Effect of Protecting Groups and Activating Conditions on 3-Deoxy-d-glycero-d-galacto-2-nonulosonic Acid (Kdn) Glycosylation: Stereoselective Synthesis of α- and β-Kdn Glycosides
{"title":"Effect of Protecting Groups and Activating Conditions on 3-Deoxy-d-glycero-d-galacto-2-nonulosonic Acid (Kdn) Glycosylation: Stereoselective Synthesis of α- and β-Kdn Glycosides","authors":"Jin-Song Yang, Yu-Xiong Ruan, Hong-Yang Wang, Ling Li, Yan-Li Zhao, Yong Qin","doi":"10.1021/acs.orglett.4c04325","DOIUrl":null,"url":null,"abstract":"Kdn is a common member of the sialic acid family. Carbohydrates containing Kdn residues are widely distributed in nature and embody important biological information. However, the methods for synthesizing Kdn glycosides are limited, which restricts their biological study. In this paper, we developed efficient α- and β-stereoselective Kdn glycosylation methods by employing differentially protected Kdn thioglycoside donors under their respective activating protocols. The 5,7-<i>O</i>-carbonate fused Kdn thioglycoside <b>1a</b> could be promoted with NIS/TfOH (cat.) in CH<sub>2</sub>Cl<sub>2</sub>/CH<sub>3</sub>CN (2:1) to afford Kdn glycosides with excellent α-selectivity in high yields. Meanwhile, based on the Ph<sub>2</sub>SO/Tf<sub>2</sub>O preactivation strategy, the nonfused Kdn thioglycoside <b>1b</b> behaved as a high-yielding and β-selective donor to couple with various carbohydrate alcohols, leading to formation of β-Kdn glycosides. The synthetic utility of these newly developed glycosyl donors has been demonstrated by the stereoselective and straightforward assembly of two natural Kdn-containing oligosaccharides.","PeriodicalId":54,"journal":{"name":"Organic Letters","volume":"86 1","pages":""},"PeriodicalIF":4.9000,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic Letters","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.orglett.4c04325","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
引用次数: 0
Abstract
Kdn is a common member of the sialic acid family. Carbohydrates containing Kdn residues are widely distributed in nature and embody important biological information. However, the methods for synthesizing Kdn glycosides are limited, which restricts their biological study. In this paper, we developed efficient α- and β-stereoselective Kdn glycosylation methods by employing differentially protected Kdn thioglycoside donors under their respective activating protocols. The 5,7-O-carbonate fused Kdn thioglycoside 1a could be promoted with NIS/TfOH (cat.) in CH2Cl2/CH3CN (2:1) to afford Kdn glycosides with excellent α-selectivity in high yields. Meanwhile, based on the Ph2SO/Tf2O preactivation strategy, the nonfused Kdn thioglycoside 1b behaved as a high-yielding and β-selective donor to couple with various carbohydrate alcohols, leading to formation of β-Kdn glycosides. The synthetic utility of these newly developed glycosyl donors has been demonstrated by the stereoselective and straightforward assembly of two natural Kdn-containing oligosaccharides.
期刊介绍:
Organic Letters invites original reports of fundamental research in all branches of the theory and practice of organic, physical organic, organometallic,medicinal, and bioorganic chemistry. Organic Letters provides rapid disclosure of the key elements of significant studies that are of interest to a large portion of the organic community. In selecting manuscripts for publication, the Editors place emphasis on the originality, quality and wide interest of the work. Authors should provide enough background information to place the new disclosure in context and to justify the rapid publication format. Back-to-back Letters will be considered. Full details should be reserved for an Article, which should appear in due course.