- Semisynthesis of abrusoside A methyl ester.
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Abrusoside A methyl ester was prepared from abrusogenin through methylation (CH2N2) and a subsequent coupling reaction with 1-chloro-2,3,4,6-tetra-O-acethylglucopyranose in the presence of AgOTf and TMU in CH2Cl2, followed by deacetylation using K2CO3 in MeOH-H2O.
- Kim,Kinghorn,Kim
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Read Online
- Stereoselective Preparation of C-Aryl Glycosides via Visible-Light-Induced Nickel-Catalyzed Reductive Cross-Coupling of Glycosyl Chlorides and Aryl Bromides
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A nickel-catalyzed cross-coupling reaction of glycosyl chlorides with aryl bromides has been developed. The reaction proceeds smoothly under visible-light irradiation and features the use of bench-stable glycosyl chlorides, allowing the highly stereoselective synthesis of C-aryl glycosides. (Figure presented.).
- Mou, Ze-Dong,Wang, Jia-Xi,Zhang, Xia,Niu, Dawen
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supporting information
p. 3025 - 3029
(2021/05/27)
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- Chemoenzymatic synthesis of arabinomannan (AM) glycoconjugates as potential vaccines for tuberculosis
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Mycobacteria infection resulting in tuberculosis (TB) is one of the top ten leading causes of death worldwide in 2018, and lipoarabinomannan (LAM) has been confirmed to be the most important antigenic polysaccharide on the TB cell surface. In this study, a convenient synthetic method has been developed for synthesizing three branched oligosaccharides derived from LAM, in which a core building block was prepared by enzymatic hydrolysis in flow chemistry with excellent yield. After several steps of glycosylations, the obtained oligosaccharides were conjugated with recombinant human serum albumin (rHSA) and the ex-vivo ELISA tests were performed using serum obtained from several TB-infected patients, in order to evaluate the affinity of the glycoconjugate products for the human LAM-antibodies. The evaluation results are positive, especially compound 21 that exhibited excellent activity which could be considered as a lead compound for the future development of a new glycoconjugated vaccine against TB.
- Li, Zhihao,Bavaro, Teodora,Tengattini, Sara,Bernardini, Roberta,Mattei, Maurizio,Annunziata, Francesca,Cole, Richard B.,Zheng, Changping,Sollogoub, Matthieu,Tamborini, Lucia,Terreni, Marco,Zhang, Yongmin
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supporting information
(2020/07/27)
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- Nonenzymatic synthesis of anomerically pure, mannosylbased molecular probes for scramblase identification studies
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The chemical synthesis of molecular probes to identify and study membrane proteins involved in the biological pathway of protein glycosylation is described. Two short-chain glycolipid analogs that mimic the naturally occurring substrate mannosyl phosphoryl dolichol exhibit either photoreactive and clickable properties or allow the use of a fluorescence readout. Both probes consist of a hydrophilic mannose headgroup that is linked to a citronellol derivative via a phosphodiester bridge. Moreover, a novel phosphoramidite chemistry-based method offers a straightforward approach for the non-enzymatic incorporation of the saccharide moiety in an anomerically pure form.
- Bütikofer, Peter,H?ner, Robert,Khorev, Oleg,Langenegger, Simon M.,Menon, Anant K.,Picca, Giovanni,Probst, Markus
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supporting information
p. 1732 - 1739
(2020/09/15)
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- 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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- 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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- Efficient Synthesis of α-Glycosyl Chlorides Using 2-Chloro-1,3-dimethylimidazolinium Chloride: A Convenient Protocol for Quick One-Pot Glycosylation
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A mild and convenient method for the synthesis of α-glycosyl chlorides in high 80–96 % yields within 15–30 min using 2-chloro-1,3-dimethylimidazolinium chloride (DMC) is disclosed. The method has a wide substrate scope and is compatible with labile OH protecting groups, including benzyl, acetyl, benzoyl, isopropylidene, benzylidene, TBDMS (tert-butyldimethylsilyl), and TBDPS (tert-butyldiphenylsilyl) groups. The excellent α selectivity obtained in this reaction is attributed to in-situ isomerization of β-glycosyl chlorides to the more stable α-glycosyl chlorides, as demonstrated by 1H NMR spectroscopic studies. Disarmed sugars with OBz or OAc groups at C-2 were chlorinated at a faster rate but ismomerized (β→α) at a slower rate than armed sugars with an OBn group at C-2. More importantly, the method enables highly desirable one-pot glycosylation reactions to take place, thus allowing efficient syntheses of disaccharides and simple O-glycosylated sugars in high overall yields without the need for separation or purification of the α-glycosyl chloride donors. This method will be especially useful for direct glycosylation reactions using glycosyl chloride donors that are unstable upon separation and purification.
