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  • Glycosylations  (5)
  • C-Glycosides  (4)
  • Sphingosines  (4)
  • 1
    Electronic Resource
    Electronic Resource
    A Novel and Efficient Route towards α-GalNAc-Ser and α-GalNAc-Thr Building Blocks for Glycopeptide Synthesis (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1167-1171 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Glycals, nitro ; Michael additions ; Glycosylations ; Glycosides, galactosamine ; Reduction, nitro group ; Glycopeptides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Michael addition of serine and threonine derivatives 4a-4c to 3,4,6-tri-O-benzyl-2-nitro-D-galactal (1) afforded the corresponding 2-deoxy-2-nitro-α-D-galactopyranosides 5a-5c in good yield and stereoselectivity. 2-deoxy-2-nitroglycosides 5a and 5b were reduced to the 2-acetamido compounds by platinized Raney nickel T4. Manipulation of the protecting groups afforded known N-Fmoc-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-galactopyranosyl)-L-serine (8a) and -threonine (8b), valuable building blocks for O-glycopeptide synthesis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    A General Method for the Synthesis of C-Glycosides of Nojirimycin (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1315-1321 
    Details
    ISSN: 0947-3440
    Keywords: C-Glycosides ; Azasugars ; Piperidinosyl fluoride ; O-Piperidinosyl trichloroacetimidate ; Nojirimycin ; Deoxynojirimycin ; Glycosylations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 2,3,4,6-tetra-O-acetyl-N-(benzyloxycarbonyl)nojirimycin (3) can be readily transformed into the corresponding azaglycal 6 or fluoride 7, which are versatile glycosyl/piperidinosyl donors. Reaction of 7 with allyltrimethylsilane, propinyltrimethylsilane, trimethylsilyl cyanide, and trimethylsilyl enol ether as carbon nucleophiles, afforded, in the presence of BF3 · OEt2 as catalyst, the corresponding C-glycosides 8-10 and 12-14 in good yields. The anomeric configurations of the C-glycosides are ascertained with the help of ROESY-NMR data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970706
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of Lacto-N-neohexaose and Lacto-N-neooctaose Using the Dimethylmaleoyl Moiety as an Amino Protective Group (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 319-326 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Amino sugars ; Protecting groups ; Glycosylations ; Trichloroacetimidates ; Oligosaccharides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The N-DMM-Protected lactosamine derivative 2 was readily transformed into the corresponding glycosyl donor 4 and into acceptor 5. A TMSOTf-catalyzed glycosidation afforded the derived tetrasaccharide 6 which led to glycosyl donor 9. Reaction of 9 with lactose derivative 10 as acceptor gave the desired hexasaccharide 11. Cleavage of all protective groups and N-acetylation afforded the target molecule 1b (lacto-N-neohexaose). Glycosylation of acceptor 10 with donor 4 furnished tetrasaccharide 16 which, employing standard procedures, gave acceptor 18. Glycosylation of 18 with donor 9 furnished, under standard conditions, octasaccharide 19. Cleavage of all protective groups and N-acetylation afforded the target molecule 1c (lacto-N-neooctaose). Both 1b and 1c were obtained in good overall yields.
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  • 4
    Electronic Resource
    Electronic Resource
    Convenient Glycoside Synthesis of Amino Sugars: Michael-Type Addition to 2-Nitro-D-galactal (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1609-1613 
    Details
    ISSN: 1434-193X
    Keywords: Glycals, nitro ; Michael additions ; Glycosylations ; Glycosides, galactosamine ; Reduction, nitro group ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of 3,4,6-tri-O-benzyl-2-nitro-D-galactal (3) was readily accomplished starting from tri-O-benzyl-D-galactal (1) by acetyl nitrate addition to 2 and base-promoted acetic acid elimination. Addition of alcohols to 3 under conditions of base catalysis afforded 2-deoxy-2-nitrogalactopyranosides 4a-e in high yields; high α-selectivity was obtained with strong bases, whereas weaker bases furnished mainly the corresponding β-galactopyranosides. Chemoselective nitro group reduction in these glycosides was successfully carried out in the case of disaccharide 4cα using Raney nickel as catalyst, thereby affording after N-acetylation the corresponding 2-acetylamino-2-deoxy derivative 5cα.
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  • 5
    Electronic Resource
    Electronic Resource
    Glycosyl Phosphatidylinositol (GPI) Anchor Synthesis Based on Versatile Building Blocks - Total Synthesis of a GPI Anchor of Yeast (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1153-1165 
    Details
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    The Dimethylmaleoyl Group as Amino Protective Group - Application to the Synthesis of Glucosamine-Containing Oligosaccharides (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2305-2316 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Protecting groups ; Amino sugars ; Glycosylations ; Trichloroacetimidates ; Glycosides, glucosamine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glucosamine was readily transformed into N-dimethylmaleoyl (DMM) protected derivative 1 which furnished trichloroacetimidate 4 as glycosyl donor. Reaction with various acceptors (5a-g) in the presence of TMSOTf as the catalyst afforded the corresponding β-glycosides 6a-g generally in high yields. Cleavage of the DMM group was readily accomplished by treatment with aqueous NaOH and then with HCl (pH 5). Starting from 1 also DMM group containing glycosyl acceptors 9 and 14a-c were synthesized. They furnished with trichloroacetimidates 12 and 4 as glycosyl donors β(1-4)- and β(1-3)-linked disaccharides 13 and 15a-c, respectively. From 18 as galactosyl donor and 14a as acceptor β(1-3)-linked disaccharide 19 was obtained in high yield, which is a versatile building block for the important Galβ(1-3)GlcNAc unit. 19 was transformed into trichloroacetimidate 21; glycosylation with 5e as acceptor gave trisaccharide 22 which furnished on partial deprotection Galβ(1-3)GlcNAcβ(1-4)Glc derivative 24. Thus, the wide applicability of DMM as amino protective group in oligosaccharide synthesis is exhibited.
