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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
(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
p. 997 - 1005
(2021/08/06)

Few-Unit-Cell MFI Zeolite Synthesized using a Simple Di-quaternary Ammonium Structure-Directing Agent
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
supporting information
p. 19214 - 19221
(2021/08/09)

L-Xylo-3-hexulose, a new rare sugar produced by the action of acetic acid bacteria on galactitol, an exception to Bertrand Hudson's rule
Background: In acetic acid bacteria such as Gluconobacter oxydans or Gluconobacter cerinus, pyrroloquinoline quinone (PQQ) in the periplasm serves as the redox cofactor for several membrane-bound dehydrogenases that oxidize polyhydric alcohols to rare sugars, which can be used as a healthy alternative for traditional sugars and sweeteners. These oxidation reactions obey the generally accepted Bertrand Hudson's rule, in which only the polyhydric alcohols that possess cis D-erythro hydroxyl groups can be oxidized to 2-ketoses using PQQ as a cofactor, while the polyhydric alcohols excluding cis D-erythro hydroxyl groups ruled out oxidation by PQQ-dependent membrane-bound dehydrogenases. Methods: Membrane fractions of G. oxydans were prepared and used as a cell-free catalyst to oxidize galactitol, with or without PQQ as a cofactor. Results: In this study, we reported an interesting oxidation reaction that the polyhydric alcohols galactitol (dulcitol), which do not possess cis D-erythro hydroxyl groups, can be oxidized by PQQ-dependent membrane-bound dehydrogenase(s) of acetic acid bacteria at the C-3 and C-5 hydroxyl groups to produce rare sugars L-xylo-3-hexulose and D-tagatose. Conclusions: This reaction may represent an exception to Bertrand Hudson's rule. General significance: Bertrand Hudson's rule is a well-known theory in polyhydric alcohols oxidation by PQQ-dependent membrane-bound dehydrogenase in acetic acid bacteria. In this study, galactitol oxidation by a PQQ-dependent membrane-bound dehydrogenase represents an exception to the Bertrand Hudson's rule. Further identification of the associated enzymes and deciphering the explicit enzymatic mechanism will prove this theory.
Xu, Yirong,Chi, Ping,Lv, Jiyang,Bilal, Muhammad,Cheng, Hairong
(2020/10/02)

Production of tagatose and talose through isomerization of galactose in a buffer solution under subcritical water conditions
Galactose was isomerized in pure water or in 10 mmol/L sodium phosphate buffer at 160 °C under pressurized conditions. The isomerization of galactose to tagatose and talose in phosphate buffer resulted in 14% and 1.4% yields, respectively, which were significantly higher than those obtained in subcritical pure water (0.6% and 6.3. Our results indicate that the galactose isomerization by Lobry de Bruyn-Alberda-van Ekenstein transformation rarely occurred at low pH due to the formation of organic acids.
Adachi, Shuji,Furushiro, Yuya,Hirayama, Yusuke,Kobayashi, Takashi,Onishi, Yuichiro
supporting information

(2020/05/25)

Method for preparing fructose (by machine translation)
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)

Method for preparing lactic acid through catalytically converting carbohydrate
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)

Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
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
p. 4807 - 4816
(2020/08/24)

PROCESSES FOR PREPARING SORBOSE FROM GLUCOSE
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)

Convergent in situ Generation of Both Transketolase Substrates via Transaminase and Aldolase Reactions for Sequential One-Pot, Three-Step Cascade Synthesis of Ketoses
We describe an efficient three-enzyme, sequential one-pot cascade reaction where both transketolase substrates are generated in situ in a convergent fashion. The nucleophilic donor substrate hydroxypyruvate was obtained from l-serine and pyruvate by a transaminase-catalyzed reaction. In parallel, three different (2S)-α-hydroxylated aldehydes, l-glyceraldehyde, d-threose, and l-erythrose, were generated as electrophilic acceptors from simple achiral compounds glycolaldehyde and formaldehyde by d-fructose-6-phosphate aldolase catalysis. The compatibility of the three enzymes was studied in terms of temperature, enzyme ratio and substrate concentration. The efficiency of the process relied on the irreversibility of the transketolase reaction, driving a shift of the reversible transamination reaction and securing the complete conversion of all substrates. Three valuable (3S,4S)-ketoses, l-ribulose, d-tagatose, and l-psicose were obtained in good yields with high diastereoselectivity.
Lorillière, Marion,Guérard-Hélaine, Christine,Gefflaut, Thierry,Fessner, Wolf-Dieter,Clapés, Pere,Charmantray, Franck,Hecquet, Laurence
p. 812 - 817
(2019/12/27)

