- Triflic Imide-Catalyzed Glycosylation of Disarmed Glycosyl ortho-Isopropenylphenylacetates and ortho-Isopropenylbenzyl Thioglycosides
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Glycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf2NH)-catalyzed glycosylation of various O-, S-, and C-nucleophiles has been achieved using disarmed glycosyl ortho-isopropenylphenylacetates (GIPPAs) and ortho-isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good-to-excellent yields. Of particular note, the comparable reactivity for the α-isomers and the β-ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid-catalyzed glycosylation to create various glycosidic bonds.
- Qiao, Zhi,Wang, Peng,Ni, Jingxuan,Li, Dongwei,Sun, Yao,Li, Tiantian,Li, Ming
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- Dehydrative Thioglycosylation of 1-Hydroxyl Glycosides Catalyzed by In Situ-Generated AlI3
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Thioglycosylation of 1-hydroxyl glycosides catalyzed by in situ-generated AlI3 from elemental aluminium and molecular iodine has been developed. This method provides an alternative route to access anomeric thioglycosides without the use of hazard Lewis acidic activators or per-modified activated thiol sources. The major advantages of this dehydrative procedure are environmental friendly, ease of operation, high anomeric diastereoselectivity, and mild reaction conditions.
- Weng, Shiue-Shien,Hsieh, Kun-Yi,Zeng, Zih-Jian
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p. 464 - 473
(2017/05/19)
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- Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones
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A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide.
- Singh, Adesh Kumar,Tiwari, Varsha,Mishra, Kunj Bihari,Gupta, Surabhi,Kandasamy, Jeyakumar
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supporting information
p. 1139 - 1144
(2017/06/20)
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- Stereoretentive palladium-catalyzed arylation, alkenylation, and alkynylation of 1-thiosugars and thiols using aminobiphenyl palladacycle precatalyst at room temperature
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A general and efficient protocol for the palladium-catalyzed functionalization of mono- and polyglycosyl thiols by using the palladacycle precatalyst G3-XantPhos was developed. The C-S bond-forming reaction was achieved rapidly at room temperature with various functionalized (hetero)aryl-, alkenyl-, and alkynyl halides. The functional group tolerance on the electrophilic partner is typically high and anomer selectivities of thioglycosides are high in all cases studied. New sulfur nucleophiles such as thiophenols, alkythiols, and thioaminoacids (cysteine) were also successfully coupled to lead to the most general and practical method yet reported for the functionalization of thiols.
- Bruneau, Alexandre,Roche, Maxime,Hamze, Abdallah,Brion, Jean-Daniel,Alami, Mouad,Messaoudi, Samir
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p. 8375 - 8379
(2015/06/02)
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- Facile preparation of α-glycosyl iodides by in situ generated aluminum iodide: Straightforward synthesis of thio-, seleno-, and o-glycosides from unprotected reducing sugars
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A facile and practical protocol was developed for the synthesis of glycosyl iodides using AlI3 generated in situ from cheap aluminum metal and molecular iodine. Furthermore, in combination with iodine-catalyzed per-O-acetylation, sequential synthesis of per-acetylated glycosyl iodides, per-acetylated thioglycosides, selenoglycoside, and O-glycosides from unprotected reducing sugars was also achieved with complete diastereocontrol in a one-pot version. Supplemental material is available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the free supplemental file. Copyright Taylor & Francis Group, LLC.
- Weng, Shiue-Shien,Li, Chia-Ling,Liao, Chun-Sheng,Chen, Ting-An,Huang, Chao-Cheih,Hung, Kuo-Tung
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p. 429 - 440
(2012/06/01)
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- Selective activation of glycosyl donors utilising electrochemical techniques: A study of the thermodynamic oxidation potentials of a range of chalcoglycosides
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A series of six chalcoglycosides (phenyl-2,3,4,6-tetra-0-benzoyl-1-seleno-β-D-glucopyranoside, phenyl-2,3,4,6-tetraO-benzyl-1-seleno-β-D-glucopyranoside, phenyl-2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside, p-tolyl-2,3,4,6-O-benzoyl-1-thio-β-D-glucop
- France, Robert R.,Rees, Neil V.,Wadhawan, Jay D.,Fairbanks, Antony J.,Compton, Richard G.
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p. 2188 - 2194
(2007/10/03)
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- THIOGLYCOSIDES AS POTENTIAL GLYCOSYL DONORS IN ELECTROCHEMICAL GLYCOSYLATION REACTIONS. PART 1: THEIR PREPARATION AND REACTIVITY TOWARD SIMPLE ALCOHOLS
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Costant potential electrolysis of several glycosyl donors such as substituted phenyl 2,3,4,6-tetra-O-acetyl, benzoyl or benzyl-1-thio-β-D-gluco or galactopyranosides in dry acetonitrile in the presence of various primary, secondary or tertiary alcohols performed in an undivided cell, gave preferentially β-linked saccharides in moderate to good yields according to the nature of the protective groups on the sugar moiety. 2-Deoxy-2-phthalimido-1-thio-β-D-gluco derivatives gave the β-glucosides selectively in excellent yields.It was found, as expected, that substitution of the phenyl group with methoxy or methyl radicals facilitates the electrochemical glycosylation reaction by lowering the oxidation potentials of the corresponding thioglycosides.
- Balovoine, Gilbert,Berteina, Sabine,Gref, Aurore,Fischer, Jean-Claude,Lubineau, Andre
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p. 1217 - 1236
(2007/10/03)
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