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  • 1
    Electronic Resource
    Electronic Resource
    Photochemical Behavior of Doubly Bridged Dewar Benzenes - Synthesis of PrismanesDedicated to Professor Horst Prinzbach on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1627-1634 
    Details
    ISSN: 0947-3440
    Keywords: Photochemistry ; Cage compounds ; Dewar benzenes ; Prismanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we report on the photochemistry of Dewar benzenes bridged at the 1,4- and 5,6-positions and substituted at the 2,3-positions. It was found that simple alkyl substitution leads to prismanes only to a minor extent. Introduction of phenyl groups into the 2- or 2,3-positions gives the corresponding doubly bridged prismanes in yields up to 80% Pentamethylene-bridged bis-Dewar benzenes 19 rearrange upon irradiation to 22. Irradiation of the doubly bridged Dewar benzene derivatives with one ester group at the 5-position does not yield isolable products. However, introduction of one tert-butylsulfonyl group such as 30-33 gives almost quantitative yields of isolable prismanes if pentamethylene or hexamethylene bridges are used. The nonbridged species, 2-tert-butylsulfonyl-1,4,5,6-tetramethylbicyclo[2.2.0]hexa-2,5-diene (44), aromatizes upon irradiation into 1-(tert-butylsulfonyl)-2,3,4,5-tetramethylbenzene (45). In contrast to the pentamethylene-bridged monosulfone 47, the corresponding disulfone 38 undergoes no photochemical reaction. This could be explained by the X-ray structure, which reveals a strong interaction between one of the tert-butyl groups and the pentamethylene chain bridging the double bond in 38.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961020
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  • 2
    Electronic Resource
    Electronic Resource
    Syntheses of Donor-Acceptor-Substituted 2,6-Stellanes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 73-81 
    Details
    ISSN: 1434-193X
    Keywords: Donor-acceptor systems ; Cage compounds ; Stelladione ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A number of condensations could be carried out using tricyclo[3.3.0.03,7]octane-2-one (stellanone, 4) and tricyclo[3.3.0.03,7]octane-2,6-dione (2,6-stelladione, 5) as starting materials. The components for condensations were 2-trimethylsilyl-1,3-dithiane (6), 1,1-bis(trimethylsilyl)-1H-cyclopropa[b]naphthalene (7), its 3,6-dimethoxy-substituted analogue 8, fluorene (12), xanthene (13), diethyl malonate (14), and malononitrile (15). The condensation reactions with 5 yielded mono- and disubstituted products, among them were the donor-acceptor-substituted 2,6-stellanes 33-35. The structures of 18 (prepared from stellanone and fluorene), 19, 24, 27, 31 and 32 (synthesized by condensation of 2,6-stelladione and 2-trimethylsilyl-1,3-dithiane and malononitrile, respectively) were determined by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Highly Strained Cage Compounds from a Fourfold Bridged Tricyclo[4.2.0.02,5]octa-3,7-diene (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1011-1013 
    Details
    ISSN: 0009-2940
    Keywords: Cage compounds ; Propellanes ; Bridged tricyclo[4.2.0.02,5]octa-3,7-diene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fourfold bridged tricyclo[4.2.0.02,5]octa-3,7-diene derivative 3 reacts with diazomethane and m1-chloroperbenzoic acid (mCPBA) to yield the monoadduct 5 in good and the bisadduct 4 in poor yield as well as the mono-and bisepoxides 7 and 8 in good yields, respectively. Also the “mixed” product 6 is obtained. All five compounds are strained propellanes. The X-ray crystallographic structure analysis of 8 reveals a distance of 2.812 Å between the epoxide rings.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260422
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