- Few-Unit-Cell MFI Zeolite Synthesized using a Simple Di-quaternary Ammonium Structure-Directing Agent
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Synthesis of a pentasil-type zeolite with ultra-small few-unit-cell crystalline domains, which we call FDP (few-unit-cell crystalline domain pentasil), is reported. FDP is made using bis-1,5(tributyl ammonium) pentamethylene cations as structure directing agent (SDA). This di-quaternary ammonium SDA combines butyl ammonium, in place of the one commonly used for MFI synthesis, propyl ammonium, and a five-carbon nitrogen-connecting chain, in place of the six-carbon connecting chain SDAs that are known to fit well within the MFI pores. X-ray diffraction analysis and electron microscopy imaging of FDP indicate ca. 10 nm crystalline domains organized in hierarchical micro-/meso-porous aggregates exhibiting mesoscopic order with an aggregate particle size up to ca. 5 μm. Al and Sn can be incorporated into the FDP zeolite framework to produce active and selective methanol-to-hydrocarbon and glucose isomerization catalysts, respectively.
- Abeykoon, Milinda,Al-Thabaiti, Shaeel,Bell, Alexis T.,Boscoboinik, J. Anibal,Dai, Heng,Dauenhauer, Paul,Dorneles de Mello, Matheus,Duan, Xuekui,Ghosh, Supriya,Kamaluddin, Huda Sharbini,Khan, Zaheer,Kumar, Gaurav,Li, Xinyu,Lu, Peng,Luo, Tianyi,Mkhoyan, K. Andre,Narasimharao, Katabathini,Qi, Liang,Rimer, Jeffrey D.,Tsapatsis, Michael
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supporting information
p. 19214 - 19221
(2021/08/09)
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- Hydroxyapatite-Supported Polyoxometalates for the Highly Selective Aerobic Oxidation of 5-Hydroxymethylfurfural or Glucose to 2,5-Diformylfuran under Atmospheric Pressure
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(NH4)5H6PV8Mo4O40 supported on hydroxyapatite (HAP) (PMo4V8/HAP (n)) was prepared through the ion exchange of hydroxy groups. This ion exchange favored the oxidative conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) in a one-pot cascade reaction with 96.0 % conversion and 83.8 % yield under 10 mL/min of O2 flow. PMo4V8/HAP (31) was used to explore the production of DFF directly from glucose with the highest yield of 47.9 % so far under atmospheric oxygen, whereas the yield of DFF increased to 54.7 % in a one-pot and two-step reaction. These results indicated that the active sites in PMo4V8/HAP (31) retained their activities without any interference toward one another, which enabled the production of DFF in a more cost-saving way by only using oxygen and one catalyst in a one-step reaction. Meanwhile, the rigid structure of HAP and strong interaction in PMo4V8/HAP (31) allowed this catalyst to be reused for at least six times with high stability and duration.
- Guan, Hongyu,Li, Ying,Wang, Qiwen,Wang, Xiaohong,Yu, Hang
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p. 997 - 1005
(2021/08/06)
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- Method for preparing fructose (by machine translation)
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The method comprises the following steps: (1) reacting glucose with a catalyst in the presence of alcohol and carrying out reaction to obtain fructose-containing product; wherein the weight ratio of the glucose to the mixture of the titanium silicalite molecular sieve and the tin-silicon molecular sieve 50 - 600 is below 30 °C: (100 °C 0.1 - 6 1 1 - 10h) The method disclosed by the invention has high glucose conversion rate and fructose yield. (by machine translation)
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Paragraph 0070-0101
(2020/07/02)
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- Method for preparing lactic acid through catalytically converting carbohydrate
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The invention relates to a method for preparing lactic acid through catalytically converting carbohydrate, and in particular, relates to a process for preparing lactic acid by catalytically convertingcarbohydrate under hydrothermal conditions. The method disclosed by the invention is characterized by specifically comprising the following steps: 1) adding carbohydrate and a catalyst into a closedhigh-pressure reaction kettle, and then adding pure water for mixing; 2) introducing nitrogen into the high-pressure reaction kettle to discharge air, introducing nitrogen of 2 MPa, stirring and heating to 160-300 DEG C, and carrying out reaction for 10-120 minutes; 3) putting the high-pressure reaction kettle in an ice-water bath, and cooling to room temperature; and 4) filtering the solution through a microporous filtering membrane to obtain the target product. The method can realize high conversion rate of carbohydrate and high yield of lactic acid, and has the advantages of less catalyst consumption, good circularity, small corrosion to reaction equipment and the like.
