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  • 1980-1984  (12)
  • 1975-1979  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Specific photoaffinity inactivation of the D-glucose transporter in small intestinal brush border membrane using new phlorizin analogs (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 5844-5854 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00523a030
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  • 2
    Electronic Resource
    Electronic Resource
    Synthese und Umwandlungen von Isoxazolidin-Nucleosiden (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 426-446 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Transformations of Isoxazolidine-NucleosidesReaction of the oxime 12 with formaldehyde, acetaldehyde or acetone in the presence of methacrylic acid methylester leads in a highly stereoselective 1,3 dipolar cycloaddition of the corresponding nitrones to the protected isoxazolidine ribosides 13, 14, 20, 21 and 26 (Scheme 1 and 2).Using a new, mild procedure to effect detriylation, the cycloaddition products were transformed into the alcohols 16-19, 22-25 and 27.Cleavage of a mixture of the glycosides 16 and 17 yielded the N-unsubstituted isoxazolidine 29 in 65% optical purity while the cleavage of 27 gave optically pure 28.Alternatively, the isoxazolidine ribosides 13, 14, 16-18 and 26 were transformed via reductive cleavage of the isoxazolidine N-O bond and subsequent lactamization into the corresponding pyrrolidinone-ribosides 30, 33, 35, 42, 49 and 50, the ribitolyl pyrrolidinones 31, 34, 36-39 and 43-46 (see Scheme 4) and the ribitolyl isoxazolidine 47.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600214
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  • 3
    Electronic Resource
    Electronic Resource
    Stereoselektivität und Reaktivität bei der 1,3-dipolaren Cycloaddition chiraler N-(Alkoxyalkyl)nitroneHerrn Prof. Dr. R. B. Woodward zum 60. Geburtstag gewidmet (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1273-1295 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivity and Reactivity in the 1,3-Dipolar Cycloaddition of Chiral N-(Alkoxyalkyl)nitronesThe stereoselectivity in the reaction of hydroxy-oxime 1 with acetaldehyde and methyl methacrylate yielding the diastereomeric isoxazolidine-ribosides 9-12 was determined to be 93%. The predominant adducts 9 and 10 were cleaved to the diastereomeric isoxazolidines 19 and 20, respectively, which upon oxidation gave the same optically active 2-isoxazoline 21, thus demonstrating the participation in the cycloaddition of both (E/Z)-isomeric nitrones 13 and 14. Based upon comparison of the optical rotations, the isoxazolidines 7, 8, 19 and 20 and the 2-isoxazolines 21 and 22 possess the same chirality, found to be R by correlating 7 with (+)-(S)-citramalic acid. - Since the hydroxy-oximes 1 and 36 showed the same stereo-selectivity in the reaction with formaldehyde and methyl methacrylate, the trityl group of 1 does not influence the stereoselectivity in the cycloaddition. The hydroxyoxime 38 led in the same type of reaction to the isoxazolidines 7, 8, 19 and 20 possessing (S)-chirality, the stereoselectivity (79-95%) being similar to the one observed with 1 (67-95%). The explanation of this stereoselectivity is based upon a stereoelectronic effect in the transition state of the cycloadditions (kinetic anomeric effect). As predicted, the N-(alkoxyalkyl)nitrones showed enhanced reactivity in the cycloaddition with unactivated olefins (leading to 47, 48, 50 and 51). The importance of exo vs. endo approach of the dipolarophile was evidenced by reacting 1 with formaldehyde and methyl acrylate giving predominantly 57 with (5S)-configuration. - Use of the hydroxy-oxime 65 allows synthesis of optically active isoxazolidines with regeneration of the starting hydroxy-oxime.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600417
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  • 4
    Electronic Resource
    Electronic Resource
    Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 1990-2016 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbocyclic Compounds from Monosaccharides. 1. Transformations in the Glucose SeriesA method for the preparation of pentasubstituted cyclopentanes from monosaccharides is presented, involving two crucial steps, viz. the reductive fragmentation of 5-bromo-5-deoxyglucosides (such as 10, 17 and 23, see Scheme 3) with Zn or butyl lithium yielding 5,6-dideoxy-hex-5-enoses (such as 11 and 24, see Schemes 3 and 4), and the subsequent cyclization of these hexenoses with N-methyl- or N-(alkoxyalkyl)hydroxylamines (via the corresponding nitrones) to form cyclopentano-isoxazolidines (see Scheme 2). Thus, the glucosides 17 and 23 were converted diastereoselectively and in good yields into the cyclopentano-isoxazolidines 27 and 45 (Schemes 5 and 7), which were characterized by their transformation into various derivatives. 27 and 45 were correlated through the common derivative 62. The configuration of the cyclization products were established by pyrolysis of the N-oxide 65 to the enol ether 67 (Scheme 10).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620629
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  • 5
    Electronic Resource
    Electronic Resource
    Desoxy-nitrozucker. 2. Mitteilung Herstellung geschützter 1-Desoxy-1-nitroaldosen (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 621-634 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Protected 1-Deoxy-1-nitroaldosesThe direct oxidation of the oxime 1 with t-butyl hydroperoxide and vanadyl acetylacetonate yielding the nitro derivative 2 (54%, Scheme 1) could not be applied to other oximes. Diastereoselective bromination of the aldonolactone oxims 7 and 10-12 according to known procedures gave the corresponding bromonitroso compounds which were oxidized to the bromonitro compounds 9, 14, 18 and 22, respectively. Oxidation of the bromonitroso compound in the D-mannopyranose series proved difficult, but the corresponding chloronitro derivative 23 was easily obtained according to Corey & Estreicher (Scheme 2 and 3). The structure of the bromonitro compound 9 was determined by an X-ray analysis, and the configurations of the bromonitro compounds 14, 18 and 22 were deduced from their molecular rotations. Reduction of the bromonitro compounds gave the protected 1-deoxy-l-nitroaldoses 2, 15/16, 19/20, and 24/25, respectively, in good overall yields. The ribose derivatives 15 and 16 were detritylated to give the nitro compound 4, and the mannose derivative 2 was partially deprotected to give the monoisopropylidene compound 26. The nitro group shows a normal anomeric effect which is reflected in the IR. spectra of the pyranose derivatives 19 and 20, and 24 and 25.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650302