    Additional Material: 1 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of carbon-bridged N-acetyl-c-lactosamine and derivatives (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 2113-2121 
    Details
    ISSN: 0947-3440
    Keywords: C-Saccharides ; C-Glycosides ; C-Lactosamine ; 1-Lithiogalactal ; Vinyllithium ; Branched sugars ; Glucosamine, C-formyl ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-C-Formyl-2-azidoglucopyranoside 12a, required for N-acetyl-C-lactosamine synthesis as electrophile, was obtained from thexyldimethylsilyl 2-azido-2-deoxy-glucopyranoside 3 via readily available 4-O-unprotected 6a and then 4-C-methylene derivative 8a in overall seven steps. Alternatively, regioselective silylation of 3 with tert-butyldimethylsilyl chloride gave 4-O-unprotected 6b which was transformed by a similar reaction sequence into 12a. In order to circumvent a Wittig reaction, 6a was transformed into triflate 13 the reaction of which with 4-C-cyano derivative 14 followed by reduction with DIBAH and base-catalyzed isomerization also afforded 12a. Reaction of 12a with 1-C-lithiated 2-phenylsul-finyl-D-galactal 15 as nucleophile furnished C-disaccharide intermediates 16a and 16b as diastereoisomers. Ensuing removal of the phenylsulfinyl group with Raney nickel and diastereospecific 2b-hydrogen and 3b-hydroxy transfer afforded β(1→4)-connected N-acetyl-C-lactosamines 19a and 19b; their structures were deduced from derivatives 20a, b and 21a, b on the basis of 1H-NMR data. Hydrogenolytic O-debenzylation of 19b afforded hydroxymethylene-bridged N-acetyl-C-lactosamine 2b′.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199512297
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of D-erythro-Ceramide-1-phosphoinositol and Its Aminoglucosylated Derivative - Intermediates in GPI-Anchor Biosynthesis (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 291-298 
    Details
    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).
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of Sphingosines, Part 8. Synthesis of Methyl-branched Sphingosines (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 419-426 
    Details
    ISSN: 0170-2041
    Keywords: Sphingosines ; Azidosphingosines ; Octadec-4-enes ; Enzymes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of 2,4-O-benzylidene-D-threose (3) with the Wittig reagent obtained from 2-bromopentadecane furnished 5-methyloctadec-4-ene derivatives (E,Z)-8. The introduction of the azido group into the 2-position and acid-catalyzed removal of the benzylidene protective group afforded 5-methyl-substituted azidosphingosines (E)-10 and (Z)-10 which were converted via azide reduction into the corresponding sphingosines (E)-1 and (Z)-1, respectively. Reaction of 3 with methylmagnesium bromide, ensuing selective 2-O-mesylation, and then 4-O-oxidation gave ketone 13. The Wittig reaction of 13 with triphenyltetradecylphosphorane afforded exclusively 4-methyloctadec-4-ene derivative (Z)-16 which was transformed into 4-methyl-substituted sphingosine (Z)-2 as described above. For the synthesis of the corresponding E isomer, 3 was converted into carbinols 21h,l. 2-O-Silyl protection and then water elimination furnished 4-methyl-substituted (4E)-octadec-4-ene derivative (E)-23 which was transformed into (E)-2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930168
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of Carbon-Bridged C-Lactose and Derivatives (1994)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1994 (1994), S. 975-981 
    Details
    ISSN: 0170-2041
    Keywords: C-Saccharides ; C-Glycosides ; 1-Lithiogalactal ; Vinyllithium ; Glucose, C-formyl- ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-C-Formylglucopyranoside 9 was readily obtained from 4-O-unprotected glucose derivative 4 in four steps, each step giving a high product yield. Reaction with 1-C-lithiated 2-phenylsulfinyl-D-galactal 10 as nucleophile furnished C-disaccharide intermediates 11a and 11b as diastereoisomers. Ensuing removal of the phenylsulfinyl group with Raney nickel and regio- and diastereospecific 2b-hydrogen and 3b-hydroxy transfer afforded β(1-4)-connected C-lactosides 13a and 13b, respectively; their structures were deduced from derivatives 14a, b and 16a, b on the basis of 1H-NMR data. Hydrogenolytic O-debenzylation of 13a and 13b afforded hydroxymethylene-bridged C-lactose 2a and 2b, respectively. Regioselective O-benzylation of 13a gave preferentially 1b-O-unprotected derivative 17aa which furnished upon oxidation carbonyl-bridged C-lactose derivative 19. Deoxygenation at C-1b of 17aa and subsequent hydrogenolytic O-debenzylation furnished methylene-bridged C-lactose 1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199419941004
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