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  • Inorganic Chemistry  (23)
  • Life and Medical Sciences  (21)
  • 550 - Earth sciences  (13)
  • 1
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stable Mercury(I)-Selenium Compounds, 1. Synthesis and Structure of Tetrakis(diphenylseleno)dimercury(I) Diperchlorate, Synthesis of Bis(diphenylseleno)dimercury(I) DinitrateThe new compounds 1 and 2 have been prepared by the reaction of diphenyl selenide with mercury(I) nitrate or perchlorate in methanolic solution. As shown by an X-ray analysis the structure of compound 1 contains the groups [(C6H5)2Se]2Hg-Hg[Se(C6H5)2]2 and O-coordinated ClO4⊖-anions. Compound 2 contains only 2 mol of diphenyl selenide for 1 mol of Hg2(NO3)2.
    Notes: Durch Umsetzung methanolischer Lösungen von Quecksilber(I)-nitrat bzw. -perchlorat mit Lösungen von Diphenylselenid in Methanol wurden die neuen Verbindungen 1 und 2 dargestellt. Nach röntgenographischen Untersuchungen liegen in 1 die Gruppen [(C6H5)2Se]2Hg—Hg[Se(C6H5)2]2 neben über ein O-Atom koordinierten ClO4⊖-Anionen vor. Die Verbindung 2 enthält nur 2 mol Diphenylselenid auf 1 mol Hg2(NO3)2.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1977-1979 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Säurekatalysierte Cyclisierung des En-Produkts aus α-Pinen und PTADAluminiumchlorid-katalysierte Reaktion des En-Produkts 2 aus 4-Phenyl-4H-1,2,4-triazol-3,5-dion (PTAD) und α-Pinen (1), des 1-(6,6-Dimelthyl-2-methylenbicyclo[3.1.1]hept-3-yl)-4-phenyl-1,2,4-triazolidin-3,5-dions, ergab 3,8,8-Trimelthyl-N-phenyl-4,5-diazatricyclo[4.2.1.03,7]nonan-4,5-dicarboxamid (6) in 78% Ausbeute. Auch Bortrifluorid-etherat, trockener Chlorwasserstoff und p-Toluolsulfonsäure katalysieren die Cyclisierung von 2 zu 6, aber nicht in diesem Maße. Der Mechanismus der Cyclisierung wird über eine Gerüstumlagerung der Carbenium-Ionen-Zwischenstufen gedeutet.
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition von Singulettsauerstoff und 4-Methyl-4H-1,2,4-triazol-3,5-dion an 7-Adamantyliden-1,3,5-cycloheptatrien und Derivate7-Adamantyliden-1,3,5-cycloheptatrien (18) wurde mittels Thermolyse des Thietans 22 hergestellt, welches wiederum durch Cycloaddition von 2-Adamantanthion mit 8-Oxoheptafulven (1) erhalten wurde. In dieser Reaktion wurde zusätzlich das Thiophen 23 erzeugt, anscheinend durch [8 + 2]-Cycloaddition. Die Addition von Singulettsauerstoff (1O2) an Heptafulven 18 führte zum [4 + 2]-Tropiliden-endoperoxid 24, während mit 4-Methyl-4H-1,2,4-triazol-3,5-dion (MTAD) das [8 + 2]-Urazol 26 gebildet wurde. Singulettsauerstoff-Addition an Thietan 22 ergab das [4 + 2]-Tropiliden-endoperoxid 27, aber mit MTAD wurde das gespannte [4 + 2]-Norcaradien-urazol 28 erhalten. Das Thiophen 23 führte mit 1O2 und mit MTAD zu den [4 + 2]-Norcaradienprodukten 29 bzw. 30, wovon die Struktur von 30 durch Röntgenstrukturanalyse ermittelt wurde.
    Notes: 7-Adamantylidene-1,3,5-cycloheptatriene (18) was prepared via thermolysis of the thietane 22, produced in the cycloaddition of 2-adamantanethione with 8-oxoheptafulvene (1). The latter reaction also afforded the thiophene 23, presumably via [8 + 2]-cycloaddition. Reaction of singlet oxygen (1O2) with heptafulvene 18 gave the [4 + 2]-tropilidene endoperoxide 24, while 4-methyl-4H-1,2,4-triazole-3,5-dione (MTAD) led to the [8 + 2]-urazole 26. Singlet oxygenation of thietane 22 produced the [4 + 2]-tropilidene endoperoxide 27, but with MTAD the strained [4 + 2]-norcaradiene urazole 28 was obtained. The thiophene 23 gave with 1O2 and MTAD the [4 + 2]-norcaradiene products 29 and 30, respectively. X-ray analysis confirmed the urazole 30 structure.
