title: Synthesis and reactivity of 4'-deoxypentenosyl disaccharides.
abstract: 4-Deoxypentenosides (4-DPs) are versatile synthons for rare or higher-order pyranosides, and they provide an entry for structural diversification at the C5 position. Previous studies have shown that 4-DPs undergo stereocontrolled DMDO oxidation; subsequent epoxide ring-openings with various nucleophiles can proceed with both anti or syn selectivity. Here, we report the synthesis of α- and β-linked 4'-deoxypentenosyl (4'-DP) disaccharides, and we investigate their post-glycosylational C5' additions using the DMDO oxidation/ring-opening sequence. The α-linked 4'-DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf2O activation, whereas β-linked 4'-DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both α- and β-linked 4'-DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the α-epoxypentenosides could be successfully converted into terminal l-iduronic acids via the syn addition of 2-furylzinc bromide. These studies support a novel approach to oligosaccharide synthesis, in which the stereochemical configuration of the terminal 4'-DP unit is established at a post-glycosylative stage.
authors.affiliation: Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907-2084, United States.
authors.forename: Panuwat
authors.initials: P
authors.lastname: Padungros
authors.forename: Ren-Hua
authors.initials: RH
authors.lastname: Fan
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Casselman
authors.forename: Gang
authors.initials: G
authors.lastname: Cheng
authors.forename: Hari R
authors.initials: HR
authors.lastname: Khatri
authors.forename: Alexander
authors.initials: A
authors.lastname: Wei
mesh_terms: D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry; D006031:Glycosylation; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D004187:Disaccharides; D004852:Epoxy Compounds; D009844:Oligosaccharides