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  • 6
    Electronic Resource
    Electronic Resource
    Deoxy-nitrosugars. 4th communication3rd Communication: [1].. Convenient synthesis of 1-deoxy-1-nitroaldoses (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 789-794 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new synthesis of 1-deoxy-1-nitroaldoses by ozonolysis of N-glycosylnitrones according to the procedure of Bailey et al. is described. Based on the oxime 1, the mannofuranosylnitrones 3-5 were obtained in yields of 86-88% and the 1-deoxy-1-nitromannose 6 in yields of 70-76%. In the same manner the 1-deoxy-1-nitroaldoses 9, 12, 18, and 19 were prepared in yields of 61-90% from the oximes 7, 10, 14 and 15, the procedure being compatible with the presence of free hydroxy groups.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660310
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  • 7
    Electronic Resource
    Electronic Resource
    L-Erythruronic Acid Derivatives as Building Blocks for Nucleoside Analogs. Synthesis of 4′-C-Aryl-D-ribonucleosides (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2570-2582 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2, 3-O-Cyclohexylidene-L-erythruronic acid (6) available in 83% yield from D-ribonolactone (7), was treated with phenvlmagnesium bromide to give the D-ribo and L-lyxo derivatives 10 and 11 in high yields (Scheme 1 and 2). The diastereoselectivity depended on the temperature and mode of operation (Table 1). The absolute configuration of 10 and 11 was determined by correlation with (R)- and (S)phenylethanediol (17 and 16) respectively, excluding intramolecular hydride shifts during formation of 10 and 11. Reaction of 6 with methcoxymethoxyphenyllithium gave the lactones 18 and 19. The L-lyxo isomer 19 was transformed in high yields into the D-ribo lactone 18. Compound 10 was transformed into the adenosine analoge 24 by reduction with Diisobutylaluminium hydride, hydrolysis, acetylation and nucleoside synthesis according to Vorbrüggen (Scheme 3). Its structure was deduced from its UV., NMR. and CD. data and from those of the isopropylidene derivative 25. Similarly, 18 was transformed into the adenosine analog 29 and into the isopropylidene derivative 30.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650828
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  • 8
    Electronic Resource
    Electronic Resource
    Deoxy-nitrosugars. 6th communication5th Communication: [1].. Stereoelectronic control in the reductive denitration of tertiary nitro ethers. A synthesis of ‘C-glycosides’ (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2210-2222 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separate, radical denitration with Bu3SnH of the pyranose derivatives 3, 4, 9, and 10 gave in good yields exclusively the ‘C-glycosides’ 5 and 11, respectively (Scheme 1). Similar reduction of the cyclohexyl derivatives 15, 16, 19 and 20 gave 4:1 mixtures of 17, 18, 21 and 22, respectively, always with predominant formation of an axial C,H-bond. In the furanose series a divergent behaviour was observed for the D-mannose-derived nitro ethers 25 and 27 and the D-ribose-derived nitro ethers 30 and 31, respectively, in that the former two gave isomerically homogeneous reduction products (26 and 28, respectively; Scheme 3) and the latter a 1:1 mixture of the diastereoisomers 32 and 33 (Scheme 4). The stereochemical results were explained on the basis of the stereoelectronic effect of the ring O-atom, the preferred conformation of the intermediate, pyramidal alkoxyalkyl radicals and steric effects in the trioxabicyclo [3.3.0]octane ring system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660733
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of D- and L-5-Oxaproline and of a New Captopril Analogue (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 1241-1252 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1,3-dipolar cycloaddition of the C-t-butyloxycarbonyl-N-mannosyl-nitrone 5, formed in situ from the partially protected D-mannose-oxime 3 and the glyoxylate 4, to ethylene gave preferentially the (3S)-N-glycosyl-isoxazolidine 6 which was transformed into the 3-isoxazolidine-carboxylate (L-5-oxaproline ester) 12 and into some derivatives thereof. The (S)-configuration of 12 was proved by chemical correlation with a derivative of L-asparagine. The D-5-oxaproline ester was obtained from the corresponding N-ribosyl-nitrone 24. Two protected dipeptides containing either C-terminal- (28) or N-terminal-5-oxaproline (= Opro) (30) were synthesized. Starting from 12, the analogue 1 of captopril® (2) was prepared and its activity as an inhibitor of the angiotensin-converting-enzyme (ACE) was examined.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660424
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  • 10
    Electronic Resource
    Electronic Resource
    Fragmentation of 6-Deoxy-6-halo-hexono-1,5-ortholactones: A Concerted, Nonstereospecific Process (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1328-1347 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the D-arabino- and D-ribo-ortholactones 13a-f and 15b-f and their treatment with Zn leading to the unsaturated esters 14a-d and 16a-d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O-bond participate in the elimination of the axial and of the equatorial C(1)-alkoxy groups, respectively.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670519
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