21 1,2-cis 2-アミノ糖を与える新規糖供与体を用いた生理活性糖鎖の合成(口頭発表の部)

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Glycosyl donors bearing azido functionality at C-2 position have been used for α-glycosylation reactions since 30 years ago. However, its preparation is not easy and the stereoselectivities in glycosylation reactions are not always high. To overcome these difficulties, we develop the novel glycosyl donors having N-benzyl-2,3-oxazolidinone for 1,2-cis selective glycosylation of 2-amino sugars. We also demonstrate its application to the synthesis of bioactive oligosaccharide. Glycosylation reactions using N-benzyloxazolidinone carrying glycosyl donors were highly α-selective. Advantages of the donors include facile preparation in gram-scale and easy deprotection of N-benzyl-oxazolidinone moiety. A one-pot oligosaccharide synthesis involving two 1,2-cis glycosidic linkages was also demonstrated using the novel glycosyl donors. To demonstrate the utility of this donor, we synthesized the anti-Helicobacter pylori oligosaccharide. The target oligosaccharide was terminal α-GlcNAc residues having core 2 type O-linked oligosaccharide. The terminal α-GlcNAc is suggested to be essential for the bioactivity. We synthesized the oligosaccharide from non-reducing terminal α-GlcNAc moieties to the reducing end, because the synthetic intermediates can be submitted to the biological assay in the aim of structure-activity relationships study.
天然有機化合物討論会の論文
2006-09-15