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On the side-chain conformation of N-acetylneuraminic acid and its epimers at C-7, C-8, and C-7,8.
The side-chain conformation of N-acetylneuraminic acid and analogs has been studied by n.m.r. spectroscopy. The results of the 1H-, 13C-n.m.r.-, and 1H-nuclear-Overhauser-enhancement measurements were used to distinguish between different local-minima conformations suggested by hard-sphere calculations. Attempts were made to correlate the major conformation determined for each compound with the behavior towards activation with N-acetylneuraminic acid-CMP-synthetase.
Christian,Schulz,Brandstetter,Zbiral
p. 1 - 11
(1987)
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Production of hydrogen, alkanes and polyols by aqueous phase processing of wood-derived pyrolysis oils
Pyrolysis oils are the cheapest liquid fuel derived from lignocellulosic biomass. However, pyrolysis oils are a very poor quality liquid fuel that cannot be used in conventional diesel and internal combustion engines. In this paper we show that hydrogen, alkanes (ranging from C1 to C6) and polyols (ethylene glycol, 1,2-propanediol, 1,4-butanediol) can be produced from the aqueous fraction of wood-derived pyrolysis oils (bio-oils). The pyrolysis oil was first phase separated into aqueous and non-aqueous fraction by addition of water. The aqueous phase of bio-oil contained sugars; anhydrosugars; acetic acid; hydroxyacetone; furfural and small amounts of guaiacols. The aqueous fraction was subjected to a low temperature hydrogenation with Ru/C catalyst at 125-175 °C and 68.9 bar. The hydrogenation step converts the various functionalities in the bio-oil (including aldehydes; acids; sugars) to corresponding alcohols. Undesired methane and light gases are also produced in this low-temperature hydrogenation step. Diols (ranging from C2 to C4) and sorbitol are obtained as major products in this step. After the low temperature hydrogenation step either hydrogen or alkanes can be produced by aqueous-phase reforming (APR) or aqueous-phase dehydration/hydrogenation (APD/H) respectively. APR was done with a 1 wt% Pt/Al2O3 catalyst at 265 °C and 55.1 bar. Hydrogen selectivities of up to 60% were observed. The hydrogen selectivity was a function of space velocity. A 4 wt% Pt/SiO2-Al 2O3 catalyst at 260 °C and 51.7 bar was used for alkane production by APD/H. The carbon conversion to gas phase products of 35% with alkane selectivity of 45% was obtained for a WHSV of 0.96 h-1 when hydrogen is produced in situ from bio-oil. Alkane selectivity can be improved by supplying hydrogen externally. Alkane selectivities as high as 97% can be obtained when HCl is added to the aqueous-phase of the bio-oil and hydrogen is supplied externally. Model compounds for further bio-oil conversion studies are suggested. The Royal Society of Chemistry 2009.
Vispute, Tushar P.,Huber, George W.
p. 1433 - 1445
(2009)
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Seven undescribed steroids from the leaves of Datura metel L.
Extraction of Datura metel L. leaves with ethanol as a solvent gave a group of steroids, including two unique 1,10-seco-withanolides (1, 4), an unusual nitrogen-containing withanolides (2), one undescribed saponin (3), two withanolides with a carbohydrate (5, 6), and one C21 steroid (7). These compounds' structures were identified based on HR-ESI-MS and 1H, 13C NMR data analyses, also compared with data from the document. Some compounds showed moderate inhibition on NO production in lipopolysaccharide-stimulated RAW 264.7 cells.
Liu, Yan,Tan, Jin-yan,Zou, Hai-dan,Qi, Zi-Tang,Naseem, Anam,Pan, Juan,Guan, Wei,Yang, Bing-you,Kuang, Hai-xue
(2021/07/14)

Selective and Scalable Synthesis of Sugar Alcohols by Homogeneous Asymmetric Hydrogenation of Unprotected Ketoses
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
supporting information
p. 721 - 725
(2020/10/19)

