cas 13100-46-4, 2,3,4,6-TETRA-O-ACETYL-BETA-D-GLUCOPYRANOSE

Articles about 13100-46-4Total 34 be found

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Honda et al.
p. 488,489-491
(1973)
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Detritylation of Ethers Using Iodine-Alcohol Reagents: An Acid-Catalyzed Reaction
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Wahlstrom, Jan L.,Ronald, Robert C.
p. 6021 - 6022
(1998)
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Heran et al.
p. 268,271
(1977)
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Selective deprotection of trityl group on carbohydrate by microflow reaction inhibiting migration of acetyl group
The trityl group is an important and useful protecting group for primary hydroxy groups on carbohydrates. However, during deprotection, neighboring acetyl groups can easily migrate to the deprotected hydroxy groups. Hence, deprotection of trityl groups was optimized using a microreactor with regard to flow rate, reagent concentration, reaction time, and substrate concentration. The optimized microflow reaction conditions inhibited migration and could be applied to large-scale reactions and other substrates.
Miyagawa, Atsushi,Tomita, Ryusuke,Kurimoto, Kenta,Yamamura, Hatsuo
p. 556 - 562
(2016)
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Lehrfeld
p. 2544
(1967)
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El-Rahman,Hornemann
p. 355,356-358
(1974)
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Discriminating non-ylidic carbon-sulfur bond cleavages of sulfonium ylides for alkylation and arylation reactions
A sulfonium ylide participated alkylation and arylation under transition-metal free conditions is described. The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of wide variety of substrates including carbohydrates.
Fang, Jing,Li, Ting,Ma, Xiang,Sun, Jiuchang,Cai, Lei,Chen, Qi,Liao, Zhiwen,Meng, Lingkui,Zeng, Jing,Wan, Qian
supporting information
p. 288 - 292
(2021/07/25)

Diastereoselective Synthesis of Thioglycosides via Pd-Catalyzed Allylic Rearrangement
Stereoselective glycosylation is challenging in carbohydrate chemistry. Herein, stereoselective thioglycosylation of glycals via palladium-catalyzed allylic rearrangement yields various substituents on α-isomer thioglycosides. Two comprehensive series of aryl and benzyl thioglycosides were obtained via a combination of thiosulfates with glycals derived from glucose, arabinose, galactose, and rhamnose. Furthermore, diosgenyl α-l-rhamnoside and isoquercitrin achieved selectivity via stereospecific [2,3]-sigma rearrangements of α-sulfoxide-rhamnoside and α-sulfoxide-glucoside, respectively.
Jiang, Xuefeng,Li, Jiagen,Wang, Ming
supporting information
p. 9053 - 9057
(2021/11/30)

NOVEL BENZIMIDAZOLE DERIVATIVES, PREPARATION METHOD THEREOF AND USE THEREOF AS ANTI-CANCER AGENT COMPRISING THE SAME
According to the present invention, there are provided a benzimidazole carbamate-sugar compound conjugate compound represented by the following Chemical Formula 1, a preparation method thereof, and a use thereof as an anti-cancer agent: Wherein, R1, R2, R3 and X are as defined in the specification and claims.
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(2021/10/02)

Regio- A nd chemoselective deprotection of primary acetates by zirconium hydrides
A combination of DIBAL-H and Cp2ZrCl2 is shown to promote the regioselective cleavage of primary acetates on a broad scope of substrates, ranging from carbohydrates to terpene derivatives, with a high tolerance toward protecting groups and numerous functionalities found in natural products and bioactive compounds. Apart from providing highly valuable building blocks in only two steps from biosourced raw materials, this selective de-O-acetylation should also be strongly helpful to solve selectivity issues in organic synthesis.
Gavel, Marine,Courant, Thibaut,Joosten, Antoine Yvan Philippe,Lecourt, Thomas
supporting information
p. 1948 - 1952
(2019/04/10)

Synthetic method of gentiobiose
The invention provides a synthetic method of gentiobiose. The synthetic method of the gentiobiose comprises the following steps: taking D-glucose as a starting material; respectively synthesizing into beta-1,2,3,4-tetra-acetylated glucose and glucose-B-glucosinolate; and carrying out coupled reaction and then carrying out deprotection to generate the gentiobiose. The controllability of the technological process is high, isomerization of the product is avoided, the yield of single-step reaction is high, and the gentiobiose is suitable for being produced on a large scale. The separating efficiency of a final product is improved. By the chemical method, large-scale production of the gentiobiose is implemented, a biological-method complicated purification process is overcome, the production period is shortened, the cost is reduced, and the purity of the product is improved.
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Paragraph 0019

