- Selective and Scalable Synthesis of Sugar Alcohols by Homogeneous Asymmetric Hydrogenation of Unprotected Ketoses
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Sugar alcohols are of great importance for the food industry and are promising building blocks for bio-based polymers. Industrially, they are produced by heterogeneous hydrogenation of sugars with H2, usually with none to low stereoselectivities. Now, we present a homogeneous system based on commercially available components, which not only increases the overall yield, but also allows a wide range of unprotected ketoses to be diastereoselectively hydrogenated. Furthermore, the system is reliable on a multi-gram scale allowing sugar alcohols to be isolated in large quantities at high atom economy.
- Tindall, Daniel J.,Mader, Steffen,Kindler, Alois,Rominger, Frank,Hashmi, A. Stephen K.,Schaub, Thomas
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supporting information
p. 721 - 725
(2020/10/19)
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- A PROCESS FOR THE HYDROGENATION OF A SUGAR OR SUGAR MIXTURE
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A process for the hydrogenation of a ketose or a ketose-containing sugar mixture to produce a product mixture comprising at least two stereoisomeric sugar alcohols is disclosed. The process comprises the provision of a reaction mixture comprising said ketose or ketose-containing sugar mixture, the addition of a concentration of solid nickel-based catalyst to said reaction mixture, and conducting a hydrogenation reaction in said reaction mixture in the presence of hydrogen gas. With this process, it is possible to obtain a predefined ratio of cis-isomer to trans-isomer of the two stereoisomeric sugar alcohols. The ratio of cis-isomer to trans-isomer can be decreased by increasing the concentration of solid nickel-based catalyst, by decreasing the starting temperature of the heating step, and/or by decreasing the heating rate of the heating step.
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Page/Page column 10-13; 16-20
(2008/12/06)
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- PROCESSES FOR PRODUCING ISOMALTOSE AND ISOMALTITOL AND USE THEREOF
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The present invention aims to provide a novel process for producing isomaltose and isomaltitol, and uses thereof, and it solves the object by establishing a process for producing isomaltose comprising a step of contacting a saccharide, having the α-1,4 glucosidic linkage as the linkage of non-reducing end and a glucose polymerization degree of at least two, with an α-isomaltosyl-transferring enzyme and an α-isomaltosylglucosaccharide-forming enzyme derived from a specific microorganism; a process for producing isomaltitol using the isomaltose produced by the above process; saccharide compositions comprising the isomaltose and/or the isomaltitol produced by the above processes; and uses thereof.
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- Oligosaccharide synthesis by dextransucrase: New unconventional acceptors
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The acceptor reactions of dextransucrase offer the potential for a targeted synthesis of a wide range of di-, tri- and higher oligosaccharides by the transfer of a glucosyl group from sucrose to the acceptor. We here report on results which show that the synthetic potential of this enzyme is not restricted to 'normal' saccharides. Additionally functionalized saccharides, such as alditols, aldosuloses, sugar acids, alkyl saccharides, and glycals, and rather unconventional saccharides, such as fructose dianhydride, may also act as acceptors. Some of these acceptors even turned out to be relatively efficient: α-D-glucopyranosyl-(1→5)-D-arabinonic acid, α-D-glucopyranosyl-(1→4)-D-glucitol, α-D-glucopyranosyl-(1→6)-D-glucitol, α-D-glucopyranosyl-(1→6)-D-mannitol, α-D-fructofuranosyl-β-D-fructofuranosyl-(1,2′:2,3′)- dianhydride, 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol ('-glucal'), and may therefore be of interest for future applications of the dextransucrase acceptor reaction.
- Demuth, Kristin,J?rdening, Hans-Joachim,Buchholz, Klaus
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p. 1811 - 1820
(2007/10/03)
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- Process for the manufacture of isomaltitol
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The present invention relates to an improved process for the manufacture of Isomaltitol by hydrogenation of Isomaltulose. According to the process, a solution of Isomaltulose having a concentration in the range of between 20% to 50% by weight, is hydrogenated at a temperature in the range of between 80° C. to 130° C., using a catalyst selected from Ruthenium, Nickel and mixtures thereof on an inert support at a pressure below 50 atmospheres, the pH being maintained in the range of 3 to 8. The resulted product is substantially free from other polymers, Among the advantages of the process it should be mentioned the fact that it enables to achieve the desired ratio between the two isomers α-Glucopyranosyl-1,1-Mannitol (GPM) and α-Glucopyranosyl-1,6-D-Sorbitol (GPS).
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- Sequential removal of monosaccharides from the reducing end of oligosaccharides and uses thereof
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Methods are provided for the sequential removal of monosaccharides from the reducing end of oligosaccharides. The present invention also discloses the use of such methods for structural determinations of oligosaccharides and to enable new structures to be generated from pre-existing oligosaccharides. In addition, the methods of the present invention may be automated by the incorporation into systems.
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- Sequential Removal of Monosaccharides from the Reducing End of Oligosaccharides. 2. Fundamental Studies of a Reaction between Hydrazino Compounds and Sugars Having a Glycosyl Moiety on a Carbon Atom Adjacent to a Carbonyl Group
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Hydrazine and certain hydrazino derivatives react with sugars having a glycosidic substituent, where the glycosyl moiety is located on a carbon atom adjecent to an aldehyde or keto group of the aglycon, resulting in cleavage of the glycosidic linkage.The reaction proceeds whether the glycon is of the α or β configuration.The released glycosyl moiety, in the presence of excess hydrazino compound, reacts further to give a hydrazone derivative.Removal of the hydrazone group gives the reducing sugar derived from the glycon.
- Bendiak, Brad,Salayan, Mary E.,Pantoja, Mario
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p. 8245 - 8256
(2007/10/03)
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- SELECTIVE DEGRADATION OF THE GLYCOSYLURONIC ACID RESIDUES OF COMPLEX CARBOHYDRATES BY LITHIUM DISSOLVED IN ETHYLENEDIAMINE
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Lithium metal dissolved in ethylenediamine had been demonstrated to cleave a 3-linked glycosyluronic acid-containing polysaccharide .The present study with model compounds has established that, by lithium treatment, carbohydrates are cleaved at the sites of the glycosyluronic acid residues, regerdless of the point at which other glycosyl residues are attached to the glycosyluronic acid residue.Treatment of carbohydrates with lithium metal dissolved in ethylenediamine also results in cleavage of methyl glycosides, reduction of aldoses, and cleavage of methyl ethers and pyruvic acetals of glycosyl residues.Model compounds were used to demonstrate that oligosaccharides containing only neutral glycosyl residues are largely stable to the reaction conditions (except for the reduction of the glycose residue of each oligosaccharide).Thus, a general procedure for the selective cleavage of underivatized carbohydrates at the glycosyluronic acid residues is described.
- Lau, James M.,McNeil, Michael,Darvill, Alan G.,Albersheim, Peter
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p. 219 - 244
(2007/10/02)
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