- Nitrogen-containing aromatic ring derivative containing galactose and application thereof
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The invention belongs to the technical field of medicines, and relates to a nitrogen-containing aromatic ring derivative containing galactose, application thereof and a pharmaceutical composition containing the compound. The invention also relates to a method for preparing the compound and the pharmaceutical composition, and application of the compound and the pharmaceutical composition in prevention or treatment of tumors, inflammatory diseases, autoimmune diseases and other diseases, especially tumors.
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Paragraph 0159; 0164-0168
(2021/06/09)
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- Glycosyl-based united cell penetrating peptide-modified brain-targeted nano-liposome as well as preparation method and application thereof (by machine translation)
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The invention relates to a glycosyl combined cell penetrating peptide-modified brain-targeted nano-liposome and a preparation method and application thereof, and belongs to the technical field of targeted drug delivery. The liposome comprises EPC, CHO, glycosyl modified polyethylene glycol phospholipid and cell penetrating peptide modified polyethylene glycol phospholipid with a certain molar ratio. By simultaneously modifying the glycosyl and the cell penetrating peptide on the surface of the nano liposome, the nano lipidosome has the capability of actively targeting brain and penetrating cell membranes. The drug carrier is used for a drug carrier, so that the carried medicines can efficiently and specifically target brain tissues and enter into brain cells to play a role. The in-vitro cell test and the in-vivo distribution experiment prove that the brain-targeted nano-liposome provided by the invention can reach the brain smoothly and accumulate in brain cells to exert efficacy. (by machine translation)
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- Brain-targeting nano liposome carrying positively charged polymer/miR-195 compound, and preparation method and application thereof
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The invention relates to a brain-targeting nano liposome carrying a positively charged polymer/miR-195 compound, and a preparation method and application thereof, and belongs to the technical field oftargeting drug delivery. In order to improve stability of nucleic acid therapeutic drugs and penetration of blood brain barriers, the invention provides the brain targeting nano liposome carrying thepositively charged polymer/miR-195 compound, wherein the liposome containing a glycosyl modified polyethylene glycol phospholipid and a cell penetrating peptide modified polyethylene glycol phospholipid is taken as a drug carrier to envelop the positively charged polymer/miR-195 compound. According to the invention, stability of miR-195 is improved through the positively charged polymer and the drug carrier, and capability of the drug to target the brain and penetrate the cell membrane is improved through the glycosyl combined cell penetrating peptide modified brain targeting nano liposome, so that the carried drugs efficiently and specifically target brain tissues to treat Alzheimer's disease and vascular dementia, particularly cognitive dysfunction caused by Alzheimer's disease and cerebral ischemia.
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Paragraph 0085; 0088
(2020/06/30)
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- Copper-mediated O-arylation of lactols with aryl boronic acids
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An efficient and novel methodology to access phenolic glycosides has been established by using copper-mediated coupling reaction of aryl boronic acids with hemiacetals. The reaction takes place normally in the presence of Cu(OAc)2 (1.0 equiv.) and pyridine (2.0 equiv.) at 40 °C. This protocol distinguishes itself by wide substrate scope, operational simplicity and giving rise to a myriad of phenolic glycosides in good to excellent yields.
- Sui, Jing-Jing,Xiong, De-Cai,Ye, Xin-Shan
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supporting information
p. 1533 - 1537
(2019/06/21)
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- Chemo-enzymatic synthesis of p-nitrophenyl β-D-galactofuranosyl disaccharides from Aspergillus sp. fungal-type galactomannan
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β-D-Galactofuranose (Galf) is a component of polysaccharides and glycoconjugates. There are few reports about the involvement of galactofuranosyltransferases and galactofuranosidases (Galf-ases) in the synthesis and degradation of galactofuranose-containing glycans. The cell walls of filamentous fungi in the genus Aspergillus include galactofuranose-containing polysaccharides and glycoconjugates, such as O-glycans, N-glycans, and fungal-type galactomannan, which are important for cell wall integrity. In this study, we investigated the synthesis of p-nitrophenyl β-D-galactofuranoside and its disaccharides by chemo-enzymatic methods including use of galactosidase. The key step was selective removal of the concomitant pyranoside by enzymatic hydrolysis to purify p-nitrophenyl β-D-galactofuranoside, a promising substrate for β-D-galactofuranosidase from Streptomyces species.
- Ota, Ryo,Okamoto, Yumi,Vavricka, Christopher J.,Oka, Takuji,Matsunaga, Emiko,Takegawa, Kaoru,Kiyota, Hiromasa,Izumi, Minoru
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- Development of Pseudomonas aeruginosa Lectin LecA Inhibitor by using Bivalent Galactosides Supported on Polyproline Peptide Scaffolds
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LecA is a galactose-binding tetrameric lectin from Pseudomonas aeruginosa involved in infection and biofilm formation. The emergent antibiotic resistance of P. aeruginosa has made LecA a promising pharmaceutical target to treat such infections. To develop LecA inhibitors, we exploit the unique helical structure of polyproline peptides to create a scaffold that controls the galactoside positions to fit their binding sites on LecA. With a modular scaffold design, both the galactoside ligands and the inter-ligand distance can be altered conveniently. We prepared scaffolds with spacings of 9, 18, 27, and 36 ? for ligand conjugation and found that glycopeptides with galactosides ligands three helical turns (27 ?) apart best fit LecA. In addition, we tested different galactose derivatives on the selected scaffold (27 ?) to improve the binding avidity to LecA. The results validate a new multivalent scaffold design and provide useful information for LecA inhibitor development.