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  • 4
    ISSN: 0009-2940
    Keywords: ansa-Zirconocenes ; ansa-Titanocenes ; Alkyne complexes ; Pyridine ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reduction of the complex [(η5-C5H4)-ansa-(η5-C5H4)]TiCl2 with magnesium in the presence of Me3SiC2-SiMe3 in THF at room temperature gives the ansa-titanocone alkyne complex [(η5-C5H4)-ansa-(η5-C5H4)]Ti(η2-Me3SiC2-SiMe3) (ansa = Me2Si-O-SiMe2, 1). The similar pyridine-stabilized zirconium complexes could be obtained by analogous reactions and addition of pyridine: [(η5-C5H4)-ansa-(η5-C5H4)]Zr(L)(η2-Me3SiC2SiMe3) (ansa = Me2Si-O-SiMe2, L = pyridine: 2; ansa = SiMe2, L = pyridine: 3). All complexes were characterized by spectroscopic methods. An X-ray structure determination of complex 3 was conducted, and the data were compared to those of the complexes rac-(EB-HI)Zr(L)(η2-Me3SiC2SiMe3) [L = (S)-(-)-nicotine: 6, EBHI = ethylenebis(tetrahydroindenyl)] and Cp2Zr(py)(Me3SiC2-SiMe3).
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 967-971 
    ISSN: 0009-2940
    Keywords: Titanocene ; Diyne ; Cumulene ; Titanacyclopentadiene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first five-membered titanacyclic cumulene (5) was prepared by treatment of the titanocene generator Cp2Ti(Me3SiC2SiMe3) with the di-tert-butylbutadiyne in a molecular one-to-one ratio. The reaction of 5 with “Cp2Zr” or of the analogous complex with “Cp2Ti” leads to cleavage of the central C-C bond in the metallacyclocumulene complexes to afford the same product, the heterodimetallic ρ, π,-alkynyl-bridged titanocene-zirconocene complex Cp2Zr(μ-η1η2-C≡CtBu)Cp2Ti(μ-η1η2-C≡CtBu) (6), in which each alkynyl group is π-bonded to one and π-bonded to the other metal as shown by X-ray diffraction studies. In solution the two alkynyl groups become equivalent. The coupling reaction of “Cp2Ti” with bis(trimethylsilyl)butadiyne in a one-to-two molecular ratio leads to the unsymmetrically substituted titanacyclopentadiene (7).
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  • 6
    ISSN: 0009-2940
    Keywords: Zirconocenes ; Titanocenes ; N-Methyl-ε-caprolactam ; β-Propiolactam ; ε-Caprolactam ; Ring-opening polymerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the nature of the metal and the ring size, lactams react with titanocene and zircocene complexes of bis-(trimethylsilyl)acetylene Cp2Ti(Me3SiC2SiMe3) and Cp2Zr-(L)(Me3SiC2SiMe3) (L = Py, THF) to yield different products. In the reaction of Cp2Zr(Py)(Me3SiC2SiMe3) with N-methyl-€-caprolactam a simple ligand exchange reaction occurs and the complex Cp2Zr(Me3SiC2SiMe3)[O=H2)5] (1) was isolated. With β-propiolactam the alkenyl-amido complex Cp2)(SiMe3)][-NH2] (2) was obtained, which indicates that an agostic metal-hydrogen interaction has taken place. The reaction of Cp2Ti(Me3-SiC2SiMe3) with €-caprolactam gives after elimination of the alkyne and molecular hydrogen the first early transition metal complex with a deprotonated coordinated €-caprolactam in a η2-amidate bonding fashion (3). The obtained complexes were characterized by NMR spectra (1, 2) and crystal structure analysis (1-3) and discussed as elemental steps in anionic ring-opening polymerization of lactams catalyzed by metallocene-alkyne complexes.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 207-211 
    ISSN: 0009-2940
    Keywords: Zirconocene ; Titanocene ; Benzoxazoles ; Thiazoles ; Benzisoxazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zirconocene alkyne complexes Cp2Zr(L)(Me3SiC2R) (L = Py, THF; R = SiMe3 tBu) react with heterocyclic compounds like benzoxazole and related thiazoles to yield ring-expanded adducts (1-3) and (4, 5) by formal C-X (X = O, S) bond cleavage and coupling with the coordinated alkyne. In the case of benziso-xazole, the alkyne is not coupled but eliminated, and with ring-enlargement of the benzisoxazole a N-bridged dimer (6) is formed. The obtained complexes 1, 3, and 6 were characterized by NMR spectra and crystal structure analysis.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 156 (1926), S. 20-26 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 17 Ill.