- Tatina, Madhu Babu,Khong, Duc Thinh,Judeh, Zaher M. A.
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supporting information
p. 2208 - 2213
(2018/06/04)
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- Quinoline-galactose hybrids bind selectively with high affinity to a galectin-8 N-terminal domain
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Quinolines, indolizines, and coumarins are well known structural elements in many biologically active molecules. In this report, we have developed straightforward methods to incorporate quinoline, indolizine, and coumarin structures into galactoside derivatives under robust reaction conditions for the discovery of glycomimetic inhibitors of the galectin family of proteins that are involved in immunological and tumor-promoting biological processes. Evaluation of the quinoline, indolizine and coumarin-derivatised galactosides as inhibitors of the human galectin-1, 2, 3, 4N (N-terminal domain), 4C (C-terminal domain), 7, 8N, 8C, 9N, and 9C revealed quinoline derivatives that selectively bound galectin-8N, a galectin with key roles in lymphangiogenesis, tumor progression, and autophagy, with up to nearly 60-fold affinity improvements relative to methyl β-d-galactopyranoside. Molecular dynamics simulations proposed an interaction mode in which Arg59 had moved 2.5 ? and in which an inhibitor carboxylate and quinoline nitrogen formed structure-stabilizing water-mediated hydrogen bonds. The compounds were demonstrated to be non-toxic in an MTT assay with several breast cancer cell lines and one normal cell line. The improved affinity, selectivity, and low cytotoxicity suggest that the quinoline-galactoside derivatives provide an attractive starting point for the development of galectin-8N inhibitors potentially interfering with pathological lymphangiogenesis, autophagy, and tumor progression.
- Pal, Kumar Bhaskar,Mahanti, Mukul,Huang, Xiaoli,Persson, Stella,Sundin, Anders P.,Zetterberg, Fredrik R.,Oredsson, Stina,Leffler, Hakon,Nilsson, Ulf J.
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p. 6295 - 6305
(2018/09/10)
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- Synthesis of aromatic and indole alpha-glucosinolates
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Aromatic and indole glucosinolates are important members of the glucosinolate family of compounds du to their potential medicinal properties. They are known to exert antioxidant and anti-carcinogenic activity either by the natural products themselves, or their metabolic products including indole-3-carbinol and isothiocyanates. Natural glucosinolates are all β-glucosinolates; however, α-glucosinolates are also promising compounds for medicinal applications and hence have to be produced synthetically for any bio-activity studies. Here we report on the successful synthesis of a series of α-glucosinolates: α-neoglucobrassicin, α-4-methoxyglucobrassicin, 2,3-dichlorophenyl-α-glucosinolate for the first time. Testing for anti-inflammatory properties of these synthetic GLs, however, did not yield the expected activity.