- Huang, Shao-Feng,Lin, Cin-Hao,Lai, Yu-Tsung,Tsai, Chia-Lung,Cheng, Ting-Jen R.,Wang, Sheng-Kai
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p. 686 - 700
(2018/03/05)
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- Beta-galactosidase-responsive synthetic biomarker for targeted tumor detection
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Tumor biomarkers are highly desirable for the screening of patients with a risk of tumor development and progression. Here, we report a beta-galactosidase (β-gal)-responsive acetaminophen (β-GR-APAP) as a synthetic plasma biomarker for targeted tumor detection. Tumor β-gal labeling via the recognition of tumor-related antigen enabled the detection of a tumor using β-GR-APAP.
- Nishihara, Tatsuya,Kuno, Satoshi,Nonaka, Hiroshi,Tabata, Sho,Saito, Natsumi,Fukuda, Shinji,Tomita, Masaru,Sando, Shinsuke,Soga, Tomoyoshi
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supporting information
p. 11745 - 11748
(2018/11/25)
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- A process for preparing nitro phenyl - α - D - pyran honeydews glycoside method
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The invention discloses a p-nitrophenyl-alpha-D-mannopyranoside preparation method. The p-nitrophenyl-alpha-D-mannopyranoside preparation method is characterized by including (1), in the presence of catalysts, enabling alpha-D-mannose under protection to contact with p-nitrophenol under the coupling reaction condition so as to obtain p-nitrophenyl-alpha-D-mannoside under protection; (2), subjecting the p-nitrophenyl-alpha-D-mannoside under protection, obtained in the step (1), to deprotection so as to obtain p-nitrophenyl-alpha-D-mannopyranoside. The p-nitrophenyl-alpha-D-mannopyranoside preparation method has the advantages of short reaction route, simplicity and convenience in operation, high yield, short reaction time and low cost.
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- Diazepinium perchlorate: a neutral catalyst for mild, solvent-free acetylation of carbohydrates and other substances
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Diazepinium perchlorate, an essentially neutral organic salt possessing excellent stability, has been found to be well suited for the acetylation of free as well as partially protected sugars, phenols, thiophenols, thiols and other alcohols as well as amines. The diazepinium perchlorate-catalyzed acetylation is mild, organic and solvent-free and leaves acid sensitive protecting groups such as TBDMS/TBDPS/Tr ethers and isopropylidene/benzylidene acetals present on a substrate unaffected. Regioselective hydroxyl protection in partially protected carbohydrate derivatives/polyhydroxylic compounds was possible and was proved to be a convenient time-saving alternative to the conventional synthesis of such compounds. Easy preparation of the catalyst, mild reaction conditions and an environmentally benign protocol are some of the notable features of this reaction. The results obtained on the acetylation of phenols and thiophenols could be rationalized through their local nucleophilicity index obtained from DFT calculations.
- Giri, Santosh Kumar,Gour, Rajesh,Kartha, K. P. Ravindranathan
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p. 13653 - 13667
(2017/03/11)
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- Preparation method of galactose-containing fatty acid derivative and application of preparation method in field of medicine
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The invention relates to a novel p-fatty alkylamide phenyl-beta-D-galactoside compound, a preparation method and application, belonging to the technical field of medicine. A structure general formula of the compound is shown in the description, wherein R is selected from (CH2)6CH3, (CH2)10CH3, (CH2)12CH3, (CH2)14CH3, and (CH2)7CH=CH (CH2)7CH3. The compound has stronger inhibitory activity to tumor cells, and can be used for tumor therapies.
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Paragraph 0023; 0024; 0042; 0043
(2016/12/01)
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- Glycosylated lanthanide cyclen complexes as luminescent probes for monitoring glycosidase enzyme activity
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The development of synthetic chemical probes for the detection of enzymes is extremely important for biological, medicinal, and industrial applications. Here we report the synthesis of an array of novel glycosylated Tb(iii) complexes, their photophysical properties in solution, and their ability to function as luminescent probes for observing glycosidase enzyme activity in real time. Our initial studies into the application of these complexes for the detection of the Concanavalin A (ConA) lectin is also reported, highlighting the broad scope of these novel chemical probes.
- Burke, Helen M.,Gunnlaugsson, Thorfinnur,Scanlan, Eoin M.