- -
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Paragraph 0029-0040
(2020/11/01)
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- Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
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Bio-refinery is attracting significant interest to produce a wide range of renewable chemicals and fuels from biomass that are alternative to fossil fuel derived petrochemicals. Similar to petrochemical industries, bio-refinery also depends on solid zeolite catalysts. Acid-base catalysis plays pivotal role in producing a wide range of chemicals from biomass. Herein, the Mg framework substituted MTW zeolite is synthesized and explored in the valorisation of glucose and furfural. Bi-functional (acidic and basic) characteristics are confirmed using pyridine adsorbed FT?IR analysis and NH3 and CO2 temperature-programmed desorption techniques. Textural properties and morphological information are retrieved from N2-sorption, X-ray photoelectron spectroscopy, and electron microscopy. The activity of the catalyst is demonstrated in the selective isomerisation of glucose to fructose in ethanol. Glucose is converted to methyl lactate in high yield using the same catalyst. Further, the bi-functional activity of this catalyst is demonstrated in the production of fuel precursor by the reaction of furfural and isopropanol. Mg?MTW zeolite exhibits excellent activity in the production of all these chemicals and fuel derivative. The catalyst exhibits no significant loss in the activity even after five recycles. One simple catalyst affording three renewable synthetic intermediates from glucose and furfural will attract significant attention to catalysis researchers and industrialists.
- Kumar, Abhinav,Srivastava, Rajendra
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p. 4807 - 4816
(2020/08/24)
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- PROCESSES FOR PREPARING SORBOSE FROM GLUCOSE
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Processes for converting glucose to sorbose with tailored selectivity. The processes include contacting glucose with a silica-containing structure that includes a zeolite having a topology of a 10-membered ring or smaller and Lewis acidic M4+ framework centers, wherein M is Ti, Sn, Zr, or Hf. Contacting the glucose is conducted under reaction conditions sufficient to isomerize the glucose to sorbose.
- -
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Paragraph 0012-0013; 0016-0018; 0035-0037; 0038
(2020/08/25)
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- Role of the Strong Lewis Base Sites on Glucose Hydrogenolysis
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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
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p. 3845 - 3853
(2018/07/31)
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- A catalyzed by a chemical method, a method of glucose isomerization to fructose
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The invention discloses a chemical method for catalyzing glucose into fructose through isomerization, and relates to fructose. The method comprises the following steps: mixing a water solution containing Mg(NO3)2.6H2O, Al(NO3)3.6H2O, and Zr(NO3)4.5H2O/Sn(NO3).6H2O/Cu(NO3)2.3H2O with a NaOH water solution and a Na2CO3 water solution, wherein the metal molar mass ratio of Mg:Al:M is equal to 3:1:1, M represents Zr, Sn, or Cu, pH is 8 to 8, and the temperature is 60 DEG C; carrying out aging on the precipitate in the mother liquid, then carrying out static crystallization, drying so as to obtain the trinary metal hydrotalcite, adding the trinary metal hydrotalcite into a glucose solution to carry out reactions, filtering so as to obtain isomerized glucose solution and a solid hydrotalcite catalyst, recycling the catalyst, and finally subjecting the filtrate to vacuum rotation evaporation so as to obtain a condensed fructose liquid, wherein the weight ratio of the trinary metal hydrotalcite to the glucose to solvent (water) is (1-4):(1-10):40.
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-
Paragraph 0043; 0044
(2017/02/28)
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- Characterization of glycerol phosphate oxidase from Streptococcus pneumoniae and its application for ketose synthesis
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Glycerol phosphate oxidase from Streptococcus pneumoniae (GPOS.pne) was purified and characterized. By the actions of GPOS.pne and dihydroxyacetone phosphate (DHAP)-dependent aldolases, various ketoses including rare sugars were synthesized with glyceraldehydes as acceptors in a one-pot four-enzyme system.