Towards efficient enzymatic conversion of d-galactose to d-tagatose: purification and characterization of l-arabinose isomerase from Lactobacillus brevis
l-arabinose isomerase (l-AI) (EC 5. 3. 1. 4. l-AI) that mediates the isomerization of d-galactose to d-tagatose was isolated from Lactobacillus brevis (MF 465792), and was further purified and characterized. Pure enzyme with molecular weight of 60.1?kDa was successfully obtained after the purification using Native-PAGE gel extraction method, which was a monomer in solution. The l-AI was found to be stable at 45–75?°C, and at pH 7.0–9.0. Its optimum temperature and pH was determined as 65?°C and 7.0, respectively. Besides, we found that Ca2+, Cu2+, and Ba2+ ions inhibited the enzyme activity, whereas the enzyme activity was significantly enhanced in the presence of Mg2+, Mn2+, or Co2+ ions. The optimum concentration of Mn2+ and Co2+ was determined to be 1?mM. Furthermore, we characterized the kinetic parameters for l-AI and determined the Km (129?mM) and the Vmax (0.045?mM min? 1) values. Notably, L. brevisl-AI exhibited a high bioconversion yield of 43% from d-galactose to d-tagatose under the optimal condition, and appeared to be a more efficient catalyst compared with other l-AIs from various organisms.
Du, Mengge,Zhao, Dongying,Cheng, Sisi,Sun, Di,Chen, Ming,Gao, Ziqing,Zhang, Chunzhi
p. 107 - 116
(2018/09/29)

Characterization of a novel D-arabinose isomerase from Thermanaeromonas toyohensis and its application for the production of D-ribulose and L-fuculose
D-Ribulose and L-fuculose are potentially valuable rare sugars useful for anticancer and antiviral drugs in the agriculture and medicine industries. These rare sugars are usually produced by chemical methods, which are generally expensive, complicated and do not meet the increasing demands. Furthermore, the isomerization of D-arabinose and L-fucose byDD-arabinose and L-fucose by D-arabinose isomerase from bacterial sources for the production of D-ribulose and L-fuculose have not yet become industrial due to the shortage of biocatalysts, resulting in poor yield and high cost of production. In this study, a thermostable D-ribulose- and L-fuculose producing D-arabinose isomerase from the bacterium Thermanaeromonas toyohensis was characterized. The recombinant D-arabinose isomerase from T. toyohensis (Thto-DaIase) was purified with a single band at 66 kDa using His-trap affinity chromatography. The native enzyme existed as a homotetramer with a molecular weight of 310 kDa, and the specific activities for both D-arabinose and L-fucose were observed to be 98.08 and 85.52 U mg?1, respectively. The thermostable recombinant Thto-DaIase was activated when 1 mM Mn2+ was added to the reactions at an optimum pH of 9.0 at 75 °C and showed approximately 50% activity for both D-arabinose and L-fucose at 75 °C after 10 h. The Michaelis-Menten constant (Km), the turnover number (kcat) and catalytic efficiency (kcat/Km) for D-arabinose/L-fucose were 111/81.24 mM, 18,466/10,688 min?1, and 166/132 mM?1 min?1, respectively. When the reaction reached to equilibrium, the conversion rates of D-ribulose from D-arabinose and L-fuculose from L-fucose were almost 27% (21 g L?1) and 24.88% (19.92 g L?1) from 80 g L?1 of D-arabinose and L-fucose, respectively.
Iqbal, Muhammad Waheed,Riaz, Tahreem,Hassanin, Hinawi A.M.,Ni, Dawei,Mahmood Khan, Imran,Rehman, Abdur,Mahmood, Shahid,Adnan, Muhammad,Mu, Wanmeng
(2019/09/30)

