title: Stereoselective Construction of β-Mannopyranosides by Anomeric O-Alkylation: Synthesis of the Trisaccharide Core of N-linked Glycans.
abstract: A new and efficient approach for direct and stereoselective synthesis of β-mannopyranosides by anomeric O-alkylation has been developed. This anomeric O-alkylation of mannopyranose-derived lactols is proposed to occur under synergistic control of a kinetic anomeric effect and metal chelation. The presence of a conformationally flexible C6 oxygen atom in the sugar-derived lactol donors is required for this anomeric O-alkylation to be efficient, probably because of its chelation with cesium ion. In contrast, the presence of a C2 oxygen atom plays a minor role. This glycosylation method has been successfully utilized for the synthesis of the trisaccharide core of complex N-linked glycans.
authors.affiliation: Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, The University of Toledo, Toledo, OH, 43606, USA.
authors.forename: Hai
authors.initials: H
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, The University of Toledo, Toledo, OH, 43606, USA.
authors.forename: Danyang
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, MI, 48128, USA. shannli@umich.edu.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, The University of Toledo, Toledo, OH, 43606, USA. Jianglong.Zhu@Utoledo.edu.
authors.forename: Jianglong
authors.initials: J
authors.lastname: Zhu
keywords: N-linked glycans; anomeric O-alkylation; glycosylation; oligosaccharides; β-mannosylation