(2017/10/31)

Total synthesis of agalloside, isolated from: Aquilaria agallocha, by the 5-O-glycosylation of flavan
Agalloside (1) is a neural stem cell differentiation activator isolated from Aquilaria agallocha by our group using Hes1 immobilized beads. We conducted the first total synthesis of agalloside (1) via the 5-O-glycosylation of flavan 25 using glycosyl fluoride 20 in the presence of BF3·Et2O. Subsequent oxidation with DDQ to flavanone 2 and deprotection successively provided agalloside (1). This synthetic strategy holds promise for use in the synthesis of 5-O-glycosylated flavonoids. The synthesized agalloside (1) accelerated neural stem cell differentiation, which is a result comparable to that for the naturally occurring compound 1.
Arai, Midori A.,Yamaguchi, Yumi,Ishibashi, Masami
p. 5025 - 5032
(2017/07/10)

Biocatalytic Process Optimization for the Production of High-Added-Value 6-O-Hydroxy and 3-O-Hydroxy Glycosyl Building Blocks
A biocatalytic process to synthesize regioselective monohydroxy glycosyl building blocks has been optimized. Lipases immobilized on commercial supports were treated with water-soluble carbodiimide (EDC) at different concentrations. In the presence of cosolvents, the stability of lipases adsorbed on octyl-Sepharose improved after the EDC modification. The new Candida rugosa lipase (CRL) modified heterogeneous biocatalysts were tested in the production of 6-OH hydroxyl-tetraacetyl glucose by a regioselective mono-deacetylation in aqueous media. Improvements in activity and excellent regioselectivity were obtained for octyl-CRL-EDC10mM preparation, with 95 % isolated yield of product on a multimilligram scale. We also observed excellent recyclability. The C-6 alcohol was transformed to a C-3 alcohol by chemical migration, and both compounds were transformed successfully in the corresponding new trichloroacetimidyl glucoderivatives. Modified CRL biocatalysts were also tested in the selective deprotection of peracetylated thymidine, and octyl-CRL-EDC10mM showed excellent specificity and improved regioselectivity to produce 3-hydroxy-5-acetyl-thymidine, a precursor of azidethymidine (AZT), in 95 % yield. The new Rhizomucor miehei lipase (RML)-modified heterogeneous biocatalysts showed excellent regioselectivity and recyclability in the 3-OH mono-deprotection of peracetylated lactal.
Callaghan, Ciara,Redmond, Martin,Alnoch, Robson Carlos,Mateo, Cesar,Filice, Marco,Palomo, Jose M.
p. 2536 - 2543
(2017/07/13)

SUGAR CONTAINING, AMPHIPHILIC COPOLYMERS
Disclosed herein are polymers made from at least one monomer of formulae (I), (II), (III), and (IV), in combination with a monomer of formula (V) that may be used in pharmaceutical formulations. These polymers comprise a hydrocarbon backbone and are made from monomers that contain at least one carbon-carbon double bond. Methods of making these polymers are also disclosed.
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Page/Page column 0083

(2016/06/01)

Glycopolymer self-assemblies with gold(I) complexed to the core as a delivery system for auranofin
A new glycomonomer 1 containing a thioacetate group in the anomeric position and mimicking the thiosugar ligand of the gold-based drug auranofin was designed and synthesized in four steps from d-glucose. Both CPADB-mediated homopolymerization and chain extension of a hydrophilic poly(OEGMEMA) macroRAFT agent were well-controlled with dispersities (D) below 1.2, highlighting the suitability of thioacetate as a thiol protecting group in RAFT polymerization. Using the homopolymer as a test system, the thioacetate protective groups were selectively removed using hydrazine acetate, and AuPEt3Cl was subsequently complexed to the exposed thiols to generate a polymeric auranofin analogue with 52% complexation efficiency. Extension of this successful procedure to three block copolymers with differing hydrophobic block lengths, poly(OEGMEMA)34-b-poly(1)47, poly(F-OEGMEMA)32-b-poly(1)27, and poly(F-OEGMEMA)32-b-poly(1)7 (where F in the last two indicates the incorporation of 2 wt % fluorescein methacrylate into the hydrophilic block), produced well-defined complexed block copolymers with complexation efficiencies comparable to that of the homopolymer. Self-assembly of the longest complexed polymer poly(OEGMEMA)34-b-poly(1-AuPEt3)47 generated spherical micelles with a hydrodynamic diameter Dh of 28 nm when prepared by slow water addition to a dilute DMF solution. The IC50 value against OVCAR-3 cells in a serum-free media was 44 μM on a gold concentration basis, compared to 0.3 μM for auranofin itself. The two shorter fluorescent complexed block copolymers formed spherical micelles with Dh 23 and 9 nm, respectively, and proved more cytotoxic than their longer counterpart, both displaying IC50 values of 13.5 μM. The addition of serum to the cell growth medium reduced the cytotoxicity of auranofin by a factor of 3.6 but had a less marked effect on the fluorescent micellar systems, reducing their toxicities by between 2.4 and 2.8 times. These micellar systems therefore show less susceptibility to deactivation by serum proteins (which is the primary limitation to auranofins in vivo effectiveness) than the free auranofin, suggesting some protective benefit offered by the hydrophilic shell. Fluorescence microscopy of the two fluorescent systems revealed an accumulation in the lysosomes of the OVCAR-3 cells. The cytotoxicity mechanism may therefore differ from that of auranofin, which is known to interact with mitochondrial proteins.
Pearson, Samuel,Lu, Hongxu,Stenzel, Martina H.
p. 1065 - 1076
(2015/09/08)

