- Regio- and Stereoselective Synthesis of 1,2- cis-Glycosides by Anomeric O-Alkylation with Organoboron Catalysis
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Regio- and stereoselective synthesis of 1,2-cis-glycosides has been achieved by catalytic anomeric O-alkylation using organoboron compounds. Modulating steric and electronic factors of both catalysts and substrates enables activation of the axially oriented anomeric oxygens of glucose-derived dialkoxyborates. The mild reaction conditions allow broad functional-group tolerance. This approach can be applied to the efficient sequential synthesis of oligosaccharides.
- Izumi, Sanae,Kobayashi, Yusuke,Takemoto, Yoshiji
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supporting information
p. 665 - 670
(2019/01/21)
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- Application of the 2-nitrobenzyl group in glycosylation reactions: A valuable example of an arming participating group
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The application of the o-nitrobenzyl (oNBn) group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. This new ether-type arming group can broadly extend the concept of the use of participating groups in glycosylation reactions. Easy protection and deprotection of the oNBn group further confirms its usefulness in synthesis. The application of o-nitrobenzyl (oNBn) ether as an arming participating group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. Copyright
- Buda, Szymon,Golebiowska, Patrycja,Mlynarski, Jacek
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supporting information
p. 3988 - 3991
(2013/07/19)
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- Biotin sulfone tagged oligomannosides as immunogens for eliciting antibodies against specific mannan epitopes
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Biotinylated tri and tetrasaccharide: α Man (1→3) α Man (1→2) α Man; α Man (1→3) α Man (1→2) α Man (1→2) α Man were prepared using methyl tertbutyl phenyl thioglycosides glycosyl donors (MBP) and biotin sulfone strategy. Three key mannosyl thioglycosidic
- Despras, Guillaume,Robert, Raymond,Sendid, Boualem,MacHez, Emeline,Poulain, Daniel,Mallet, Jean-Maurice
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experimental part
p. 1817 - 1831
(2012/05/20)
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- Armed-disarmed effect on the stability of cysteine thioglucosides
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Thioglucosides of cysteine show variable stability depending on the nature of the protecting groups on the glycosyl donor. Armed protecting groups (benzyl) lead to products that decompose readily while disarmed protecting groups (acetyl) lead to more stable products. Since this armed/disarmed effect of the protecting group on the stability of the thioglucosides is more pronounced for cysteine with an unprotected carboxylic group, the proposed mechanism is that decomposition is initiated by an intramolecular protonation of glycosyl sulfide and subsequent displacement of the sulfide by adventitious nucleophiles.
- Nokwequ, Mbulelo G.,Nkambule, Comfort M.,Gammon, David W.
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- Disaccharide-containing macrocycles by click chemistry and intramolecular glycosylation
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In this study o- and m-xylylene moieties in combination with a triazolylmethyl moiety have been successfully employed as a relatively rigid spacer system in intramolecular glycosylation reactions. Phenyl 3,4,6-tri-O-benzyl-2-O-propargyl-1-thio-D-glucopyra
- Tiwari, Vinod K.,Kumar, Amit,Schmidt, Richard R.