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p. 9133 - 9145
(2016/10/07)
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- Development and optimization of a competitive binding assay for the galactophilic low affinity lectin LecA from: Pseudomonas aeruginosa
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Infections with the Gram-negative bacterium Pseudomonas aeruginosa result in a high mortality among immunocompromised patients and those with cystic fibrosis. The pathogen can switch from planktonic life to biofilms, and thereby shields itself against antibiotic treatment and host immune defense to establish chronic infections. The bacterial protein LecA, a C-type lectin, is a virulence factor and an integral component for biofilm formation. Inhibition of LecA with its carbohydrate ligands results in reduced biofilm mass, a potential Achilles heel for treatment. Here, we report the development and optimization of a fluorescence polarization-based competitive binding assay with LecA for application in screening of potential inhibitors. As a consequence of the low affinity of d-galactose for LecA, the fluorescent ligand was optimized to reduce protein consumption in the assay. The assay was validated using a set of known inhibitors of LecA and IC50 values in good agreement with the known Kd values were obtained. Finally, we employed the optimized assay to screen sets of synthetic thio-galactosides and natural blood group antigens and report their structure-activity relationship. In addition, we evaluated a multivalent fluorescent assay probe for LecA and report its applicability in an inhibition assay.
- Joachim, Ines,Rikker, Sebastian,Hauck, Dirk,Ponader, Daniela,Boden, Sophia,Sommer, Roman,Hartmann, Laura,Titz, Alexander
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p. 7933 - 7948
(2016/08/30)
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- Synthetic multivalent ligands for cholera & cholera-like toxins: Protected cyclic neoglycopeptides
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Synthesis of a set of novel glycopeptide analogues as potential cholera/cholera-like toxin inhibitors in their protected form is described. They include di-, tri-, tetra- and pentavalent scaffolds. The synthetic steps were achieved using a combination of solvent-free mechanochemical as well as the conventional solution-phase reactions. During the conventional DIC-HOBt-mediated peptide coupling followed for the preparation of certain glycopeptide analogues an interesting in situ Fmoc deprotection was observed which has been demonstrated to hold potential for synthesiszing glycopeptides/neoglycopeptides with extended polyamide chains.
- Kumar, Vajinder,Yadav, Narender,Kartha, K.P. Ravindranathan
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- Carbohydrate mediated drug delivery: Synthesis and characterization of new lipid-conjugates
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A new synthetic methodology for cationic glycolipids using p-aminophenyl-α-d-mannopyranoside (PAPM) and p-aminophenyl-α-d-galactopyranoside (PAPG) with spacer in between the quaternary nitrogen atom and the sugar unit is developed. In addition, a new clas
- Ahmad, Moghis U.,Ali, Shoukath M.,Ahmad, Ateeq,Sheikh, Saifuddin,Chen, Paul,Ahmad, Imran
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- Carbohydrate mediated drug delivery: Synthesis and characterization of new lipid-conjugates
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A new synthetic methodology for cationic glycolipids using p-aminophenyl-α-d-mannopyranoside (PAPM) and p-aminophenyl-α-d-galactopyranoside (PAPG) with spacer in between the quaternary nitrogen atom and the sugar unit is developed. In addition, a new clas
- Ahmad, Moghis U.,Ali, Shoukath M.,Ahmad, Ateeq,Sheikh, Saifuddin,Chen, Paul,Ahmad, Imran
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- Synthesis and inhibitory activity evaluation of 2,6-disubstituted purine derivatives
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A series of novel 2,6-disubstituted purine derivatives were designed and synthesized from 2,6-dichloropurine. The structures of target compounds were determined by 1H-NMR, 13C-NMR, and HRMS. The synthesized compounds were evaluated for their inhibitory activities against lung cancer cell lines of A549 and liver cancer cell lines of Bel-7402. 2-(4-Benzyloxy-phenylamino)-6-(cyclohexylamino)purine(3), 2-(4-chloro-phenylamino)-6-(n-butylamino)purine (5), 2-(4-morpholinoamino)-6-(4-hydroxy-phenylamino)purine (9), and 2-(4-O-galactosyl-phenylamino)-6-(cyclohexylamino)purine (12) exhibited moderate inhibitory activity.
- Liu, Hongxia,Li, Libo,Qurat-Ul-Ain, Shaikh,Jiang, Tao
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p. 473 - 477
(2015/03/30)
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- CARBOHYDRATE FUNCTIONALISED SURFACES
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Carbohydrates are biomolecules that are involved in a range of biological processes and play key roles in, for instance, host immune response and cellular adhesion. Accordingly, functionalisation of medical devices such as stents, valves, catheters, prostheses and other devices for in vivoimplantation with carbohydrates is an area in which considerable interest is developing. Disclosed herein are surfaces having carbohydrates immobilised thereon. The carbohydrate has a linker moiety covalently bound thereto and the linker moiety has a carbon atom that forms a covalent bond with an atom on the target surface. The carbon based bond is a strong, non-hydrolysable covalent bond. Diazonium salts are utilised to produce the functionalised surfaces and they are particularly advantageous as they result in non-toxic readily escapable by-products
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Paragraph 0200-0202
(2014/09/29)
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- Synthesis of cross-linked glycopeptides and ureas by a mechanochemical, solvent-free reaction and determination of their structural properties by TEM and X-ray crystallography
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A highly efficient and cost-effective green method for the synthesis of complex glycopeptides and ureas mediated by carbonyl diimidazole under solvent-free conditions is reported. The reactions could be performed conveniently in a planetary ball mill by dry grinding, and the isolation of the novel sugar derivatives thus produced could be very efficiently achieved by size exclusion chromatography with environmentally benign substances. A diacetone galactose based diamide, upon crystallization, could be examined by X-ray crystallography and was found to possess a heart-shaped structure. Although the 4-aminophenyl galactoside based diamide synthesized formed spherical particles, the alanine-based diamide formed nanofilamentous/-tubular structures as analyzed by TEM imaging.
