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  • 1
    Electronic Resource
    Electronic Resource
    Dominance of through-bond interaction in a syn-tricyclo[6.4.0.02,7]dodecatetraene moiety (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3856-3860 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dominanz der Through-Bond-Wechselwirkung bei einer Verbindung mit syn-Tricyclo[6.4.0.02,7]dodecatetraen-EinheitDas He(I)-Photoelektronen(PE)-Spektrum von 3, einer Verbindung mit der syn-Tricyclo[6.4.0.02,7]dodecatetraen-Einheit 2, wurde durch Vergleich mit dem des anti-Tricyclo[6.4.0.02,7]dodecatetraens 1 und durch semiempirische Rechnungen zugeordnet. Es wird gezeigt, daß bei 3 die through-bond-Wechselwirkung zwischen den beiden Butadien-Einheiten über die through-space-Wechselwirkung dominiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180935
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  • 2
    Electronic Resource
    Electronic Resource
    Verbotene Reaktionen.  -  [2 + 2]-Cycloreversion starrer Cyclobutane (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1-9 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Forbidden Reactions.  -  [2 + 2] Cycloreversion of Rigid CyclobutanesCyclobutane derivatives, severely restrained from generating noninteractive 1,4-diradicals, are examined thermochemically to provide quantitative evidence to support a forbidden-concerted, antiaromatic mechanism for their [2 + 2] cyclorevision.
    Notes: Die thermochemische Analyse von Cyclobutanderivaten, die keine wechselwirkungsfreien 1,4-Diradikale bilden können, liefert quantitative Evidenz für einen symmetrieverbotenen, konzertierten Mechanismus ihrer [2 + 2]-Cycloreversion mit antiaromatischem Übergangszustand.
    Additional Material: 14 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210102
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  • 3
    Electronic Resource
    Electronic Resource
    The Pagodane Route to Dodecahedranes Unsaturated (Hyperstable) and Saturated BissecododecahedranesDedicated to Prof. Dr. Günther Maier on the occasion of his 60th birthday (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1719-1739 
    Details
    ISSN: 0009-2940
    Keywords: Bissecododecahedranes, saturated, unsaturated ; Homoconjugation ; Hyperstability ; Addition reactions ; Cage effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In bissecododecahedra-1,10(11)-dienes, the syn-periplanar and unusually proximate arrangement of the π bonds is responsible for extraordinary physical properties such as strong throughspace homoconjugation, low oxidation potentials, and a special reactivity pattern. In pursuit of route B to dodecahedranes[1], the hyperstability predicted (MM2) for these bissecodienes and the related monoenes has been experimentally verified only for the latter in their resistance towards catalytic hydrogenation. Non-hydrogenative saturation of (3,8-difunctionalized) bissecodienes (3, 8, 13) and monoenes (4, 9, 14) becomes increasingly hampered due to the increased steric congestion on the more spherical molecular surfaces but can be achieved in „high-driving-force” reactions [cis-hydroxylation (26, 27, 41, 42), epoxidation (38, 54, 57, 58, 60, 63, 80, 83), cyclopropanation (55, 59, 61, 64]. In contrast, cycloadditive four-, five- (73), and six-membered (76) ring annulation again is limited to monoadditions. The half-cages in the bissecododecahedrane structures provide for remarkable steric steering and protection [e.g. anti-selective protonation (alkylation) of carbanions 57a (84a)2-, lack of hydrazone formation from ketones 58, 89, resistance of syn-bis(acid chloride) 86 towards hydrolysis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250728
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  • 4
    Electronic Resource
    Electronic Resource
    The Pagodane Route to Dodecahedranes Scope and Limitation of the Dehydrocyclization StratagemDedicated to Prof. Dr. George A. Olah on the occasion of his 65th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1741-1751 
    Details
    ISSN: 0009-2940
    Keywords: Bissecododecahedranes, hydrogenolysis, catalytic dehydrocyclization ; Dodecahedranes ; Cyclizations, non-dehydrogenative ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stepwise route B from pagodanes to dodecahedranes was completed by double catalytic dehydrocyclization of saturated (alkylated) bisseco precursor substrates (2, 3, 5, 16). Based on pagodane, dodecahedranes (9, 10, 13, 14, 17) were obtained in up to 53% yield. Transannular C,C bond formation at the bisseco stage and partial (C-alkyl) or total (C-OR, C-CO2R) removal of substituent groups under the necessarily forcing reaction conditions constituted preparative limitations. Attempts at alternative ring closure methodologies (homo-Norrish type II, homoenolization, carbene insertion) have remained unsuccessful.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250729
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  • 5
    Electronic Resource
    Electronic Resource
    The Pagodane Route to Dodecahedranes Directed Conversions - The Pagodane → Bissecododecahedradiene StageDedicated to Prof. Dr. William von E. Doering on the occasion of his 75th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1697-1717 
    Details
    ISSN: 0009-2940
