title: Regio- and stereoselective glycosylation: synthesis of 5-haloimidazole alpha-ribonucleosides.
abstract: We describe the synthesis of novel 5-haloimidazole ribonucleosides as precursors of modified cobalamins. A regio- and stereoselective glycosylation of protected ribose with silylated 4(5)-haloimidazoles produces 5-haloimidazole ribonucleosides predominantly in the alpha-configuration (60-75%) without any 4-substituted imidazole ribonucleoside. The structure of the 5-fluoroimidazole ribonucleoside was confirmed by X-ray crystallography and 2D NMR spectroscopy.
authors.affiliation: Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, USA.
authors.forename: Tilak
authors.initials: T
authors.lastname: Chandra
authors.forename: Xiang
authors.initials: X
authors.lastname: Zou
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Valente
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Brown
mesh_terms: D006031:Glycosylation; D007093:Imidazoles / Q000737:chemistry*; D008968:Molecular Conformation; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D007093:Imidazoles; D012263:Ribonucleosides