- Kumar, Vajinder,Giri, Santosh Kumar,Venugopalan, Paloth,Kartha, K.P. Ravindranathan
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p. 1605 - 1613
(2015/02/02)
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- Carbohydrate coatings via aryldiazonium chemistry for surface biomimicry
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Carbohydrates are extremely important biomolecules and their immobilization onto solid surfaces is of interest for the development of new biomimetic materials and of new methods for understanding processes in glycobiology. We have developed an efficient surface modification methodology for the functionalization of a range of materials with biologically active carbohydrates based on aryldiazonium chemistry. We describe the synthesis and characterization of carbohydrate reagents, which were subsequently employed for the one-step, solution-based modification of carbon, metals, and alloys with monosaccharides. We used a combination of spectroscopic and nanogravimetric methods to characterize the structure of the carbohydrate layers; we report an average surface coverage of 7.8 × 10-10 mol cm-2 under our experimental conditions. Concanavalin A, a mannose-binding lectin, and Peanut Agglutinin, a galactose-binding lectin, were found to bind from solution to their respective monosaccharide binding partners immobilized at the surface. This result suggests that the spontaneous chemisorption of aryldiazonium monosaccharide precursors leads to the formation of monosaccharide layers that retain the biological recognition specificity of the parent carbohydrate molecule. Finally, we carried out measurements using fluorescently labeled Bovine Serum Albumin (BSA) and found that these carbohydrate coatings reduce unspecific adsorption of this protein at carbon surfaces. These results suggest that aryldiazonium-derived carbohydrate coatings may offer a promising strategy for preventing undesirable protein accumulation onto surfaces.
- Jayasundara, Dilushan R.,Duff, Thomas,Angione, M. Daniela,Bourke, Jean,Murphy, Deirdre M.,Scanlan, Eoin M.,Colavita, Paula E.
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p. 4122 - 4128
(2013/11/19)
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- Glycosylated tris-bipyridine ferrous complexes to provide dynamic combinatorial libraries for probing carbohydrate-carbohydrate interactions
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2,2-Bipyridines having β-lactoside, β-d-glucoside, β-d-galactoside, and N-acetyl-β-d-glucosaminide were prepared and then, complexed with ferrous ion to afford trivalent glycoclusters having tris-bipyridine ferrous complex cores. Each glycocluster provides a dynamic combinatorial library composed of four diastereomeric stereoisomers (Δmer, Δfac, Λmer, and Λfac) whose ratios depend on their relative stabilities. CD spectral analyses of these glycoclusters showed that various cations (Na+, Mg2+, K+ or Ca2+) enriched Δ-forms of the glycocluster having β-lactosides and N-acetyl-β-d-glucosaminides possibly by cations-induced intramolecular carbohydrate-carbohydrate interactions.
- Nakamura, Motomi,Tsutsumi, Mayuka,Ishikawa, Yoshiaki,Umemiya, Haruka,Izawa, Kazumi,Abe, Haruka,Togashi, Yosuke,Kinone, Tatsuya,Sekiguchi, Sho,Igumi, Mihiro,Ide, Kanako,Hasegawa, Teruaki,Hasegawa, Toki
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p. 3019 - 3026
(2013/03/29)
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- GLYCOMIMETIC COMPOUNDS AS ANTI-INFECTIOUS AGAINST PATHOGENS LECTINS
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The present invention relates to a calixarene-based glycosylated compound (I) having the formula: (I) wherein D is independently selected in the group comprising a —CH2-group, an oxygen atom, a sulphur atom, a sulfinyl group or a sulfonyl group, E is independently selected in the group comprising a hydrogen, an alkyl having from 1 to 10 carbon atoms, an aryl having from 6 to 20 carbon atoms, a nitrogen dioxide group, an azide group, an amino group, a guanidinium group, a halogen atom, a —CH2R group wherein R is a hydroxyl, a halogen, an amino group, a N(alkyl)2 group, a NH(alkyl) group, or E represents a —CO—R′ wherein R′ is a hydrogen atom, a hydroxyl group or an amino, B represents a A-C group wherein A is independently selected in the group comprising an oxygen atom, a sulfur atom, a NH group or a (CH2)i group, i being an integer from 1 to 10, C is independently selected in the group comprising a hydrogen, an alkyl, an alkenyl, an alkynyl, or C is a group of formula (II). The present invention also relates to a pharmaceutical composition characterized in that it comprises the said calixarene-based glycosylated compound (I), in combination with pharmaceutically acceptable carriers or diluents. The present invention also relates to the use of the said calixarene-based glycosylated compound (I) or the said pharmaceutical composition, for the manufacture of a drug intended to prevent or treat bacterial infections from pathogens that use lectins in the first steps of infection.