    Keywords: Pagodane → dodecahedrane pathways ; Pagodane opening reactions ; Cage effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three conceptual routes (A, B, C) from [1.1.1.1]pagodane (1) to pentagonal dodecahedrane (2) are evaluated by MM2 (MM3) calculations. After limited experimental success with a catalytic one-pot route (A), a more selective transformation along one of two stepwise routes (B/C) is explored. An expeditious entry into route C is achieved by hydrogenolytic cyclobutane opening in 1; secopagodane 7 (100%), however, resists both progression along route C (dehydrogenative C - C bond formation to isododecahedrane 8) and crossover into route B (hydrogenolysis to bissecododecahedrane 5). The first transformation along route B, the 2sigma;→2π-isomerization of the highly strained 1 to bissedodecahedra-1,10(11)-diene 3, is not attainable by metal catalysis and cannot productively be brought about by thermal activation: The necessarily very high reaction temperatures (〉 700°C) enforce instead a mechanistically interesting fragmentation into two C10H10 halves to give ultimately naphthalene. The very rapid pagodane opening occurring after one-electron oxidation, too, is not a preparatively useful alternative. Highly efficient, on the other hand, is a two-step process affording a high yield of the product and consisting of regiospecific, photochemically induced bromine addition to the central four-membered ring (→ dibromosecopagodane 37) followed by reductive bromine elimination (→ diene 3). In spite of the necessarily rather severe reaction conditions in both steps, this procedure is applicable to the preparation of various 3,8-difunctionalized bissecodienes (dienedione 11, diene diesters 43, 50, 52, dichlorodiene 56). Limitations of this procedure are met with the 4,4,9,9-tetrachloropagodane 60 (inert) and the [2.2.1.1]pagodane 80 (bridgehead bromination). The lateral half-cages of the (seco)-pagodane structures are explored for preparatively (dis)advantageous steric effects, that might be later exploited on the way towards functionalized dodecahedrane derivatives.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250727
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Gasphasenoxidation („Charge-Stripping“) von ionisierten Pagodanen und verwandten Käfigkohlenwasserstoffen.  -  Eine theoretisch-experimentelle Studie zu Tetramethylen-Dikationen (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 187-189 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-Phase Oxidation (“Charge Stripping”) of Pagodane Radical Cations and Related Cage Hydrocarbons.  -  A Theoretical-Experimental Search into Tetramethylene DicationsA theoretical screening of the family of tetramethylene dications furnished the open C2h trans configuration as the global minimum. The pagodane dications must owe their stability to the rigidity of their molecular framework. By means of charge-strip-Ping mass spectrometry stable dications could be generated for [1.1.1.1]pagodane, its diene valence isomer, and several analogues (including „half-pagodanes“). Ionization energies for the gas-phase oxidation of the radical cations were determined. A distinction whether common or isomeric radical cations serve as precursors in the charge stripping reactions could not be achieved due to either the relatively large uncertainties in the determination of the Qmin values or due the fact that in these particular cases charge stripping does not discriminate between structurally closely related hydrocarbon isomers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210126
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  • 8
    Electronic Resource
    Electronic Resource
    Electronic Interactions in Saturated and Unsaturated [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]Triblattanes  -  PE-Spectroscopic Investigations (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2299-2307 
    Details
    ISSN: 0009-2940
    Keywords: Triblattanes ; PE ; Orbital sequence ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(I)-PE spectra of the parent [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]triblattanes 1-4, of their unsaturated or ketonic congeners 5-13 and benzo derivatives 14-20 have been recorded. For 1-4, the energy difference between the highest occupied orbitals (e” and a' mainly localized at the central bicyclo-[2.2.2]octane unit) and the subsequent MOs increases with increasing number of ethano bridges. This observation is rationalized by using a first-order perturbation-theoretical approach. The analysis of the PE spectra of the exo-methylene (5-7), ketone (8-10), and endo-olefinic derivatives (11-13) unveils a strong π/σ mixing. The splitting of the π-bands in 7 (0.95 eV) and 13 (1.0 eV), respectively, is traced back to a stronger π/σ mixing of the e MOs as compared to the a2 MOs. An analogous interaction causes the splitting of the first bands of the ketones 8-10 (0.45-1.49 eV). For the benzo derivatives 14-20 the split of the π-bands is relatively small (0.35-0.7 eV).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261019
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  • 9
    Electronic Resource
    Electronic Resource
    Functionalized Enantiomerically Pure [1.1.1]-, [2.1.1]-, [2.2.1]-, and [2.2.2]Triblattanes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2275-2297 
    Details
    ISSN: 0009-2940
    Keywords: Trishomocubanes ; Spirocyclopropanes ; [1.1.1]-, [2.1.1]-, [2.2.1]-, [2.2.2]Triblattanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methylene (2, 7, 10) and spirocyclopropane derivatives (8, 11, 12) are made accessible from rac-trishomocubane(mono-, di-, tri-)ones and optically pure unsaturated and benzoannulated [2.1.1]- (19, 48), [2.2.1]- (30, 53), and D3-symmetrical [2.2.2]triblattanes (3, 4) from the enantiomers of these ketones by expeditious (one pot) ring enlargement and olefination procedures. In the case of the central [2.2.2]trienes (+)-3/( - )-3, novel members of the (CH)14 family, optical resolution is advantageously postponed to the stage of the intermediate [2.2.2]triones (35, 41) and effected via their (R,R)-2,3-butanediol acetals. In the α-diketone series only the [2.1.1]dione (70) is sufficiently stable to allow isolation; tetrone 73 and hexone 5 are indirectly identified as quinoxalines 74 and 76, respectively. Tribenzo[2.2.2]triblattane ( - )-4 is established as the M-helical enantiomer by X-ray crystallography. Generally the thermal stabilization pathway of unsaturated and benzoannulated triblattanes is a [4 + 2] cycloreversion with the primary cycloreversion products [e.g. (1α,2α,7α,10α)-tricyclo[8.4.0.02,7]tetradeca-3,5,9,11,13-pentaene (78) from rac-3] being unstable under the drastic reaction conditions required. The stereochemical course of the perepoxidation of rac-3 is investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261018
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