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  • Analytical Chemistry and Spectroscopy  (34)
  • Organic Chemistry  (7)
  • General Chemistry  (5)
  • Wiley-Blackwell  (46)
  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [2 + 2] Photocycloaddition of 2-(trimethylsilyloxy)-1,3-butadiene to a number of 2-cycloalkenones proved to be quite a general reaction leading to good yields of the cycloadducts (Table). This finding is surprising since dienes, in general, are better known as quenchers of enone triplets rather than as photochemical reactants. Both the high substrate concentrations, which can be employed in these cycloadditions, and the remarkable regio and stereoselectivity of the processes qualify them as valuable for syntheses. In a first application, the photoproducts 1a, b were transformed in three steps into a viable precursor 4 of the pentalenolactone-G and -H antibiotics.
    Additional Material: 1 Tab.
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Eine einfache Synthese von substituierten Perhydro-1,3-thiazin-4-onen und 2-Thioxoperhydro-4-pyrimidinonenDie basisch katalysierte Cyclisierung der N-Propenoylthioharnstoffe 3 liefert je nach den Reaktionsbedingungen entweder 2,6-disubstituierte 2,3,5,6-Tetrahydro-4H-1,3-thiazin-4-one 4 oder 1,6-disubstituierte 2-Thiouracile 5. Unter denselben Reaktionsbedingungen können die Verbindungen 5 durch eine Art Dimroth-Umlagerung aus den 1,3-Thiazin-4-onen 4 erhalten werden.
    Notes: Depending on the reaction conditions either 2,6-disubstituted 2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones 4 or 1,6-disubstituted 2-thiouracils 5 are readily prepared by base-catalyzed cyclization of N-propenoylthioureas 3. Compounds 5 could also be obtained by Dimroth-type rearrangement of 1,3-thiazin-4-ones 4 under the same reaction conditions.
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 293-296 
    ISSN: 0170-2041
    Keywords: Pyridazine, derivatives ; Pyrazolo-pyridazine, derivative ; Pyrido-pyridazine, derivative ; Isoxazolo-pyridazine, derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3-c]-pyridazine 6 was formed. The pyrido-pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo-pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.
    Additional Material: 2 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 461-464 
    ISSN: 0170-2041
    Keywords: Antitumor agents ; Oxaziridines ; Aldimines, unsaturated ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient method for the synthesis of previously unknown oxaziridines having unsaturated substituents at the 3-position (3a-k) is based on the selective oxidation of the imino group of α,β-unsaturated aldimines 2 with m-chloroperbenzoic acid. The title compounds and 2-tert-butyl-3-(phenylethynyl)oxaziridine (3k) exhibit potent activity against experimental tumor cells in vitro.
    Additional Material: 4 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 203-204 
    ISSN: 0935-6304
    Keywords: “Theoretical plate” concept in chromatography ; “Stage model” (Martin & Synge) ; “Plate model” (Said) ; Modified plate model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 507-515 
    ISSN: 0935-6304
    Keywords: Constant volume Varigrad ; Hydrostatic Varigrad ; Incremental method of gradient elution ; Modified incremental method, advantages of Poisson distribution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Different methods for producing a pre-assigned gradient in liquid chromatography are presented. A systematic approach to the calculations involved is given. The derived equations are mostly Poisson and Poisson summation distributions which are tabulated in the literature. The incremental method of gradient elution developed by Scott has been modified. In the modified apparatus two mixing chambers are used instead of one. This leads to an appreciable decrease in the number of reservoirs needed for the same precision in fitting a desired gradient. The application of the derived equations, together with other Varigrad modifications, will be given in Part 2 of this paper (to be published shortly in this Journal).
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 63-67 
    ISSN: 0935-6304
    Keywords: Chromatography theory ; Elementary principles ; General equations for eff. plates in conically shaped columns ; Conical columns are more efficient than composite ones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of composite chromatographic columns has been re-examined and general equations relating their efficiency to those of individual columns were derived. The derivations were based on elementary principles without reference to the principle of variance additivity. Derived also, were general equations for the efficiency of columns with continuously varying diameters, HETP and other properties from which formulae for special cases of practical interest were deduced. An example comparing the efficiencies of two columns, one conical and the other composite was given. The calculations show clearly that the conical column is superior in efficiency for the same total length and total retention volume.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 441-443 
    ISSN: 0935-6304
    Keywords: Kovats' index ; Simple linear index ; Relative volatility determination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 115-116 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 242-247 
    ISSN: 0935-6304
    Keywords: Liquid chromatography, LC ; Gradient elution ; Hydrostatic equilibrium ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gradient elution under hydrostatic equilibrium is extended to the treatment of the case where the two liquids have different densities. Analytic expressions are derived only for the cases where both mixing chamber and reservoir have constant cross-sectional areas.As in the case where the densities of the liquids are equal, pressigned concentration gradients can be duplicated quite satisfactorily by combining a mixing chamber having a constant cross-sectional area and a reservoir having an area which changes linearly with reservoir height. A numerical example is given to illustrate the use of the derived equations.
    Additional Material: 6 Ill.
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