- High-yield DL-mandelic acid synthesis process
-
The invention provides a high-yield DL-mandelic acid synthesis process. The synthesis process specifically comprises the following steps: 1, treating benzaldehyde by using sodium hydrogen sulfite to obtain benzaldehyde sodium hydrogen sulfite; 2, extracting the benzaldehyde sodium hydrogen sulfite by using an organic solvent, recovering unreacted benzaldehyde in the benzaldehyde sodium hydrogen sulfite, and adding sodium cyanide after the extraction is completed to prepare mandelonitrile; 3, adding an inorganic acid, and then carrying out heating and pressure maintaining treatment to hydrolyze the mandelonitrile so as to obtain mandelic acid; and 4, purifying the mandelic acid. According to the method, the step of extracting the p-benzaldehyde sodium hydrogen sulfite salt is added, so that the probability that the product purity is reduced due to benzoin condensation is reduced, the recycled benzaldehyde can be returned to the raw material for use, and the yield can be increased in multiple rounds of reactions; and the hydrolysis process of the mandelonitrile adopts heating and pressure maintaining treatment, so that consumption of inorganic acid can be reduced, and the hydrolysis efficiency is improved.
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Paragraph 0021-0026
(2021/09/04)
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- Designing of amino functionalized imprinted polymeric resin for enantio-separation of (±)-mandelic acid racemate
-
S-Mandelic acid (MA) enantio-selective resinous material functionalized with –NH2 groups has been developed and effectively utilized in chiral separation of (±)-MA racemate solution. S-MA has first combined with the polymerizable p-aminophenol and form the corresponding amide derivative, which was then polymerized with phenol/formalin using HCl as a catalyst. The stereo-selective –NH2 functionalized binding sites were then generated within the resin upon the alkaline degradation of the amide linkages followed by acidic treatments that will expel the resin incorporated S-MA out of the polymeric material to get the S-MA imprinted polymer (S-MAPR). The synthesized S-MA chiral amide derivative along with the developed polymeric resin was investigated by various techniques including FTIR and NMR spectra that confirmed the executed chemical modifications. In addition, the morphological appearance of the obtained resins were observed using SEM images. Moreover, the S-MAPR resin was examined to optimize the enantio-selective separation conditions and the studies indicated that the adsorption reached the highest value at pH 7 and the maximum capacity was 243 ± 1 mg/g. In addition, the chiral separation of (±)-MA racemic solution was successfully executed by the S-MAPR separation column with 55% and 82% enantiomeric excess of R- and S-MA within both the initial loading and recovery eluant solutions, respectively.
- Alhawiti, Aliyah S.,Monier,Elsayed, Nadia H.
-
-
- Method for synthesizing mandelic acid
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The invention relates to the technical field of compound preparation, and provides a method for synthesizing mandelic acid, which comprises the following steps: by using styrene as a basic raw material, trichloroisocyanuric acid as a chlorinating agent an
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-
Paragraph 0032; 0034-0035; 0037-0038; 0040-0041; 0043
(2021/02/06)
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- Synthesis of α-hydroxycarboxylic acids from various aldehydes and ketones by direct electrocarboxylation: A facile, efficient and atom economy protocol
-
In present work, the formation of α-hydroxycarboxylic acids have been described from various aromatic aldehydes and ketones via direct electrocarboxylation method with 80-92% of yield without any side product and can be purified by simple recrystallization using sacrificial Mg anode and Pt cathode in an undivided cell, CO2at (1 atm) was continuously bubbled in the cell throughout the reaction using tetrapropylammonium chloride as a supporting electrolyte in acetonitrile. The synthesized compounds obtained in fair to excellent yield with a high level of purity. The characterization of electrocarboxylated compounds was done with spectroscopic techniques like IR, NMR (1H & 13C), mass and elemental analysis.
- Singh, Kishanpal,Sohal, Harvinder Singh,Singh, Baljit
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p. 839 - 845
(2021/04/09)
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- Expanding the repertoire of nitrilases with broad substrate specificity and high substrate tolerance for biocatalytic applications
-
Enzymatic conversion of nitriles to carboxylic acids by nitrilases has gained significance in the green synthesis of several pharmaceutical precursors and fine chemicals. Although nitrilases from several sources have been characterized, there exists a scope for identifying broad spectrum nitrilases exhibiting higher substrate tolerance and better thermostability to develop industrially relevant biocatalytic processes. Through genome mining, we have identified nine novel nitrilase sequences from bacteria and evaluated their activity on a broad spectrum of 23 industrially relevant nitrile substrates. Nitrilases from Zobellia galactanivorans, Achromobacter insolitus and Cupriavidus necator were highly active on varying classes of nitriles and applied as whole cell biocatalysts in lab scale processes. Z. galactanivorans nitrilase could convert 4-cyanopyridine to achieve yields of 1.79 M isonicotinic acid within 3 h via fed-batch substrate addition. The nitrilase from A. insolitus could hydrolyze 630 mM iminodiacetonitrile at a fast rate, effecting 86 % conversion to iminodiacetic acid within 1 h. The arylaliphatic nitrilase from C. necator catalysed enantioselective hydrolysis of 740 mM mandelonitrile to (R)-mandelic acid in 4 h. Significantly high product yields suggest that these enzymes would be promising additions to the suite of nitrilases for upscale biocatalytic application.