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Paragraph 0159-0161
(2013/10/07)
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- Glycosynthase with broad substrate specificity-an efficient biocatalyst for the construction of oligosaccharide library
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A versatile glycosynthase (TnG-E338A) with strikingly broad substrate scope has been developed from Thermus nonproteolyticus β-glycosidase (TnG) by using site-directed mutagenesis. The practical utility of this biocatalyst has been demonstrated by the facile generation of a small library containing various oligosaccharides and a steroidal glycoside (total 25 compounds) in up to 100 % isolated yield. Moreover, an array of eight gluco-oligosaccharides has been readily synthesized by the enzyme in a one-pot, parallel reaction, which highlights its potential in the combinatorial construction of a carbohydrate library that will assist glycomic and glycotherapeutic research. Significantly, the enzyme provides a means by which glycosynthase technology may be extended to combinatorial chemistry.
- Wei, Jinhua,Lv, Xun,Lue, Yang,Yang, Gangzhu,Fu, Lifeng,Yang, Liu,Wang, Jianjun,Gao, Jianhui,Cheng, Shuihong,Duan, Qian,Jin, Cheng,Li, Xuebing
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supporting information
p. 2414 - 2419
(2013/05/23)
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- Use of iodine for efficient and chemoselective glycosylation with glycosyl ortho-alkynylbenzoates as donor in presence of thioglycosides
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A novel and high yielding glycosylation protocol with glycosyl ortho-alkynylbenzoates as donors and iodine as promoter is described. The donors are stable and can be chemoselectively activated in the presence of thioethyl and thiophenyl glycosides. The application of this methodology in one-pot consecutive glycosylation reaction is described.
- Dutta, Samrat,Sarkar, Swarbhanu,Gupta, Shyam Ji,Sen, Asish Kumar
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supporting information
p. 865 - 870
(2013/02/25)
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- Control of protein-binding kinetics on synthetic polymer nanoparticles by tuning flexibility and inducing conformation changes of polymer chains
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Although a number of procedures to create synthetic polymer nanoparticles (NPs) with an intrinsic affinity to target biomacromolecules have been published, little has been reported on strategies to control the binding kinetics of target recognition. Here,
- Hoshino, Yu,Nakamoto, Masahiko,Miura, Yoshiko
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supporting information
p. 15209 - 15212
(2012/11/13)
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- Rational design and synthesis of optimized glycoclusters for multivalent lectin-carbohydrate interactions: Influence of the linker arm
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The design of multivalent glycoclusters requires the conjugation of biologically relevant carbohydrate epitopes functionalized with linker arms to multivalent core scaffolds. The multigram-scale syntheses of three structurally modified triethyleneglycol analogues that incorporate amide moiety(ies) and/or a phenyl ring offer convenient access to a series of carbohydrate probes with different water solubilities and rigidities. Evaluation of flexibility and determination of preferred conformations were performed by conformational analysis. Conjugation of the azido-functionalized carbohydrates with tetra-propargylated core scaffolds afforded a library of 18 tetravalent glycoclusters, in high yields, by CuI-catalyzed azide-alkyne cycloaddition (CuAAC). The compounds were evaluated for their ability to bind to PA-IL (the LecA lectin from the opportunistic pathogen Pseudomonas aeruginosa). Biochemical evaluation through inhibition of hemagglutination assays (HIA), enzyme-linked lectin assays (ELLA), surface plasmon resonance (SPR), and isothermal titration microcalorimetry (ITC) revealed improved and unprecedented affinities for one of the monovalent probes (Kd=5.8 μM) and also for a number of the tetravalent compounds that provide several new nanomolar ligands for this tetrameric lectin. Copyright
- Cecioni, Samy,Praly, Jean-Pierre,Matthews, Susan E.,Wimmerova, Michaela,Imberty, Anne,Vidal, Sebastien
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supporting information; experimental part
p. 6250 - 6263
(2012/07/03)
-
- GLYCOMIMETIC COMPOUNDS AS ANTI-INFECTIOUS AGAINST PATHOGENS LECTINS
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The present invention relates to a calixarene-based glycosylated compound (I) having the formula : (I) wherein D is independently selected in the group comprising a –CH2 –group, an oxygen atom, a sulphur atom, a sulfinyl group or a sulfonyl group, E is independently selected in the group comprising a hydrogen, an alkyl having from 1 to 10 carbon atoms, an aryl having from 6 to 20 carbon atoms, a nitrogen dioxide group, an azide group, an amino group, a guanidinium group,a halogen atom, a –CH2 R group wherein R is a hydroxyl, a halogen, an amino group, a N(alkyl)2 group, a NH(alkyl) group, or E represents a –CO-R' wherein R' is a hydrogen atom, a hydroxyl group or an amino, B represents a A–C group wherein A is independently selected in the group comprising an oxygen atom, a sulfur atom, a NH group or a (CH2 )i group, i being an integer from 1 to 10, C is independently selected in the group comprising a hydrogen, an alkyl, an alkenyl, an alkynyl, or C is a group of formula (II). The present invention also relates to a pharmaceutical composition characterized in that it comprises the said calixarene-based glycosylated compound (I), in combination with pharmaceutically acceptable carriers or diluents. The present invention also relates to the use of the said calixarene-based glycosylated compound (I) or the said pharmaceutical composition, for the manufacture of a drug intended to prevent or treat bacterial infections from pathogens that use lectins in the first steps of infection.