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  • 9
    ISSN: 0730-2312
    Keywords: IGF-I receptor ; T-cells ; OKT-3 ; PHA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The biological effects of the IGFs are mediated through interaction with specific cell surface receptors. It has been previously reported that mitogenic activation of T-lymphocytes by phytohemagglutinin (PHA) is associated with increased IGF-I receptor content. However, the mechanisms which regulate IGF-I receptor expression during T-lymphocyte activation are unknown. To explore further the regulation of IGF-I receptor expression in T-cells, we investigated IGF-I receptor content and mRNA abundance in T-lymphocytes after stimulation either by PHA or OKT-3, the latter being a monoclonal antibody directed against the CD-3 antigen of the T-cell receptor IGF-I binding in T-cells demonstrated increased IGF-I receptor content after stimulation by both PHA and OKT-3. Peak binding was induced after 72 h of treatment with PHA and 48 h of treatment with OKT-3. Affinity cross-linking of 125I-IGF-I to T-cell membranes demonstrated a single ∼ 130 kDa band which was increased after treatment with PHA or OKT-3. This band was inhibited by the addition of α-IR3, a monoclonal antibody to the IGF-I receptor. Both PHA and OKT-3 increased IGF-I receptor mRNA abundance with peak increases at 20 h and 60 h, respectively. Parallel increases in IGF-I receptor and β-actin mRNA abundance were observed, consistent with previous studies demonstrating increased actin gene expression after T-cell activation. Thus, the increase in IGF-I receptor mRNA abundance markedly preceded the increase in IGF-I receptor content after PHA stimulation, but the increase in IGF-I receptor mRNA abundance followed the increase in IGF-I receptor content after OKT-3. These studies suggest, therefore, that IGF-I receptor content in both of these activated cells is not regulated primarily at the level of steady state mRNA.
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  • 10
    ISSN: 0730-2312
    Keywords: mouse sarcoma 180 cells ; tissue inhibitor of metalloproteinases ; angiogenesis ; endothelial cells ; metalloproteinases ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have previously shown that mouse sarcoma 180 cells produce vascular endothelial growth factor [VGEF; Rosenthal et al., 1990, Growth Factors, 4: 53-59], endothelial mitogen that stimulates angiogeneis. Recent reports have implicated metallaproteinases and their inhibitors in the regulation of vascular morphogeneis, tumor invasion, and metastasis. We report here that mouse sarcoma 180 cells produce two collagenase inhibitors. These inhibitors were purified by heparin-Sepharose affinity chromatography, gel filtration, and C4 reverse phase h.p.l.c. Analytical gel electrophoresis of the purified inhibitors (MS-22 and MS-31) revealed molecular masses of 22,000 and 32,000 Da under reducing conditions, and 20,000 and 30,000 Da under nonreducing conditions, respectively. The NH2-terminal amino acid sequence of MS-22 was identical to that of tissue inhibitor of metalloproiteinases type 2 (TIMP-2) produced by human melanoma cells (Stetler-Stevenson et al., 1989, J. Biol. Chem. 264: 17374-17378) over the first 30 amino acids. The NH2-terminal amino acid sequence of MS-31 was identical to that of murine TIMP-1 [Gewert et al., 1989 EMBO J 6:651-657]. Statistical analysis of the amino acid composition data of these two mouse sarcoma 180-derived collagenase inhibitors confirms the identificationof MS-22 as TIMP-2 and MS-31 as TIMP-1.
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