Synthesis of uniformly deuterated n-dodecyl-β -d-maltoside (d39 -DDM) for solubilization of membrane proteins in TROSY NMR experiments
This work reports the first synthesis of uniformly deuterated n-dodecyl-β -D-maltoside (d39-DDM). DDM is a mild non-ionic detergent often used in the extraction and purification of membrane proteins and for solubilizing them in experimental studies of their structure, dynamics and binding of ligands. We required d39-DDM for solubilizing large α-helical membrane proteins in samples for [15N-1H]TROSY (transverse relaxation-optimized spectroscopy) NMR experiments to achieve the highest sensitivity and best resolved spectra possible. Our synthesis of d39-DDM used d7-D-glucose and d25-n-dodecanol to introduce deuterium labelling into both the maltoside and dodecyl moieties, respectively. Two glucose molecules, one converted to a glycosyl acceptor with a free C4 hydroxyl group and one converted to a glycosyl donor substituted at C1 with a bromine in the α-configuration, were coupled together with an α(1 → 4) glycosidic bond to give maltose, which was then coupled with n-dodecanol by its substitution of a C1 bromine in the α-configuration to give DDM. 1H NMR spectra were used to confirm a high level of deuteration in the synthesized d39-DDM and to demonstrate its use in eliminating interfering signals from TROSY NMR spectra of a 52-kDa sugar transport protein solubilized in DDM.
Hiruma-Shimizu, Kazumi,Kalverda, Arnout P.,Henderson, Peter J. F.,Homans, Steve W.,Patching, Simon G.
p. 737 - 743
(2015/02/19)

Escherichia coli LacZ β-galactosidase inhibition by monohydroxy acetylated glycopyranosides: Role of the acetyl groups
Escherichia coli LacZ β-galactosidase is an extensively employed glycosidase for many different scientific purposes. Here, we describe how acetyl moieties protecting hydroxyl groups of the glycosides make these molecules better inhibitors to the enzyme activity. In particular, the presence of a unique hydroxyl group in the peracetylated glycosides still enhanced the inhibitory capacity of the molecule more. Molecular docking studies showed that the acetylation in the carbohydrate structure helps the substrate to accommodate into the active site. From a small biocatalytic synthesized library of different monohydroxy acetylated glycosides we can conclude that galactosidic structures are better for inhibition capacity. The best inhibitors were two monohydroxy lactal derivatives. The one with the OH free, in C-6 of the galactosidic part of the disaccharide, was a better inhibitor (Ki of 95 μM) than that with the OH free in C-3 in the glucosidic part of the molecule (Ki of 143 μM).
Brabcova, Jana,Carrasco-Lopez, Cesar,Bavaro, Teodora,Hermoso, Juan A.,Palomo, Jose M.
p. 31 - 38
(2014/06/24)

