Synthesis and Reactivity of 4鈥?Deoxypentenosyl Disaccharides

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• 作者：Panuwat Padungros ; Ren-Hua Fan ; Matthew D. Casselman ; Gang Cheng ; Hari R. Khatri ; Alexander Wei
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：June 6, 2014
• 年：2014
• 卷：79
• 期：11
• 页码：4878-4891
• 全文大小：623K
• 年卷期：v.79,no.11(June 6, 2014)
• ISSN：1520-6904

文摘

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 伪- and 尾-linked 4鈥?deoxypentenosyl (4鈥?DP) disaccharides, and we investigate their post-glycosylational C5鈥?additions using the DMDO oxidation/ring-opening sequence. The 伪-linked 4鈥?DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf₂O activation, whereas 尾-linked 4鈥?DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both 伪- and 尾-linked 4鈥?DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the 伪-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鈥?DP unit is established at a post-glycosylative stage.