- Vo, Quan V.,Rochfort, Simone,Nam, Pham C.,Nguyen, Tuan L.,Nguyen, Trung T.,Mechler, Adam
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- UDP-GlcNAc Analogues as Inhibitors of O-GlcNAc Transferase (OGT): Spectroscopic, Computational, and Biological Studies
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A series of glycomimetics of UDP-GlcNAc, in which the β-phosphate has been replaced by either an alkyl chain or a triazolyl ring and the sugar moiety has been replaced by a pyrrolidine ring, has been synthesized by the application of different click-chemistry procedures. Their affinities for human O-GlcNAc transferase (hOGT) have been evaluated and studied both spectroscopically and computationally. The binding epitopes of the best ligands have been determined in solution by means of saturation transfer difference (STD) NMR spectroscopy. Experimental, spectroscopic, and computational results are in agreement, pointing out the essential role of the binding of β-phosphate. We have found that the loss of interactions from the β-phosphate can be counterbalanced by the presence of hydrophobic groups at a pyrroline ring acting as a surrogate of the carbohydrate unit. Two of the prepared glycomimetics show inhibition at a micromolar level.
- Ghirardello, Mattia,Perrone, Daniela,Chinaglia, Nicola,Sádaba, David,Delso, Ignacio,Tejero, Tomas,Marchesi, Elena,Fogagnolo, Marco,Rafie, Karim,van Aalten, Daan M. F.,Merino, Pedro
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supporting information
p. 7264 - 7272
(2018/05/04)
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- ALPHA-D-GALACTOSIDE INHIBITORS OF GALECTINS
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The present invention relates to a compound of the general formula (1). wherein the pyranose ring is a-D-galactopyranose, A is selected from The compound of formula (1) is suitable for use in a method for treating a disorder relating to the binding of a galectin, such as galectin-3 to a ligand in a mammal, such as a human. Furthermore the present invention concerns compounds for use in a method of treatment of a disorder relating to the binding of a galectin, such as galectin-3 to a ligand in a mammal, such as a human.
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Page/Page column 130; 131
(2016/08/23)
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- Analyte detection utilizing polynucleotide sequences, composition, process and kit
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A method of detecting in a sample an analyte (A) having a molecularly recognizable portion thereon, which comprises: providing (B) a molecular bridging entity having thereon: (i) a portion capable of recognizing the molecularly recognizable portion on the analyte; and (ii) a portion comprising a polynucleotide sequence; and (C) a signalling entity having thereon: (i) a polynucleotide portion capable of annealing to the polynucleotide portion of the bridging entity, thereby to form a stable polynucleotide hybrid, and (ii) a signal generating portion; forming a complex comprising: (1) the analyte (A) complexed through its molecularly recognizable portion to (2) the recognizing portion of the entity (B); the entity (B) being complexed through the polynucleotide portion thereon to (3) the polynucleotide portion of the signalling entity; and detecting a signal by means of the signal generating portion present in the complex.
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- Protecting group free synthesis of urea-linked glycoconjugates: Efficient synthesis of β-urea glycosides in aqueous solution
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A method for the protecting group free synthesis of β-urea-linked glycoconjugates has been developed. The one step process, involving reactions between urea and d-glucose, N-acetyl-d-glucosamine or d-xylose in acidic aqueous solution, furnishes the corresponding β-urea glycosides in modest yields. This simple and efficient procedure is applicable to the synthesis of β-urea tethered amino acid-carbohydrate conjugates. This journal is the Partner Organisations 2014.
- Ichikawa, Yoshiyasu,Minami, Takahiro,Kusaba, Shohei,Saeki, Nobuyoshi,Tonegawa, Yuta,Tomita, Yumiko,Nakano, Keiji,Kotsuki, Hiyoshizo,Masuda, Toshiya
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p. 3924 - 3931
(2014/06/09)
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- Improved synthesis of per-O-acetylated C1 hydroxyglycopyranose and structural study as non-covalent organic framework
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An improved method for the synthesis of per-O-acetylated C-1-hydroxyglycopyranose was developed by hydrolysis of per-O-acetylated glycopyranosyl α-chlorides derived from sugars with C-2 axial acetates for example l-rhamnose and d-mannose. 2,3,4-Tri-O-acetyl-α-l-rhamnopyranose crystallized in tetragonal space group I4, a rare phenomenon in carbohydrate literature. The three dimensional packing of the molecule with the help of regular hydrogen bond and C-H···O interactions resulted in the formation of porous framework showing channels with pore size 7 A?.