Design, synthesis, and biological evaluation of novel carbohydrate-based sulfamates as carbonic anhydrase inhibitors
Carbonic anhydrases (CAs) IX and XII are enzymes with newly validated potential for the development of personalized, first-in-class cancer chemotherapies. Here we present the design and synthesis of novel carbohydrate-based CA inhibitors, several of which were very efficient inhibitors (Ki10 nM) with good selectivity for cancer-associated CA isozymes over off-target CA isozymes. All inhibitors comprised a carbohydrate core with one hydroxyl group derivatized as a sulfamate. Five different carbohydrates were chosen to present a selection of molecular shapes with subtle stereochemical differences to the CA enzymes active site. Variable modifications of the remaining sugar hydroxyl groups were incorporated to provide an incremental coverage of chemical property parameters that are associated with biopharmaceutical performance. All sulfamate inhibitors displayed ligand efficiencies that are consistent with those reported for good drug lead candidates.
Lopez, Marie,Trajkovic, Jonathan,Bornaghi, Laurent F.,Innocenti, Alessio,Vullo, Daniela,Supuran, Claudiu T.,Poulsen, Sally-Ann
supporting information; experimental part
p. 1481 - 1489
(2011/05/12)

Kinetic analysis of β-phosphoglucomutase and its inhibition by magnesium fluoride
The isomerization of β-glucose-1 -phosphate (βG1 P) to β-glucose-6-phosphate (G6P) catalyzed by β-phosphoglucomutase (βPGM) has been examined using steady- and presteady-state kinetic analysis. In the presence of low concentrations of β-glucose-1,6- bisphosphate (βG16BP), the reaction proceeds through a Ping Pong Bi Bi mechanism with substrate inhibition (K cat = 65 s -1 , K βG1P = 15 μM, K βG1P = 0.7 μM, K i = 122 μM). If αG16BP is used as a cofactor, more complex kinetic behavior is observed, but the nonlinear progress curves canbe fit to reveal further catalytic parameters (k cat = 74 s-1 , K βG1P = 15 μM, K βG16BP = 0.8 μM, K i = 122 μM, K αG16BP = 91μM for productive binding, K αG16BP = 21 μM for unproductive binding). These data reveal that variations in the substrate structure affect transition-state affinity (approximately 140 000-fold in terms of rate acceleration) substantially more than ground-state binding (110-fold in terms of binding affinity). When fluoride and magnesium ions are present, time-dependent inhibition of the βPGM is observed. The concentration dependence of the parameters obtained from fitting these progress curves shows that a βG1 P-MgF 3- βPGM inhibitory complex is formed under the reaction conditions. The overall stability constant for this complex is approximately 2 × 10 -16 M 5 and suggests an affinity of the MgF 3 - moiety to this transition-state analogue (TSA) of ≤70 nM. The detailed kinetic analysis shows how a special type of TSA that does not exist in solution is assembled in the active site of an enzyme. Further experiments show that under the conditions of previous structural studies, phosphorylated glucose only persists when bound to the enzyme as the TSA. The preference for TSA formation when fluoride is present, and the hydrolysisof substrates when it is not, rules out the formation of a stable penta valent phosphorane intermediate in the active site of βPGM.
Golicnik, Marko,Olguin, Luis F.,Feng, Guoqiang,Baxter, Nicola J.,Waltho, Jonathan P.,et al.
experimental part
p. 1575 - 1588
(2009/07/30)

Degradable polymer and process for production thereof
In one embodiment of the present invention, a degradable polymer having a peroxide bond therein is disclosed. The degradable polymer can be utilized in the fields of medicals or medical materials, can be applied to a DDS or gene delivery system, and can be used as a novel polymeric material or environmentally-friendly material. A polyperoxide, which is an alternating copolymer, has in a side chain thereof, a functional group (which is a substituent comprising a therapeutic molecule), a water-soluble substituent, or a biodegradable substituent.
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Page/Page column 8

(2009/04/24)

METHODS, COMPOUNDS, COMPOSITIONS AND VEHICLES FOR DELIVERING 3-AMINO-1-PROPANESULFONIC ACID
The invention relates to methods, compounds, compositions and vehicles for delivering 3-amino-1-propanesulfonic acid (3APS) in a subject, preferably a human subject. The invention encompasses compounds that will yield or generate 3APS, either in vitro or in vivo. Preferred compounds include amino acid prodrugs of 3APS for use, including but not limited to, the prevention and treatment of Alzheimer's disease.
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Page/Page column 53-54

(2008/12/06)

Novel and efficient chemoenzymatic synthesis of D-glucose 6-phosphate and molecular modeling studies on the selective biocatalysis
A concise chemoenzymatic synthesis of glucose 6-phosphate is described. Candida rugosa lipase was found to be an efficient catalyst for both regio- and stereoselective deacetylation of the primary hydroxy group in the peracetylated D-glucose. In addition, we report an improved synthesis of 1,2,3,4,6-penta-O- acetyl-α-D-glucopyranose providing a large-scale procedure for the acetylation of α-D-glucose without isomerization at the anomeric center. The high overall yield and the easy scalability makes this chemoenzymatic strategy attractive for industrial application. Furthermore, molecular modeling of phosphonate transition-state analog for the enzymatic hydrolysis step supports the substrate selectivity observed with Candida rugosa lipase. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Rodriguez-Perez, Tatiana,Lavandera, Ivan,Fernandez, Susana,Sanghvi, Yogesh S.,Ferrero, Miguel,Gotor, Vicente
p. 2769 - 2778
(2008/03/13)

