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  • 1
    Electronic Resource
    Electronic Resource
    Photochemische Mitteilungen, 76 Studien im Umfeld der Oxanorbornadien → Oxepin-Isomerisierung. Eine intramolekulare Dien/Enon-[4 + 2]-Photocycloaddition (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2465-2474 
    Details
    ISSN: 0009-2940
    Keywords: Oxanorbornadiene → oxepine isomerization, limitations ; [6 + 4] Tropone dimerization ; Diene enone [4 + 2] photocycloaddition, intramolecular ; Oxaquadricyclanes, X-ray structure, thermolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Transformations, 761). - Studies in the Area of the Oxanorbornadiene → Oxepine Isomerization. An Intramolecular Diene/Enone [4 + 2] PhotocycloadditionAt room temperature, the “tropone-annulated” oxanorborna diene 2b dimerizes regio- and stereospecifically to give a [6 + 4] adduct (5). Direct photoexcitation of this adduct induces intramolecular diene/enone [4 + 2] addition to 16 followed by a [2 + 2] cycloaddition to provide the dodecacycle 17. An X- ray crystal structure analysis of 17 documents the influence of the heteroatom and of the quasi-bisected ester functions on the length of the three types of oxaquadricyclane - three-membered ring bonds. Direct and sensitized excitation of 2b, c produces polymers; yet, after changing the troponoid chromophor (9, 10) oxaquadricyclane formation takes place (13, 14). In the thermolysis of the annulated oxaquadricyclanes (13, 14) the different cyclopropane C - C bonds are cleaved at a comparable rate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241117
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  • 2
    Electronic Resource
    Electronic Resource
    Studien im Umfeld funktionalisierter/anellierter acs-Tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-dien-Gerüste  -  Röntgenstrukturanalysen einer „face-to-face“-Dibenzoverbindung und eines Tetraoxadihydro-pagodans (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3442-3472 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies towards Functionalized/Annulated acs-Tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-diene Skeletons  -  X-ray Structural Analyses of a „face-to-face“ Dibenzo Compound and a TetraoxadihydropagodaneHexacyclo[5.4.1.02,6.03,10.04,8.09,12]dodecane-5,11-dione (15), which is efficiently available from 7-acetoxynorbornadiene (1) and tetrachlorocyclopentadienone dimethyl acetal, is the key substance for the synthesis of hexacyclo[6.5.1.02,7.03,11.04,9.010,14]tetradeca-5,12-diene (24) as well as of various 5,12-functionalized acs-tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-dienes (32, 36, 40, 41), of some related 2,3-benzo- (84, 85) and „face-to-face“ 2,3:7,8-dibenzo compounds (54-58), which are sought as photosubstrates. The two isomeric „face-to-face“ dipyridazines 65/68 are obtained starting from a pagodane intermediate (60) via the tetraformyl derivative 63. X-ray structural analyses together with MM2 calculations for the dibenzo compound 54 and for the tetraoxadihydropagodane 64 (a [4]peristylane) derived from 63, provide detailed structural informations.
    Notes: Das aus 7-Acetoxynorbornadien (1) und Tetrachlorcyclopentadienon-dimethylacetal effizient zugängliche Hexacyclo[5.4.1.02,6.03,10.04,8.09,12]dodecan-5,11-dion (15) ist die Schlüsselsubstanz für die Herstellung des Hexacyclo[6.5.1.02,7.03,10.04,9.010,14]tetradeca-5,12-diens (24) sowie einiger u. a. als Photosubstrate gesuchter, unterschiedlich 5,12-funktionalisierter acs-Tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-diene (32, 36, 40, 41), der zugehörigen 2,3-Benzo- (84, 85) und „face-to-face“ 2,3:7,8-Dibenzoverbindungen (54-58). Die zwei isomeren „face-to-face“-Dipyridazine 65/68 werden, ausgehend von einem Pagodan-Zwischenprodukt (60), über das Tetraformylintermediat 63 synthetisiert. Für die Dibenzoverbindung 54 und das aus 63 entstandene Tetraoxadihydro-pagodan 64 (ein [4]Peristylan) liefern Röntgenstrukturanalysen, im Vergleich mit MM2-Rechnungen, detaillierte Strukturinformationen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191121
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  • 3
    Electronic Resource
    Electronic Resource
    cis-/trans-[1.1.1]-Trithia- und trans-[4.4.4]-Hexathia-tris-σ-homobenzole (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 741-756 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: cis-/trans-[1.1.1]-Trithia- and trans-[4.4.4]-Hexathia-tris-σ-homobenzenesStarting from the cis- and trans-benzene trioxides 2/7 the cis-/trans-[1.1.1]-Trithia-tris-σ-homobenzenes 1/6 and the trans-dioxathia-/oxadithia analogs 19/21 are synthesized by regioselective epoxide opening reactions with appropriate S-nucleophiles. Under the influence of heat and light cis-trisulfide 1 quickly looses sulfur and does not undergo [σ2 + σ2 + σ2]cycloreversion. Attempts to build up cis-[4.4.4]-tris-σ-homobenzenes from 2 by threefold six-membered ring anellation, in the special case of 1,2-benzenedithiol as 1,4-dinucleophil, led preferably to the trans-[4.4.4]-hexathia-tris-σ-homobenzene 44 (X-ray analysis) manifesting effective S-neighbouring group participation. cis-Trisulfide 1 is a poor tridentate ligand: only with Ni(ClO4)2 a 2:1 complex (presumably octahedral, 48) is formed.