- Li, Zijie,Qiao, Yingxin,Cai, Li,Nakanishi, Hideki,Gao, Xiao-Dong
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supporting information
p. 504 - 507
(2015/03/05)
-
- Facile enzymatic synthesis of ketoses
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Studies of rare ketoses have been hampered by a lack of efficient preparation methods. A convenient, efficient, and cost-effective platform for the facile synthesis of ketoses is described. This method enables the preparation of difficult-to-access ketopentoses and ketohexoses from common and inexpensive starting materials with high yield and purity and without the need for a tedious isomer separation step. A spoonful of sugar: A convenient, efficient, and cost-effective platform for the facile synthesis of ketoses is described. This method, which involves a one-pot mulitenzyme (OPME) reaction, enables the preparation of rare ketopentoses and ketohexoses from common and inexpensive starting materials with high yield and purity and without the need for a tedious isomer separation step.
- Wen, Liuqing,Huang, Kenneth,Wei, Mohui,Meisner, Jeffrey,Liu, Yunpeng,Garner, Kristina,Zang, Lanlan,Wang, Xuan,Li, Xu,Fang, Junqiang,Zhang, Houcheng,Wang, Peng George
-
supporting information
p. 12654 - 12658
(2015/10/28)
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- Catalytic effect of aluminium chloride on the example of the conversion of sugar model compounds
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Abstract In this work, the catalytic effect of the Bronsted acid hydrochloric acid, the Bronsted base sodium hydroxide and the Lewis acid AlCl3 on the conversion of biomass derived carbohydrates is investigated. On the example of the glycolaldehyde conversion, it is shown that the Lewis acid catalyses the ketol-endiol-tautomerism, the dehydration, the retro-aldol-reaction and the benzilic-acid-rearrangement. The main products are C4- and C6-carbohydrates as well as their secondary products 2-hydroxybut-3-enoic acid 1 and several furans. Under the same reaction conditions hydrochloric acid catalyzes mainly the dehydration and sodium hydroxide the tautomerism and subsequent aldolization.
- Schwiderski, Martin,Kruse, Andrea
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- Titanium-beta zeolites catalyze the stereospecific isomerization of d -glucose to l -sorbose via intramolecular C5-C1 hydride shift
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Pure-silica zeolite beta containing Lewis acidic framework Ti4+ centers (Ti-Beta) is shown to catalyze the isomerization of d-glucose to l-sorbose via an intramolecular C5-C1 hydride shift. Glucose-sorbose isomerization occurs in parallel to glucose-fructose isomerization on Ti-Beta in both water and methanol solvents, with fructose formed as the predominant product in water and sorbose as the predominant product in methanol (at 373 K) at initial times and over the course of >10 turnovers. Isotopic tracer studies demonstrate that 13C and D labels placed respectively at the C1 and C2 positions of glucose are retained respectively at the C6 and C5 positions of sorbose, consistent with its formation via an intramolecular C5-C1 hydride shift isomerization mechanism. This direct Lewis acid-mediated pathway for glucose-sorbose isomerization appears to be unprecedented among heterogeneous or biological catalysts and sharply contrasts indirect base-mediated glucose-sorbose isomerization via 3,4-enediol intermediates or via retro-aldol fragmentation and recombination of sugar fragments. Measured first-order glucose-sorbose isomerization rate constants (per total Ti; 373 K) for Ti-Beta in methanol are similar for glucose and glucose deuterated at the C2 position (within a factor of ~1.1), but are a factor of ~2.3 lower for glucose deuterated at each carbon position, leading to H/D kinetic isotope effects expected for kinetically relevant intramolecular C5-C1 hydride shift steps. Optical rotation measurements show that isomerization of d-(+)-glucose (92% enantiomeric purity) with Ti-Beta in water (373 K) led to the formation of l-(-)-sorbose (73% enantiomeric purity) and d-(-)-fructose (87% enantiomeric purity) as the predominant stereoisomers, indicating that stereochemistry is preserved at carbon centers not directly involved in intramolecular C5-C1 or C2-C1 hydride shift steps, respectively. This new Lewis acid-mediated rearrangement of glucose to sorbose does not appear to have a metalloenzyme analog.
- Gounder, Rajamani,Davis, Mark E.
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p. 1469 - 1476
(2013/07/26)
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- Productive sugar isomerization with highly active Sn in dealuminated β zeolites
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A water-tolerant Lewis acid catalyst was synthesized by grafting Sn IV in isopropanol under reflux onto dealuminated zeolites with the BEA (β) topology. This synthesis method allows the production of highly active Snβ-type catalysts without the need for long hydrothermal syntheses or hydrogen fluoride, while using cheap Sn-precursors, industrially available β zeolites and standard catalyst synthesis unit operations. Extensive characterization of the best catalyst shows highly dispersed Sn in the zeolite matrix (XRD, 29Si MAS NMR and 1H MAS NMR) without the formation of SnO2 (XRD and UV-Vis). The catalyst was tested for the model isomerization of sugars such as glucose to fructose. The catalytic activity proved to be purely heterogeneous and the catalyst was recycled and reused without significant loss in activity. Isomerization productivities above 4 kg product per kg of catalyst per hour are reported with appreciably low Sn loadings, corresponding to exceptionally high turnover frequencies, viz. 500 cycles per Sn per hour at 110 °C, which surpass the activity per Sn of the original hydrothermally synthesized Snβ.