- Singhamahapatra, Anadi,Sahoo, Laxminarayan,Paul, Katuri J.V.,Varghese, Babu,Loganathan, Duraikkannu
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p. 6121 - 6124
(2013/10/22)
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- Short synthetic route to benzaldehyde-functionalized idose and talose derivatives by acetoxonium ion rearrangements
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Carbohydrate-carbohydrate interactions (CCI) are mediated by complexation of metal ions. Angyal postulated on the requirements for hydroxy group arrangement in pyranoses to account for metal-ion complexation. These requirements are particularly well fulfilled in α-ido- and α-talopyranosides, whose ring hydroxy groups have all axial and axial-equatorial-axial configurations, respectively. Surface plasmon resonance (SPR) and gold-nanoparticle techniques have proved to be powerful tools to investigate CCIs. Benzaldehyde-functionalized glycans can be used for attachment to both gold nanoparticles and SPR sensor surfaces. Therefore, benzaldehyde-equipped ido- and talopyranosides were synthesized by the almost forgotten Paulsen acetoxonium rearrangement. This approach provides peracetylated idose and talose in only two steps from common glucose and galactose precursors, respectively, in overall yields of up to 41 % and, therefore, avoids long and laborious procedures to obtain these rare carbohydrates. The derivatives are being used in ongoing CCI studies using SPR to test Angyal's postulate about the structural requirements for hydroxy group arrangements. Almost forgotten: The Paulsen acetoxonium rearrangement provides a facile and rapid access to rare carbohydrates. Through a cascade of antimony pentachloride induced acetoxonium rearrangements, ido- and talopyranose derivatives can be synthesized from simple glucose and galactose precursors in a one-pot procedure. Copyright
- Kopitzki, Sebastian,Thiem, Joachim
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p. 4008 - 4016
(2013/07/26)
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- Synthesis, biological evaluation, wac and NMR studies of s-galactosides and non-carbohydrate ligands of cholera toxin based on polyhydroxyalkylfuroate moieties
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The synthesis of several non-carbohydrate ligands of cholera toxin based on polyhydroxyalkylfuroate moieties is reported. Some of them have been linked to D-galactose through a stable and well-tolerated S-glycosidic bond. They represent a novel type of non-hydrolyzable bidentate ligand featuring galactose and polyhydroxyalkylfuroic esters as pharmacophoric residues, thus mimicking the GM1 ganglioside. The affinity of the new compounds towards cholera toxin was measured by weak affinity chromatography (WAC). The interaction of the best candidates with this toxin was also studied by saturation transfer difference NMR experiments, which allowed identification of the binding epitopes of the ligands interacting with the protein. Interestingly, the highest affinity was shown by non-carbohydrate mimics based on a polyhydroxyalkylfuroic ester structure. No carbs here: Saturation transfer difference (STD) NMR studies of bidentate ligands of cholera toxin (see figure, WAC = weak affinity chromatography) show the methylfuran moiety as the main contact point in the interaction with the toxin. Several polyhydroxyalkylfuroate-based structures are synthesized and analyzed and show similar or even better affinity than the bidentate ligands. They constitute the first examples of non-carbohydrate ligands for cholera toxin. Copyright
- Ramos-Soriano, Javier,Niss, Ulf,Angulo, Jesus,Angulo, Manuel,Moreno-Vargas, Antonio J.,Carmona, Ana T.,Ohlson, Sten,Robina, Inmaculada
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supporting information
p. 17989 - 18003
(2014/01/17)
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- Click chemistry: An efficient synthesis of heterocycles substituted with steroids, saponins, and digitalis analogues
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The copper-catalyzed azide-alkyne cycloaddition (CuAAC) has been used for the construction of 1,2,3-triazole containing steroids in good to excellent yields. Combination of propargylic glycosides and steroidal azides as reaction partner allowed the synthesis of a privileged class of natural product analogues. The versatility of this protocol makes this chemistry a useful attractive approach for the synthesis of target molecules. Georg Thieme Verlag Stuttgart · New York.