Direct conversion of cellulose into isosorbide over Ni doped NbOPO4catalysts in water
Isosorbide is a versatile chemical intermediate for the production of a variety of drugs, chemicals, and polymers, and its efficient production from natural cellulose is of great significance. In this study, bifunctional catalysts based on niobium phosphates were prepared by a facile hydrothermal method and used for the direct conversion of cellulose to isosorbide under aqueous conditions. NH3-TPD analysis showed that a high acid content existed on the catalyst surface, and pyridine infrared spectroscopic analysis confirmed the presence of both Lewis acid and Br?nsted acid sites, both of which played an important role in the process of carbohydrate conversion. XRD and H2-TPR characterization determined the composition and the hydrogenation centers of the catalyst. An isosorbide yield of 47% could be obtained at 200 °C for 24 h under 3 MPa H2 pressure. The Ni/NbOPO4 bifunctional catalyst retains most of its activity after five consecutive runs with slightly decreased isosorbide yield of 44%. In addition, a possible reaction mechanism was proposed that the synergistic effect of surface acid sites and hydrogenation sites was favorable to enhancing the cascade dehydration and hydrogenation reactions during the conversion of cellulose to isosorbide. This study provides as an efficient strategy for the development of novel multifunctional heterogeneous catalysts for the one-pot valorisation of cellulose. This journal is
Guo, Jiaxing,He, Minyao,Li, Cuiqing,Liu, ShanShan,Song, Yongji,Wang, Hong,Wang, Xincheng
supporting information
p. 10292 - 10299
(2020/07/14)

Boron oxide modified bifunctional Cu/Al2O3 catalysts for the selective hydrogenolysis of glucose to 1,2-propanediol
A series of B2O3 modified Cu/Al2O3 catalysts were prepared for the hydrogenolysis of glucose. The catalysts were fully characterized by BET, ICP, N2O adsorptive decomposition, XRD, SEM, TG, H2-TPR, CO-FTIR, XPS, and NH3-TPD. The strong interaction between B2O3 and CuO could promote the dispersion of copper and inhibit the reduction of CuO, creating a proper mol ratio of Cuδ+/Cu0 for the hydrogenolysis of glucose to oxygen-containing chemicals. Furthermore, the doping of B2O3 also introduced more acid sites onto the CuB/Al2O3 catalysts, which is favorable for the cleavage of hydroxyl through dehydration. Therefore, the selective hydrogenolysis of glucose to 1,2-propanediol was dependent on the contribution of Cuδ+, Cu0, and acid sites. The catalytic activity and 1,2-propanediol selectivity were improved significantly by doping B2O3 into Cu/Al2O3. Among the catalysts, 1CuB/Al2O3 showed the highest selectivity for 1,2-propanediol, with the value of 49.5% at 96.6% conversion of glucose.
Liu, Chengwei,Shang, Yaning,Wang, Shen,Liu, Xin,Wang, Xianzhou,Gui, Jianzhou,Zhang, Chenghua,Zhu, Yulei,Li, Yongwang
(2020/02/18)

Highly efficient catalytic conversion of cellulose into acetol over Ni-Sn supported on nanosilica and the mechanism study
Selective conversion of cellulose into high value-added C3 chemicals is a great challenge in biorefinery due to the complicated reaction process. In this work, 61.6% yield of acetol was obtained by one pot conversion of cellulose using Ni-Sn/SiO2 catalysts. A series of characterization methods including TEM, STEM-HAADF, EDS, AAS, XRD, XPS, H2-TPR, Py-FTIR, and CO2-TPD were carried out to explore the structure-activity relationship. The strong basicity of the catalysts was a key factor affecting the production of acetol. In addition, catalysts with the hydrothermally stable L-acid sites and no B-acid sites inhibited side reactions and ensured efficient conversion of cellulose into small molecules. Further studies showed that the formation of the Ni3Sn4 alloy significantly promoted the acetol production, and its weak hydrogenation activity inhibited further conversion of acetol. Noninteger valence tin species (Snδ+ and SnOx) were formed both in Ni3Sn4 and Sn/SiO2. These Sn species were the source of basic sites and the active sites for catalyzing cellulose to acetol. Under the synergistic catalysis of Sn/SiO2 and the Ni3Sn4 alloy, cellulose was efficiently converted into acetol. This work provides guidance for the selective conversion of cellulose into C3 products.
Liu, Xiaohao,Liu, Xiaodong,Xu, Guangyue,Zhang, Ying,Wang, Chenguang,Lu, Qiang,Ma, Longlong
p. 5647 - 5656
(2019/11/05)

