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  • 1
    Electronic Resource
    Electronic Resource
    Glycosylimidate, 18. Regioselektive Reaktionen partiell geschützter Zucker Einfache Synthese von 3,4-Diazido-3,4-didesoxy-L-arabinose aus D-Arabinose (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1546-1556 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosyl Imidates, 18.- Regioselective Reactions of Partially Protected Sugars Convenient Synthesis of 3,4-Diazido-3,4-dideoxy-L-arabinose from D-ArabinoseBenzyl β-D-arabinopyranoside (1) gave with 1.5 equivalents of mesyl chloride exclusively the 2,3-di-O-mesyl compound 2. Treatment with NaN3 in DMF caused inversion at C-2, C-3, and C-4 and yielded benzyl 3,4-diazido-3,4-dideoxy-α-L-arabinopyranoside (11). Acid-catalyzed debenzylation and subsequent base-catalyzed treatment with trichloroacetonitrile gave the 1-O-activated trichloroacetimidate 16; reaction with the 3,4-O-unprotected 2-azido-2-deoxyxylopyranoside 18 gave regiospecifically the 3-O-connected disaccaride 20. Reduction of the azido groups, N-acetylation, and O-deacetylation led to the O-unprotected disaccaride 23. the structures of the compounds obtained or their O-acetylated derivatives, respectively, were assigned by 1H NMR data.
    Notes: Umsetzung von Benzyl-β-D-arabinopyranosid (1) mit 1.5 äquivalenten Mesylchlorid lieferte ausschließlich die 2,3-Di-O-mesyl-Verbindung 2. Behandlung mit Natriumazid in DMF ergab unter Inversion an C-2, C-3 und C-4 Benzyl-3,4-diazido-3,4-didesoxy-α-L-arabino-pyranosid (11). Säurekatalysierte Debenzylierung und anschließende basenkatalysierte Umsetzung mit Trichloracetonitril führte zum 1-O-aktivierten Trichloracetimidat 16, das mit dem 3,4-O-ungeschützten 2-Azido-2-desoxyxylopyranosid 18 regiospezifisch das 3-O-ver-knüpfte Disaccharid 20 lieferte. Reduktion der Azidgruppen, N-Acetylierung und O-Des-acetylierung führte zum O-ungeschützten Disaccharid 23. Die Strukturen der erhaltenen Verbindungen wurden, soweit erforderlich, über O-acetylierte Derivate 1H-NMR-spektroskopisch gesichert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850804
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  • 2
    Electronic Resource
    Electronic Resource
    Glycosyl Imidates, 42 Selectively Protected Lactose and 2-Azido Lactose, Building Blocks for Glycolipid Synthesis (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1099-1106 
    Details
    ISSN: 0170-2041
    Keywords: Lactose ; Azidolactose ; Glycosyl acceptors ; Glycosyl donors ; Regioselective protection ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylimidate, 42. - Selektiv geschützte Lactose und 2-Azidolactose als Bausteine für die Synthese von GlycolipidenDurch regioselektive Alkylierung der 3′-OH-Gruppe von Benzyl-β-lactosid mit der Stannylierungsmethode wurden die 3′-OH- und 4′-OH-ungeschützten Lactosederivate 5 und 10 sowie das 4′-OH-ungeschützte Lactosederivat 9 hergestellt, das aufgrund seiner unterschiedlichen Schutzgruppe für 3′-OH für weitere Umwandlungen geeignet ist. Diese Bausteine sind wertvolle Glycosylakzeptoren für die Synthese von Glycolipiden. Zur Synthese von Glycosyldonoren mit Gal(β1 → 4)GlcNAc-Struktur wurde das 2-Azidolactosederivat 19 verwendet. Durch regioselektive Alkylierung der 3′-OH-Gruppe mit der Stannylierungsmethode sowie durch Anwendung anderer regioselektiver Schutzgruppen-Verfahren wurden die Trichloroacetimidate 17, 24 und 30 hergestellt, die aufgrund ihrer speziellen Schutzgruppen für 3′-OH, 4′-OH und 6′-OH für weitere Umwandlungen geeignet sind.