Converting galactose into the rare sugar talose with cellobiose 2-epimerase as biocatalyst
Cellobiose 2-epimerase from Rhodothermus marinus (RmCE) reversibly converts a glucose residue to a mannose residue at the reducing end of β-1,4-linked oligosaccharides. In this study, the monosaccharide specificity of RmCE has been mapped and the synthesis of D-talose from D-galactose was discovered, a reaction not yet known to occur in nature. Moreover, the conversion is industrially relevant, as talose and its derivatives have been reported to possess important antimicrobial and anti-inflammatory properties. As the enzyme also catalyzes the keto-aldo isomerization of galactose to tagatose as a minor side reaction, the purity of talose was found to decrease over time. After process optimization, 23 g/L of talose could be obtained with a product purity of 86% and a yield of 8.5% (starting from 4 g (24 mmol) of galactose). However, higher purities and concentrations can be reached by decreasing and increasing the reaction time, respectively. In addition, two engineering attempts have also been performed. First, a mutant library of RmCE was created to try and increase the activity on monosaccharide substrates. Next, two residues from RmCE were introduced in the cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus (CsCE) (S99M/Q371F), increasing the kcat twofold.
Van Overtveldt, Stevie,Gevaert, Ophelia,Cherlet, Martijn,Beerens, Koen,Desmet, Tom
(2018/10/20)

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)

D-Tagatose manufacture through bio-oxidation of galactitol derived from waste xylose mother liquor
In this study, the bio-oxidation of galactitol to the valuable d-tagatose is presented. This proposed strategy could start with the refined by-product of waste xylose mother liquor formed by chemical hydrogenation. Through a computationally guided enzyme screening approach, a robust polyol dehydrogenase (PdPDH) was rapidly identified from a massive number of candidates. When coupled with a water-forming NADH oxidase (StNOX) for environmentally benign cofactor regeneration, subsequent reaction optimization facilitated the complete transformation of 100 g L-1 galactitol into the desired product within 15 h, with a yield of 91% in a 2 L scale preparative reaction. Compared to the current enzymatic isomerization system, our approach avoids low conversion, high operative temperatures and by-product formation, while enabling simplified product isolation.
Sha, Feng,Zheng, Yucong,Chen, Jiao,Chen, Kequan,Cao, Fei,Yan, Ming,Ouyang, Pingkai
supporting information
p. 2382 - 2391
(2018/05/31)

One-pot, two-step cascade synthesis of naturally rare l-: Erythro (3 S,4 S) ketoses by coupling a thermostable transaminase and transketolase
An efficient simultaneous cascade of two enzymatic steps catalyzed by a thermostable transaminase and transketolase was performed at elevated temperatures allowing the synthesis of naturally rare l-erythro (3S,4S) ketoses. l-ribulose, 5-deoxy-l-ribulose, d-tagatose and l-psicose, which are highly valuable chiral building blocks and display prominent biological properties, were obtained on a preparative scale with excellent stereoselectivities and good yields. A thermostable transketolase from Geobacillus stearothermophilus catalyzed at high temperatures the stereospecific synthesis of l-erythro (3S,4S)-configured ketoses from (2S)-hydroxylated aldehydes and β-hydroxypyruvate in which the latter is generated in an unprecedented manner in situ from natural l-serine and pyruvate using a novel thermostable l-α-transaminase from the thermophilic bacterium Thermosinus carboxydivorans. Overall, this cascade synthesis prevents the thermal decomposition of the labile β-hydroxypyruvate and offers an efficient and environmentally friendly procedure.
Lorillière, Marion,De Sousa, Maxime,Bruna, Felipe,Heuson, Egon,Gefflaut, Thierry,De Berardinis, Véronique,Saravanan, Thangavelu,Yi, Dong,Fessner, Wolf-Dieter,Charmantray, Franck,Hecquet, Laurence
p. 424 - 435
(2017/08/14)

PRODUCTION OF ALPHA-HYDROXY CARBOXYLIC AIDS AND ESTERS FROM HIGHER SUGARS USING TANDEM CATALYST SYSTEMS
The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.
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Page/Page column 2; 13-14

(2017/02/09)