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Page/Page column 23
(2012/06/30)
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- H2SO4-SiO2: Highly efficient and reusable catalyst for per-O-acetylation of carbohydrates under solvent-free conditions
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Sulfuric acid immobilized on silica gel (H2SO 4-SiO2) was used as an efficient promoter for per-O-acetylation of carbohydrates with acetic anhydride under solvent-free conditions. The substrates include not only monosaccharides and disaccharides, but also glycosides. The catalyst is recyclable and stable at room temperature, and the reaction protocol is simple, is cost-effective, and gives good isolated yield with high purity. The large-scale reactions also proceeded conveniently and in high yields. Taylor & Francis Group, LLC.
- Zhang, Jianbo,Zhang, Bo,Zhou, Jiafen,Li, Juan,Shi, Chunjuan,Huang, Ting,Wang, Zhongfu,Tang, Jie
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experimental part
p. 165 - 177
(2012/01/19)
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- O-Glycosidation reactions promoted by in situ generated silver N-heterocyclic carbenes in ionic liquids
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We herein report O-glycosidation reactions promoted via silver N-heterocyclic carbene complexes formed in situ in ionic liquids. Seven different room temperature ionic liquids were screened for the glycosidation reaction of 4-nitrophenol with tetra-O-acetyl-α-d-galactopyranosyl bromide. Good to excellent yields were obtained using Ag-NHC complexes derived from imidazolium halide salts to promote the glycosidation reaction, whereas yields considered moderate to low were obtained without use of the silver carbene complex. Anion metathesis of the ionic liquids with inexpensive alkylammonium halides also resulted in silver N-heterocyclic carbene formation and subsequent O-glycosidation in the presence of silver carbonate. Effective utility of this methodology has been demonstrated with biologically relevant acceptors (including flavones and steroids) where O-β-glycoside products were obtained selectively in moderate to good yields. We have also demonstrated that the Ag-NHC complex is a superior promoter to traditionally used silver carbonate for the glycosidation of polyphenolic acceptors. The ionic liquids used in the study could be recycled three times without apparent loss in activity.
- Talisman, Ian Jamie,Kumar, Vineet,Razzaghy, Jacqueline,Malhotra, Sanjay V.
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experimental part
p. 883 - 890
(2011/06/20)
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- Application of silver N-heterocyclic carbene complexes in O-glycosidation reactions
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We report the efficient O-glycosidation of glycosyl bromides with therapeutically relevant acceptors facilitated by silver N-heterocyclic carbene (Ag-NHC) complexes. A set of four Ag-NHC complexes was synthesized and evaluated as promoters for glycosidation reactions. Two new bis-Ag-NHC complexes derived from ionic liquids 1-benzyl-3-methyl-1H-imidazolium chloride and 1-(2-methoxyethyl)-3-methylimidazolium chloride were found to efficiently promote glycosidation, whereas known mono-Ag complexes of 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride and 1,3-bis(2,6-di-isopropylphenyl) imidazolium chloride failed to facilitate the reaction. The structures of the promoters were established by X-ray crystallography and these complexes were employed in the glycosidation of different glycosyl bromide donors with biologically valuable acceptors, such as estrone, estradiol, and various flavones. The products were obtained in yields considered good to excellent, and all reactions were highly selective for the β isomer regardless of neighboring group effects.
- Talisman, Ian J.,Kumar, Vineet,Deschamps, Jeffrey R.,Frisch, Mark,Malhotra, Sanjay V.
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experimental part
p. 2337 - 2341
(2011/12/04)
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- Application of halide molten salts as novel reaction media for O-glycosidic bond formation
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In this study we have explored the application of halide molten salts as reaction media for O-glycosidic bond formation under basic conditions and mild heating. Eighteen different room-temperature ionic liquids and molten salts, representing four different classes of cations (i.e. imidazolium, pyridinium, pyrrolidinium and ammonium), were screened in the glycosidation reaction of p-nitrophenol with aceto-bromo-α-D-galactose. 1-Butyl-4-methylimidazolium chloride (BMIM·Cl) gave the best results and was applied in the reactions of other phenolic substrates to give the products with up to 80% yields. All the reactions were highly selective to give the β-anomers, and the molten salt BMIM·Cl could easily be reused with no apparent loss in activity.
- Kumar, Vineet,Talisman, Ian Jamie,Malhotra, Sanjay V.
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supporting information; experimental part
p. 3377 - 3381
(2010/08/19)
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- Solvent-free mechanochemical synthesis of aryl glycosides
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Aryl glycosides have been prepared from a range of readily available glycosyl halides by a solvent-free mechanochemical procedure employing a planetary ball mill in excellent yields. Besides being a solvent-free reaction, the procedure has been successful in eliminating the need for employing any phase-transfer catalyst in the reaction. Copyright Taylor & Francis Group, LLC.
