- Synthesis of glycosyl chlorides using catalytic Appel conditions
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The stereoselective synthesis of glycosyl chlorides using catalytic Appel conditions is described. Good yields of α-glycosyl chlorides were obtained using a range of glycosyl hemiacetals, oxalyl chloride and 5 mol% Ph3PO. For 2-deoxysugars treatment of the corresponding hemiacetals with oxalyl chloride without phosphine oxide catalyst also gave good yields of glycosyl chloride. The method is operationaly simple and the 5 mol% phosphine oxide by-product can be removed easily. Alternatively a one-pot, multi-catalyst glycosylation can be carried out to transform the glycosyl hemiacetal directly to a glycoside.
- Pongener, Imlirenla,Nikitin, Kirill,McGarrigle, Eoghan M.
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supporting information
p. 7531 - 7535
(2019/08/20)
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- Stereoselective Synthesis of Quercetin 3-O-Glycosides of 2-Amino-2-Deoxy-d-Glucose under Phase Transfer Catalytic Conditions
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This article describes the stereoselective synthesis of quercetin 3-O-glycosides of 2-amino-2-deoxy-d-glucose. Efficient 1,2-trans-glycosylation of protected quercetin with N-acetyl-protected 2-amino-2-deoxy-d-glucose chloride was achieved under phase transfer catalytic conditions in a 0.15 M aqueous K2CO3/chloroform system using tetrabutylammonium bromide as the catalyst. On the contrary, glycosylation with the N-phthalimido-protected bromide donor under the same conditions was found to give predominantly 1,2-cis-glycoside product.
- Cao, Zhiling,Qu, Yingying,Zhou, Jiexing,Liu, Weiwei,Yao, Guowei
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- A facile and stereoselective synthesis of 3,4,6-tri-O-acetyl-2-deoxy-2- phthalimido-β-D-glucopyranosyl chloride
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Acetylation of D-glucosamine catalysed by sulfuric acid and N-phthaloylation of the glucosyl acetate yielded 1,3,4,6- tetra-O-acetyl-2- deoxy-2-phthalimido-α-D-glucopyranose. This gave the corresponding pure β-glucosyl chloride upon treatment with PCl5-BF3. An anomeric chlorination with thionyl chloride combined with the Lewis acids (ZnCl2, SnCl4 and BiCl3) resulted in an α/β anomer mixture.
- Cao, Zhiling,Liu, Wenjie,Qu, Yingying,Yao, Guowei,Gao, Dachao,Liu, Weiwei
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p. 467 - 469
(2013/09/12)
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- Differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d-glucopyranosyl chlorides and their application in the synthesis of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside
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Four differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d- glucopyranosyl chlorides were synthesized and used as glycosyl donors in reactions with diosgenin. The following amine group protections were tested: trifluoroacetyl (TFA), 2,2,2-trichloroethoxycarbonyl (Troc), phthaloyl (Phth), and tetrachlorophthaloyl (TCP). Products of glycosylation were deprotected to yield diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside. The efficiency of the procedures is discussed. Additionally, a single-crystal X-ray diffraction analysis for 3,4,6-tri-O-acetyl-2-deoxy-2-tetrachlorophthalimido-β-d- glucopyranosyl chloride is reported. Orientations of the pyranose substituents as well as the planarity of the acetoxy and phthalimide groups in the crystal lattice are discussed. Structural evidence is presented for a mesomeric effect in both groups. The preference of the cis over trans orientation of the acetoxy group is confirmed in the crystal lattice.
- Bednarczyk, Dorota,Walczewska, Agata,Grzywacz, Daria,Sikorski, Artur,Liberek, Beata,Myszka, Henryk
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- A convenient preparation of glycosyl chlorides from aryl/alkyl thioglycosides
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(equation presented) Because of the vast structural diversity encountered in the field of glycobiology, versatile methods for orthogonal oligosaccharide assembly are always of interest. Reported herein is the preparation of glycosyl chloride donors obtained by reaction of the corresponding thioglycoside precursors with chlorosulfonium chloride reagent 4. The crude chlorides thus obtained can be used directly in subsequent glycosylation reactions, and examples of the generality of this approach are provided.
- Sugiyama, Shin,Diakur, James M.
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p. 2713 - 2715
(2007/10/03)
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- Conversion of p-methoxyphenyl glycosides into the corresponding glycosyl chlorides and bromides, and into thiophenyl glycosides
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p-Methoxyphenyl (pMP) β-D-glycopyranosides (Glc, Gal, GlcNPhth, GalNPhth, GlcNTroc, Galβ4Glc, Galα4Gal) were prepared from the corresponding 1-O-acetyl sugars in 79-90% yield, using boron trifluoride etherate as promoter. Treatment of the pMP glycosides with acyl chlorides or bromides in the presence of various Lewis acids gave the corresponding glycosyl chlorides and bromides in 81-98% yield. Treatment of the acyl-protected pMP glycosides with thiophenol and boron trifluoride etherate gave the corresponding thioglycosides in 80-100% yield and high (> 20:1) β/α selectivity. The stability of pMP glycosides was investigated against a series of reagents.
- Zhang, Zhiyuan,Magnusson, Goeran
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- 2-(Trimethylsilyl)ethyl Glycosides. Transformation into Glycopyranosyl Chlorides
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2-(Trimethylsilyl)ethyl (TMSET) glycosides were transformed in high yields into the corresponding 1-chloro sugars by treatment with 1,1-dichloromethyl methyl ether/zinc chloride.With acetyl, benzoyl, and benzyl protection of the 2-postion, the α-glycopyranosyl chloride was the major product, whereas with the 2-phthalimido sugar 13, the β-chloride 21 was obtained.The fully benzylated TMSET glucopyranoside 1 gave the α-chloro sugar 22 carrying a 6-O-formyl group whereas the partially benzylated sugars 16 and 17 gave the chloro sugars with all protecting groups intact.
- Jansson, Karl,Noori, Ghazi,Magnusson, Goeran
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p. 3181 - 3185
(2007/10/02)
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- A convenient synthetic route to the disaccharide repeating-unit of peptidoglycan.
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Glycosylation of the readily accessible benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O-[(R)-1-(methoxycarbonyl)ethyl]-alpha- D- glucopyranoside with 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl chloride (2), using the silver triflate method i
- Kantoci,Keglevic,Derome
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p. 227 - 235
(2007/10/02)
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