Structure of the thermophilic l-Arabinose isomerase from Geobacillus kaustophilus reveals metal-mediated intersubunit interactions for activity and thermostability
Thermophilic l-arabinose isomerase (AI), which catalyzes the interconversion of l-arabinose and l-ribulose, can be used to produce d-tagatose, a sugar substitute, from d-galactose. Unlike mesophilic AIs, thermophilic AIs are highly dependent on divalent metal ions for their catalytic activity and thermostability at elevated temperatures. However, the molecular basis underlying the substrate preferences and metal requirements of multimeric AIs remains unclear. Here we report the first crystal structure of the apo and holo forms of thermophilic Geobacillus kaustophilus AI (GKAI) in hexamer form. The structures, including those of GKAI in complex with l-arabitol, and biochemical analyses revealed not only how the substrate-binding site of GKAI is formed through displacement of residues at the intersubunit interface when it is bound to Mn2+, but also revealed the water-mediated H-bonding networks that contribute to the structural integrity of GKAI during catalysis. These observations suggest metal-mediated isomerization reactions brought about by intersubunit interactions at elevated temperatures are responsible for the distinct active site features that promote the substrate specificity and thermostability of thermophilic AIs.
Choi, Jin Myung,Lee, Yong-Jik,Cao, Thinh-Phat,Shin, Sun-Mi,Park, Min-Kyu,Lee, Han-Seung,Di Luccio, Eric,Kim, Seong-Bo,Lee, Sang-Jae,Lee, Sang Jun,Lee, Sung Haeng,Lee, Dong-Woo
p. 51 - 62
(2016/03/19)

METHOD OF PRODUCING TAGATOSE
PROBLEM TO BE SOLVED: To provide a method of producing tagatose conveniently and efficiently. SOLUTION: Galactose is selected as a raw sugar and is subjected to subcritical water treatment, so that it can be isomerized to tagatose conveniently and efficiently. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0031-0033

(2017/01/23)

A catalyzed by a chemical method, a method of glucose isomerization to fructose
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)

Production of keto-disaccharides from aldo-disaccharides in subcritical aqueous ethanol
Isomerization of disaccharides (maltose, isomaltose, cellobiose, lactose, melibiose, palatinose, sucrose, and trehalose) was investigated in subcritical aqueous ethanol. A marked increase in the isomerization of aldo-disaccharides to keto-disaccharides was noted and their hydrolytic reactions were suppressed with increasing ethanol concentration. Under any study condition, the maximum yield of keto-disaccharides produced from aldo-disaccharides linked by β-glycosidic bond was higher than that produced from aldo-disaccharides linked by α-glycosidic bond. Palatinose, a keto-disaccharide, mainly underwent decomposition rather than isomerization in subcritical water and subcritical aqueous ethanol. No isomerization was noted for the non-reducing disaccharides trehalose and sucrose. The rate constant of maltose to maltulose isomerization almost doubled by changing solvent from sub-critical water to 80 wt% aqueous ethanol at 220°C. Increased maltose monohydrate concentration in feed decreased the conversion of maltose and the maximum yield of maltulose, but increased the productivity of maltulose. The maximum productivity of maltulose was ca. 41 g/(h kg-solution).
Gao, Da-Ming,Kobayashi, Takashi,Adachi, Shuji
p. 998 - 1005
(2016/05/09)

Catalytic effect of aluminium chloride on the example of the conversion of sugar model compounds
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
p. 64 - 70
(2015/04/14)

Characterization of glycerol phosphate oxidase from Streptococcus pneumoniae and its application for ketose synthesis
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
supporting information
p. 504 - 507
(2015/03/05)

Facile enzymatic synthesis of ketoses
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)

