- Development of a Novel Method for Trimethylsilylation of Saccharides?
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The trimethylsilyl (TMS) group is widely used in carbo?hydrate synthesis, although this protecting group is unstable and its post-synthetic purification challenging. The successful trimethylsilyl?ation of carbohydrates mediated by recyclable and efficient
- Chen, Jyun-Siao,Ke, Yi-Fan,Lin, Heng-Yan,Lin, Wesley,Yen, Wei-Chung,Wu, Hsin-Ru,Luo, Shun-Yuan
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- Carbohydrate-Derived Metal-Chelator-Triggered Lipids for Liposomal Drug Delivery
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Liposomes are versatile three-dimensional, biomaterial-based frameworks that can spatially enclose a variety of organic and inorganic biomaterials for advanced targeted-delivery applications. Implementation of external-stimuli-controlled release of their cargo will significantly augment their wide application for liposomal drug delivery. This paper presents the synthesis of a carbohydrate-derived lipid, capable of changing its conformation depending on the presence of Zn2+: an active state in the presence of Zn2+ ions and back to an inactive state in the absence of Zn2+ or when exposed to Na2EDTA, a metal chelator with high affinity for Zn2+ ions. This is the first report of a lipid triggered by the presence of a metal chelator. Total internal reflection fluorescence microscopy and a single-liposome study showed that it indeed was possible for the lipid to be incorporated into the bilayer of stable liposomes that remained leakage-free for the fluorescent cargo of the liposomes. On addition of EDTA to the liposomes, their fluorescent cargo could be released as a result of the membrane-incorporated lipids undergoing a conformational change.
- Holmstr?m, Thomas,Galsgaard Malle, Mette,Wu, Shunliang,Jensen, Knud J?rgen,Hatzakis, Nikos S.,Pedersen, Christian Marcus
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- RETRACTED ARTICLE: Chemical synthesis and antigenic activity of a phosphatidylinositol mannoside epitope from: Mycobacterium tuberculosis
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Phosphatidylinositol mannosides (PIMs) have been investigated as lipidic antigens for a new subunit tuberculosis vaccine. A non-natural diacylated phosphatidylinositol mannoside (Ac2PIM2) was designed and synthesized by mimicking the natural PIM6 processi
- Zhao, Shi-Yuan,Li, Na,Luo, Wan-Yue,Zhang, Nan-Nan,Zhou, Rong-Ye,Li, Chen-Yu,Wang, Jin
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supporting information
p. 14067 - 14070
(2020/11/21)
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- Both d - And l -Glucose Polyphosphates Mimic d - myo-Inositol 1,4,5-Trisphosphate: New Synthetic Agonists and Partial Agonists at the Ins(1,4,5)P3Receptor
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Chiral sugar derivatives are potential cyclitol surrogates of the Ca2+-mobilizing intracellular messenger d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Six novel polyphosphorylated analogues derived from both d- and l-glucose were synthesized. Binding to Ins(1,4,5)P3 receptors [Ins(1,4,5)P3R] and the ability to release Ca2+ from intracellular stores via type 1 Ins(1,4,5)P3Rs were investigated. β-d-Glucopyranosyl 1,3,4-tris-phosphate, with similar phosphate regiochemistry and stereochemistry to Ins(1,4,5)P3, and α-d-glucopyranosyl 1,3,4-tris-phosphate are full agonists, being equipotent and 23-fold less potent than Ins(1,4,5)P3, respectively, in Ca2+-release assays and similar to Ins(1,4,5)P3 and 15-fold weaker in binding assays. They can be viewed as truncated analogues of adenophostin A and refine understanding of structure-activity relationships for this Ins(1,4,5)P3R agonist. l-Glucose-derived ligands, methyl α-l-glucopyranoside 2,3,6-trisphosphate and methyl α-l-glucopyranoside 2,4,6-trisphosphate, are also active, while their corresponding d-enantiomers, methyl α-d-glucopyranoside 2,3,6-trisphosphate and methyl α-d-glucopyranoside 2,4,6-trisphosphate, are inactive. Interestingly, both l-glucose-derived ligands are partial agonists: they are among the least efficacious agonists of Ins(1,4,5)P3R yet identified, providing new leads for antagonist development.
- Shipton, Megan L.,Riley, Andrew M.,Rossi, Ana M.,Brearley, Charles A.,Taylor, Colin W.,Potter, Barry V. L.