Hydrothermally Stable Ruthenium–Zirconium–Tungsten Catalyst for Cellulose Hydrogenolysis to Polyols
In this work, we describe a catalytic material based on a zirconium–tungsten oxide with ruthenium for the hydrogenolysis of microcrystalline cellulose under hydrothermal conditions. With these catalysts, polyols can be produced with high yields. High and stable polyol yields were also achieved in recycling tests. A catalyst with 4.5 wt % ruthenium in total achieved a carbon efficiency of almost 100 %. The prepared Zr-W oxide is mesoporous and largely stable under hydrothermal conditions (493 K and 65 bar hydrogen). Decomposition into the components ZrO2 and WO3 could be observed at temperatures of 1050 K in air.
Lucas, Martin,Fabi?ovicová, Katarina,Claus, Peter
p. 612 - 618
(2017/12/28)

Role of the Strong Lewis Base Sites on Glucose Hydrogenolysis
This work reports the individual role of strong Lewis base sites on catalytic conversion of glucose hydrogenolysis to acetol/lactic acid, including glucose isomerisation to fructose and pyruvaldehyde rearrangement/hydrogenation to acetol/lactic acid. Las
Yazdani, Parviz,Wang, Bo,Gao, Feng,Kawi, Sibudjing,Borgna, Armando
p. 3845 - 3853
(2018/07/31)

METHOD FOR PRODUCING ISOPROPANOL BY CATALYTIC CONVERSION OF CELLULOSE
This invention provides a method for producing isopropanol from cellulose, which is characterized by: cellulose is catalytically converted to isopropanol under existence of a Cu-Cr catalyst. In the method, the Cu-Cr catalyst contains an active phase of CuCr2O4 or further contains an active phase selected from a group consisting of CuO and Cr2O3; the mass ratio of cellulose and water is 15 wt% or below; and the temperature of catalytic reaction is 200-270℃.
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(2017/07/13)

Influence of the Surface Chemistry of Multiwalled Carbon Nanotubes on the Selective Conversion of Cellulose into Sorbitol
Carbon nanotubes (CNT) were submitted to liquid-phase chemical treatments using HNO3 and subsequently to gas-phase thermal treatments to incorporate different sets of oxygenated groups on the surface. The modified CNT were used as supports for 0.4 wt % Ru in the direct conversion of ball-milled cellulose to sorbitol and high conversions were reached after 3 h at 205 °C. Ru supported on the original CNT, although less active, was the most selective catalyst for the one-pot process (70 % sorbitol selectivity after 2 h). Unlike the one-pot process, the support acidity greatly promoted the rate of cellulose hydrolysis (35 % increase after 2 h) and the glucose selectivity (12 % increase after 2 h). The rate of glucose hydrogenation was almost not affected by the support modification. However, the catalyst acidity improved the sorbitol selectivity from glucose. The support acidity was a central factor for the one-pot conversion of cellulose, as well as for the individual hydrolysis and hydrogenation steps, and the original CNT supported Ru catalyst was the most efficient and selective catalyst for the direct conversion of cellulose to sorbitol.
Ribeiro, Lucília S.,Delgado, Juan J.,de Melo órf?o, José J.,Ribeiro Pereira, M. Fernando
p. 888 - 896
(2017/03/13)