Purification of an l-arabinose isomerase from Enterococcus faecium DBFIQ E36 employing a biospecific affinity strategy
l-Arabinose isomerase is an intracellular enzyme that can convert l-arabinose to l-ribulose and d-galactose to d-tagatose, a promising but rare nutraceutical. Most of l-arabinose isomerases purified up to date employed the combination between DNA recombinant technology and affinity chromatography based on poly-histidine tail recognition, but few of the enzymes were obtained and purified in a non-recombinant way. For these reasons, a specific affinity bioadsorbent containing l-arabitol as ligand, a competitive inhibitor of the enzyme, was designed and synthesized for achieving pure preparations of the enzyme l-arabinose isomerase from wild-type Enterococcus faecium DBFIQ E36 strain, isolated from raw cow milk. The two-step purification procedure consisted in fractionation by ammonium sulphate precipitation followed by affinity chromatography with obtained bioadsorbent, allowing the purification, to electrophoretical homogeneity, of target enzyme. Characterization studies were performed with purified l-arabinose isomerase in order to increase knowledge of their physicochemical properties. In this sense, enzyme exhibited an optimum temperature of 50 C and optimum pH of 7.0, maintaining good stability in the ranges 20-45 C and pH 6.5-8. Ki were calculated, employing d-galactose as substrate, for l-arabitol and l-ribitol, achieving values of 7.9 mM and 183 mM, respectively. Km and Vmax values obtained were 35 mM and 81 U mg-1 at 50 C, respectively. Mass spectrometry assay revealed a 48 kDa monomer whereas gel permeation chromatography achieved a 187 kDa molecular weight for native enzyme. Finally, 2D-electrophoresis and isoelectrofocusing analysis revealed an isoelectric point value of 3.80. Results have unveiled both an acidic nature and promising properties for l-arabinose isomerase isolated from E. faecium DBFIQ E36.
Torres, Pedro R.,Manzo, Ricardo M.,Rubiolo, Amelia C.,Batista-Viera, Francisco D.,Mammarella, Enrique J.
p. 99 - 105
(2014/03/21)

Efficient production of d -tagatose using a food-grade surface display system
d-Tagatose, a functional sweetener, is commonly transformed from d-galactose by l-arabinose isomerase (l-AI). In this study, a novel type of biocatalyst, l-AI from Lactobacillus fermentum CGMCC2921 displayed on the spore surface of Bacillus subtilis 168, was developed for producing d-tagatose. The anchored l-AI, exhibiting the relatively high bioactivity, suggested that the surface display system using CotX as the anchoring protein was successfully constructed. The stability of the anchored l-AI was significantly improved. Specifically, the consolidation of thermal stability representing 87% of relative activity was retained even at 80 °C for 30 min, which remarkably favored the production of d-tagatose. Under the optimal conditions, the robust spores can convert 75% d-galactose (100 g/L) into d-tagatose after 24 h, and the conversion rate remained at 56% at the third cycle. Therefore, this biocatalysis system, which could express the target enzyme on the food-grade vector, was an alternative method for the value-added production of d-tagatose.
Liu, Yi,Li, Sha,Xu, Hong,Wu, Lingtian,Xu, Zheng,Liu, Jing,Feng, Xiaohai
p. 6756 - 6762
(2015/04/22)

Tagatose production using simulated moving bed separation
Disclosed is a process for the production of d-tagatose from lactose after acid hydrolysis to provide a hydrolysate having 1 equiv of d-glucose and 1 equiv of d-galactose for each unit of lactose converted. More particularly, the invention relates to a process for the isomerization of d-galactose to d-tagatose and the use of a simplified separation scheme based on simulated moving bed (SMB) separation. The isomerization of d-galactose to d-tagatose is carried out in the presence of calcium oxide or calcium hydroxide. The process is useful for providing a simplified processing route to providing pure d-tagatose and glucose as two products from lactose hydrolysate. In an alternate embodiment, a process is disclosed for the production of d-tagatose from fermented lactose hydrolysate to provide a crystallized d-tagatose product. D-tagatose is useful as a food additive, as a sweetener, as a texturizer, as a stabilizer, or as a humectant.
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Paragraph 0070

(2013/12/04)

Titanium-beta zeolites catalyze the stereospecific isomerization of d -glucose to l -sorbose via intramolecular C5-C1 hydride shift
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.
p. 1469 - 1476
(2013/07/26)

Productive sugar isomerization with highly active Sn in dealuminated β zeolites
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.
p. 2777 - 2785
(2013/10/08)

