of 4-ethynyl-1-vinylcyclobutene (3). The effect of substituents on the course of the reaction is investigated: whereas alkyl, vinyl, and phenyl substituents, respectively, in the 4-position of 1a do not influence the photoaddition, 2-substituted enynes yield the corresponding cyclobutanes in poor yields only. Finally, 1-substituted vinylacetylenes (besides the substituents mentioned above the influence of ethynyl, chloro, and methoxy groups has been investigated) do not provide photodimers; they are cis-trans-isomerized instead. The mechanism of the photoaddition is discussed.
    Notes: Vinylacetylen (1a) dimerisiert bie Bestrahlung in Gegenwart von Triplettsensibilisatoren mit einer Triplettenergie 〉 250 KJ/mol zu cis- und trans-1,2-Diethinylcyclobutan (cis- und trans-2) sowie kleineren Mengen an 4-Ethinyl-1-vinylcyclobuten (3). Die Auswirkung von Substituenten auf diese Reaktion wird untersucht: während Alkyl-, Vinyl- und Phenylsubstituenten in 4-Stellung von 1a keinen Einfluß auf die Photoaddition haben, dimerisieren 2-substituierte Enine nur noch in schlechten Ausbeuten zu den entsprechenden Cyclobutanen. Schließlich bilden. 1-Substituierte Vinylacetylene (außer den obigen Substituenten wurde der Einfluß von Ethinyl-, Chlor - und Methoxyresten untersucht) keine Photodimeren, sondern werden lediglich cis-trans-isomerisiert. Der Mechanismus der Photoaddition wird diskutiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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