One-pot catalytic conversion of cellulose into polyols with Pt/CNTs catalysts
A series of Pt nanoparticles supported on carbon nanotubes (CNTs) were synthesized using the incipient-wetness impregnation method. These catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM) techniques. The characterization results indicate that the Pt nanoparticles were highly dispersed on the surface of the CNTs, and the mean size was less than 5 nm. These catalysts were utilized to convert cellulose to hexitol, ethylene glycerol (EG), and 1,2-propylene glycol (1,2-PG) under low H2 pressure. The total yields were as high as 71.4% for EG and 1,2-PG using 1 Pt/CNTs as the catalyst in the hydrolytic hydrogenation of cellulose under mild reaction conditions.
Yang, Li,Yan, Xiaopei,Wang, Qiwu,Wang, Qiong,Xia, Haian
supporting information
p. 87 - 92
(2015/03/05)

Unravelling the Ru-Catalyzed Hydrogenolysis of Biomass-Based Polyols under Neutral and Acidic Conditions
The aqueous Ru/C-catalyzed hydrogenolysis of biomass-based polyols such as erythritol, xylitol, sorbitol, and cellobitol is studied under neutral and acidic conditions. For the first time, the complete product spectrum of C2-C6 polyols is identified and, based on a thorough analysis of the reaction mixtures, a comprehensive reaction mechanism is proposed, which consists of (de)hydrogenation, epimerization, decarbonylation, and deoxygenation reactions. The data reveal that the Ru-catalyzed deoxygenation reaction is highly selective for the cleavage of terminal hydroxyl groups. Changing from neutral to acidic conditions suppresses decarbonylation, consequently increasing the selectivity towards deoxygenation.
Hausoul, Peter J. C.,Negahdar, Leila,Schute, Kai,Palkovits, Regina
p. 3323 - 3330
(2015/10/19)

Aqueous phase hydrogenolysis of glucose to 1,2-propanediol over copper catalysts supported by sulfated spherical carbon
Aqueous phase hydrogenolysis of glucose was carried out over copper catalysts supported by sulfated spherical carbon for selective production of 1,2-propanediol. The sulfated carbon shows higher acidity by sulfation of its resin precursor than unsulfated or commercial ones. By changing copper loading, the hydrogenolysis capability and the acidity of catalysts were modified to suitable extents, which can optimize the selectivity to 1,2-propanediol. At a moderate copper loading, 5.0Cu/s-AC catalyst has the highest yield of 1,2-propanediol. This catalyst has a lifetime of over 300 h. However, its stability is required to be further improved.
Liang, Dong,Liu, Chengwei,Deng, Shuping,Zhu, Yulei,Lv, Chunxiang
p. 108 - 113
(2014/07/08)

Promoting effect of SnOx on selective conversion of cellulose to polyols over bimetallic Pt-SnOx/Al2O3 catalysts
Cellulose is the most abundant source of biomass in nature, and its selective conversion into polyols provides a viable route towards the sustainable synthesis of fuels and chemicals. Here, we report the marked change in the distribution of polyols in the cellulose reaction with the Sn/Pt atomic ratios in a wide range of 0.1-3.8 on the SnOx-modified Pt/Al 2O3 catalysts. Such a change was found to be closely related to the effects of the Sn/Pt ratios on the activity for the hydrogenation of glucose and other C6 sugar intermediates involved in the cellulose reaction as well as to the notable activity of the segregated SnO x species for the selective degradation of the sugar intermediates on the Pt-SnOx/Al2O3 catalysts. At lower Sn/Pt ratios of 0.1-1.0, there existed electron transfer from the SnOx species to the Pt sites and strong interaction between the catalysts, as characterized by temperature-programmed reduction in H2 and infrared spectroscopy for CO adsorption, which led to their superior hydrogenation activity (per exposed Pt atom), and in-parallel higher selectivity to hexitols (e.g. sorbitol) in the cellulose reaction, as compared to Pt/Al 2O3. The hexitol selectivity reached the greatest value of 82.7% at the Sn/Pt ratio of 0.5, nearly two times that of Pt/Al 2O3 at similar cellulose conversions (～20%). As the Sn/Pt ratios exceeded 1.5, the Pt-SnOx/Al2O3 catalysts exhibited inferior hydrogenation activity (per exposed Pt atom), due to the formation of the crystalline Pt-Sn alloy, which led to the preferential conversion of cellulose to C2 and especially C3 products (e.g. acetol) over hexitols, most likely involving the isomerization of glucose to fructose and retro-aldol condensation of these sugars on the segregated SnOx species, apparently in the form of Sn(OH)2. These findings clearly demonstrate the feasibility for rational control of the cellulose conversion into the target polyols (e.g. acetol or propylene glycol), for example, by the design of efficient catalysts based on the catalytic functions of the SnOx species with tunable hydrogenation activity.
Deng, Tianyin,Liu, Haichao
p. 116 - 124
(2013/02/26)