The crystal structure of galactitol-1-phosphate 5-dehydrogenase from Escherichia coli K12 provides insights into its anomalous behavior on IMAC processes
Endogenous galactitol-1-phosphate 5-dehydrogenase (GPDH) (EC 1.1.1.251) from Escherichia coli spontaneously interacts with Ni2+-NTA matrices becoming a potential contaminant for recombinant, target His-tagged proteins. Purified recombinant, untagged GPDH (rGPDH) converted galactitol into tagatose, and d-tagatose-6-phosphate into galactitol-1-phosphate, in a Zn2+- and NAD(H)-dependent manner and readily crystallized what has permitted to solve its crystal structure. In contrast, N-terminally His-tagged GPDH was marginally stable and readily aggregated. The structure of rGPDH revealed metal-binding sites characteristic from the medium-chain dehydrogenase/reductase protein superfamily which may explain its ability to interact with immobilized metals. The structure also provides clues on the harmful effects of the N-terminal His-tag. Structured summary of protein interactions: GPDH and GPDH bind by molecular sieving (View interaction) GPDH and GPDH bind by x-ray crystallography (View interaction) GPDH and GPDH bind by cosedimentation in solution (View interaction).
Esteban-Torres, Maria,Rivas, Blanca De Las,Munoz, Rosario,Alvarez, Yanaisis,Acebron, Ivan,Mancheno, Jose M.,Kohring, Gert-Wieland,Roa, Ana Maria,Sobrino, Monica
p. 3127 - 3133,7
(2020/07/31)

Activity improvement of UDP-galactose-4-epimerase for tagatose substrates by 3D structure-based combinatorial mutagenesis
Uridine diphosphogalactose-4-epimerase (UDP-galactose-4-epimerase, GalE, EC 5.1.3.2) mediates 4-epimerization of free monosaccharides in a low activity as well as original UDP-galactose substrate in a high activity (Appl Biochem Biotechnol 163:444-451). To improve GalE for monosaccharide 4-epimerization, random mutations were introduced and the effects of single mutations on the conversion of tagatose were evaluated. Among 3060 random mutated GalE variants, two clones showing the improved conversion activity of tagatose 4-epimerization were selected and their mutation points were sequenced. To investigate the effect of each mutations, the 5 mutation points (D58E, N100S, P193S, I196N, and T317S) found in the two selected clones were further introduced into the wild-type GalE and the variant enzymes were purified for kinetic study. The enzyme carrying D58E single mutation (GalE D58E), which is located near the cofactor binding pocket in a 3D structure docking model, showed the kinetic parameters of KM = 388 mM and kcat = 1.77 min-1 for tagatose substrate and it was 3.3-fold greater kcat/K M than the wild-type enzyme. When the N179S mutation, which is located near the substrate-binding pocket according to our previous study, was further combined with GalE D58E, the kinetic parameters of the double mutant enzyme was found to have 3.7-fold higher kcat/KM than the wild-type. The effect of the mutations on the activity improvement based on the 3D structure docking model and further biotechnological potential is discussed.
Kim, Hye-Jung,Kang, Sueng Yeun,Choi, Joon Ho,Kim, Pil
p. 35 - 39
(2012/11/06)

Supramolecular stabilization of acid tolerant l-arabinose isomerase from Lactobacillus sakei
l-Arabinose isomerase stability is a crucial criterion for the industrial application of this biocatalyst. Noria and NoriaPG are capable of increasing the l-arabinose isomerase stability not only at high temperatures but also at low pH. Such results highlight, for the first time, the use of the Noria series of molecules for protein stabilization and activation.
Jebors, Said,Tauran, Yannick,Aghajari, Nushin,Boudebbouze, Samira,Maguin, Emmanuelle,Haser, Richard,Coleman, Anthony W.,Rhimi, Moez
supporting information; experimental part
p. 12307 - 12309
(2012/01/03)

A novel l-arabinose isomerase from Lactobacillus fermentum CGMCC2921 for d-tagatose production: Gene cloning, purification and characterization
The araA gene encoding l-arabinose isomerase (l-AI) from the acidophilus bacterium Lactobacillus fermentum CGMCC2921 was cloned and over-expressed in Escherichia coli. The open reading frame of the l-AI consisted of 1425 nucleotides encoding 474 amino acid residues. The molecular mass of the enzyme was estimated to be approximately 53 kDa on SDS-PAGE. The purified recombinant enzyme showed maximum activity at 65 °C and pH 6.5, which were extremely suitable for industrial applications. It required divalent metal ions, either Mn2+ or Co2+, for enzymatic activity and thermostability improvement at higher temperatures. The enzyme was active and stable at acidic pH, it exhibited 83% of its maximal activity at pH 6.0 and retained 88% of the original activity after incubation at pH 6.0 for 24 h. Kinetic parameter study showed that the catalytic efficiency was relatively high, with a k cat/Km of 9.02 mM-1 min-1 for d-galactose. The purified L. fermentum CGMCC2921 l-AI converted d-galactose into d-tagatose with a high conversion rate of 55% with 1 mM Mn2+ after 12 h at 65 °C, suggesting its excellent potential in d-tagatose production.
Xu, Zheng,Qing, Yujia,Li, Sha,Feng, Xiaohai,Xu, Hong,Ouyang, Pingkai
experimental part
p. 1 - 7
(2012/01/30)