    Notes: Die cis-/trans-[1.1.1]-Trithia-tris-σ-homobenzole 1/6 und die trans-O,O,S-/O,S,S-Analogen 19/21 wurden ausgehend von den cis-/trans-Trioxiden 2/7 über regioselektive Epoxidöffnungsreaktionen mit geeigenten S-Nucleophilen hergestellt. cis-Trisulfid 1 verliert bei Wärme- bzw. Lichteinfluß rasch Schwefel bzw. geht nicht die [σ2 + σ2 + σ2]-Cycloreversion ein. Versuche, ausgehend vom cis-Trioxid 2 unter dreifacher Sechsringanellierung cis-[4.4.4]-Tris-σ-homobenzol-Gerüste aufzubauen, ergaben mit 1,2-Benzoldithiol als 1,4-Dinucleophil bevorzugt trans-[4.4.4]-Hexathia-tris-σ-homobenzol 44 (Röntgenstrukturanalyse)  -  als Ergebnis effizienter S-Nachbargruppenbeteiligung. cis-Trisulfid 1 ist ein mäßiger dreizähniger Ligand, nur mit Ni(ClO4)2 wurde ein (wahrscheinlich octaedrischer) 2:1-Komplex (48) gebildet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210422
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  • 4
    Electronic Resource
    Electronic Resource
    Ein neuer Weg zu isoanellierten Heteroaromaten, 1. Synthese und Reaktionen von Furofuranen, Thienofuranen, Furobenzofuranen und Benzothienofuranen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 975-995 
    Details
    ISSN: 0009-2940
    Keywords: Pentalenes, dihetero- ; Cyclizations, 1,7-dipolar ; Carbonyl ylides ; Cycloallenes ; Diels-Alder reactions ; o1-Quinodimethanes, hetero analogues ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Route to Isoannulated Heteroaromatic Compounds, 1. - Synthesis and Reactions of Furofurans, Thienofurans, Furobenzofurans, and BenzothienofuransA general method for the synthesis of furo-and thienofurans 4-7 has been developed. The reaction principle is based on the thermal transformation of suitably structured epoxyhexenynes (15-19) following the general reaction sequence 1→2→3 (annulation type A). Derivatives of the so far unknown diheteropentalenes furo[3,4-b]furan (4b, c, d, g, h), furo-[3,4-b]benzofuran (6b, d, e, 45) as well as benzo[4,5]thieno-[2,3-c]furan (7b, d) are obtained by short-time thermolysis. Likewise two representatives of the previously reported thieno[2,3-c]furan system are prepared (5b, c). By flash vacuum thermolysis the benzo-annulated epoxyhexenyne 19b rearranges in poor yield to the isobenzofuran 52 (identified as dimethyl acetylenedicarboxylate adduct 47) and 2-cyano-α1-naphthol (46). The structure of the furo[3,4-b]furan 4b has been established by X-ray structural analysis. A mechanistic explanation of the transformation of the epoxyhexenynes to diheteropentalenes is proposed. Indications for the occurrence of carbenes as product-determining species are obtained with the phenylcyano-substituted oxiranes 15c, h and 17e which - in additon to the furofurans 4c, h and 6e - lead to the furylindenes 31c, h/32c, h and 41, resp. The Diels-Alder reactivity of the furo-and thienofurans 4g, 5b, c, and 6b has been examined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260419
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