title: Improved synthesis and the crystal structure of methyl 4,6-dideoxy-4-(3-deoxy-L-glycero-tetronamido)-alpha-D-mannopyrano side, the methyl alpha-glycoside of the intracatenary repeating unit of the O-polysaccharide of Vibrio cholerae O:1.
abstract: The crude product of deamination of the commercially available L-homoserine was acetylated and the 2-O-acetyl-3-deoxy-L-glycero-tetronolactone (18) formed was used to N-acylate methyl perosaminide (methyl 4-amino-4,6-dideoxy-alpha-D-mannopyranoside, 12) and its 2,3-O-isopropylidene derivative. The major product isolated from the reaction was the crystalline methyl 4-(4-O-acetyl-3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-alpha-D-+ ++mannopyranoside (1, 70-75%) resulting from acetyl group migration in the initially formed 2'-O-acetyl derivative. O-Deacetylation of 1 gave the title amide 2. Compound 2, obtained crystalline for the first time, was fully characterized, and its crystal structure was determined. Deoxytetronamido derivatives diastereomeric with 1 and 2, respectively, were obtained by the acylation of 12 with 2-O-acetyl-3-deoxy-D-glycero-tetronolactone (prepared from D-homoserine), and subsequent deacetylation. Structures of several byproducts of the reaction of 12 with 18 have been deduced from their spectral characteristics. Since these byproducts were various O-acetyl derivatives of 2, the title compound could be obtained in approximately 90% yield by deacetylating (Zemplén) the crude mixture of N-acylation products, followed by chromatography.
authors.affiliation: NIDDK, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: M
authors.initials: M
authors.lastname: Gotoh
authors.forename: C N
authors.initials: CN
authors.lastname: Barnes
authors.forename: P
authors.initials: P
authors.lastname: Kovác
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D018360:Crystallography, X-Ray / Q000379:methods; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008766:Methylmannosides / Q000138:chemical synthesis* / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019081:O Antigens; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D014734:Vibrio cholerae / Q000737:chemistry* / Q000276:immunology
chemical_list: D007202:Indicators and Reagents; D008766:Methylmannosides; D019081:O Antigens; D011135:Polysaccharides, Bacterial; C089001:methyl 4,6-dideoxy-4-(3-deoxyglycerotetronamido)mannopyranoside