- Streamlined Iterative Assembly of Thio-Oligosaccharides by Aqueous S-Glycosylation of Diverse Deoxythio Sugars
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A streamlined iterative assembly of thio-oligosaccharides was developed by aqueous glycosylation. Facile syntheses of various deoxythio sugars with the sulfur on different positions from commercially available starting materials were described. These syntheses featured efficient chemical methods including our recently reported BTM-catalyzed site-selective acylation. The resulting deoxythio sugars could then be used for the Ca(OH)2-promoted protecting group-free S-glycosylation in water at room temperature. The aqueous glycosylation reaction proceeded smoothly to afford the corresponding 1,2-trans S-glycosides in good yields with high chemo- and stereoselectivity. An appropriate choice of protecting groups for the thiol in the glycosyl donor was necessary for the development of iterative synthesis of thio-oligosaccharides. The aqueous glycosylation was then applied to the synthesis of a trimannoside moiety of N-linked glycans core region.
- Fan, Qiuhua,Jia, Peijing,McCarty, Bethany J.,Tang, Weiping,Wen, Peng
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- Direct, stereoselective thioglycosylation enabled by an organophotoredox radical strategy
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While strategies involving a 2e- transfer pathway have dictated glycosylation development, the direct glycosylation of readily accessible glycosyl donors as radical precursors is particularly appealing because of high radical anomeric selectivity and atom- and step-economy. However, the development of the radical process has been challenging owing to notorious competing reduction, elimination and/or SN side reactions of commonly used, labile glycosyl donors. Here we introduce an organophotocatalytic strategy through which glycosyl bromides can be efficiently converted into corresponding anomeric radicals by photoredox mediated HAT catalysis without a transition metal or a directing group and achieve highly anomeric selectivity. The power of this platform has been demonstrated by the mild reaction conditions enabling the synthesis of challenging α-1,2-cis-thioglycosides, the tolerance of various functional groups and the broad substrate scope for both common pentoses and hexoses. Furthermore, this general approach is compatible with both sp2 and sp3 sulfur electrophiles and late-stage glycodiversification for a total of 50 substrates probed.
- Bi, Fangchao,Gao, Feng,Ji, Peng,Wang, Wei,Zhang, Yueteng
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p. 13079 - 13084
(2021/01/09)
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- Synthesis of thioglycoside analogues of maradolipid
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We describe here the first synthesis of thioglycoside analogues of maradolipid, based on a new procedure for the synthesis of 1-thiotrehalose developed recently in our laboratories. The challenging α,α- (1→1′) thioglycosidic linkage was constructed by Sch
- Zeng, Xiaojun,Smith, Raymond,Zhu, Xiangming
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p. 4165 - 4170
(2013/05/23)
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- A facile and highly stereoselective synthesis of 1-thiotrehalose
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A facile and highly stereoselective synthesis of 1-thiotrehalose, that is, α,α-S-linked trehalose, is described. Glycosylation of configurationally pure α-glucosyl thiol 5 with glucosyl trichloroacetimidate 6 or glucosyl thioimidate 9 followed by deprotection afforded 1-thiotrehalose in excellent α-stereoselectivity and high yield. A different synthetic route to the key building block, α-glucosyl thiol 5, was also investigated in this report.
- Xin, Guohong,Zhu, Xiangming
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supporting information; experimental part
p. 4309 - 4312
(2012/09/22)
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- A facile preparation of trehalose analogues: 1,1-thiodisaccharides
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The synthesis of 1,1-thiodisaccharide trehalose analogues in good to excellent yields by a Lewis acid (BF3·Et2O)-catalysed coupling of sugar per-O-acetate with thiosugar is described. The reactivity of different sugar per-O-acetates and thiosugars is explored.
- Morais, Goreti Ribeiro,Humphrey, Andrew J.,Falconer, Robert A.
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experimental part
p. 1039 - 1045
(2009/09/05)
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- Synthesis of interglycosidically S-linked 1-thio-oligosaccharides under microwave irradiation
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Microwave irradiation (MWI) has accelerated the synthesis of S-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)thiouronium bromide (2a), whose reaction with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (1a) in the presence of Et3N afforded stereoselectively the acetylated β,β-1-thiotrehalose 4a. Similarly, the respective D-galactopyranosyl 4b and 2-acetylamino-2-deoxy-D-glucopyranosyl 4c analog as well as 4,4′-di-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl) 4d and 4,4′-di-O-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl) 4e derivatives of 2,2′,3,3′,6,6′-hexa-O-acetyl β,β-1-thiotrehalose were prepared. Copyright Taylor & Francis, Inc.
- El Ashry, El Sayed H.,Awad, Laila F.,Hamid, H. M. Abdel,Atta, Atta I.
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p. 745 - 753
(2007/10/03)
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- Hydrogen fluoride-mediated synthesis of 1-thiotrehaloses involving reaction of D-glucose with hydrogen sulfide
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Hydrogen sulfide reacted with D-glucosde in hydrogen fluoride solution to yield preponderantly α,α-1-thiotrehalose, β,β-1-thiotrehalose, and the α,β anomer. Conditions were found under which the thiotrehaloses were obtained in the respective proportions of 8:5:5. Hydrogen sulfide reacted with D-glucose in hydrogen fluoride solution to yield preponderantly α,α-1-thiotrehalose, β,β-1-thiotrehalose and the α,β anomer. Conditions were found under which the thiotrehaloses were obtained in the respective proportions of 8:5:5.
- Defaye,Gadelle,Pedersen
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- Synthesis of Thiodisaccharides using Phase-transfer Catalysis
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Synthesis of thiodisaccharides or thioglycosides was performed by phase-transfer catalysis using phosphonium or ammonium salts.Starting from glycosyl halides, reaction with Na2S gave the corresponding thiodisaccharides with inversion of configuration at the anomeric centre.With unstable glycosyl halides, a solid-liquid system was used.Unsymmetrical thiodisaccharides and 1-thioglycosides were prepared by reaction of glycosyl halides with thiolate or 1-thioglucose under p.t.c. conditions.
- Chretien, Francoise,Cesare, Pierre Di,Gross, Bernard
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p. 3297 - 3300
(2007/10/02)
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