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p. 5442 - 5457
(2020/07/21)
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- Substrate specificity of tuliposide-converting enzyme, a unique non-ester-hydrolyzing carboxylesterase in tulip: Effects of the alcohol moiety of substrate on the enzyme activity
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6-Tuliposides A (PosA) and B (PosB) are glucose esters accumulated in tulip (Tulipa gesneriana) as major defensive secondary metabolites. Pos-converting enzymes (TgTCEs), which we discovered previously from tulip, catalyze the conversion reactions of PosA
- Kato, Yasuo,Futanaga, Takashi,Nomura, Taiji
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supporting information
p. 664 - 667
(2019/01/04)
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- Synthesis and binding affinity analysis of α1-2- and α1-6-O/S-linked dimannosides for the elucidation of sulfur in glycosidic bonds using quartz crystal microbalance sensors
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The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards α1-2- and α1-6-linked dimannosides with S- or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrene-mediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the α1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the α1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the α1-2-analog displayed very similar binding compared to the O-linked structure.
- Norberg, Oscar,Wu, Bin,Thota, Niranjan,Ge, Jian-Tao,Fauquet, Germain,Saur, Ann-Kathrin,Aastrup, Teodor,Dong, Hai,Yan, Mingdi,Ramstr?m, Olof
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supporting information
p. 35 - 42
(2017/10/25)
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- TREATING WATER STRESS IN PLANTS
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The present invention relates to methods and uses of photo-labile compounds which are trehalose-6-phosphate or trehalose-6-phosphonate or agriculturally acceptable salts thereof in the treatment of water stress in plants. The invention also concerns methods and the use of the compounds for resurrection of water stressed plants, and for improvement of yield of crop plants under water stressed conditions compared with untreated plants.
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- Orthogonal protection of saccharide polyols through solvent-free one-pot sequences based on regioselective silylations
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tert-Butyldimethylsilyl (TBDMS) and tert-butyldiphenylsilyl (TBDPS) are alcohol protecting groups widely employed in organic synthesis in view of their compatibility with a wide range of conditions. Their regioselective installation on polyols generally r
- Traboni, Serena,Bedini, Emiliano,Iadonisi, Alfonso
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p. 2748 - 2756
(2017/01/09)
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- Simple one-pot regioselective 6-O-phosphorylation of carbohydrates and trehalose desymmetrization
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Biologically essential carbohydrate 6-phosphates, especially trehalose 6-phosphate, can be synthesized easily in excellent overall yields in 2 steps involving minimum protecting group manipulations. We can cleave the diphenylphosphate group for further synthetic objectives.
- Abragam Joseph,Chang, Chun-Wei,Wang, Cheng-Chung
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supporting information
p. 11497 - 11499
(2013/12/04)
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- Gold-catalyzed amide synthesis from aldehydes and amines in aqueous medium
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An efficient gold-catalyzed amide synthesis from aldehydes and amines in aqueous medium under mild reaction conditions has been developed.
- Li, Gai-Li,Kung, Karen Ka-Yan,Wong, Man-Kin
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supporting information; scheme or table
p. 4112 - 4114
(2012/06/16)
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- Characterization of ulvan extracts to assess the effect of different steps in the extraction procedure
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An effective application development of the polysaccharide ulvan requires a comprehensive knowledge about the influence of the extraction process on composition of the extracts and in ulvan itself. In this context, the two main objectives of the present work are (1) the establishment of an efficient extraction process for ulvan and (2) development of an accurate characterization methodology to evaluate the extract composition and ulvan content. Three ulvan-rich extracts obtained by different schemes of extraction were studied. The methodology for the analysis was improved and a detailed analysis of extracted ulvan was provided. The polysaccharide is rich in ulvanobiuronic acid 3-sulfate type A [→4)-β-d-GlcAp-(1 → 4)-α-l-Rhap 3S-(1→], with minor amounts of ulvanobiuronic acid 3-sulfate type B [→4)-α-l-IdoAp-(1 → 4)-α-l-Rhap 3S-(1→]. The extract with the higher degree of purification is a high molecular weight polysaccharide (790 kDa) composed of rhamnose (22.4%), glucuronic acid (22.5%), xylose (3.7%), iduronic acid (3.1%) and glucose (1.0%). It is highly sulfated (32.2%) and contains 1.3% of proteins and 10.3% of inorganic material. Applying simple extraction scheme it was possible to obtain an extract from green algae with high content of ulvan without affecting the overall chemical structure of the polysaccharide.