- Patil, Premanand Ramrao,Ravindranathan Kartha
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experimental part
p. 411 - 419
(2009/04/11)
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- Cross-linked surface-grafted glycopolymer for multivalent recognition of lectin
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An α-link mannose-conjugated acrylamide monomer was synthesized. This monomer was polymerized by free radical polymerization with acrylamide, a cross-linker, and a surface linker directly on the gold surface. The surface linker, with an active carbon-carbon double bond, was preimmobilized on the gold surface by the thiol anchor. Thus, a cross-linked mannose-conjugated polymer thin layer was grafted onto a gold surface. This thin layer of polymer showed high binding sensitivity and excellent selectivity to its target lectin, concanavalin A (Con A), surpassing the formerly used linear glycopolymer and self-assembled glycol monolayers, validated by the techniques of quartz crystal microbalance, atomic force microscopy, and surface plasmon resonance. Remarkable response was observed to Con A at a concentration as low as 5 × 10 -10 M. The response is proportional to the Con A concentration up to 10-7 M in phosphate-buffered saline. The use of cross-linked polymer decreased the flexibility of the polymer backbone between the carbohydrate binding sites. Therefore, the cost of conformational entropy for multivalent binding was minimized. The binding constants of the so-prepared cross-linked polymer with Con A were measured to be between 2.5 × 106 and 3.2 × 106 M-1. These values are significantly larger than that obtained in our early study with a carbohydrate self-assembled monolayer. In addition to the carbohydrate-lectin recognition, additional selectivity may be achieved by controlling the degree of cross-linking.
- Yu, Lei,Huang, Mingchuan,Wang, Peng G.,Zeng, Xiangqun
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p. 8979 - 8986
(2008/03/14)
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- Sol-Gel Polycondensation of Tetraethyl Orthosilicate (TEOS) in Sugar-Based Porphyrin Organogels: Inorganic Conversion of a Sugar-Directed Porphyrinic Fiber Library through Sol-Gel Transcription Processes
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Sugar-appended porphyrins (1a-e) with monosaccharide groups at their periphery have been rationally designed for a new class of gelating reagents. A few of these compounds have the tendancy to form one-dimensional aggregates stable enough to show successful gelation ability for DMF-alcohol mixed solvents. The aggregation mode in the specific columnar super structures has been evaluated in detail by UV-visible spectrometry (UV/Vis), circular dichroism (CD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). All UV-visible spectra of sugar-appended porphyrinic gels obtained from la-c exhibit Soret band absorptions, which shift to lower wave-length and are significantly broadened. This phenomenon indicates that these porphyrin cores strongly interact with each other in an H-aggregate fashion, which drives the generation of a one-dimensional porphyrin-stacking array. The CD spectra of the organogels from 1a and 1b, which are in anomers, exhibit an almost symmetric pattern, whereas the gel from 1c gives a completely different pattern. This implies that the gel fibrils wind themselves in a right- or left-handed fashion; this reflects chirality in the specific molecular structure of the gelators. The results from SEM for the gel fibrils are in good agreement with the CD patterns. The gel fibrils in la possess left-handed helicity, whereas those in lb wind themselves right-handedly. Macroscopic helical morphology reflects the microscopic structure well at a molecular level, which gives structural variety of the gel fibrils, which can be defined by the sugar library. Inorganic conversion of the organic helical fibrils by a sol-gel transcription process successfully gives the helical-silica structures, which finely inherit the organic morphology. A striking observation is that a unimolecular porphyrin-stacking array is also transcribed into silica fibers when the optimized sol-gel reaction conditions are selected. A sugar-based organic-fiber library in porphyrinic gels thus provides a variety of inorganic materials through the sol-gel transcription process.
- Kawano, Shin-Ichiro,Tamaru, Shun-Ichi,Fujita, Norifumi,Shinkai, Seiji
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p. 343 - 351
(2007/10/03)
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- Synthesis and utility of sulfated chromogenic carbohydrate model substrates for measuring activities of mucin-desulfating enzymes
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A chromogenic substrate, 4-nitrophenyl 2-acetamido-2-deoxy-β-D-glucopyranoside 6-sodium sulfate was synthesized and used in combination with β-N-acetylhexosaminidase for detection of the sulfatase, MdsA, by release of 4-nitrophenol. MdsA was originally isolated from the bacterium Prevotella strain RS2 and is believed to be involved in desulfation of sulfomucins, major components of the mucus barrier protecting the human colon surface. The exo nature of the MdsA sulfatase was indicated by its inability to de-esterify the disaccharide 4-nitrophenyl β-D-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D- glucopyranoside 6-sodium sulfate. This latter compound was prepared from monosaccharide precursors by two different methods, the shorter requiring just six steps from 4-nitrophenyl 2-acetamido-2-deoxy-β-D-glucopyranoside and giving an overall yield of 26.4%. The syntheses of 4-nitrophenyl β-D-galactopyranoside 3-triethylammonium sulfate and 6-triethylammonium sulfate and their use in combination with β-galactosidase as chromogenic substrates for detecting Bacteroides fragilis sulfatases with different specificities was also demonstrated.