Copper-based catalysts for efficient valorization of cellulose
Noble causes: Cellulose is effectively converted into methanol, propylene, and ethylene glycol over Cu-based catalysts. Overall yields of above 93 %, together with 63 % yield of C1-C3 compounds, can be reached over simple noble-metal
Tajvidi, Kameh,Pupovac, Kristina,Kuekrek, Murhat,Palkovits, Regina
p. 2139 - 2142
(2013/01/15)

Selective conversion of microcrystalline cellulose into hexitols on nickel particles encapsulated within ZSM-5 zeolite
A highly active and selective Ni/ZSM-5 catalyst was prepared by a simple method. A selectivity of 91.2% to hexitols was obtained at intermediate conversion in the hydrolytic hydrogenation of cellulose.
Liang, Guanfeng,Cheng, Haiyang,Li, Wei,He, Limin,Yu, Yancun,Zhao, Fengyu
supporting information; experimental part
p. 2146 - 2149
(2012/09/10)

Heteropoly acids as efficient acid catalysts in the one-step conversion of cellulose to sugar alcohols
Cellulose and even spruce can be converted efficiently into valuable platform chemicals via combined hydrolysis and hydrogenation in the aqueous phase. Thereby, heteropoly acids together with supported ruthenium catalysts show not only high activity but also remarkable selectivity to sugar alcohols reaching up to 81% yield of C4 to C6 sugar alcohols in only 7 h at 160 °C.
Palkovits, Regina,Tajvidi, Kameh,Ruppert, Agnieszka M.,Procelewska, Joanna
supporting information; experimental part
p. 576 - 578
(2011/03/17)

METHOD FOR PRODUCING ETHYLENE GLYCOL FROM POLYHYDROXY COMPOUND
A method for producing ethylene glycol, including (a) adding a polyhydroxy compound and water to a sealed high-pressure reactor, (b) removing air and introducing hydrogen, and (c) allowing the polyhydroxy compound to react in the presence of a catalyst while stiffing. The catalyst includes a first active ingredient and a second active ingredient. The first active ingredient includes a transition metal of Group 8, 9, or 10 selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum, and/or a mixture thereof. The second active ingredient includes a metallic state of molybdenum and/or tungsten, or a carbide, nitride, or phosphide thereof. The method is carried out at a hydrogen pressure of 1-12 MPa, at a temperature of 120-300° C. for not less than 5 min in a one-step catalytic reaction. The efficiency, selectivity, and the yield of ethylene glycol are high. The preparation process is simple and the materials used are renewable.
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(2011/04/14)

