title: 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.
abstract: 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.
authors: NIDDK, LBC, National Institutes of Health, Bethesda, MD 20892-0815, USA. xup3@mail.nih.gov.
authors: Peng
authors: P
authors: Xu
authors: Department of Chemistry, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-1709, USA. Edwin.Stevens@wku.edu.
authors: Edwin D
authors: ED
authors: Stevens
authors: Southern Regional Research Center, US Department of Agriculture, 1100 Robert E Lee Blvd, New Orleans, LA 70124, USA. Al.French@ars.usda.gov.
authors: Alfred D
authors: AD
authors: French
authors: NIDDK, LBC, National Institutes of Health, Bethesda, MD 20892-0815, USA. kpn@helix.nih.gov.
authors: Pavol
authors: P
authors: Kováč
mesh_terms: D002240:Carbohydrate Sequence; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008362:Mannosides / Q000138:chemical synthesis* / Q000737:chemistry; D019081:O Antigens / Q000737:chemistry*; D041241:Vibrio cholerae O1 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008362:Mannosides; D019081:O Antigens