- Costa, Carina,Alves, Anabela,Pinto, Paula R.,Sousa, Rui A.,Borges Da Silva, Eduardo A.,Reis, Rui L.,Rodrigues, Alírio E.
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experimental part
p. 537 - 546
(2012/06/15)
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- TMSOTf-catalyzed silylation: Streamlined regioselective one-pot protection and acetylation of carbohydrates
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A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated with subsequent reactions in one-pot fashion, has been developed. Its usefulness was demonstrated by applications to streamlined regioselective one-pot protection and nonenzymatic acetylation of unprotected sugars. Monosaccharide and trehalose building blocks with orthogonally well-differentiated hydroxy groups were efficiently prepared starting with free sugars in one-pot fashion without the need for prior per-O-silylation. Regioselectively protected and acetylated building blocks were prepared directly from unprotected sugars in a one-pot manner involving up to five TMSOTf-catalyzed reactions, including a new TMSOTf-catalyzed silylation of carbohydrates. Copyright
- Joseph, A. Abragam,Verma, Ved Prakash,Liu, Xin-Yi,Wu, Chia-Hui,Dhurandhare, Vijay M.,Wang, Cheng-Chung
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experimental part
p. 744 - 753
(2012/03/11)
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- Iron(iii) chloride-tandem catalysis for a one-pot regioselective protection of glycopyranosides
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Tandem catalysis by using iron(iii) chloride hexahydrate leads to carbohydrate building blocks displaying an orthogonal protecting group pattern as illustrated by the regioselective protection of trehalose and maltose disaccharides.
- Bourdreux, Yann,Lemetais, Aurelie,Urban, Dominique,Beau, Jean-Marie
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supporting information; experimental part
p. 2146 - 2148
(2011/04/21)
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- Gram-scale synthesis of the A'B'-subunit of angelmicin B
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A gram-scale enantiospecific synthesis of the A'B'-subunit of angelmicin B is reported. The synthesis involves a Lewis acid catalyzed contrasteric Diels-Alder reaction and a tandem silyl zincate 1, 6-addition/enolate oxidation sequence.
- Milgram, Benjamin C.,Liau, Brian B.,Shair, Matthew D.
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supporting information; experimental part
p. 6436 - 6439
(2012/02/02)
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- METHOD FOR PREPARING HEXOSE DERIVATIVES
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A method for preparing hexose derivatives comprises the steps of providing a silylated hexose, treating the silylated hexose with a first carbonyl compound in the presence of a catalyst to form an ketalized hexose, treating the ketalized hexose with a second carbonyl compound followed by treating with a first reductant to form an etherized hexose, and converting the etherized hexose into a target hexose derivative, which can be 2-alcohol hexose, 3-alcohol hexose, 4-alcohol hexose, or a 6-alcohol hexose. In particular, the present invention can prepare the hexose derivatives with highly regioselective scheme to protect individual hydroxyls of monosaccharide units and install an orthogonal protecting group pattern in a one-pot manner
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Page/Page column 2; Sheet 3/9
(2009/05/29)
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- Tandem catalysis for a one-pot regioselective protection of carbohydrates: The example of glucose
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(Chemical Equation Presented) Fine-tuning the conditions for a tandem reaction using a single catalyst in a single reaction vessel leads to carbohydrate building blocks displaying different patterns of protecting groups (see picture). This process greatly simplifies the access to oligomers, as illustrated by the rapid assembly of a trisaccharide.
- Francais, Antoine,Urban, Dominique,Beau, Jean-Marie
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p. 8662 - 8665
(2008/09/18)
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- Rapid carbohydrate protecting group manipulations assisted by microwave dielectric heating
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The protocols for oligosaccharide synthesis are often tedious due to extended synthetic routes and reaction times. We herein describe methods assisted by microwave dielectric heating, which enable very short reaction times and high yields for the introduction and removal of eleven of the most commonly used protecting groups in carbohydrate syntheses. Several examples are reported, where solid supported reagents in combination with microwave dielectric heating have been used. This results in both faster and easier synthesis and purification.
