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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 947-958 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intermediacy of metallocarbenes in decomposition reactions of iodonium ylides with [Rh2(OAc)4] was established by comparison with reactions of the corresponding diazo compounds. The sensitivity of the RhII-catalyzed intermolecular cyclopropane formation from substituted styrenes and bis(methoxycarbonyl)(phenyliodono)methanide (1a) or dimethyl diazomalonate (1b) is identical. The Hammett plot (with σ+) has a slope of -0.47. Iodonium ylides and diazo compounds afford the same products in [Rh2(OAc)4]-catalyzed cyclopropane formations, cycloadditions, and intramolecular CH insertions, and exhibit the identical selectivity in intramolecular competitions for cyclopropane formation and insertion. The intramolecular CH insertion of the ylide 20c, when carried out in the presence of a chiral catalyst ([Rh2{(-)-(S)-ptpa}4]), results in formation of 21a having an ee of 67%, identical to the ee obtained with the diazo compound 20b.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 454-458 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic method of measuring the olive oil-gas partition coefficients is described. It is based on the relationship existing between the retention time of each substance and its solubility in olive oil used as a stationary liquid phase. The validity of this method has been tested by varying the length of the column, the percentage of liquid phase and the flow rate of the carrier gas. Using this technique, the partition coefficients of 24 hydrocarbons, 8 aliphatic, 6 aromatic and 10 chlorinated, have been determined (see Table 4).
    Additional Material: 4 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 191-197 
    ISSN: 0899-0042
    Keywords: TADDOL ; titanium complexes ; chiral Lewis acid ; polymer-supported ; polystyrene-divinylbenzene ; enantioselective ; Diels-Alder ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the first polymer-supported TADDOL is reported. Its efficiency as chiral ligand of Ti(IV) was studied in the Diels-Alder cycloaddition of cyclopentadiene to 3-crotonoyl-1,3-oxazolidin-2-one, and was superior to that observed for its homogeneous equivalent. (4R,5R)-α,α,α′,α′-2-pentaphenyl-4,5-dimethanol-1,3-dioxolane. Recycling of the heterogeneous Ti(IV)-TADDOLate was also studied, being the most suitable method for the repreparation of the catalyst from the ligand after use. Chirality 9:191-197, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0899-0042
    Keywords: chirality ; cyclopyrrolone ; isomers ; racemization ; stability ; zopiclone ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We investigated the degradation and racemization of zopiclone (ZOP) enantiomers in plasma and partially aqueous solutions (ethanol:phosphate buffer). Degradation and racemization increased with increasing pH and temperature. Degradation products were identified by means of mass spectrometry, which revealed hydrolysis of the carbamate function and opening of the pyrrolidone ring. In plasma, neither degradation nor racemization occurred after 6 months of storage at -20°C and subsequent extraction. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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  • 5
    ISSN: 0899-0042
    Keywords: NSAIDs ; enantioselectivity ; prostaglandin E2 ; thromboxane B2 ; HUVEC ; PMN ; keratinocytes ; P388D1 ; platelets ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacological activity of rac-ketoprofen and its enantiomers was investigated in vitro using different cellular models. The effect of these compounds on arachidonic acid metabolism was assessed by measuring the inhibition of prostanoid generation under the action of several agonists. Thus, we have evaluated the inhibition of (1) thromboxane B2 synthesis in rabbit platelets and human polymorphonuclear leukocytes (PMNs), (2) prostaglandin E2 synthesis in three cultured cells, namely human umbilical vein endothelial cells (HUVEC), human keratinocytes, and mouse macrophage-like P388D1 cells. The IC50 values found for (+)-(S)-ketoprofen were in the range between 0.1 nM and 0.8 μM, being slightly lower in all models than those found for rac-ketoprofen (0.4 nM-3 μM). On the other hand, (-)-(R)-ketoprofen showed inhibition of cyclooxygenase only at concentrations two or three orders of magnitude higher than those required for the (+)-(S) enantiomer. These results, obtained with cell types of relevance for inflammatory processes and with compounds of high optical purity, demonstrate that the prostanoid biosynthesis inhibition caused by the drug rac-ketoprofen is exclusively due to its dextrorotatory enantiomer. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 538-541 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempts to synthesize stereospecifically menthanethiol (2) and menthyl thiocyanate (3) from suitable electrophilic neomenthyl substrates (4a-c), and a variety of sulfur nucleophiles failed or predominantly led to β-elimination products. Almost quantitative yields of mixtures of 2 and its 3-epimer (8) were obtained by reductive cleavage of (-)-3-menthone ethylene dithioacetal (7), but stereoselectivity was low (ratio of 2/8, 41:59) and the mixture could not be resolved. Recrystallization and subsequent oxidation of the dinitrophenyl sulfides of 2 and 8 allowed the isolation of the dinitrophenyl menthyl and neomenthyl sulfoxides (12 and 13, respectively), and an irresolvable mixture of the sulfones 14 and 15.
    Additional Material: 1 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 63-66 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1983-1987 
    ISSN: 0947-3440
    Keywords: Thromboxane model compounds ; Carbohydrates ; Epoxidations ; Glycosides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of halohydrin 7, a potential precursor of the heterocyclic moiety of thromboxane A2 (TXA2) is described. Claisen-Meerwein-Eschenmoser rearrangement of hex-3-enopyranosides 4 and 8 yields the branched olefin sugars 5 and 9. Epoxidation studies with perbenzimidic acid (Payne's method) and m-chloroperbenzoic acid (Anderson's method) were performed. Under treatment of the 2,3-anhydrosugar 6 with LiBr, the epimeric halohydrins 7 and 10 were obtained in a ratio of 3:2.
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  • 9
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The standard Gibbs energies of transfer, ΔGt° from water to water-N,N-dimethylformamide mixtures for the dissociation process of several organic acids (formic, acetic, propionic, n-butyric, isobutyric, n-valeric, isovaleric, 2-methylbutyric and trimethylacetic acids) obtained from the pKa* values are discussed in terms of the extended Scaled Particle Theory from quantum mechanical calculations in order to estimate the cavity and electrostatic contributions. The residual energy term was correlated with the hydrogen bond acceptor density and the Kamlet-Taft β parameters. The main contribution to ΔGt° was due to dipolar and specific interactions.
    Additional Material: 6 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 1347-1350 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heats of adsorption on silicagel, for different cycloalcanes, have been measured by gas-solid chromatography. The experiments were carried out between 180 and 210°C. Values based on the corresponding retention times and temperature parameters for cyclopentane, cyclohexane, cycloheptane, and cyclooctane were found to be 7.5, 8.3, 10.0 and 11.5 kcal/mole, respectively.
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