Regioselective hydrolysis of different peracetylated β-monosaccharides by immobilized lipases from different sources. Key role of the immobilization
The effect of the immobilization strategy on the activity, specificity and regioselectivity of three different lipases [those from Thermomyces lanuginose (TLL), Aspergillus niger (ANL) and Candida antarctica B (CAL-B)] in the hydrolysis of peracetylated β-monosaccharides has been evaluated. Three very different immobilization strategies were utilized, covalent attachment, anionic exchange and interfacial activation on a hydrophobic support. The octyl-TLL immobilized preparation was the most efficient biocatalyst in the hydrolysis of 1,2,3,4,6-pentaO-acetyl-β-D-galactopyranose, producing specifically 6-hydroxy-l,2,3,4-tetra-O-acetyl-β-D-galactopyranose in 95 % overall yield, whereas the CNBr-TLL preparation was 48 times slower and regioselective towards the anomeric position, producing the 1-hydroxy derivative in 70% yield. The PEI-TLL immobilized preparation was the most efficient catalyzing the hydrolysis of 1,2,3,4,6-penta-O-acetyl-β-D-glucopyranose, permitting us to obtain up to 70% of the 6-hydroxy product. In the hydrolysis of 2-acetamido2-deoxy-l,3,4,6-tetra-0-acetyl-β-D-glucopyranose, the octyl-CALB preparation was not selective at all for the production of monohydroxy products whereas when CAL-B was immobilized on PEI-agarose, the enzyme was highly specific and regioselective producing the 6-hydroxy-2- acetamido-2-deoxy-l,3,4-tri-O-acetyl-β-D-glucopyranose in 70 % yield.
Palomo, Jose M.,Filice, Marco,Fernandez-Lafuente, Roberto,Terreni, Marco,Guisan, Jose M.
p. 1969 - 1976
(2008/09/18)

1,2,3,4-Tetra-O-acetyl-β-D-gluco-pyranuronic acid monohydrate at 120 K and anhydrous 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose at 292 K
The structure of the title acid as the monohydrate, C14H 18O11·H2O, displays hydrogen bonding which connects the molecules in layers parallel to (101). In the anhydrous glucopyranose, C14H20O10, only chain connectivity is attained but, due to disorder of the OH group, only partially and in two modes, one less favoured than the other. This provides incomplete connectivity between molecules in corrugated layers parallel to (010).
Baddeley, Thomas C.,Howie, R. Alan,Skakle, Janet M.S.,Wardell, James L.
p. o711-o714
(2007/10/03)

Regio-selective deprotection of peracetylated sugars via lipase hydrolysis
Purified lipases (via interfacial activation on hydrophobic supports) from different microbial extracts have been evaluated in the regio-selective hydrolysis of peracetylated sugars (peracetylated glucose, ribose and sucrose). Among the enzymes tested, lipases from Candida rugosa (CRL) and from Pseudomonas fluorescens (PFL) exhibited the best properties in these reactions. Then, we have prepared two different immobilized lipase preparations obtained by interfacial activation on hydrophobic supports or by covalent attachment on glutaraldehyde agarose. Interfacially activated lipases exhibited a higher activity than covalently attached enzymes (even by a 100-fold factor), giving the higher yields of mono deacetylated sugars (in some instances by more than a threefold factor) in short reaction times. In the hydrolysis of 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose catalyzed by PFL adsorbed on octyl agarosa, hydrolyzed mainly the 3 position (30% of yield) while the CRL gave the hydrolysis only in position 5 (about 50% of yield). Depending on the enzyme immobilized preparation, we have been able also to obtain selective hydrolysis of 1,2,3,4,6-penta-O-acetyl-α/β-D-glucopyranose obtaining a free hydroxyl group in position 1, 4 or 6. Moreover, selective hydrolysis in the 4′ position of peracetylated sucrose was achieved when the hydrolysis is performed with CRL immobilized on octyl-agarose (yield was 77%).
Fernandez-Lorente, Gloria,Palomo, Jose M.,Cocca, Jany,Mateo, Cesar,Moro, Paola,Terreni, Marco,Fernandez-Lafuente, Roberto,Guisan, Jose M.
p. 5705 - 5711
(2007/10/03)