- Deobald, Anna M.,Camargo, Leandro R. S.,Alves, Diego,Zukerman-Schpector, Julio,Correa, Arlene G.,Paixao, Marcio W.
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supporting information; scheme or table
p. 4003 - 4010
(2012/01/05)
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- Thiyl glycosylate of olefinic proteins: S-linked glycoconjugate synthesis
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Tagged for thiolation: A novel glycoconjugation strategy utilizes a non-natural olefin-containing amino acid (homoallylglycine, Hag) as a "tag" for modification and a photoinitiated hydroglycothiolation reaction that is selective only for the Hag olefinic "tag". Application of this method to a number of model proteins allowed complete and precise site-selective glycosylate generating glycoconjugates that include, for example, virus-like particles displaying up to 180 glycans at preselected positions (see scheme).
- Floyd, Nicola,Vijayakrishnan, Balakumar,Koeppe, Julia R.,Davis, Benjamin G.
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supporting information; experimental part
p. 7798 - 7802
(2010/04/05)
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- A mild and general method for preparation of α-glycosyl chlorides
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A mild and efficient chlorination method for production of glycosyl chlorides is first described which employs inexpensive trichlorotriazine (TCT) and DMF as a chlorination reagent and is compatible with typical acid-labile hydroxyl protecting functions. The scope and limitations, reaction mechanism and its application in the sequential glycosylations are discussed.
- Chang, Chih-Wei,Chang, Shih-Sheng,Chao, Chin-Sheng,Mong, Kwok-Kong T.
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supporting information; experimental part
p. 4536 - 4540
(2009/12/03)
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- A facile preparation of peracylated α-aldopyranosyl chlorides with thionyl chloride and tin tetrachloride
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Aldopyranose peracetates react with thionyl chloride and tin tetrachloride, producing the corresponding peracylated aldopyranosyl chlorides in very good to excellent yields (88-100%) with exclusive α-anomeric selectivity and short reaction times. The use of peracylated sugars as the substrate in large scale reactions also proceeds in high yield. Crown Copyright
- Wang, Qingbing,Fu, Jie,Zhang, Jianbo
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scheme or table
p. 2989 - 2991
(2009/04/05)
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- Traceless Staudinger ligation of glycosyl azides with triaryl phosphines: Stereoselective synthesis of glycosyl amides
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α-Glycosyl amides can be synthesized from the corresponding O-benzyl-α-glycosyl azides using a traceless Staudinger ligation with diphenylphosphanyl-phenyl esters 4. All the phosphines employed and their phenol precursors are stable to air at 4 °C for months. Fast intramolecular trapping of the reduction intermediates results in the direct formation of the amide link, which, in turn, prevents epimerisation and allows retention of configuration at the anomeric carbon. Yields and α-selectivity are high when the reaction is performed in polar aprotic solvents. Removal of the benzyl ether protecting groups is achieved by catalytic hydrogenation. α-Glycosyl amides represent a class of virtually unexplored nonhydrolyzable monosaccharide derivatives that may find a useful application as sugar mimics. Conformational studies by NMR spectroscopy confirm that deprotected α-glycosyl amides in the gluco, galacto, and fuco series retain the normal pyranose conformation of the monosaccharide. The reaction of phosphines 4 with tetra-O-acetyl-glycosyl azides is nonstereoconservative, and β-glycosyl amides are obtained in good yields and with complete stereoselectivity starting from both α and β azides.
- Bianchi, Aldo,Bernardi, Anna
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p. 4565 - 4577
(2007/10/03)
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- Acylation of carbohydrates over Al2O3: Preparation of partially and fully acylated carbohydrate derivatives and acetylated glycosyl chlorides
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Selective and per-O-acylation of carbohydrate derivatives using acyl chlorides and Al2O3, a solid support reagent, is reported. This protocol does not require the addition of any base or activator. This methodology has been further extended to the selective acylation of carbohydrate diols and the one-pot preparation of acetylated glycosyl chlorides direct from free reducing sugars. The yields obtained in most of the cases are excellent.
