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  • Articles  (2)
  • Furanoses, 3,6-anhydro  (1)
  • Resolutions, kinetic enzyme-catalyzed  (1)
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  • Articles  (2)
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  • 1
    ISSN: 0170-2041
    Keywords: Carbohydrates ; Furanoses, 3,6-anhydro ; Glycosides, pyruvylated ; Anhydrofuranoses ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of methyl 2,3-di-O-acyl-D-glycopyranosides 1 of glucose and mannose with catalytic amounts of trifluoromethanesulfonic acid afforded the corresponding bis(5-O-acyl-3,6-anhydro-D-glycofuranose) 1,2′:2,1′-dianhydrides 6 in 12-58% yield the structure of which was confirmed for the α-D-glucose derivative 6a by an X-ray analysis. In addition, in the presence of methyl pyruvate (2a) or methyl 2-acetoxy-acrylate (2b) various amounts of diastereomeric 3,6-anhydro-5-O-benzoyl-1,2-O-(1-methoxycarbonyl)ethylidene-α-D-glucofuranoses 5 and acylated methyl α-D-glucopyranosides 3 and 4, respectively, were formed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: Cyanohydrins and cyanohydrin esters, optically active ; Resolutions, kinetic enzyme-catalyzed ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzyme-Catalyzed Reactions, 71). - Enantioselective Esterification of Racemic Cyanohydrins and Enantioselective Hydrolysis or Transesterification of Cyanohydrin Esters by LipasesPure cyanohydrin enantiomers (S)-1/(R)-1 and their O-acyl derivatives (R)-3/(S)-3 are obtained from three different lipasecatalyzed reactions: i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective acylation of racemic cyanohydrins 1, iii) enantioselective transesterification of 3 with primary alcohols. Both the cyanohydrin esters and the free cyanohydrins (which are prone to racemization) are isolated as enantiomers with high optical purity on a preparative scale. Hydrolysis of the racemic butyrates 3b, e with Candida cylindracea lipase and pseudomonas sp. lipase, respectively, for example, affords the free (S)-cyanohydrins (S)-2-hydroxypentanenitril [(S)-1a] and (S)-mandelonitrile [(S)-1b)] in high yield with 97 and 96% ee, respectively. (S)-1a is obtained with the same optical purity by candida sp. lipase-catalyzed transesterification of 3b with 1-octanol.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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