Regioselective enzymatic hydrolysis of acetylated pyranoses and pyranosides using immobilised lipases. An easy chemoenzymatic synthesis of α- and β-D-glucopyranose acetates bearing a free secondary C-4 hydroxyl group
Protected sugars with only one free hydroxyl group are useful building blocks for the synthesis of a large number of glycoderivatives. In order to avoid the problems of the classical chemical synthesis, we studied the regioselective enzymatic hydrolysis of different fully acetylated glycopyranoses and glycopyranosides. The main challenge was to obtain the hydrolysis of the substrates in only one position, with high regioselectivity, while avoiding any further hydrolysis towards partially acetylated sugars. Candida rugosa (CRL) and Pseudomonas fluorescens (PFL) lipases (EC 3.1.1.3) immobilised on octyl agarose afforded regioselective hydrolysis only in the 6- and 1-positions, respectively. Furthermore, a new one-pot chemoenzymatic approach has been developed in order to obtain α- and β-protected glucopyranoses bearing a free secondary C-4 hydroxyl group. For instance, 1,2,3,6-tetra-O-acetyl-α-D-glucopyranose was easily synthesised in good overall yield (70%) starting from 1,2,3,4,6-penta-O-acetyl-α-D-glucopyranose by regioselective enzymatic hydrolysis in the 6-position, catalysed by CRL, followed by a temperature- and pH-controlled acyl migration.
Terreni, Marco,Salvetti, Raul,Linati, Laura,Fernandez-Lafuente, Roberto,Fernandez-Lorente, Gloria,Bastida, Agatha,Guisan, Jose M.
p. 1615 - 1621
(2007/10/03)

Highly efficient deacetylation by use of the neutral organotin catalyst [tBu2SnOH(Cl)]2
Deprotection of acetyl esters is effected cleanly by the neutral organotin catalyst, [tBu2SnOH(Cl)]2. The mildness of the reaction gives rise to great synthetic versatility and in the process a variety of functional groups are tolerated. Differentiations between primary, secondary, and tertiary alcohols and between acetyl ester and other esters are feasible. No racemization occurs with chiral acetyl esters. Exclusive deprotection of primary acetyl esters in carbohydrates and nucleosides is observed. The crude product thus obtained can be used for further reactions without purification.
Orita, Akihiro,Hamada, Yuuki,Nakano, Takehiko,Toyoshima, Shinji,Otera, Junzo
p. 3321 - 3327
(2007/10/03)

Self-assembly of β-glucosidase and D-glucose-tethering zeolite crystals into fibrous aggregates
β-Glucosidase and D-glucose-tethering micrometer-sized zeolite crystals self-assemble into thin (2-20 μm) and very long (>1 cm) fibrous aggregates in water. The process proceeds at a faster rate in a buffer solution of pH 4.8 at which the enzymatic activity is highest. The zeolite and enzyme remain intact within the fibrous material. Furthermore, the enzymatic activity of β-glucosidase is preserved even after they are kept in water for more than 6 months at room temperature. With the zeolite to enzyme weight ratio of 5, all the zeolite crystals are buried within the round fibrils which consist of either a single strand or helical double strands. Upon increasing the ratio to 10, clusters of unburied zeolite crystals appear on the exterior of the fibrils, while narrow flat fibers with smooth surfaces are formed upon decreasing the ratio to 2.5. The process is proposed to initiate by the tight binding between the zeolite-bound D-glucose moieties and β-glucosidase followed by crystallization of the enzyme over the zeolite-bound enzyme monolayer. This report thus reveals a novel behavior of β-glucosidase and demonstrates an unprecedented phenomenon that an enzyme and its substrate-tethering inorganic crystals self-assemble into structured aggregates.
Lee,Lee,Choi,Park,Yoon
p. 12151 - 12157
(2007/10/03)

