Synthesis of methyl 6-deoxy-4-O-(sodium sulfonato)-α-L-talopyranoside, its C-4 epimer and both isosteric [4-C-(potassium sulfonatomethyl)] derivatives (original) (raw)
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Carbohydrate Research, 1998
Syntheses of p-tri¯uoroacetamidophenyl glycosides of the haptenic pentasaccharide and the nonreducing disaccharide unit of the title pentasaccharide are reported. The synthesis of the terminal Nformylkansosamine unit started from methyl 6-deoxy-2,3-O-isopropylidene-l-lyxo-hexopyran-4uloside which, after C-3 methylation, was transformed into a glycosyl donor [3-O-benzyl-4-N-benzylformamido-4,6-dideoxy-3-C-methyl-2-O-methyl- ,-l-mannopyranosyl trichloroacetimidate (20), and used for the synthesis of p-tri¯uoroacetamidophenyl (4-formamido-4,6-dideoxy-3-Cmethyl-2-O-methyl-l-mannopyranosyl)-(133)-6-deoxy-2-O-methyl-d-mannopyranoside (29). Ethyl (3-O-benzyl-4-N-benzylformamido-4,6-dideoxy-3-C-methyl-2-O-methyl-l-mannopyranosyl)-(133)-4-O-benzyl-6-deoxy-2-O-methyl-l-thio-d-mannopyranoside (31), prepared by glycosylation of ethyl 4-O-benzyl-6-deoxy-2-O-methyl-1-thio-d-mannopyranoside with 20, served as glycosyl donor in a 2+3 block synthesis of the title pentasaccharide.
Syntheses of methyl glycosides of 6-deoxyheptoses
Canadian Journal of Chemistry, 1994
Methyl a-D-glycopyranosides of 6-deoxy-D-altro-heptose, 6-deoxy-D-n~anno-heptose, and 6-deoxy-D-talo-heptose have been prepared. Displacements of methyl 2,3,4-tri-0-benzylhexopyranoside 6-trifluoromethanesulfonates with potassium cyanide, followed by reduction of the resulting heptopyranosidurononitriles with diisobutylaluminurn hydride, hydrolysis of the imine, further reduction with sodium borohydride, and catalytic 0-debenzylation, give the corresponding methyl 6-deoxyheptopyranosides. Configurational change at C-4 of methyl 6-deoxy-7-O-tert-butyldiphenyIsilyl-a-~-rt1anno-heptopyranoside to give the talo isomer was effected by oxidation followed by stereoselective reduction. 'H nuclear magnetic resonance data of the glycosides, and gas chromatography of acetylated glycosides of (R)-and (S)-2-butanol serve to establish ring and enantiomeric configurations of the parent sugars when these are encountered as constituents of lipopolysaccharides or extracellular carbohydrate polymers, as in Carnpylobacter species. GERALD 0. ASPINALL, AWNDO G. MCDONALD et RAMESH K. SOOD. Can. J. Chem. 72,247 (1994).
The synthesis of 2-acetamido-2-deoxy-3-O-α-D-mannopyranosyl-D-glucose
Carbohydrate Research, 1971
Condensation of tetra-O-acetyl-α-D-mannopyranosyl bromide with benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-D-glucopyranoside gave crystalline benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-(tetra-O-acetyl-α-D-mannopyranosyl)-α-D-glucopyranoside. Removal of the benzylidene group gave a crystalline compound which was de-O-acetylated to crystalline benzyl 2-acetamido-2-deoxy-3-O-α-D-mannopyranosyl-α-D-glucopyranoside, characterized as the hexaacetate. The same products were obtained by de-O-acetylation of the condensation product, followed by hydrolysis of the benzylidene group and acetylation. Catalytic hydrogenolysis of the benzyl group gave crystalline 2-acetamido-2-deoxy-3-O-α-D-mannopyranosyl-α-D-glucose, characterized by a crystalline heptaacetate. This disaccharide may be used as a reference compound in the study of glycoproteins by partial hydrolysis with acid, and as the starting material for the synthesis of glycopeptides.