Iridoid glycosides from the leaves of Sambucus ebulus
Six new iridoid glycosides (1-6) of the "Valeriana type" were isolated from leaves of Sambucus ebulus. The structures were elucidated by 1D- and 2D-NMR spectroscopy, mass spectrometry, and chemical degradation methods as 10-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (1), 7-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (2), 10-O-acetylpatrinoside-aglycone-11-O-[α-L-rhamnopyranosyl-(1→2) -β-D-ribohexo-3-ulopyranoside] (3), patrinoside-aglycone-11-O-[4″-O- acetyl-α-L-rhamnopyranosyl-(1→2)-β-D-ribohexo-3-ulopyranoside] (4), 10-O-acetylpatrinoside-aglycone-11-O-[4″-O-acetyl-α-L- rhamnopyranosyl-(1→2)-β-D-glucopyranoside] (5), and patrinoside-aglycone-11-O-2′-deoxy-β-D-glucopyranoside (6). Compounds 1-4 represent the first examples of acylated iridoid diglycosides bearing the uncommon D-ribohexo-3-ulopyranosyl sugar moiety. Compound 6 is the first iridoid glycoside with a 2-deoxy-D-glucopyranosyl sugar moiety.
Pieri, Valerio,Schwaiger, Stefan,Ellmerer, Ernst P.,Stuppner, Hermann
experimental part
p. 1798 - 1803
(2010/03/26)

Osmium catalyzed dihydroxylation of 1,2-dioxines: A new entry for stereoselective sugar synthesis
A series of 3,6-substituted 3,6-dihydro-1,2-dioxines were dihydroxylated with osmium tetroxide to furnish 1,2-dioxane-4,5-diols (peroxy diols) in yields ranging from 33% to 98% and with de values not less than 90%. The peroxy diols were then reduced to generate a stereospecific tetraol core with R,R,S,S or "allitol" stereochemistry. The peroxy diols and their acetonide derivatives were also ring-opened with Co(II) salen complexes to give novel hydroxy ketones in 77-100% yield, including the natural sugar psicose. Importantly, preliminary work on the catalytic asymmetric ring-opening of meso-peroxy diols using the Co(II) Jacobsens's catalyst indicates that asymmetric sugar synthesis from 1,2-dioxines is possible.
Robinson, Tony V.,Taylor, Dennis K.,Tiekink, Edward R. T.
p. 7236 - 7244
(2007/10/03)

Amino acid catalyzed neogenesis of carbohydrates: A plausible ancient transformation
Hexose sugars play a fundamental role in vital biochemical processes and their biosynthesis is achieved through enzyme-catalyzed pathways. Herein we disclose the ability of amino acids to catalyze the asymmetric neogenesis of carbohydrates by sequential cross-aldol reactions. The amino acids mediate the asymmetric de novo synthesis of natural L- and D-hexoses and their analogues with excellent stereoselectivity in organic solvents. In some cases, the four new stereocenters are assembled with almost absolute stereocontrol. The unique feature of these results is that, when an amino acid is employed as the catalyst, a single reaction sequence can convert a protected glycol aldehyde into a hexose in one step. For example, proline and its derivatives catalyze the asymmetric neogenesis of allose with > 99% ee in one chemical manipulation. Furthermore, all amino acids tested catalyzed the asymmetric formation of natural sugars under prebiotic conditions, with alanine being the smallest catalyst. The inherent simplicity of this catalytic process suggests that a catalytic prebiotic "gluconeogenesis" may occur, in which amino acids transfer their stereochemical information to sugars. In addition, the amino acid catalyzed stereoselective sequential cross-aldol reactions were performed as a two-step procedure with different aldehydes as acceptors and nucleophiles. The employment of two different amino acids as catalysts for the iterative direct aldol reactions enabled the asymmetric synthesis of deoxysugars with > 99% ee. In addition, the direct amino acid catalyzed C2+C 2+C2 methodology is a new entry for the short, highly enantioselective de novo synthesis of carbohydrate derivatives, isotope-labeled sugars, and polyketide natural products. The one-pot asymmetric de novo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic asymmetric transformation (DYKAT) mediated by an amino acid.
Cordova, Armando,Ibrahem, Ismail,Casas, Jesus,Sunden, Henrik,Engqvist, Magnus,Reyes, Efraim
p. 4772 - 4784
(2007/10/03)