- Soederberg, Eva,Westman, Jacob,Oscarson, Stefan
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p. 397 - 410
(2007/10/03)
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- Long-range two-dimensional 1H-29Si heteronuclear shift correlation using gradients. Application to tetra-TMS-α-O-methyl-D-glucopyranose and tetra-TES-α-O-methyl-D-glucopyranose
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The gradient-enhanced 1H,29Si HMQC experiment was applied to tetra-TMS-α-O-methyl-D-glucopyranose and tetra-TES-α-O-methyl-D-glucopyranose as test samples. All the expected 2J(1H, 29si) and 3J (1H,29Si) cross peaks were observed, allowing the full 29Si NMR assignment. An analysis of the trend of 29Si chemical shifts depending on the position of the silylating group in the sugar ring and on the different hindrances of TMS and TES groups is also reported. Copyright
- Provera, Stefano,Davalli, Silvia,Raza, Giorgio H.,Contini, Stefania,Marchioro, Carla
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- Stereoselective synthesis of α-C-D-gluco- and D-galactopyranosyl glycosides from an isoprenoid synthon
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Addition of the allylsilane Me3SiCH2C:CH2CH2CO2Me to D-gluco and D- galactopyranosyl derivatives gives in good yields α-C-glycopyranosides which are easily converted into glycosylated β-keto esters, butenolide and dihydropyrone.
- Jegou, Anne,Pacheco, Carole,Veyrieres, Alain
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p. 14779 - 14790
(2007/10/03)
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- Stereoselective synthesis of α-C-glycopyranosyl isoprenoid compounds
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Addition of the allylsilane Me3SiCH2C:CH2CH2CO2Me (3) to D-gluco and D-galactopyranosyl derivatives gives in good yields 3-(α-C-glycopyranosylmethyl)-but-3-enoates which can undergo oxidation to β-ketoesters, electrophile-promoted cyclizations or double bond migration.
- Jégou, Anne,Pacheco, Carole,Veyrières, Alain
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- Large-scale synthesis of D-mannose 6-phosphate and other hexose 6-phosphates
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The syntheses of D-mannose 6-phosaphate (4), several D-mannopyranoside 6-phosphates, and methyl α-D-glucopyranoside 6-phosphate are described.Phophorylation of methyl 2,3,4-tri-O-(trimethylsilyl)-α-D-mannopyranoside (2) with phosphorus oxychloride followe
- Meldal, Morten,Christensen, Mette Knak,Bock, Klaus
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p. 115 - 128
(2007/10/02)
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- A convenient method for the cleavage of the D-mannosyl-L-gulose disaccharide from bleomycin-A2.
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In order to elucidate the biological role of the sugar residue of the antitumor drug bleomycin, this was deglycosylated by beta-elimination under mild alkaline conditions, and by solvolysis with hydrogen fluoride. The latter procedure proved to be better because it led to the complete deglycosylation without modification of the peptide, thus allowing further biological investigations of this component.
- Kenani,Lamblin,Henichart
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- An Efficient Synthesis of Anhydroalditols and Allyl C-Glycosides
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Efforts to expedite production of anhydroalditols have led to a new, efficient synthesis of these compounds from alkyl glycosides.Silylation of the glycoside followed by reductive cleavage in the presence of triethylsilane and trimethylsilyl trifluoromethanesulfonate were carried out in the same reaction flask.Subsequent aqueous workup gave excellent yields of anhydroalditol(s).In some cases ring contraction was observed, but the use of bulkier silyl protecting groups gave greater yields of the expected product.This method was also shown to be an efficient means to prepare allyl C-glycosides, without any independent protecting or activating step, by simply replacing triethylsilane with allyltrimethylsilane in the synthetic scheme.
- Bennek, John A.,Gray, Gary R.
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p. 892 - 897
(2007/10/02)
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- Chemical Studies on the Mistletoe. V. The Structure of Taxillusin, a New Flavonoid Glycoside Isolated from Taxillus kaempferi
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A new flavonoid glycoside, taxillusin was isolated from Taxillus kaempferi (DC.) Danser and (2R,3R)-taxifolin 3-β-D-glucopyranoside 6''-gallate was assigned to this substance from studies on the hydrolysis products and from analyses of the 1H-NMR and carbon-13 NMR spectra.
- Sakurai, Atsushi,Okumura, Yasuaki
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p. 542 - 544
(2007/10/02)
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