The synthesis of 2-acetamido-2-deoxy-6-O-α-d-manno-pyranosyl-d-glucose
Carbohydrate Research, 1971
Condensation of tetra-U-acetyl-aD -mannopyranosyl bromide with either benzyl 2-acetamido-3-O-acetyl-or 3,4-di-O-acetyl-2-deoxy-aD -glucopyranoside (obtained via the 6-O-trityl-and 3,4-di-0-acetyl-6-O-trityl derivatives) gave benzyl 2-acetamido-2-deoxy-6-O-aD -mannopyranosyl-aD -glucopyranoside penta-and hexaacetate in 42% and 65% yield, respectively_ Removal of the protective O-acetyl and 0-benzyl groups gave the title compound, which was characterized by a hepta-Oacetyl derivative. All intermediates were obtained in crystalline form. The title compound is useful as a reference standard for determination of the structure of the carbohydrate core of glycoproteins.
Angewandte Chemie International Edition in English, 1987
Dedicated to Professor Leopold Horner on the occasion of his 75th birthday Glycopeptides are partial structures of the connecting regions of glycoproteins and, like these, always contain glycosidic bonds between the carbohydrate and peptide parts. Glycoproteins are not only widely distributed but are also decisive factors in post-translational biological selectivity, especially in biological recognition. Targeted syntheses of glycopeptides require stereoselective formation of the glycosidic bonds between the carbohydrate and the peptide parts and protective group methods that enable selective deblocking of only one functional group in these polyfunctional molecules. These heavy demands have been met by the well-established use of benzylic protective groups, which can be removed by hydrogenolysis, combined with the use of base-labile 2-phosphonioethoxycarbonyl (Peoc) or 9-fluorenylmethoxycarbonyl (Fmoc) protective groups or of bromoethyl esters, which can be removed under neutral conditions. The acidolysis of tert-butyloxycarbonyl (Boc) groups and of tert-butyl esters has also been successfully used, although, under acidic conditions, anomerization or rupture of the glycosidic bonds may occur, especially when nucleophiles are present. The stable, two-stage 2-(pyridyl)ethoxycarbonyl (Pyoc) protective groups allow a more reliable synthesis of complex glycopeptides since they can be removed, after modifications, under mild conditions. Particularly suitable for the synthesis of sensitive glycopeptides are the stable ally1 protective groups. They can be removed from the complex glycopeptides in a highly selective and effective manner by means of noble-metal catalysts under practically neutral conditions. These methods have been employed to synthesize glycopeptides corresponding to partial structures of interesting glycoproteins. Deprotected glycopeptides representing tumor-associated antigen structures can be coupled to bovine serum albumin, which serves as a biological carrier molecule, without the necessity of using a n artificial coupling component (spacer). 294 0 VCH Verlagsgesellschaf, mbH, 0-6940 Weinheim.
Monatshefte fur chemie, 2017
Phosphoethanolamine derivatives of the bacterial saccharide l-glycero-d-manno-heptose have been prepared using a phosphoramidite-based coupling reaction at position 4 of a side-chain-protected 2,3-O-orthoester methyl heptoside and at position 3 of a 3,4-diol heptoside, respectively. Global deprotection afforded the corresponding 2-aminoethylphosphodiester derivatives as substrates for crystallographic and binding studies with lectins and antibodies targeting the inner core structure of bacterial lipopolysaccharides.
Carbohydrate Research, 2009
Dedicated to Professor Dr. Hans Kamerling on the occasion of his 65th birthday Keywords: Methyl b-D-mannopyranosyl-(1?2)-b-Dmannopyranoside Monodeoxy and mono-O-methyl congeners Mapping of anti-Candida albicans antibodies Functional group modification a b s t r a c t A panel of six complementary monodeoxy and mono-O-methyl congeners of methyl b-D-mannopyranosyl-(1?2)-b-D-mannopyranoside were synthesized by stereoselective glycosylation of monodeoxy and mono-O-methyl monosaccharide acceptors with a 2-O-acetyl-glucosyl trichloroacetimidate donor, followed by a two-step oxidation-reduction sequence at C-2 0 . The b-manno configurations of the final deprotected congeners 2-7 were confirmed by measurement of 1 J C1,H1 heteronuclear and 3 J 1 0 ,2 0 homonuclear coupling constants. These disaccharide derivatives will be used to map the protective epitope recognized by a protective anti-Candida albicans monoclonal antibody C3.1 (IgG3) and to determine its key polar contacts with the binding site. j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a r r e s detail the size and topology of the mAb IgG3 (C3.1) antibody binding site, a panel of six monodeoxy and mono-O-methyl congeners 2-7 of the disaccharide methyl b-D-mannopyranosyl-(1?2)-b-Dmannopyranoside have been synthesized. For each congener a single hydroxyl group on the reducing-end residue of the parent disaccharide 1 has been modified by either deoxygenation or methylation ).