METHOD FOR PRODUCING SUGAR ALCOHOL
A process for producing sugar alcohols having six carbon atoms, which comprises hydrogenating ketohexose, such as psicose, tagatose, sorbose and the like, in the presence of a catalyst containing a metal selected from the elements belonging to the eighth family in the periodic table, such as nickel, ruthenium, platinum, palladium and the like, is provided. According to this process, sugar alcohols having six carbon atoms can be produced efficiently at a large amount, the separation and recovering of the catalyst after completing the reaction are facilitated, and sugar alcohols having a desired production ratio can be produced efficiently.
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(2008/06/13)

METHOD OF DESALTING SUGAR SOLUTION AND ANION EXCHANGER
The present invention provides the means for suppressing the production of decomposition reactant, isomerization reactant, colored material, and so on when a saccharide solution is desalted, thereby suppressing the production of impurities and preventing coloration of an ion exchange resin and decrease in the desalting capacity of the ion exchange resin. The desalting of a saccharide solution is performed by using an anion exchange resin supporting a carbonate ion and/or a hydrogencarbonate ion.
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(2008/06/13)

Aldol Addition of Lithium and Boron Enolates of 1,3-Dioxan-5-ones to Aldehydes. A New Entry into Monosaccharide Derivatives
Methods allowing control of stereoselectivity in aldol reactions of enolates derived from 1,3-dioxan-5-ones (4) are described. Boron enolates, generated in situ, react with benzaldehyde to give the corresponding anti aldol selectively (the anti:syn ratio of up to 96:4) in high yield. Lithium enolates give high anti selectivity only with aldehydes branched at the α-position. Enantioselective deprotonation of CS symmetrical dioxanones (e.g., 4b) can be accomplished efficiently, with enantiomeric excess of up to 90%, with chiral lithium amide bases of general structure PhCH-(Me)N(Li)R (9, 10) if the R group is sufficiently bulky (e.g, R = adamantyl) or is fluorinated (e.g., R = CH2CF3). Dioxanone boron and lithium enolates react readily with glyceraldehyde derivatives (19), yielding protected ketohexoses (20 and 21).
Majewski, Marek,Nowak, Pawel
p. 5152 - 5160
(2007/10/03)

Total synthesis of the L-hexoses
Enantiomerically pure polyhydroxylated natural products are synthesized by using a reiterative two-carbon extension cycle consisting of four key transformations. The generality and efficiency of this methodology are demonstrated in the total synthesis of all eight L-hexoses.
Ko, Soo Y.,Lee, Albert W. M.,Masamune, Satoru,Reed III, Lawrence A.,Sharpless, K. Barry,Walker, Frederick J.
p. 245 - 264
(2007/10/02)

Interglucosyl Attack of Hydroxyl Group to Epoxy Ring of 2A,3A-Anhydro-(2AS)-α-cyclodextrin. Selective Preparation of 3A,2B-Anhydro-α-cyclodextrin
2A,3A-Anhydro-(2AS)-α-cyclodextrin was isomerized exclusively to 3A,2B-anhydro-α-cyclodextrin by the reaction with aqueous alkali.This implies the selective and interglucosyl attack of 3F-OH to the epoxy ring.
Fujita, Kahee,Tahara, Tsutomu,Sasaki, Hideaki,Egashira, Yoshimitsu,Shingu, Tetsuro,et al.
p. 917 - 920
(2007/10/02)

Analysis of Aldoses and Alditols by Capillary Gas Chromatography as Alditol Trifluoroacetates
Analysis of aldoses and alditols by capillary gas chromatography as alditol trifluoroacetates was carried out by using a fused silica capillary column (cyanopropyl-bonded phase) and a hydrogen flame ionization detector.Seventeen alditols were completely resolved within 18 min.The detection limits were about 1-4 ng/injection which are one hundred times smaller than as those of a packed column.Special care was necessary in the use of internal standards for the simultaneous determination of multiple components, and good reproducibility was obtained by using double internal standards.Keywords- aldose; alditol; alditol trifluoroacetate; capillary gas chromatography
Haga, Hidehiko,Nakajima, Terumi
p. 1562 - 1564
(2007/10/02)