- Tiwari, Pallavi,Misra, Anup Kumar
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p. 339 - 350
(2007/10/03)
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- Immobilization of glycoconjugate polymers on cellulose membrane for affinity separation
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Membranes with immobilized glycoconjugate polymers were prepared and lectin adsorption was evaluated. Glycoconjugate polymers having the carbohydrates, lactose, and mannose, the amino groups of the reaction point, and a fluorescence label were synthesized, while cellulose membranes were carboxymethylated. The content of the carboxyl group was evaluated by titration. Subsequently, the glycoconjugate polymers were immobilized on the cellulose membranes by amide linkages formed by condensation reaction. Analysis of the luminescence of the fluorescence labels revealed that the glycoconjugate polymers had been immobilized on the cellulose membranes. Examination of lectin adsorption by the glycoconjugate polymer on the membrane revealed that the membrane with the immobilized mannose-having polymer adsorbed 53% of the applied ConA and the membrane with the immobilized lactose-having polymer adsorbed 83% of the applied RCA120. The membrane with immobilized glycoconjugate polymers selectively adsorbed each lectin. In addition, membranes with different types of immobilized glycoconjugate polymers were used in stacks, and in this case, the membranes selectively adsorbed lectin. Thus, membranes with immobilized glycoconjugate polymers efficiently and easily purify lectin.
- Miyagawa, Atsushi,Kasuya, Maria Carmelita Z.,Hatanaka, Kenichi
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p. 348 - 356
(2007/10/03)
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- Design, synthesis, and enzymatic property of a sulfur-substituted analogue of trigalacturonic acid
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A sulfur-substituted analogue of trigalacturonic acid (3) was synthesized. The synthesis features the application of 3-cyano-3-(tert-butyldimethylsilyl) oxypropylthioether (CSP) as a novel protective group for thiols. This analogue was designed with the expectation that it would be a stable analogous substrate for endo-polygalacturonase isolated from Stereum purpureum based on computer modeling experiments. Surface plasmon resonance experiments revealed that 3 forms a stable complex with the target enzyme.
- Yamamoto, Kazunori,Watanabe, Naoki,Matsuda, Hiroko,Oohara, Keiichiro,Araya, Tomoyuki,Hashimoto, Masaru,Miyairi, Kazuo,Okazaki, Isao,Saito, Minoru,Shimizu, Tetsuya,Kato, Hiroaki,Okuno, Toshikatsu
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p. 4932 - 4935
(2007/10/03)
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- Highly stereoselective synthesis of peracylated α-aldopyranosyl chlorides from aldopyranose peracetates and thionyl chloride catalyzed by BiCl3 generated in situ from the procatalyst BiOCl
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Aldopyranose peracetates react with thionyl chloride and BiCl3, generated in situ from a substoichiometric amount of the procatalyst BiOCl, producing the corresponding peracylated aldopyranosyl chlorides in very good to excellent yields (82-97%
- Ghosh, Rina,Chakraborty, Arijit,Maiti, Swarupananda
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p. 9631 - 9634
(2007/10/03)
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- Reaction of 1,2-trans-glycosyl acetates with phosphorus pentachloride: New efficient approach to 1,2-trans-glycosyl chlorides
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Reaction of phosphorus pentachloride with 1,2-trans-glycosyl esters is described. The reaction mechanism presumably involves formation of a tetrachlorophosphonium ion as one of the key reactive intermediates, which can be induced either by Lewis acids or by using acetonitrile as the reaction solvent. Two novel, efficient methods for the synthesis of the thermodynamically unstable glycosyl chlorides were developed based on this reaction.
- Ibatullin, Farid M.,Selivanov, Stanislav I.