Cloning, expression, and characterization of a d-psicose 3-epimerase from clostridium cellulolyticum H10
The noncharacterized protein ACL75304 encoded by the gene Ccel-0941 from Clostridium cellulolyticum H10 (ATCC 35319), previously proposed as the xylose isomerase domain protein TIM barrel, was cloned and expressed in Escherichia coli. The expressed enzyme was purified by nickel-affinity chromatography with electrophoretic homogeneity and then characterized as d-psicose 3-epimerase. The enzyme was strictly metal-dependent and showed a maximal activity in the presence of Co2+. The optimum pH and temperature for enzyme activity were 55 °C and pH 8.0. The half-lives for the enzyme at 60 °C were 6.8 h and 10 min when incubated with and without Co2+, respectively, suggesting that this enzyme was extremely thermostable in the presence of Co2+ but readily inactivated without metal ion. The Michaelis-Menten constant (Km), turnover number (kcat), and catalytic efficiency (kcat/Km) values of the enzyme for substrate d-psicose were estimated to be 17.4 mM, 3243.4 min-1, and 186.4 mM min-1, respectively. The enzyme carried out the epimerization of d-fructose to d-psicose with a conversion yield of 32% under optimal conditions, suggesting that the enzyme is a potential d-psicose producer.
Mu, Wanmeng,Chu, Feifei,Xing, Qingchao,Yu, Shuhuai,Zhou, Leon,Jiang, Bo
scheme or table
p. 7785 - 7792
(2012/07/13)

Mixed-acid systems for the catalytic synthesis of methyl levulinate from cellulose
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
experimental part
p. 810 - 812
(2011/06/22)

Synthesis of rare sugars with l-fuculose-1-phosphate aldolase (FucA) from Thermus thermophilus HB8
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
supporting information; experimental part
p. 5084 - 5087
(2011/10/09)

Enzymatic synthesis of d-sorbose and d-psicose with aldolase RhaD: Effect of acceptor configuration on enzyme stereoselectivity
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
supporting information; experimental part
p. 7081 - 7084
(2012/01/13)

Aldose-ketose interconversion in pyridine in the presence of aluminium oxide
The reaction rate of the Lobry de Bruyn-Alberda van Ekenstein transformation of aldoses to ketoses in boiling pyridine was strongly increased by the addition of aluminium oxide. In addition to aldose-ketose transformation, 2-epimers of the starting aldoses and 3-epimers of the primarily produced ketoses were formed to some extent, as reported also when these reactions are carried out without aluminium oxide. The relative amounts of the primary ketose and the starting aldose in the reaction mixtures may be explained on the basis of their stability, predicted from reported free energy calculations. Isomerisation of ketoses to aldoses was much slower than the reverse reaction. The relative free energies are also in these cases important, the very stable xylo-2-hexulose gave only 7% and 6% of the aldoses gulose and idose, respectively, after boiling for 7 h in pyridine in the presence of aluminium oxide.
Ekeberg, Dag,Morgenlie, Svein,Stenstrom, Yngve
p. 1992 - 1997
(2008/02/10)

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)

Fully active alternansucrases partially deleted in its carboxy-terminal and amino-terminal domains and mutants thereof
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)

Borate as a phosphate ester mimic in aldolase-catalyzed reactions: Practical synthesis of L-fructose and L-iminocyclitols
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
p. 2555 - 2559
(2007/10/03)

