Synthesis and 13C-NMR spectroscopic investigations of rhamnobioses

Lipták, András; Nánási, Pál; Neszmélyi, András; Wagner, Hildebert

doi:10.1016/0040-4020(80)87028-1

Cited by 65 publications

(37 citation statements)

References 32 publications

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“…Our assignments for 14 and 18 are in agreement with those published by Liptak et al (9) except for the relative assignments of C-zA and C-3B in 18. We want to note that the difference between these shifts is small and that their reassignment was made possible by using techniques and high field strength not available at the time of the original assignment.…”

Section: A-l-rhap-(14 3)-a-~-galp-(l+ 3)-p-d-glcnacp-(1+4)-[a-l-rhap-supporting

confidence: 82%

“…13, 17) with glycosyl acceptors 4 and 6 (9, 10) gave the desired disaccharides 13 (9) and 17 (9) in 36.7 and 70.8% yields, respectively. These glycosylations were accompanied by extensive acetylation of the acceptors 4 and 6, giving acetates 5 and 7 in 22.3 and 14.8% yields, respectively.…”

Section: A-l-rhap-(14 3)-a-~-galp-(l+ 3)-p-d-glcnacp-(1+4)-[a-l-rhap-mentioning

confidence: 99%

“…Dibenzyl derivative 4 was selected; it was first prepared by Liptak et al (9) by LiA1H4-A1C13 reduction of methyl 4-0-benzyl-2,3-0-exobenzylidene-a-L-rhamnopyranoside in ca. 21% overall yield from 2.…”

Section: A-l-rhap-(14 3)-a-~-galp-(l+ 3)-p-d-glcnacp-(1+4)-[a-l-rhap-mentioning

confidence: 99%

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Synthetic oligosaccharides related to Group B streptococcal polysaccharides. The rhamnotriose moiety of the common antigen

Pozsgay¹,

Brisson²,

Jennings³

1987

Can. J. Chem.

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. Can. J. Chem. 65,2764Chem. 65, (1987. The methyl glycoside (1) of the a-~-~ha~-(1+2)-a-~-~ha~-(1+2)-a-~-~hap-(l+ portion of the group-specific, common antigen polysaccharide of Group B Streptococci has been synthesized. The key compound of the synthesis was methyl 3,4-di-0-benzyl-a-L-rhamnopyranoside (4). Controlled acetolysis of 4 gave 1 ,2-di-0-acetyl-3,4-di-0-benzyl-a-L-rhamnopyranose (lo), which upon reaction with 4 under catalysis by trimethylsilyl trifluoromethanesulfonate (TMS-TQ yielded the a-(142)-linked dirhamnoside. Subsequent rhamnosylation followed by deprotection gave 1. TMS-Tf was also used in rhamnosylation reactions with tetra-0-acetyl-a-L-rhamnopyranose. Acetylation of acceptor alcohols was found to be a major side reaction in the TMS-Tf assisted glycosylations. One-dimensional nuclear Overhauser enhancement differential spectroscopy indicated that, in solution, 1 takes up a bent instead of an extended conformation.V~N C E POZSGAY, JEAN-ROBERT BR~SSON et HAROLD J. JENNINGS. Can. J. Chem. 65, 2764Chem. 65, (1987. On a synthttisk le glycoside de m6thyle (1) de la portion a-L-Rhap-(1+2)-a-L-Rhap-(l+2)-a-L-Rhap-(l+ du polysaccharide antigknique commun et specifique du streptocoque du groupe B. Le composC clC de la synthkse est le di-0-benzyl-3.4 a-L-rhamnopyrannoside de mtthyle (4). Une acCtolyse contr81Ce du produit 4 conduit au di-0-acttyl-1,2 di-0-benzyl-3,4 a-L-rhamnopyrannose (10) qui, par une rCaction avec le composC 4 catalysCe par le trifluoromCthanesulfonate de trimCthylsilyle (Tf-TMS), conduit au dirhamnoside qui comporte la liaison a -( 1 4 2 ) . Une rhamnosylation subskquente, suivie d'une dkprotection, conduit au composC 1. On a aussi utilisC le Tf-TMS dans des rCactions de rhamnosylation impliquant le tCtra-0-acCtyl c*-L-rhamnopyrannose. 0 n a trouvC que I'acCtylation des alcools accepteurs est une rCaction secondaire importante dans les rtactions de glycosylation assistees par le Tf-TMS. La spectroscopie diffkrentielle, unidimensionnelle de I'effet Overhauser nuclCaire indique que, en solution, la conformation du composC 1 est plutBt replike qu'ttendue.[Traduit par la revue]

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Section: A-l-rhap-(14 3)-a-~-galp-(l+ 3)-p-d-glcnacp-(1+4)-[a-l-rhap-supporting

confidence: 82%

Section: A-l-rhap-(14 3)-a-~-galp-(l+ 3)-p-d-glcnacp-(1+4)-[a-l-rhap-mentioning

confidence: 99%

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Synthetic oligosaccharides related to Group B streptococcal polysaccharides. The rhamnotriose moiety of the common antigen

Pozsgay¹,

Brisson²,

Jennings³

1987

Can. J. Chem.