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p. 9577 - 9580
(2007/10/03)
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- Fluorogenic compounds
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Disclosed are novel coumarin based fluorogenic compounds useful in assaying for biological activity. Specifically, these fluorogenic compounds exhibit fluorescence at particular wavelengths when cleaved by target enzymes. Preferred compounds include sugar and peptide derivatives of umbelliferone derivatives bearing a heterocyclic five membered ring at the 3-position. These compounds can be used for rapidly detecting food pathogens and for determining sterilization effectiveness. The compounds may also be used in a form bounded to a polymeric support or to a biomolecule or macromolecule.
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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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- Zirconium tetrachloride as a convenient catalyst for the glycosylation of sterols with 2,3,4,6,6'-penta-O-acetyl-5-hydroxymethylgalactosyl fluoride
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Zirconium tetrachloride was found to catalyze glycosylation of various sterols with peracetylated 5-hydroxymethylene galactosyl fluoride.
- Pikul, Stanislaw,Greg Switzer
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p. 1165 - 1168
(2007/10/03)
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- A convenient synthesis of peracetylated glycosyl halides using bismuth(III) halides as catalysts
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A new halogenation procedure for peracetylated glycopyranosides is reported, using bismuth(III) halides and halogenosilanes under very mild conditions.
- Montero, Jean-Louis,Winum, Jean-Yves,Leydet, Alain,Kamal, Mehrnaz,Pavia, Andre A.,Roque, Jean-Pierre
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p. 175 - 180
(2007/10/03)
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- Process for the preparation of protected mono-sugar and oligo-sugar halides
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The reaction of protected monosaccharides or oligosaccharides or protected monosaccharide and oligosaccharide derivatives containing an anomeric hydroxyl group with secondary α-haloenamines affords high yields of protected glycosyl halides, which are valuable intermediates for the introduction of sugar groups in the synthesis of oligosaccharides, glycolipids or glycopeptides.
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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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- Tetra-O-acetyl-β-D-glucopyranosyl Chloride: Occurrence of gg and gt Rotamers in the Crystal and Correlation between Conformation at C-6 and Anomeric Stabilization
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An X-ray structural analysis of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl chloride (5β) shows the crystal lattice to contain consecutive layers of two forms, each in the 4C1 conformation, but differing in the orientation of the 6-acetoxy group relative to the pyranoid ring: the gauche-gauche (gg) rotamer, exhibiting standard bond lengths and torsional angles, and the gauche-trans (gt) form, in which an unusually long C-5-O-5 bond distance of 1.536 Angstroem is observed, though without major distortion of the chair conformation.In solution, only the gg form prevails.The similarity of conformational features of 5β in its gg form and of its β-methoxy analog 7β is so close that the anomeric effects for equatorial Cl and OCH3 on a pyranoid ring must be glossy identical. - Force-field calculations on the anomeric 1-chloro- and 1-methoxy derivatives of tetraacetyl-D-glucopyranose allow a realistic estimation of the magnitude of the anomeric effect and a surprisingly accurate assessment of the degree of anomeric stabilization in the individual C-6 rotameric forms, the gg conformer invariably being the energetically most favored.
- Lichtenthaler, Frieder W.,Roenninger, Stephan,Kreis, Uwe
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p. 1001 - 1006
(2007/10/02)
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- PREPARATION OF GLYCOSYL HALIDES UNDER NEUTRAL CONDITIONS
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The anomeric hydroxyl group of various furanose and pyranose hemiacetals can be replaced by a fluorine, chlorine, bromine or iodine atom under neutral conditions using haloenamines.
- Ernst, Beat.,Winkler, Tammo.
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p. 3081 - 3084
(2007/10/02)
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- SYNTHESES OF "ANOMERIC" GEM DIHALOGENATED GLUCOPYRANOSYL DERIVATIVES
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free-radical bromination of peracetylated β-D-glucopyranosyl chloride constitutes an efficient route to new C-1 gem dihalogenated sugars.
- Praly, J. P.,Descotes, G.
