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  • Carbonyl ylides  (1)
  • Cyclodextrin inclusion compound  (1)
  • [6 + 4] Tropone dimerization  (1)
  • 1990-1994  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Molecular encapsulation of transition metal complexes in cyclodextrins. Part 2. Synthesis and crystal structures of 2:1 adducts between α-cyclodextrin and metallocenium hexafluorophosphates [η5-C5H5)2M]PF6(M = Fe, Co, Rh) (1991)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 10 (1991), S. 255-265 
    Details
    ISSN: 1573-1111
    Keywords: Cyclodextrin inclusion compound ; metallocene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title metallocenium salts form crystalline 2:1 host:guest inclusion compounds withα-cyclodextrin, [(η5-C5H5)2M]PF6 · 2α-CD · 8H2O (1, M = Fe;2, M = Co;3, M = Rh). The X-ray crystal structures of1 and3, and the lattice constants, crystal system and space group of2 have been determined. Crystal data: triclinic, space groupP1 (No. 1),Z = 1;1,a = 13.865 (2) Å,b = 13.839 (2) Å,c = 15.520 (2) Å,α = 91.43 (2)°,β = 85.81 (2)°,γ = 120.22 (2)°, andR F = 0.089 for 4257 observed MoK α reflections [I 〉 3δ(I)];2,a = 13.810 (2) Å,b = 13.872 (2) Å,c = 15.560 (2) Å,α = 93.99 (2)°,β = 87.06 (2)°,γ = 120.04 (2)°;3,a = 13.756 (1) Å,b = 13.863 (1) Å,c = 15.561 (2) Å,α =94.39 (1)°,β = 86.92 (1)°,γ = 119.89 (1)°, andR F = 0.061 for 11142 observed MoK α reflections [I 〉 3δ(I)]. In the crystals of1 and3, two α-cyclodextrin molecules are arranged head-to-head to form a dimer by means of intermolecular hydrogen bonding across the secondary hydroxyl faces of adjacent α-CD monomers. The dimers are stacked along the crystallographicc axis to form a channel-type structure. The metallocenium cation is encapsulated within the cavity of the dimer, while the PF 6 − anion is located outside the cavity, being centered between the primary hydroxyl faces of adjacent dimers. Eight water molecules of hydration per asymmetric unit reside in the spaces between the α-CD columns. In view of the almost identical crystal data for2 a similar structure can be assumed for the cobaltocenium adduct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066209
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  • 2
    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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  • 3
    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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