- Synthesis of Glycosyl Chlorides and Bromides by Chelation Assisted Activation of Picolinic Esters under Mild Neutral Conditions
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A general method has been developed for the formation of glycosyl chlorides and bromides from picolinic esters under mild and neutral conditions. Benchtop stable picolinic esters are activated by a copper(II) halide species to afford the corresponding products in high yields with a traceless leaving group. Rare β glycosyl chlorides are accessible via this route through neighboring group participation. Additionally, glycosyl chlorides with labile protecting groups previously not easily accessible can be prepared.
- Balzer, Paul G.,Blaszczyk, Stephanie A.,Duan, Xiyan,Ma, Zhi-Xiong,Simmons, Christopher J.,Stevens, Christopher M.,Tang, Weiping,Wang, Hao-Yuan,Wen, Peng,Ye, Wenjing,Yin, Dan
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supporting information
(2020/02/28)
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- Lewis acid promoted anomerisation of alkyl O- and S-xylo-, arabino- and fucopyranosides
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Pentopyranoside and 6-deoxyhexopyranosides, such as those from D-xylose, L-arabinose and L-fucose are components of natural products, oligosaccharides or polysaccharides. Lewis acid promoted anomerisation of some of their alkyl O- and S-glycopyranosides i
- Doyle, Lisa M.,Meany, Fiach B.,Murphy, Paul V.
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supporting information
p. 85 - 94
(2018/12/05)
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- Stereoselective Epimerizations of Glycosyl Thiols
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Glycosyl thiols are widely used in stereoselective S-glycoside synthesis. Their epimerization from 1,2-trans to 1,2-cis thiols (e.g., equatorial to axial epimerization in thioglucopyranose) was attained using TiCl4, while SnCl4 promoted their axial-to-equatorial epimerization. The method included application for stereoselective β-d-manno- and β-l-rhamnopyranosyl thiol formation. Complex formation explains the equatorial preference when using SnCl4, whereas TiCl4 can shift the equilibrium toward the 1,2-cis thiol via 1,3-oxathiolane formation.
- Doyle, Lisa M.,O'Sullivan, Shane,Di Salvo, Claudia,McKinney, Michelle,McArdle, Patrick,Murphy, Paul V.
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supporting information
p. 5802 - 5805
(2017/11/10)
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- Studies on the conformational flexibility of α-l-rhamnose-containing oligosaccharides using 13C-site-specific labeling, NMR spectroscopy and molecular simulations: Implications for the three-dimensional structure of bacterial rhamnan polysaccha
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Bacterial polysaccharides are comprised of a variety of monosaccharides, l-rhamnose (6-deoxy-l-mannose) being one of them. This sugar is often part of α-(1 → 2)- and/or α-(1 → 3)-linkages and we have therefore studied the disaccharide α-l-Rhap-(1 → 2)-α-l
- Jonsson, K. Hanna M.,Saewen, Elin,Widmalm, Goeran
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p. 2453 - 2463
(2012/04/23)
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- Fast and efficient preparation of an α-fucosyl building block by reductive 1,2-benzylidene ring-opening reaction
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1,2-Benzylidene ring opening on fucose was promoted in the presence of different reducing agents and Lewis acids, providing a fast access to fucosyl building blocks.
- Werz, Daniel B.,Schuster, Heiko J.,Tietze, Lutz F.
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scheme or table
p. 1969 - 1972
(2009/04/11)
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- Stereospecific synthesis of sugar-1-phosphates and their conversion to sugar nucleotides
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As Leloir glycosyltransferases are increasingly being used to prepare oligosaccharides, glycoconjugates, and glycosylated natural products, efficient access to stereopure sugar nucleotide donor substrates is required. Herein, the rapid synthesis and purification of eight sugar nucleotides is described by a facile 30 min activation of nucleoside 5′-monophosphates bearing purine and pyrimidine bases with trifluoroacetic anhydride and N-methylimidazole, followed by a 2 h coupling with stereospecifically prepared sugar-1-phosphates. Tributylammonium bicarbonate and tributylammonium acetate were the ion-pair reagents of choice for the C18 reversed-phase purification of 6-deoxysugar nucleotides, and hexose or pentose-derived sugar nucleotides, respectively.
- Timmons, Shannon C.,Jakeman, David L.
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p. 865 - 874
(2008/09/16)
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- Exploiting nucleotidylyltransferases to prepare sugar nucleotides
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(Graph Presented) Enzymatic approaches to prepare sugar nucleotides are gaining in importance and offer several advantages over chemical synthesis including high yields and stereospecificity. We report the cloning, expression, and purification of two new wild-type thymidylyltransferases and observed catalysis with a wide variety of substrates. Significant product inhibition was not observed with the enzymes studied over a 24 h period, enabling the efficient preparation of 15 sugar nucleotides, clearly demonstrating the synthetic utility of these biocatalysts.
- Timmons, Shannon C.,Mosher, Roy H.,Knowles, Sheryl A.,Jakeman, David L.
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p. 857 - 860
(2007/10/03)
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- Stereoselective chemical synthesis of sugar nucleotides via direct displacement of acylated glycosyl bromides
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Figure presented The use of Leloir glycosyltransferases to prepare biologically relevant oligosaccharides and glycoconjugates requires access to sugar nucleoside diphosphates, which are notoriously difficult to efficiently synthesize and purify. We report a novel stereoselective route to UDP- and GDPα-D-mannose as well as UDP- and GDP-β-L-fucose via direct displacement of acylated glycosyl bromides with nucleoside 5′- diphosphates.
- Timmons, Shannon C.,Jakeman, David L.
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p. 1227 - 1230
(2007/10/03)
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- Design and Synthesis of Peptide Mimetics of GDP-Fucose: Targeting Inhibitors of Fucosyltransferases
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Novel peptide mimetics of GDP-fucose were designed and synthesized targeting inhibitors of the fucosyltransferases that transfer L-fucose from GDP-fucose to oligosaccharides, on the basis of the background that nikkomycin Z, a peptide mimetic of UDP-N-acetylglucosamine, shows potent inhibitory activity toward an N-acetylglucosamine transfer enzyme. The synthetic routes of the GDP-fucose mimetics take advantage of an enzymatic aldol reaction catalyzed by L-threonine aldolase to prepare the guanine carrying β-hydroxy-α- L-amino acid, a key synthetic intermediate.
- Tanaka, Toru,Tsuda, Chihiro,Miura, Tsuyoshi,Inazu, Toshiyuki,Tsuji, Shuichi,Nishihara, Shoko,Hisamatsu, Mitsuko,Kajimoto, Tetsuya
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p. 243 - 246
(2007/10/03)
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- Large-scale synthesis of β-L-fucopyranosyl phosphate and the preparation of GDP-β-L-fucose
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A practical 15-mmol large-scale synthesis of β-L-fucopyranosyl dicyclohexylammonium phosphate from L-fucose in 63percent overall yield was developed.The synthesis took advantage of a neighboring Bz-2 group participating in a Koenigs-Knorr like glycosylati
- Adelhorst, Kim,Whitesides, George M.
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- Synthesis of Oligosaccharides Corresponding to the Common Polysaccharide Antigen of Group B Streptococci
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To facilitate mapping of the immunodominant region of the common polysaccharide antigen of group B streptococci, tetrasaccharide 1-O--α-rhamnopyranosyl>-D-glucitol (2) was synthesized in a stepwise fasion
- Pozsgay, Vince,Jennings, Harold J.
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p. 4042 - 4052
(2007/10/02)
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