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p. 1405 - 1408
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF 1,2-TRANS-1-THIOGLYCOSES USING ALUMINIUM CHLORIDE: EVIDENCE FOR 1,2-CIS-1-CHLOROGLYCOPYRANOSYLPERACETATES AS THE ACTUAL REACTION INTERMEDIATES
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Synthesis of 1,2-trans-1-thioglycosylacetates has been achieved in excellent yields from corresponding 1,2-trans-glycosylacetates using aluminium chloride via 1,2-cis-1-chloroglycopyranosylacetates with retention of configuration.
- Rajanikanth, B.,Seshadri, R.
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p. 2295 - 2296
(2007/10/02)
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- A GLYCOSYLATION REACTION: CONVERSION OF METHYL GLYCOSIDES TO GLYCOSYL CHLORIDES BY BORON TRICHLORIDE
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Methyl glycosides react readily with boron trichloride in dichloromethane solutions at -78 deg C to give the corresponding glycosyl chlorides for subsequent use in glycosylation reactions.This reaction is compatible with the presence of glycosyl linkages
- Perdomo, Guillermo R.,Krepinsky, Jiri J.
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p. 5595 - 5598
(2007/10/02)
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- DIRECT TRANSFORMATION OF METHYL GLYCOPYRANOSIDES INTO CORRESPONDING GLYCOSYL HALIDES
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Is has been demonstrated that the reaction of methyl hexopyranosides with an excess of acyl halides, carried out in the presence of Lewis acids, leads to corresponding, thermodynamically favored glycosyl halides.
- Grynkiewicz, Grzegorz,Konopka, Miroslawa
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p. 149 - 153
(2007/10/02)
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- The Reaction of N-Dichloromethylene-N,N-dialkylammonium Chlorides with Free Sugars: an Efficient Synthesis of Glycosyl Chlorides
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The treatment of aldose derivatives that are protected at all but the anomeric hydroxy groups with N-dichloromethylene-N,N-dialkylammonium chlorides (alkyl = Me, Et) provides an improved method of preparing the corresponding glycosyl chlorides.Analogous derivatives containing an unprotected C1-C2 diol give 2-O-(N,N-dialkylcarbamoyl)glycosyl chlorides.
- Copeland, Christopher,McAdam, David P.,Stick, Robert V.
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p. 1239 - 1247
(2007/10/02)
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- Stereoselective Thioglycoside Syntheses. Part 4. A New Approach to 1,4-linked 1-Thio-disaccharides and a Synthesis of Thiomaltose
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Two approaches are devised for the preparation of thiomaltose (16).Condensation between the sodium salt of 1-thio-α-D-glucopyranose (3) and methyl 2,3,6-tri-O-benzoyl-4-O-trifluoromethylsulphonyl-α-D-galactopyranoside (5) in hexamethylphosphoramide, leads to the methyl α-thiomaltoside derivative (6).On the other hand, the displacement of the C-4 trifluoromethanesulphonate of 1,6-anhydro-D-galactopyranose diacetate (13) by the sodium salt (3) gave the 1,6-anhydro-thio-disaccharide (14).The precursor of (13), 2,3-di-O-acetyl-1,6-anhydro-β-D-galactopyranose (12) was obtained in near quantitative yield from the known 2-O-acetyl-1,6-anhydro-3,4-O-isopropylidene-β-D-galactopyranose (9) by successive hydrolysis of the acetal group, orthoester formation (11), and selective opening of this intermediate through controlled acidic hydrolysis.Acetolysis of the methyl thio-maltoside (8) or the corresponding 1,6-anhydro-thio-disaccharide (14) followed by de-O-acylation afforded 4-S-α-D-glucopyranosyl-4-thio-D-glucopyranose in excellent yields. 1,2,3,6-Tetra-O-acetyl-4-S-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl)-4-thio-β-D-glucopyranose (15), a useful precursor of thiomaltotriosyloligosaccharides, is also prepared from the acetolysis reaction.
- Blanc-Muesser, Michele,Defaye, Jacques,Driguez, Hugues
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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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