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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1153-1165 
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Sphingosines ; Ceramides ; Ceramides-1-phosphates ; Glycosylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -For the design of a synthesis of target molecule 1 the retrosynthetic analysis yielded building blocks 2-5, of which ceramide 2-phosphite derivative 2 and aminoethyl phosphite derivative 5 are known. The generation of α-glucosaminyl (1→6)inositol building block 3 was based on pseudodisaccharide 6 which was selectively benzoylated at 6b-O and then selectively benzylated at 3b-O to give 3. The synthesis of tetramannosyl building block 4 started from known ortho ester derivative 8 which was transformed into versatile mannosyl donors 13 and 18 and into acceptor 22. Reaction of 13 with 22 gave α-disaccharide 23, deacetylation and then mannosylation with 18 gave trisaccharide 25; ensuing deacetylation and mannosylation with 13 gave tetrasaccharide 27; deallylation, acetylation, regioselective removal of the anomeric O-acetyl group and treatment with CCl3CN/DBU afforded 4. Glycosylation of 3 with donor 4 led to pseudohexasaccharide 31 in high yield. Replacement of the O-acyl groups by O-benzyl groups and then exchange of the menthyloxycarbonyl group by an O-acetyl group gave 36 which enabled regioselective attachment of 2 and 5. To this end, the 6e-O-silyl group was removed and then the aminoethyl phosphate residue was attached with reagent 5 to give 38 in high yield. 1a-O-Deacetylation and then reaction with 2 afforded 40 as fully protected 1 which was liberated in two steps; treatment with acid removed all acid labile protective groups and finally catalytic hydrogenation afforded the desired GPI anchor 1 which could be fully structurally assigned.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Diacylglycerolphosphates ; Glycophosphoinositol anchors ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The exploration of the molecular and structural basis for the sorting of GPI-anchored proteins is based on labeled partial structures of GPI′s which can be incorporated into the GPI anchor biosynthesis and cellular transport systems. To this end, from mannosyl donor 6 and the D-glucosaminyl-(1→6)-D-myo-inositol derivative 7 as acceptor, the pseudotrisaccharide 8 was prepared. Compound 8 was transformed into the GPI partial structures 5a,b which contain the pseudotrisaccharide ligated to two different phosphatidyl residues. Compounds 5a,b have Boc protection at the 2-amino group of the glucosamine residue (2b-position) and a free amino group at the 6b-position. The 6b-amino group was used for the ligation of the 3-(7-nitrobenzofurazan-4-yl)-aminopropanoyl group as a fluorescent label, the 5-azido-2-nitrobenzoyl and 4-azidophenylaminothiocarbonyl groups as photolabels, and the 4-azido-2-hydroxybenzoyl group as a radiolabel after the introduction of radioactive iodine by an electrophilic aromatic substitution. Thus, after acid-catalyzed removal of the protective groups, the unprotected target molecules 1-4 were obtained.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Sphingosines ; Ceramides ; Ceramide-1-phosphates ; Inositols ; Glycophosphosphingolipids, synthesis ; Glycophosphoinositol anchors ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The readily available 2,3:4,5-di-O-cyclohexylidene-D-myo-inositol derivative 3 was converted into the 1-O-unprotected D-myo-inositol derivative 6. Reaction with the phosphite derivative 7 of 3-O-tert-butyldimethylsilyl-protected ceramide furnished the target molecule D-erythro-ceramide-1-phosphoinositol (1). Reaction of O-(3,4,6-tri-O-acetyl-2-azido-β-D-glucopyranosyl)trichloroacetimidate (20) with 3 gave exclusively α(1→6)-connected glycoside 21 which was converted into the 1α-O-unprotected derivative 24. Reaction with the D-erythro-azidophytosphingosine-derived ceramide-1-phosphite derivative 17 led, after oxidation and removal of the cyanoethyl group, to protected 2-azido-D-glucopyranosyl-α(1→6)-D-myo-inositol-1-phospho-ceramide (25) which could be fully deprotected in two steps to afford the target molecule, the ceramide derivative of 2-amino-2-deoxy-D-glucopyranosyl-α(1→6)-D-myo-inositol-1-phosphate (2).
    Type of Medium: Electronic Resource
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