Synthesis and molecular structure of the 5-methoxycarbonylpentyl α-glycoside of the upstream, terminal moiety of the O-specific polysaccharide of Vibrio cholerae O1, serotype Inaba

The trimethylsilyl trifluoromethanesulfonate (TMSOTf)-catalyzed reaction of methyl 6-hydroxyhexanoate with 3-O-benzyl-4-(2,4-di-O-acetyl-3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-2-O-levulinoyl-α-d-mannopyranosyl trichloroacetimidate followed by a two-step deprotection (hydrogenolysis over Pd/C cat...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2015-02, Vol.20 (2), p.2892-2902
Main Authors: Xu, Peng, Stevens, Edwin D, French, Alfred D, Kováč, Pavol
Format: Article
Language:English
Subjects:
Carbohydrate Sequence
crystal structure
Crystallography, X-Ray
glycosidation
glycosylation
Hydrogen Bonding
Magnetic Resonance Spectroscopy
Mannosides - chemical synthesis
Mannosides - chemistry
O Antigens - chemistry
Vibrio cholerae
Vibrio cholerae O1
Vibrio cholerae O1 - chemistry
Vibrio cholerae O1 - metabolism
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Summary:The trimethylsilyl trifluoromethanesulfonate (TMSOTf)-catalyzed reaction of methyl 6-hydroxyhexanoate with 3-O-benzyl-4-(2,4-di-O-acetyl-3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-2-O-levulinoyl-α-d-mannopyranosyl trichloroacetimidate followed by a two-step deprotection (hydrogenolysis over Pd/C catalyst and Zemplén deacylation, to simultaneously remove the acetyl and levulinoyl groups) gave 5-(methoxycarbonyl)pentyl 4-(3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-α-D-mannopyranoside. The structure of the latter, for which crystals were obtained in the analytically pure state for the first time, followed from its NMR and high-resolution mass spectra and was confirmed by X-ray crystallography. The molecule has two approximately linear components; a line through the aglycon intersects a line through the mannosyl and tetronylamido groups at 120°. The crystal packing separates the aglycon groups from the tetronylamido and mannosyl groups, with only C-H...O hydrogen bonding among the aglycon groups and N-H...O, O-H...O and C-H...O links among the tetronylamido and mannosyl groups. A carbonyl oxygen atom accepts the strongest O-H...O hydrogen bond and two strong C-H...O hydrogen bonds. The geometric properties were compared with those of related molecules.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules20022892