- Clinch, Keith,Evans, Gary B,Furneaux, Richard H,Rendle, Phillip M,Rhodes, Phillippa L,Roberton, Anthony M,Rosendale, Douglas I,Tyler, Peter C,Wright, Damian P
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p. 1095 - 1111
(2007/10/03)
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- Post-photoaffinity labeling modification using aldehyde chemistry to produce a fluorescent lectin toward saccharide-biosensors
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A new method to construct a fluorescent saccharide biosensor based on a lectin protein is successfully proposed using post-photoaffinity labeling modification coupled to aldehyde chemistry.
- Nagase,Shinkai,Hamachi
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p. 229 - 230
(2007/10/03)
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- Synthesis and biological activity of glycosyl conjugates of N-(4-hydroxyphenyl)retinamide
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Three glycosyl (glucosyl, galactosyl, mannosyl) conjugates of 4-hydroxyphenylretinamide have been synthesized and tested on a broad variety of tumor cells. All three compounds are active on promyelocytic leukemia cell lines HL60 but less than the parent compound 4-HPR. Among them, the mannosyl analog stands out by its very low toxicity. Copyright
- Winum, Jean-Yves,Leydet, Alain,Seman, Michel,Montero, Jean-Louis
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p. 319 - 324
(2007/10/03)
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- New organogelators bearing both sugar and cholesterol units: An approach toward molecular design of universal gelators
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The gelators of organic solvents are classified into two categories on the basis of their basic intermolecular forces: hydrogen-bonded or nonhydrogen-bonded. To utilize these two interactions cooperatively for organogel formation we newly synthesized seven gelators (1-7) and two reference compounds (8 and 9) which have both a cholesterol moiety and a saccharide moiety within one molecule. The solubility of 1-7 changed drastically from totally insoluble one to very soluble one depending on the saccharide absolute configuration. In general, the gelator became very insoluble when it includes many equatorial OH groups, whereas it became very soluble when it includes many axial OH groups. Gelators 2 and 5 bearing two equatorial OH groups and one axial OH group acted as good gelators and in several cases the sol-gel phase-transition temperatures (measured in a sealed tube) were higher than the boiling points. The SEM observations of the xerogels established that the stable gels contain the entangled fibrous network. These results indicate that a very stable organogel can be designed by a cooperative coagulative effect of a cholesterol-cholesterol interaction and a saccharide-saccharide interaction.
- Amaike,Kobayashi,Shinkai
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p. 2553 - 2558
(2007/10/03)
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- A facile access to aryl α-sialosides: The combination of a volatile amine base and acetonitrile in glycosidation of sialosyl chlorides
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We have succeeded in achieving a facile access to 4-nitrophenyl and 4-methylumbelliferyl-α-sialosides. To sialosyl chlorides which are fully protected with acetyl groups as glycosyl donors, the action of phenols with diisopropylethylamine in acetonitrile brought about high yield as well as facile product isolation.
- Kuboki, Atsuhito,Sekiguchi, Takahiro,Sugai, Takeshi,Ohta, Hiromichi
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p. 479 - 482
(2007/10/03)
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- Iodine : A versatile reagent in carbohydrate chemistry IV. Per-O-Acetylation, regioselective acylation and acetolysis
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Iodine has been found to be an effective Lewis acid for promoting the per-O-acetylation of unprotected sugars. Under controlled conditions it can bring about regioselective acylation of carbohydrate derivatives. At higher concentration and with longer reaction times, iodine can effect the selective acetolysis of benzyl ether-protected primary hydroxyl groups. All of these reactions proceed in high yield, are easy to carry out and make use of readily available iodine, which is both cheap and easy to handle.
- Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 11753 - 11766
(2007/10/03)
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- Silver Imidazolate-assisted Glycosidations. Part 7. Synthesis of 1,2-trans-Linked Aryl Glycosides
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Efficient preparations of 1,2-trans-linked aryl glycosides starting from fully acetylated glycopyranosyl bromides are described.The promoting system is silver imidazolate and zink chloride.
- Garegg, Per J.,Hultberg, Hans,Ortega, Carmen,Samuelsson, Bertil
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p. 513 - 514
(2007/10/02)
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- STEREOSELECTIVE SYNTHESES OF O- AND S-NITROPHENYL GLYCOSIDES. PART III. SYNTHESES IN THE &α-D-GALACTOPYRANOSE AND &α-MALTOSE SERIES
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The action of p-nitrophenol penta-O-acetyl-β-D-galactopyranose in dichloromethane, in the presence of stannic tetrachloride gave p-nitrophenyl α-D-galactoside in fair yield.This technique failed when o-nitrophenol was used.Tetra-O-acetyl-β-D-galactopyranosyl and hepta-O-acetyl-β-maltosyl chlorides were converted to p- or o-nitrophenyl α-D-glycosides and p-nitrophenyl α-D-1-thioglycosides in good yield using hexamethylphosphoramide as a solvent and the sodium salt of the phenols as nucleophiles.The galactosides have been functionalized for further condensation at the C-4 position by selective benzoylation.
- Apparu, Maecel,Blanc-Muesser, Michele,Defaye, Jacques,Driguez, Hugues
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p. 314 - 320
(2007/10/02)
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