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p. 2945 - 2956
(2012/07/27)
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- Synthetic oligosaccharides as tools to demonstrate cross-reactivity between polysaccharide antigens
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Escherichia coli O148 is a nonencapsulated enterotoxigenic (ETEC) Gram negative bacterium that can cause diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome in humans. The surface-exposed O-specific polysaccharide (O-SP) of the lipopolysaccharide
- Pozsgay, Vince,Kubler-Kielb, Joanna,Coxon, Bruce,Santacroce, Paul,Robbins, John B.,Schneerson, Rachel
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experimental part
p. 5922 - 5941
(2012/10/07)
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- Stereoselective tandem epoxidation-alcoholysis/hydrolysis of glycals with molybdenum catalysts
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Molybdenum catalysts are efficient and selective catalysts for the tandem epoxidation/alcoholysis or epoxidation/hydrolysis of glucal and galactal derivatives. In glucal derivatives the selectivity is mainly controlled by the allylic substituent at position 3 of the glycal, obtaining in general the products derived from the initial formation of the α-epoxide (gluco) when this hydroxy group is protected, while products derived from the β-epoxide (manno) are mainly obtained when it is unprotected. In galactal derivatives the estereoselectivity is always high to give the α-epoxide (galacto) and independent of the protecting groups. Copyright
- Marin, Irene,Matheu, M. Isabel,Diaz, Yolanda,Castillon, Sergio
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supporting information; experimental part
p. 3407 - 3418
(2011/02/23)
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- Synthesis of truncated analogues for studying the process of glycosyl phosphatidylinositol modification
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Figure presented Many eukaryotic proteins are modified with a glycosylphosphatidylinositol (GPI) anchor at their C-termini. This post-translational modification causes these proteins to be noncovalently tethered to the plasma membrane. The synthesis of tr
- John, Franklin,Hendrickson, Tamara L.
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supporting information; experimental part
p. 2080 - 2083
(2010/07/03)
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- Concise total syntheses of aspalathin and nothofagin
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Chemical Fig. Reprentation Syntheses of the C-glycosyl flavone natural products aspalathin and nothofagin have been accomplished in eight steps from tribenzyl glucal, tribenzylphloroglucinol, and either 4-(benzyloxy) phenylacetylene or 3,4-bis(benzyloxy)phenylacetylene. The key step of the syntheses involves a highly stereoselective Lewis acid promoted coupling of 1,2-di-o-acyl-3,4,6-tribenzylglucose with tribenzylphloroglucinol, which gives rise to the corresponding β-C-aryl glycoside in 30-65% yields.
- Yepremyan, Akop,Salehani, Baback,Minehan, Thomas G.
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supporting information; experimental part
p. 1580 - 1583
(2010/06/17)
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- Stereoselective synthesis of α-glucosides by neighbouring group participation via an intermediate thiophenium ion
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The use of a 2-O-(thiophen-2-yl)methyl protecting group allows highly stereoselective α-glucosylation of a trichloroacetimidate donor; increased stereoselectivity, presumably arising from the intramolecular formation of a transient intermediate thiophenium ion, correlates with increased bulk of the glycosyl acceptor.
- Cox, Daniel J.,Fairbanks, Antony J.
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experimental part
p. 773 - 780
(2009/09/30)
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- New thioglycoside derivatives for use in odourless synthesis of MUXF3 N-glycan fragments related to food allergens
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Thioglycosides are valuable tools for complex oligosaccharides' constructions. They present precious advantages due to their stability and crystalline nature. However, their major drawbacks are the repulsive smell of thiols utilised as precursors and, oft
- Collot, Mayeul,Savreux, Julie,Mallet, Jean-Maurice
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p. 1523 - 1535
(2008/09/18)
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- Sequential one-pot glycosidations catalytically promoted: Unprecedented strategy in oligosaccharide synthesis for the straightforward assemblage of the antitumor PI-88 pentasaccharide
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(Chemical Equation Presented) The pentasaccharide sequence of the most active components of the antitumor drug PI-88, currently in phase II clinical trial, has been rapidly assembled in high overall yield and in only three steps starting from three monosa
- Valerio, Silvia,Pastore, Antonello,Adinolfi, Matteo,Iadonisi, Alfonso
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p. 4496 - 4503
(2008/09/21)
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- Tandem epoxidation-alcoholysis or epoxidation-hydrolysis of glycals catalyzed by titanium(IV) isopropoxide or Venturello's phosphotungstate complex
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Venturello's phosphotungstate complex and titanium(IV) isopropoxide [Ti(O-i-Pr)4] were successfully used as catalysts for the epoxidation-alcoholysis of glycals using hydrogen peroxide [H2O 2]. Reaction substrates included a range of variously protected glycals and different alcohols were used as solvents. Ti(O-i-Pr)4 was only effective in methanol as solvent, but gave methyl glycosides in high yields and high selectivities. The Venturello complex proved to be a very versatile and efficient catalyst. Apart from epoxidation-alcoholysis in alcoholic solvents it also showed activity in biphasic conditions to allow for glycosylation of long-chain alcohols and was very effective in the stereoselective dihydroxylation of benzylated glucal.