Esterase-catalysed regioselective 6-deacylation of hexopyranose per-acetates, acid-catalysed rearrangement to the 4-deprotected products and conversions of these into hexose 4- and 6-sulfates
The esterase from Rhodosporidium toruloides has been used to catalyse the hydrolysis of a series of per-acetylated α-D-hexopyranoses and α-D-hexopyranosides. Per-acetylated glucose 4, mannose 6, N-acetylgalactosamine 8, galactose 10, methyl α-D-glucoside 12, methyl α-D-mannoside 14 and methyl α-D-galactoside 16 have been selectively cleaved at the C-6 position by the esterase to give the 6-OH derivatives 5, 7, 9, 11, 13, 15 and 17. Acid-catalysed rearrangement of acetates 5, 7, 13, 15, 11, 17 and 9 with 4→6 acetyl migration gives the corresponding 4-deprotected derivatives 22-28, respectively. Hydrolyses of β-D-glucose pentaacetate 20 and α-D-lactose octaacetate 21 have been attempted, but no hydrolyses have been observed. 1,2,3,6-TetraacyIated α-D-hexopyranoses 3 and 22, derivatives of N-acetylglucosamine and glucose respectively, and 2,3,6-triacetylated α-D-hexopyranosides 24 and 25, derivatives of glucose and mannose, respectively, have been hydrolysed by the esterase to the corresponding 4,6-dihydroxy acetates 29, 18, 30 and 31. Acylation of methyl α-D-glucopyranoside 32 catalysed by the esterase provides the C-6 monoacetate 33 and the C-3 monoacetate 34 in 4 and 5% yield, respectively. The sodium salts of N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose and mannose 6-sulfates 38-42, respectively, are prepared in two steps from the 6-deacetylated hexopyranoses 2, 5, 9, 11 and 7, respectively. The sodium salts of N-acetylglucosamine, glucose and mannose 4-sulfates 43-45, respectively, are prepared in two steps from the 4-deacetylated precursors 3, 22 and 26 which are obtained via acid catalysed 4→6 acyl migration of compounds 2, 5 and 7.
Horrobin, Tina,Tran, Chuong Hao,Crout, David
p. 1069 - 1080
(2007/10/03)

Detritylation of mono- and di-saccharide derivatives using ferric chloride hydrate
Quantitative detritylation of mono- and di-saccharide derivatives of diverse structure was achieved with FeCl3 · 6H2O in CH2Cl2 at room temperature. Benzyl, isopropylidene, isopropylthio, allyl, acetyl, and benzoyl O-protecting groups were not effected under the designated conditions.
Ding, Xianglan,Wang, Wei,Kong, Fanzuo
p. 445 - 448
(2007/10/03)

Synthesis and Properties of Glucose and Galactose Phosphonate Derivatives
Phosphonate analogs of glucose-6-phosphate and galactose-6-phosphate, namely, 6-deoxy-6-phosphono-α,β-D-glucopyranose and 6-deoxy-6-phosphono-α,β-D-galactopyranose, were synthesized.They were shown to be weak inhibitors of 1L-myo-inositol-1-phosphatase. Key words: 6-deoxy-6-phosphono-α,β-D-glucopyranose, 6-deoxy-6-phosphono-α,β-D-galactopyranose, 1L-myoinositol-1-phosphatase, inhibitors
Padyukova, N. Sh.,Afsar, S.,Dixon, H. B. F.,Karpeiskii, M. Ya.
p. 328 - 331
(2007/10/02)

A new method of orthoesterification, under kinetic control, at non-anomeric positions. Application to the D-glucose and D-mannose series and selective hydrolysis of the corresponding orthoesters
The reaction of ketene acetals with D-glucose, D-mannose, and their methyl glycosides is described as a new route to unusual cyclic orthoesters (at non anomeric positions). The reaction proceeds by preferential attack of the reagent on the primary hydroxyl group. The synthesis of strained rings (2,3-diequatorial orthoester) is possible. The resulting methoxyethylidene derivatives are very sensitive to hydrolysis, and mild conditions lead to hydroxyacetates that are potentially useful intermediates for carbohydrates synthesis.
Bouchra,Calinaud,Gelas
p. 227 - 237
(2007/10/02)

FACILE SYNTHESIS OF SILYLATED THIOGLYCOSIDES
The one pot conversion of 1,2,4,6-tetra-O-acetyl-β-D-glucopyranose, 1, into phenyl 2,4,6-tri O-acetyl-3-O-trialkylsilyl-1-thio-β-D-glucopyranosides, 3, is described.The method is applicable to use with galactopyranosyl-, 2-deoxyglucopyranosyl-, and ribofuranosyl-starting materials.
Nambiar, Sudhir,Daeuble, John F.,Doyle, Ronald J.,Taylor, K. Grant
p. 2179 - 2182
(2007/10/02)