Prebiotic carbohydrate synthesis: Zinc-proline catalyzes direct aqueous aldol reactions of α-hydroxy aldehydes and ketones
Zn-proline catalyzed aldolisation of glycoladehyde gave mainly tetroses whereas in the cross-aldolisation of glycoladehyde and rac-glyceraldehyde, pentoses accounted for 60% of the sugars formed with 20% of ribose. The Royal Society of Chemistry 2005.
Kofoed, Jacob,Reymond, Jean-Louis,Darbre, Tamis
p. 1850 - 1855
(2007/10/03)

Catalytic asymmetric epoxidation
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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(2008/06/13)

Formation of 3-hexuloses in aldol reactions, analysis of the products as their O-isopropylidene derivatives by GC-MS
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
p. 2171 - 2176
(2007/10/03)

Novel thermostable isomerase and use hereof, in particular for producing tagatose
A novel L-arabinose isomerase active enzyme and its corresponding gene, derived from a thermophilic source are provided. The enzyme is suitable for the production of D-tagatose, a useful low-calorie sweetener. The enzyme may be obtained from a Thermoanaerobacter species such as Thermoanaerobacter mathranii.
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(2008/06/13)

PROCESS FOR PRODUCING CRYSTALLINE TAGATOSE
The present invention provides a method for producing tagatose crystals from an aqueous system using no organic solvent. In this method, seed crystals of tagatose are added to a tagatose solution in which a tagatose purity of solid contents in the solution is at least 70% and a solid contents concentration in the solution is 60 to 98 mass%, and crystallization of tagatose is carried out by stirring and cooling the solution while keeping a degree of super saturation of tagatose at 1.25 or lower. It is preferred that the solution containing tagatose is a solution containing no organic solvent. It is further preferred that a part of massecuite for which the crystallization is completed is added to a mother liquor so as to produce the tagatose crystals semi-continuously or continuously. It is furthermore preferred that the tagatose crystals formed from the massecuite are separated by centrifugation or filtration and dried to obtain tagatose crystals.
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(2008/06/13)

New Boronic Acid Fluorescent Reporter Compounds. 2. A Naphthalene-Based On-Off Sensor Functional at Physiological pH
(Matrix presented) A new boronlc acid fluorescent on-off reporter compound (1) was synthesized. This fluorescent sensor shows a 41-fold emission intensity increase upon addition of 50 mM fructose in 0.1 M aqueous phosphate buffer at pH 7.4.
Gao, Xingming,Zhang, Yanling,Wang, Binghe
p. 4615 - 4618
(2007/10/03)

One-pot synthesis of L-fructose using coupled multienzyme systems based on rhamnulose-1-phosphate aldolase
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
p. 6828 - 6831
(2007/10/03)

Catalytic asymmetric epoxidation
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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(2008/06/13)

Base catalysed isomerisation of aldoses of the arabino and lyxo series in the presence of aluminate
Base-catalysed isomerisation of aldoses of the arabino and lyxo series in aluminate solution has been investigated. L-Arabinose and D-galactose give L-erythro-2-pentulose (L-ribulose) and D-lyxo-2-hexulose (D-tagatose), respectively, in good yields, whereas lower reactivity is observed for 6-deoxy-D-galactose (D-fucose). From D-lyxose, D-mannose and 6-deoxy-L-mannose (L-rhamnose) are obtained mixtures of ketoses and C-2 epimeric aldoses. Small amounts of the 3-epimers of the ketoses were also formed. 6-Deoxy-L-arabino-2-hexulose (6-deoxy-L-fructose) and 6-deoxy-L-glucose (L-quinovose) were formed in low yields from 6-deoxy-L-mannose and isolated as their O-isopropylidene derivatives. Explanations of the differences in reactivity and course of the reaction have been suggested on the basis of steric effects.
Ekeberg, Dag,Morgenlie, Svein,Stenstrom, Yngve
p. 779 - 786
(2007/10/03)

Methods for treating plants and enhancing plant growth using polyacylglycosides and/or polyalkylglycosides and formulations for same
Methods and formulations for treating plants and enhancing plant growth and for safening high concentrations of one or more phytocatalysts, wherein one or more formulations, comprising, a high concentration of one or more phytocatalysts, and an effective amount of one or more polyacylglycosides and polyalkylglycosides; and isomers, and metabolites, salts, hydrates, esters, amines, and derivatives of the polyacylglycosides and polyalkylglycosides, and combinations thereof, is applied to the plants.
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(2008/06/13)