- Levecque, Pieter,Gammon, David W.,Kinfe, Henok Hadgu,Jacobs, Pierre,De Vos, Dirk,Sels, Bert
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scheme or table
p. 1557 - 1568
(2009/07/10)
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- An efficient stereoselective dihydroxylation of glycals using a bimetallic system, RuCl3/CeCl3/NaIO4
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A catalytic dihydroxylation reaction on glycals has been developed using a bimetallic oxidizing system to furnish sugar 1,2-diols in a highly setroselective manner.
- Tiwari, Pallavi,Misra, Anup Kumar
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p. 2911 - 2913
(2007/10/03)
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- Synthesis of 1-deoxyhept-2-ulosyl-glycono-1,5-lactone utilizing α-selective O-glycosidation of 2,6-anhydro-1-deoxy-d-hept-1-enitols
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A series of 1-deoxy-heptulo-2-pyranosyl-glycono-1,5-lactones were synthesized utilizing completely α-selective O-glycosidation of heptenitols. Anomeric configuration of the products was confirmed by 3JC,H coupling measurement and X-ray crystal structural analysis. The benzyl-protected ketosyl saccharides were partly unstable, and glycosidic linkage was prone to cleave under the usual debenzylation conditions. To prevent this, we surveyed various additives for the Pd-catalyzed hydrogenation reaction and found that basic alumina was the most effective.
- Namme, Rie,Mitsugi, Takashi,Takahashi, Hideyo,Shiro, Moto,Ikegami, Shiro
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p. 9183 - 9192
(2007/10/03)
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- Unprecedented transformation of thioglycosides to their corresponding 1-O-acetates in the presence of HClO4-SiO2
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An unprecedented conversion of thioalkyl/aryl glycoside to the corresponding 1-O-acetates has been described using acetic anhydride and HClO4-SiO2 at rt. Although this transformation does not play an important role in the oligosaccha
- Agnihotri, Geetanjali,Tiwari, Pallavi,Misra, Anup Kumar
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p. 491 - 498
(2007/10/03)
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- Efficient activation of glycosyl N-(phenyl)trifluoroacetimidate donors with ytterbium(III) triflate in the glycosylation reaction
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The mild, moisture-stable and cheap catalyst Yb(OTf)3 activates glycosyl N-(phenyl)trifluoroacetimidates in the stereoselective synthesis of 1,2-trans and 1,2-cis glycosides. A suitable choice of the reaction solvent led to good yields and stereoselectivity ratios. The protocol was successfully applied to acceptors and donors both exhibiting a wide range of reactivity.
- Adinolfi, Matteo,Barone, Gaspare,Iadonisi, Alfonso,Schiattarella, Marialuisa
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p. 5573 - 5577
(2007/10/03)
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- Synthesis and conformational investigation of methyl 4a-carba-D-arabinofuranosides
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The synthesis of carbasugar analogues of methyl α-D-arabinofuranoside and methyl β-D-arabinofuranoside (3 and 4) is reported. The route developed involves the conversion of D-mannose into a suitably protected diene (13), which is then cyclized via olefin metathesis. The resulting cyclopentene (14) is stereoselectively hydrogenated to provide an intermediate that can be used for the synthesis of both targets. Through the use of NMR spectroscopy, we have probed the ring conformation of 3 and 4, as well as the rotamer populations about the C4-C5 and C1-O1 bonds. These studies have demonstrated that there are differences in ring conformation between these carbasugars and their glycoside parents (1 and 2). However, only minor differences are seen in the rotameric equilibrium about the C4-C5 bond in 3 and 4 relative to 1 and 2. In regard to the C1-O1 bond, NOE data from 3 and 4 suggest that the favored position about this bond is similar to that in the glycosides; that is, the methyl group is anti to C2. However, confirmation of this preference through measurement of 3JC,C between the methyl group and C2 or C4a was not successful.