Enzymes in Carbohydrate Synthesis: Lipase-Catalyzed Selective Acylation and Deacylation of Furanose and Pyranose Derivatives
A number of furanose and pyranose derivatives were selectively acylated and deacylated on a preparative scale in lipase-catalyzed reactions.The primary hydroxyl functions of the methyl furanosides of D-ribose, D-arabinose, D-xylose, and 2-deoxy-D-ribose were selectively acetylated by crude porcine pancreatic lipase in tetrahydrofuran by using 2,2,2-trifluoroethyl acetate as the acyl donor.Selective deacetylations of the primary hydroxyl functions in the peracetylated methyl furanosides of D-ribose, D-arabinose, D-xylose, and 2-deoxy-D-ribose were best accomplished in a 9:1 solution of 0.1 N phosphate buffer (pH 7) and N,N-dimethylformamide using Candida cylindracea lipase.Selective cleavage of the 1-O-acetyl groups from 1,2,3,5-tetra-O-acetyl-D-ribose and -D-xylose were similarly accomplished with Aspergillus niger lipase.Similar regioselectivites were observed in the pyranose series.The Candida lipase was found to be the best for selective deacylation of the primary position from the peracylated methyl pyranosides, and porcine pancreatic lipase was the best for selective hydrolysis of the 1-O-acetyl groups from peracetylated pyranoses.
Hennen, William J.,Sweers, H. Marcel,Wang, Yi-Fong,Wong, Chi-Huey
p. 4939 - 4945
(2007/10/02)

Selective deacetylation of anomeric sugar acetates with tin alkoxides
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Nudelman, Abraham,Herzig, Jacob,Gottlieb, Hugo E.,Keinan, Ehud,Sterling, Jeffrey
p. 145 - 152
(2007/10/02)

Syntheses and 1H- and 13C-Nuclear Magnetic Resonance Spectra of All Positional Isomers of Tetra-O-acetyl-D-glucopyranoses, and Their Monobenzyl and Monotrityl Derivatives
All the isomers of the tetra-O-acetyl-D-glucopyranoses, and their monobenzyl and monotrityl derivatives were synthesized and systematic 1H- and 13C-nuclear magnetic resonance (1H- and 13C-NMR) studies were carried out.Complete assignments of the 1H- and 13C-NMR signals were achieved by 1H- and 13C-decoupling techniques and by the use of a shift reagent and changes of solvents.Moreover, when necessary, 1H- and 13C-shift-correlated 2D NMR spectroscopy at higher frequency (Bruker AM 400) was applied.The shifts on deacetylation, benzylation, and tritylation were estimated on the basis of the 1H- and 13C-chemical shifts of these compounds, and the effects of deacetylation and benzyl- or trityl-substitution are discussed.Keywords - tetra-O-acetyl-D-glucopyranose; monobenzyl tetra-O-acetyl-D-glucopyranose; monotrityl tetra-O-acetyl-D-glucopyranose; 1H-NMR; 13C-NMR; deacetylation shift; benzylation shift; tritylation shift
Utamura, Toshiko,Kuromatsu, Keiko,Suwa, Kiyoko,Koizumi, Kyoko,Shingu, Tetsuro
p. 2341 - 2353
(2007/10/02)

A New Method for Cleaving Carbohydrate Triphenylmethyl and Benzyl Ethers
Carbohydrate triphenylmethyl and benzyl ethers are converted into their trimethylsilyl ethers by iodotrimethylsilane.The silyl ethers are hydrolysed to give partially free sugars.From multiple benzylated glycosides it is possible to remove selectively the primary benzyl group, under more vigorous conditions total debenzylation occurs.
Klemer, Almuth,Bieber, Michael,Wilbers, Hubert
p. 1416 - 1421
(2007/10/02)

TiCl4-CATALYZED CONVERSION OF 1,2,3,4-TETRA-O-ACETYL-6-O-TRITYL-β-D-GLUCOPYRANOSE INTO TRIACETYLLEVOGLUCOSAN - THE MECHANISM OF THE REACTION
In chloroform solutions containing some alcohol, 1,2,3,4-tetra-O-acetyl-6-O-trityl-β-D-glucopyranose is transformed, on the effect of TiCl4, into triacetyllevoglucosan, which can be isolated in the pure state in 70 percent yield.The method has also been found suitable for the preparation of the tribenzoyl derivative.The conversion takes place in two steps, a rapid detritylation followed by a slower cyclization process.During detritylation, a compound of the alkoxytitanium trichloride type is formed.In the cyclization step this loses AcOTiCl3, which formes a coordination complex with triacetyllevoglucosan in an equilibrium reaction, or an ionic complex with trityl chloride.
Zara-Kaczian, E.,Deak, GY.,Holly, S.
p. 271 - 284
(2007/10/02)