    Notes: Performing regioselective alkylation at 3′-OH of benzyl β-lactoside 1 by the stannylation method we prepared the 3′-OH- and 4′-OH-unprotected lactose derivatives 5 and 10 and the 4′-OH-unprotected lactose derivative 9 containing a different protecting group at 3′-OH, suitable for further transformations. These building blocks are valuable glycosyl acceptors in glycolipid synthesis. For the synthesis of glycosyl donors with Gal(β1 → 4)GlcNAc-structure we used the 2-azido lactose derivative 19. By regioselective alkylation of 3′-OH by the stannylation method and application of other common regioselective protecting procedures we prepared the trichloroacetimidates 17, 24, and 30 containing special protecting groups at 3′-OH, 4′-OH, and 6′-OH which are suitable for further transformations in these positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890276
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  • 3
    Electronic Resource
    Electronic Resource
    Spiroketal Synthesis.  -  A Case of Intramolecular Glycoside Bond Formation (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 377-382 
    Details
    ISSN: 0170-2041
    Keywords: Glycosides ; Disaccharides ; Undecaose ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From 4-O-unsubstituted glucose derivatives 1a, b the 4-hydroxymethyl-substituted glucose derivatives 9a, b were obtained via oxidation to the ketone, Wittig reaction with methylenetriphenylphosphorane, borane addition, and subsequent oxidation to yield the diastereomeric galactose-derived compounds 5a, b; the required inversion of configuration at C-4 was accomplished through oxidation to the formyl derivatives, base-catalyzed isomerisation, and then reduction. Transformation of hydroxymethyl derivatives 9a, b into the iodo derivatives 11a, b and reaction with n-butyllithium generated the C-lithiated species 11aA, bA which furnished with O-benzyl-protected gluconolactone 12 the ketose derivatives 13a, b. Treatment with Et2O-BF3 afforded under concomitant 6-O-debenzylation the spiroketals 15a, b. Hydrogenolytic O-debenzylation and subsequent O-acetylation led to compounds 16a and 16b, respectively. The anomeric ketoside configuration was derived from NOE experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199219920166
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  • 4
    Electronic Resource
    Electronic Resource
    Glycosyl imidates, 47. Stereospecific synthesis of α- and β-L-fucopyranosyl phosphates and of gdp-fucose via trichloroacetimidate (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 121-124 
    Details
    ISSN: 0170-2041
    Keywords: Fucopyranosyl phosphate ; Fucose 1-phosphate ; Glycosyl phosphate ; GDP-fucose ; Guanosine diphosphofucose ; Trichloroacetimidates ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the benzyl- and acetyl-protected α-trichloroacetimidates 1 and 6α with dialkyl and diaryl phosphates in the presence of traces of acid affords stereoelectively the thermodynamically more stable α-L-fucopyranosyl phosphates 2, 7 and 8, respectively, in high yields. The use of very pure, recrystallized dibenzyl phosphate results in the stereoeletive formation of the β-L-fucopyranosyl phosphates 3 and 9. In each case separation of the anomers is not required because of the very high stereoselectivity of the reactions. After deprotection the fucose 1-phosphate 12 is coupled with GMP morpholidate 10 to yield GDP-fucose 13. After the development of a new purification procedure for GDP-fucose 13 we have obtained a very pure compound suitable for biochemical investigations. Analytical and preparative HPLC has been performed on reversed-phase columns using a volatile buffer system (triethylammonium hydrogen carbonate) as the eluant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910122