- Dijkmans, Jan,Gabriels, Dries,Dusselier, Michiel,De Clippel, Filip,Vanelderen, Pieter,Houthoofd, Kristof,Malfliet, Annelies,Pontikes, Yiannis,Sels, Bert F.
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p. 2777 - 2785
(2013/10/08)
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- Mixed-acid systems for the catalytic synthesis of methyl levulinate from cellulose
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Mixed-acid systems consisting of both Lewis and Bronsted acids were found to be efficient catalysts for direct synthesis of methyl levulinate from cellulose. The Royal Society of Chemistry.
- Tominaga, Ken-Ichi,Mori, Atsushi,Fukushima, Yuriko,Shimada, Shigeru,Sato, Kazuhiko
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experimental part
p. 810 - 812
(2011/06/22)
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- Synthesis of rare sugars with l-fuculose-1-phosphate aldolase (FucA) from Thermus thermophilus HB8
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We report herein a one-pot four-enzyme approach for the synthesis of the rare sugars d-psicose, d-sorbose, l-tagatose, and l-fructose with aldolase FucA from a thermophilic source (Thermus thermophilus HB8). Importantly, the cheap starting material DL-GP (DL-glycerol 3-phosphate), was used to significantly reduce the synthetic cost.
- Li, Zijie,Cai, Li,Qi, Qingsheng,Styslinger, Thomas J.,Zhao, Guohui,Wang, Peng George
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supporting information; experimental part
p. 5084 - 5087
(2011/10/09)
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- Enzymatic synthesis of d-sorbose and d-psicose with aldolase RhaD: Effect of acceptor configuration on enzyme stereoselectivity
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It was previously reported that DHAP-dependent aldolase RhaD selectively chooses l-glyceraldehyde from racemic glyceraldehyde to produce l-fructose exclusively. Contrastingly, we discovered that d-glyceraldehyde is also tolerated as an acceptor and the stereoselectivity of the enzyme is lost in the corresponding aldol addition. Furthermore, we applied this property to efficiently synthesize two rare sugars d-sorbose and d-psicose.
- Li, Zijie,Cai, Li,Qi, Qingsheng,Wang, Peng George
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supporting information; experimental part
p. 7081 - 7084
(2012/01/13)
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- Fully active alternansucrases partially deleted in its carboxy-terminal and amino-terminal domains and mutants thereof
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Nucleic acid sequences of truncated or mutated alternansucrases, vectors containing these nucleic acids sequences, host cells transformed with the nucleic acid sequences encoding truncated or mutated alternansucrases are provided. Furthermore, a process to recombinantly alternansucrase with a high level of expression, while retaining the enzymatic activity is described.
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Page/Page column 15-16
(2008/06/13)
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- Osmium catalyzed dihydroxylation of 1,2-dioxines: A new entry for stereoselective sugar synthesis
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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.
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p. 7236 - 7244
(2007/10/03)
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- Borate as a phosphate ester mimic in aldolase-catalyzed reactions: Practical synthesis of L-fructose and L-iminocyclitols
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Dihydroxyacetone phosphate (DHAP)-dependent aldolases have been widely used for the organic synthesis of unnatural sugars or derivatives. The practicality of using DHAP-dependent aldolases is limited by their strict substrate specificity and the high cost and instability of DHAP. Here we report that the DHAP-dependent aldolase L-rhamnulose 1-phosphate aldolase (RhaD) accepts dihydroxyacetone (DHA) as a donor substrate in the presence of borate buffer, presumably by reversible in situ formation of DHA borate ester. The reaction appears to be irreversible, with the products thermodynamically trapped as borate complexes. We have applied this discovery to develop a practical one-step synthesis of the non-caloric sweetener L-fructose. L-Fructose was synthesized from racemic glyceraldehyde and DHA in the presence of RhaD and borate in 92% yield on a gram scale. We also synthesized a series of L-iminocyclitols, which are potential glycosidase inhibitors, in only two steps.