- Callam,Lowary
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p. 8961 - 8972
(2007/10/03)
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- Inositolphosphoglycan mediators structurally related to glycosyl phosphatidylinositol anchors: Synthesis, structure and biological activity
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The preparation of the pseudopentasaccharide 1a, an inositolphosphoglycan (IPG) that contains the conserved linear structure of glycosyl phosphatidylinositol anchors (GPI anchors), was carried out by using a highly convergent 2+3-block synthesis approach which involves imidate and sulfoxide glycosylation reactions. The preferred solution conformation of this structure was determined by using NMR spectroscopy and molecular dynamics simulations prior to carrying out quantitative structure-activity relationship studies in connection with the insulin signalling process. The ability of 1a to stimulate lipogenesis in rat adipocites as well as to inhibit cAMP dependent protein kinase and to activate pyruvate dehydrogenase phosphatase was investigated. Compound 1a did not show any significant activity, which may be taken as a strong indication that the GPI anchors are not the precursors of the IPG mediators.
- Martin-Lomas, Manuel,Khiar, Noureddine,Garcia, Salud,Koessler, Jean-Luc,Nieto, Pedro M.,Rademacher, Thomas W.
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p. 3608 - 3621
(2007/10/03)
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- A new method of anomeric protection and activation based on the conversion of glycosyl azides into glycosyl fluorides
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Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic diol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides. Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic idol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides.
- Broder,Kunz
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p. 221 - 241
(2007/10/02)
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- Diastereoselective Free-Radical Reactions. Part 3. The Methyl Glucopyranos-1-yl and 1,2-O-Isopropylideneglucopyranos-1-yl Radicals: Conformational Effects on Diastereoselectivity
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The 3,4,6-tri-O-benzyl-2-O-t-butyldimethylsilyl-1-O-methyl-D-glucopyranos-1-yl and the 3,4,6-tri-O-benzyl-1,2-O-isopropylidene-D-glucopyranos-1-yl radicals are quenched with high selectivity (>25:1) from the α- and β-face, respectively, by t-dodecanethiol
- Crich, David,Lim, Linda B. L.
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p. 2209 - 2214
(2007/10/02)
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- tHE SYNTHESIS OF 2'-DEOXY-β-DISACCHARIDES: NOVEL APPROACHES
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Benzylated 1,2-orthoacetates were converted by dry acetic acid into 1,2-trans-diacetates which behaved as excellent β-glycosyl donors with various non-acylated glycosyl acceptors in the presence of trimethylsilyl triflate.Deacetylation, followed by xantha
- Trumtel, Michel,Tavecchia, Paolo,Veyrieres, Alain,Sinay, Pierre
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- AN EASY SYNTHESIS OF 2'-DEOXY-β-DISACCHARIDES
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1,2-Di-O-acetyl-3,4,6-tri-O-benzyl-β-D-glucopyranose and analogs are excellent β-glycosyl donors in the presence of trimethylsilyltriflate.The resulting disaccharides are easily converted into the corresponding 2'-deoxy-β-disaccharides, opening a practical route to this important class of natural molecules.
- Trumtel, Michel,Veyrieres, Alain,Sinay, Pierre
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p. 2529 - 2532
(2007/10/02)
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- THE SYNTHESIS OF 2-O-α-D-GALACTOPYRANOSYL-D-GALACTOPYRANOSE AND 2-O-(2-O-α-D-GALACTOPYRANOSYL-α-D-GALACTOPYRANOSYL)-D-GLUCOPYRANOSE UNDECA-ACETATE
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The synthesis of 2-O-α-D-galactopyranosyl-D-galactopyranose was accomplished by condensation of 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl chloride with 2,2,2-trichloroethyl 3,4,6-tri-O-benzyl-α-D-galactopyranoside in the presence of mercuric cyanide.The
- Doboszewski, Bogdan,Zamojski, Aleksander
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