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  • 2015-2019
  • 1985-1989  (1)
  • 1960-1964  (5)
  • 1987  (1)
  • 1962  (5)
  • Natural products
  • Substitution
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 26 (1987), S. 489-503 
    ISSN: 0570-0833
    Keywords: Natural products ; Synthetic methods ; Polyketides ; Stereoselectivity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sequences of directly adjacent stereogenic centers were first discovered for the monosaccharides, which therefore constituted the first focus of interest in Stereoselective synthesis. The structures of many polyketide-derived natural products that have been elucidated in recent years often exhibit longer sequences of stereogenic centers in which hydroxy-substituted secondary carbon atoms alternate with tertiary carbon atoms. This finding inspired the development of methods allowing the specific construction of first two and then - more importantly-three neighboring stereogenic centers. The diverse methodologies that have thereby emerged reveal common principles and stress the variety of approaches possible in stereoselective synthesis.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 98-111 
    ISSN: 0570-0833
    Keywords: Mass spectrometry ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectrometry is a very useful method for the determination of the structure of organic compounds although the technique has not yet been widely employed in this field. Of particular interest is the high sensitivity of the instrument, making possible the use of very small amounts of sample, and the information obtainable regarding the size of the molecule and position of the groups therein. A certain volatility is required and the choice of a suitable derivative is, therefore, sometimes of importance. The fragmentations of the molecules in the ion source may be considered as reactions of “carbonium ions without solvent.” The application of the method in the determination of the structure of some natural products is outlined, using lipids, amino acids, peptides and alkaloids as examples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 178-195 
    ISSN: 0570-0833
    Keywords: Enzyme catalysis ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Micro-organisms form enzymes that catalyze many reactions which are difficult to carry out in the laboratory or which involve many steps. Enzymes even react with substances which are normally foreign to them. The frequently high stereospecificity of microbiological reactions is of particular significance. The most important types of reactions are: hydroxylations, dehydrogenations (oxidations), and hydrogenations (reductions), cleavage of ester and C-C bonds, and transglycosidations. The variety of the compounds converted is extremely great.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 312-327 
    ISSN: 0570-0833
    Keywords: Substitution ; Arene ligands ; Ferrocene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: π-Complexes of aromatic compounds with transition metals display aromatic characteristics. This is shown, among other things, by the fact that many such compounds undergo aromatic substiution reactions. A survey of substitutions and secondary reactions in such systems is given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 382-393 
    ISSN: 0570-0833
    Keywords: Electrophilic reactions ; Reaction mechanisms ; Substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results obtained in recent years from investigations into the mechanisms of electrophilic substitution reaction at sp3-hybridized carbon atoms are reviewed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 394-399 
    ISSN: 0570-0833
    Keywords: Substitution ; Arene ligands ; Ferrocene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
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