- Sugiyama, Masakazu,Hong, Zhangyong,Whalen, Lisa J.,Greenberg, William A.,Wong, Chi-Huey
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p. 2555 - 2559
(2007/10/03)
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- Formation of 3-hexuloses in aldol reactions, analysis of the products as their O-isopropylidene derivatives by GC-MS
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A method for analysis of mixtures of 3-hexuloses by gas chromatography mass spectrometry of their di-O-isopropylidene derivatives has been elaborated. The origin of characteristic fragment ions in the mass spectra is suggested on the basis of the spectra of d12 analogues, obtained by acetonation with acetone-d6 and on MS/MS investigations. The method has been applied to product mixtures from aldol reactions between glycero-tetrulose and glycolaldehyde and between 2-pentuloses and formaldehyde. An interesting result is the formation of ribo-3-hexulose with a high degree of stereoselectivity in alkali catalysed reaction between erythro-2-pentulose and formaldehyde.
- Ekeberg, Dag,Morgenlie, Svein
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p. 2171 - 2176
(2007/10/03)
-
- Catalytic asymmetric epoxidation
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The present invention provides a variety of methods that are based on stereoselective epoxidation of an olefin by an epoxidizing agent derived from a reaction between an oxidizing agent and a chiral ketone. For example, present invention provides methods for producing an epoxide from an olefin, for increasing a relative concentration of at least one stereoisomer of an olefin, and for stereoselectively producing an α-acyloxy carbonyl compound. Preferably, the chiral ketone is of the formula: or a derivative thereof which is capable of converting to the chiral ketone of Formula I under the reaction conditions, where a, b, n, X, R1, R2, R3, R4, R5and R6are those defined herein.
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- One-pot synthesis of L-fructose using coupled multienzyme systems based on rhamnulose-1-phosphate aldolase
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Two methods have been developed for the highly efficient enzymatic synthesis of L-fructose: one is based on rhamnulose-1-phosphate aldolase and acid phosphatase using racemic glyceraldehyde and dihydroxyacetone phosphate as substrates; the other is to gen
- Franke, Dirk,Machajewski, Timothy,Hsu, Che-Chang,Wong, Chi-Huey
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p. 6828 - 6831
(2007/10/03)
-
- Catalytic asymmetric epoxidation
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The present invention provides a variety of methods that are based on stereoselective epoxidation of an olefin by an epoxidizing agent derived from a reaction between an oxidizing agent and a chiral ketone. For example, present invention provides methods for producing an epoxide from an olefin, for increasing a relative concentration of at least one stereoisomer of an olefin, and for stereoselectively producing an α-acyloxy carbonyl compound. Preferably, the chiral ketone is of the formula: or a derivative thereof which is capable of converting to the chiral ketone of Formula I under the reaction conditions, where a, b, n, X, R1, R2, R3, R4, R5 and R6 are those defined herein.
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- Stereospecific molybdic acid-catalyzed isomerization of 2-hexuloses to branched-chain aldoses
-
On treatment with a catalytic amount of molybdic acid in aqueous solution, the 2-ketohexoses D-fructose, L-sorbose and D-tagatose undergo a stereospecific intramolecular rearrangement to give the corresponding 2-C-(hydroxymethyl)aldoses, 2-C-(hydroxymethyl)-D-ribose (D-hamamelose), 2-C-(hydroxymethyl)-L-lyxose, and 2-C-(hydroxymethyl)-D-xylose, respectively. At equilibrium, the ratio of 2-ketose to 2-C-(hydroxymethyl)aldose ranged from 14:1 (fructose) to 32:1 (sorbose). A similar treatment of D-psicose failed to yield a significant amount of the corresponding branched-chain aldose. The equilibria can be shifted with the addition of boric acid to the reaction mixture; under these conditions, ratios of 3:1 and 7:1 were obserwed for D-fructose and L-sorbose, respectively. A mechanistic study with D-(3-13C)fructose afforded D-(1-13C)hamamelose, thus confirming C-3 - C-4 bond cleavage with concomitant C-2 - C-3 transposition suggested from recent studies with D-(2-13C)fructose. Copyright (C) 1999 Elsevier Science Ltd.