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“…The magnitudes of the ' J~, H for the anomeric carbons and their attached protons in 6 were determined from a gated decoupled 13C NMR experiment (fucose ' J~,H 156.8 Hz; rhamnose Jca 17 1.0 Hz). They were consistent with a fucose p glycosidic linkage and a rhamnose a glycosidic linkage (9), as in xestovanin A (1).…”

Section: New Metabolites From the Bamjeld Specimensmentioning

confidence: 63%

“…A continuing investigation of the terpenoid metabolism of X. vanilla has led to the isolation of seven new metabolites, isoxestovanin A (6), xestovanin B (7), xestovanin C (8), dehydroxestovanin A (9), epidehydroxestovanin A (lo), dehydroxestovanin C ( l l ) , and secodehydroxestovanin A (12), whose structures are reported herein. One of the metabolites, isoxetovanin A (6), has the new isoxestovanane triterpenoid carbon skeleton, five (compounds 7, 8, 9, 10, and 11) have the xestovanane carbon skeleton, and one (compound 12) has the secoxestovanane skeleton.…”

mentioning

confidence: 99%

Triterpenoid glycosides from the Northeastern Pacific marine sponge Xestospongia vanilla

Morris¹,

Northcote²,

Andersen³

1991

Can. J. Chem.

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. Can. J. Chem. 69, 1352Chem. 69, (1991. Isoxestovanin A (6), xestovanin B (7), xestovanin C (8), dehydroxestovanin A (9). epidehydroxestovanin A (lo), dehydroxestovanin C (ll), and secodehydroxestovanin A (12). seven new triterpenoid glycosides, have been isolated from the Northeastern Pacific sponge Xestospongia vanilla. The structures of the metabolites were determined by a combination of spectroscopic analysis and chemical degradation. The aglycone of 6 has the new isoxestovanane triterpenoid carbon skeleton. Compounds 7, 8, and 11 are the first X. vanilla triterpenoid glycosides known to contain three monosaccharide subunits.

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Conformational analysis and molecular dynamics simulation of α-(1 → 2) and α-(1 → 3) linked rhamnose oligosaccharides: Reconciliation with optical rotation and NMR experiments

et al. 1997

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Molecular mechanics and dynamics calculations were carried out on the disaccharides α‐L‐Rhap‐(1 → 2)‐α‐L‐Rhap‐(1 → OMe) (1) and α‐L‐Rhap‐(1 → 3)‐α‐L‐Rhap‐(1 OMe) (2), and the trisaccharide α‐L‐Rhap‐(1 → 2)‐α‐L‐Rhap‐(1 → 3)‐α‐L‐Rhap‐(1 → OMe) (3). The semiflexible conformational behavior of these molecules was characterized by the occupation of a combination of different glycosidic linkage and side‐chain conformational positions whose relative occupations were sensitive to dielectric screening. Molecular dynamics simulations of the trisaccharide 3 showed little difference between the linkage conformations in the trisaccharide and the component disaccharides 1 and 2. Experimental optical rotation data of 1 and 2 were obtained as a function of temperature in varying solvents. The molecular models were combined with the semiempirical theory of Stevens and Sathyanarayana to yield calculated optical rotations. Interpretation of the data of both 1 and 2 implied that a combination of conformations, both in glycosidic and side‐chain positions, could explain the experimental data. Solvents effects were important in influencing the conformational mix and averaged optical rotation. Three‐bond heteronuclear coupling constants 3JC, H were obtained for the glycosidic linkages of 1 and 2 in D2O and DMSO. Analysis of the coupling constants with a Karplus curve showed that small reductions in the glycosidic torsion angles of the conformations of the models used here of ca. 10°–15° in ϕ and 5°–10° in ψ were required to give better agreement with experiment; a combination of conformations for both 1 and 2 was consistent with the data. There was a negligible influence on the coupling constants of 1 on changing the solvent from D2O to DMSO. © 1997 John Wiley & Sons, Inc.

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Synthesis and 13C-NMR spectroscopic investigations of rhamnobioses

Cited by 65 publications

References 32 publications

Synthetic oligosaccharides related to Group B streptococcal polysaccharides. The rhamnotriose moiety of the common antigen

Synthetic oligosaccharides related to Group B streptococcal polysaccharides. The rhamnotriose moiety of the common antigen

Triterpenoid glycosides from the Northeastern Pacific marine sponge Xestospongia vanilla

Conformational analysis and molecular dynamics simulation of α-(1 → 2) and α-(1 → 3) linked rhamnose oligosaccharides: Reconciliation with optical rotation and NMR experiments

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