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  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymers containing 1-trifluoromethylvinylene, 1,4-phenylene, and/or 2,5-thiophenediyl units (6a, b and 8a-d), obtained by base-free Wittig condensation reactions with phase transfer catalysts, were investigated combining direct evaporation in the ion source of a double focusing mass spectrometer with the “Linked-Scan” metastable technique. This method could be shown to allow the unequivocal identification and differentiation of components in polymers up to high mass regions (m/z ≤ 3000). The degree of polycondensation up to 18 aromatic/heteroaromatic units in the chain was determined by mass chromatography, which correlated with the HPLC results. Terminal groups and sequence ions were characterized by comparison of metastable transitions of selected ions with model compounds. Detailed information on the polycondensation reaction was obtained. In addition to linear products, cyclic species with 3 to 18 arylene-1-trifluoromethylvinylene units were formed. The main fragmentations may be explained by sterical effects of both the α-trifluoromethylstilbene moiety and the heteroaromatic analogues in the polymeric chains.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 130 (1923), S. 199-204 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2914-2920 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wittig Reactions of Cyanohydrines and Redox Reaction of 4-NitromandelonitrileSubstitued mandelonitriles 5 (R1 = H, OCH3, NO2) react in the presence of sodium tert- butoxide as a base like the corresponding aldehydes with substituted benzylidenetriphenylphosphoranes via the Wittig reaction to yield 4,4′-disubstituted stilbenes 8, for which the (E)/(Z) stereoisomer ratios are given. Our results refer to a reaction with a preceding cyanohydrine-aldehyde equilibrium. 4-Nitromandelonitrile (5a) forms in a basic methanolic solution via a redox reaction a mixture of dimethyl 4,4′-azoxybenzenedicarboxylate (11) and methyl 4-nitrobenzoate (12).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3384-3388 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and X-Ray Structure of (E)-α-(Trifluoromethyl)stilbeneStarting from benzyltriphenylphosphonium chloride and ω,ω,ω-trifluoroacetophenone α-(trifluoromethyl)stilbene was prepared with 91% yield with a phase transfer-catalyzed Wittig reaction with solid KF but without bases. The isolated isomer was found by X-ray structure analysis to have the thermodynamic preferred (E)-configuration. For this configuration it was determined a torsion angle of 71.3° between the two cis-configurated phenyl rings because of steric hindrance. AH⃜F hydrogen bridge (distance: 223.8 pm) stabilizes the (E)-isomer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2342-2346 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Basefree Wittig Reactions with Phase Transfer CatalytsKetones like trifluoroacetyl compounds  -  giving the haloform reaction in basic solutions  -  are able to react with mono or bis phosphonium fluorides without bases via Wittig reactions with very good yields. The phosphonium fluorides are prepared very easily from other phosphonium halides under phase transfer catalysis of crown ethers. The ratio of the stereoisomeric alkenes in the product and the spectra of the trans- respectively trans-trans alkenes are given.
    Additional Material: 2 Tab.
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  • 6
    ISSN: 0170-2041
    Keywords: Deoxyfuconojirimycin ; Amino sugars ; Indolizidine derivatives ; Fucosidase inhibitors ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monosaccharides Containing Nitrogen in the Ring, XXXIX.  -  Synthesis of Analogues of 1,5-Dideoxy-1,5-imino-L-fucitol, Inhibitors of α-L-FucosidaseVariation of the side chain in the 1,3-dithiane derivative 1 of D-galactose leads to a series of analogues of 1,5-dideoxy-1,5-imino-L-fucitol (deoxyfuconojirimycin) (33), which are potent inhibitors of α-L-fucosidase. Cleavage of the dithioacetal in 5 followed by reduction of the aldehyde 6 and deblocking results in 1,5-dideoxy-1,5-imino-L-galactitol (8). The aldehyde 6 is converted by Wittig reaction to 10 and 14 via 9 and 13, which are homologues of 1,5-dideoxy-1,5-imino-L-fucitol (33). Cyclization of the Wittig product 15 yields the γ-lactam 18. After reduction of the acetylated γ-lactam 19 and subsequent deblocking the trihydroxyindolizidine 24 is obtained, which is an analogue of castanospermine with L-fuco configuration. The chloride 30, which is available from 27, can be converted by intramolecular substitution and removal of the blocking groups to the bicyclic aziridine derivative (3R,4S,5R,6S) -1-azabicyclo[4.1.0]heptane-3,4,5-triol (32). First results on the inhibitory activities of all new analogues on α-L-fucosidase are presented.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 11 (1960), S. 11-19 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Epoxydverbindungen werden durch Umsetzung mit Phenolsulfonsäuren, Pikrinsäure, Pikramid und N-Methylpikramid in Dioxan in Derivate überführt. Es bilden sich durch Öffnung des Epoxydrings in 1- bzw. 2-Stellung jeweils zwei stellungsisomere Derivate. Für die Papierchromatographie eignen sich insbesondere die durch Umsetzung mit Pikrinsäure in Dioxan in der Siedehitze erhaltenen Derivate. Ihr papierchromatographisches Verhalten wurde näher untersucht. Sie werden auf formamidimprägniertem Papier mit Mischungen von Zyklohexan-Toluol (insbesondere 2:1) chromatographiert. Da die Farbe der Derivate pH-abhängig ist, ist für jede Verbindung zunächst nur ein orangefarbiger Fleck sichtbar. Erst bei höherem pH-Wert (Behandeln mit Ammoniak-Dampf) wird das zweite, stellungsisomere Derivat als gelber, im UV-Licht fluoreszierender Fleck sichtbar.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 11 (1960), S. 1-10 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Das Verhalten von Epoxydverbindungen (Epichlorhydrin, Glyzidol sowie verschiedener Mono- und Bis-Glycidäther) bei der Papierchromatographie und insbesondere ihr Nachweis auf dem Papier wurde untersucht. Epichlorhydrin und Alkyl-monoglycidäther von C1 bis C6-Alkoholen verdunsten zu schnell vom Papier und lassen sich daher nicht direkt chromatographieren.Schwerer flüchtige hydrophile Epoxydverbindungen können mit Petroläther-n-Propanol-Wasser (1:7:2) bzw. Petroläther-Methanol-Wasser (2:1:1) chromatographiert werden.Höhere Bis-glycidäther sind bereits zu hydrophob und laufen auf nicht vorbehandeltem Papier in allen Fließmittelsystemen an der Front mit.Der Nachweis von Epoxydverbindungen auf dem Papier mit Na-Thiosulfat/Bromthymolblau bzw. nach Umwandlung auf dem Papier in γ-Oxyamine mit Ninhydrin ist ziemlich unempfindlich (Nachweisgrenzen 150 bis 300 bzw. 50 bis 100 μg). Es ist daher zweckmäßiger, die Epoxydverbindungen in Form leicht nachweisbarer, schwerflüchtiger Derivate zu chromatographieren.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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