- Hricoviniova-Bilikova, Zuzana,Hricovini, Milos,Petrusova, Maria,Serianni, Anthony S.,Petrus, Ladislav
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-
- Synthesis of carbohydrates via tandem use of the osmium-catalyzed asymmetric dihydroxylation and enzyme-catalyzed aldol addition reactions
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A new strategy is described for the asymmetric synthesis of carbohydrate derivatives via the tandem use of the osmium-catalyzed asymmetric dihydroxylation (AD) and aldolase-catalyzed aldol addition reactions. Both D- and L-forms of fructose, 6-deoxy-galacto-2-heptulose, and 6-phenyl-galacto-2-hexulose were synthesized to illustrate this methodology.
- Henderson, Ian,Sharpless, K. Barry,Wong, Chi-Huey
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p. 558 - 561
(2007/10/02)
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- Facile Synthesis of the Next Higher Ketoses from Aldoses
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A novel and facile synthesis of the next higher ketohexoses in high yield is successfully achieved by treating aldopentoses with formaldehyde in the presence of 3-ethylbenzothiazolium bromide as a catalyst.
- Matsumoto, Toshihiko,Enomoto, Tatsuya,Kurosaki, Toshikazu
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p. 610 - 611
(2007/10/02)
-
- Changes in Stereoselectivity in the Triose Aldol Condensation with Incresed Concentration of Alkaline Earth Metal Ions
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The presence of strontium and calcium chlorides in the triose aldol condensation has been found to affect the diastereoselectivity markedly.Whereas arabino-2-hexulose (fructose) is the major product under ordinary conditions, high concentrations of the alkaline-earth metal ions cause a change in favour of the xylo- and lyxo-diastereomers.No such effect was observed when high concentrations of alkali-metal chlorides were used.
- Morgenlie, Svein
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p. 546 - 549
(2007/10/02)
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- Synthesis of L-fructose and derivatives thereof
-
It is disclosed that L-fructose can be produced in high yield from L-sorbose. The process involves the inversion of the hydroxyl groups on carbon atoms C3 and C4 of L-sorbose to produce L-fructose. This inversion can be accomplished in simple, commercial equipment with the aid of common reagents. L-sorbose or an appropriately blocked derivative thereof is reacted so as to introduce or create a good leaving group, preferably mesyl or tosyl, at chiral carbon C3 thereby displacing the hydroxyl previously at that position. The leaving group is then displaced, preferably under alkaline conditions, in such a way that the hydroxyl oxygen atom at chiral carbon C4 attaches to chiral carbon C3, thereby displacing the leaving group while forming a 3,4-oxirane (epoxide) ring. The 3,4-oxirane ring forms in a downward position relative to the Haworth presentation thereby inverting chiral carbon C3 during formation of the 3,4-oxirane ring. The 3,4-oxirane ring is then opened under acidic or alkaline conditions to yield a sugar ring with a hydroxyl group in a position above the sugar ring at chiral carbon C4, and a hydroxyl group in a downward position at C3. Removal of any remaining blocking groups yields L-fructose. This may be accomplished by acid hydrolysis. There are also disclosed novel classes of compounds which act as intermediaries in the synthesis of L-fructose.
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- Kinetics, Catalysis, and Mechanism of the Secondary Reaction in the Final Phase of the Formose Reaction
-
In the final phase of the formose reaction sugars are formed by the reaction of glycolaldehyde, glyceraldehyde and dihydroxyacetone.The application of high-pressure liquid chromatography allows for the first time to investigate intermediate and final products quantitatively.The results of kinetical investigations allow to suggest a reaction mechanism for the secondary reaction in the final phase of the formose reaction.This mechanism is compared with that of the starting phase and other known mechanisms.From the results metal ion-catalyzed aldol reactions have to be assumed.
- Harsch, Guenther,Bauer, Hermann,Voelter, Wolfgang
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p. 623 - 635
(2007/10/02)
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- GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF HEXULOSES AND PENTULOSES AS THEIR O-ISOPROPYLIDENE DERIVATIVES: ANALYSIS OF PRODUCT MIXTURES FROM TRIOSE ALDOL-CONDENSATIONS
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Identification and quantitation of hexuloses and pentuloses in mixtures has been achived by gas chromatography-mass spectrometry of their O-isopropylidene derivatives.The method has been applied to product mixtures from triose aldol-condensations.The use of strongly basic anion-exchange resins as catalysts in the aldol condensation gives considerably higher proportions of fructose than when alkali or alkaline-earth hydroxides are applied.
- Morgenlie, Svein
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p. 215 - 222
(2007/10/02)
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