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese von N-Ethylguanosin-5′-carboxamid (1988)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1013-1014 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of N-Ethylguanosine-5′-carboxamideN-Ethylguanosine-5′-carboxamide (5) was prepared by condensation of O-benzoyl-protected riburonic acid glycosyl halide 1 and N2-acetylguanine (2) with mercury(II) cyanide as a catalyst. The N7-isomer, obtained as a byproduct, was separated by reversed-phase medium-pressure liquid chromatography. The structures were determined by NMR and UV spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198819881017
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  • 6
    Electronic Resource
    Electronic Resource
    Glycosyl Imidates, 62. - Synthesis of the Heptasaccharide Moiety of Ganglioside BGM1 (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 859-864 
    Details
    ISSN: 0170-2041
    Keywords: Glycosphingolipids ; Ganglio series ; Blood group B determinant ; Glycosides ; Trichloroacetimidates ; Saccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the O-acetyl protected heptasaccharide moiety (2) of BGM1 was performed according to the following reaction sequence: Reaction of 2,3-di-O-acetyl-4,6-O-benzylidenegalactosyl trichloroacetimidate 4 (as donor) with 3-O-unprotected 2-azidogalactose 5 (as acceptor) gave β(1→3)-connected disaccharide 6. Subsequent O-deacetylation followed by reaction with galactosyl donor 8 afforded regioselectively trisaccharide 9 which was converted into tetrasaccharide 12 by treatment with fucosyl donor 11. Transformation of 12 via acid-catalyzed O-deisopropylidenation, O-acetylation, anomeric O-desilylation, and then base-catalyzed treatment with trichloroacetonitrile afforded trichloroacetimidate 16 as tetraosyl donor. Reaction of 16 with the known 4b-O-unprotected sialyllactose derivative 17 gave in acetonitrile at -40°C in the presence of TMSOTf as the catalyst the desired heptasaccharide 18. Azido group reduction with propanedithiol, N-acetylation, hydrogenolytic O-debenzylation, and O-debenzylidenation under acidic conditions followed by O-acetylation afforded the target molecule 2. The structural assignments were based on the 1H-NMR data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301136
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of sphingosines, 9. Synthesis of phytosphingosine derivatives (1994)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1994 (1994), S. 83-90 
    Details
    ISSN: 0170-2041
    Keywords: Phytosphingosines ; Azides ; Sphingosines ; Dodec-5-enes ; Dodec-5-ynes ; Tetrols ; Epoxides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the lithium acetylide prepared from bromooctene 2 with 2,4-O-benzylidene-D-threose (1) yielded the epimeric dodec-5-ynetetrol derivatives 3a, b. Reaction of the Grignard reagent of bromooctene 2 with 1 gave (E,Z)-dodec-5-ene-tetrol derivatives (E,Z)-12a,b. From these precursors D-ribo-phytosphingosine derivatives 7b, (E)-18, and (Z)-18, respectively, were obtained. Also interesting anhydro derivatives, for instance 3,4-epoxides 11a and (E)-21, and 1,4-anhydro phytosphingosine derivatives 9a, 10a, and (E)-23, respectively, were synthesized. A very useful method is described for the assignment of the configuration at C-4 of the 1,3-O-benzylidene-1,2,3,4-tetrol derivatives 3a, 3b, (E,Z)-12a, and (E,Z)-12b by means of NMR spectroscopy.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199419940115
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  • 8
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    Synthesis of different nucleoside 5'-diphospho-sulfoquinovoses and their use for studies on sulfolipid biosynthesis in chloroplasts (1989)
    Wiley
    Details
    Publication Date: 1989-09-01
    Print ISSN: 0014-2956
    Electronic ISSN: 1432-1033
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley on behalf of Federation of European Biochemical Societies.
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  • 9
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    Structure and synthesis of biologically active glycopeptides and glycolipids (1991)
    Elsevier
    Details
    Publication Date: 1991-10-01
    Print ISSN: 0959-440X
    Electronic ISSN: 1879-033X
    Topics: Biology , Medicine
    Published by Elsevier
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