- Rayavarapu, Pratima,Shah, Shikha,Sunder, Avinash Vellore,Wangikar, Pramod P.
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p. 289 - 296
(2020/05/18)
-
- Preparation of α-hydroxyphenylacetic acid with cyclodextrins as an effective phase-transfer catalyst and its reaction mechanism
-
An effective procedure for the synthesis of α-hydroxyphenylacetic acid with cyclodextrin (CD) catalysts was developed. The phase-transfer catalyst types, catalyst loadings, reaction times, reaction temperatures, and substrate molar ratios were investigated to optimize the reaction conditions. In addition, the factors that affect the reaction were studied, and the relationship between benzaldehyde and β-cyclodextrin (β-CD) was analyzed through 2D-ROESY. The equilibrium constant when β-CD was used as the catalyst was calculated. The results indicated that β-CD is the optimal catalyst for the reported reaction (yield: 69.08%). Furthermore, the mechanism underlying the reported reaction was proposed.
- Tian, Bing Ren,Zhang, Rui Xia,Chu, Hui Min,Huang, Qing,Wang, Zhi Zhong
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p. 359 - 368
(2019/05/16)
-
- Three-Component Synthesis of Isoquinoline Derivatives by a Relay Catalysis with a Single Rhodium(III) Catalyst
-
A rhodium(III)-catalyzed one-pot three-component reaction of N-methoxybenzamide, α-diazoester, and alkyne was developed, providing an alternative way to synthesize isoquinoline derivatives. Mechanistically, it is a relay catalysis, and the reaction occurred via successive O-alkylation and C-H activation processes, both of which were promoted by the same catalyst.
- Zhou, Chao,Jiang, Jijun,Wang, Jun
-
supporting information
p. 4971 - 4975
(2019/09/03)
-
- Thiamine Diphosphate Dependent KdcA-Catalysed Formyl Elongation of Aldehydes
-
The formose reaction, one of the oldest name reactions in organic chemistry, uses formaldehyde as a C1 unit resulting in different monosaccharides and sugar-like compounds. Nucleophilic formyl elongation is an attractive option to obtain 1,2-fu
- Germer, Philipp,Gauchenova, Ekaterina,Walter, Lydia,Müller, Michael
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p. 4276 - 4280
(2019/08/02)
-
- Characterization of a new nitrilase from Hoeflea phototrophica DFL-43 for a two-step one-pot synthesis of (S)-β-amino acids
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A nitrilase from Hoeflea phototrophica DFL-43 (HpN) demonstrating excellent catalytic activity towards benzoylacetonitrile was identified from a nitrilase tool-box, which was developed previously in our laboratory for (R)-o-chloromandelic acid synthesis from o-chloromandelonitrile. The HpN was overexpressed in Escherichia coli BL21 (DE3), purified to homogeneity by nickel column affinity chromatography, and its biochemical properties were studied. The HpN was very stable at 30–40?°C, and highly active over a wide range of pH values (pH 6.0–10.0). In addition, the HpN could tolerate against several hydrophilic organic solvents. Steady-state kinetics indicated that HpN was highly active towards benzoylacetonitrile, giving a KM of 4.2?mM and a kcat of 170?s?1, the latter of which is ca. fivefold higher than the highest record reported so far. A cascade reaction for the synthesis of optically pure (S)-β-phenylalanine from benzoylacetonitrile was developed by coupling HpN with an ω-transaminase from Polaromonas sp. JS666 in toluene-water biphasic reaction system using β-alanine as an amino donor. Various (S)-β-amino acids could be produced from benzoylacetonitrile derivatives with moderate to high conversions (73–99%) and excellent enantioselectivity (> 99% ee). These results are significantly advantageous over previous studies, indicating a great potential of this cascade reaction for the practical synthesis of (S)-β-phenylalanine in the future.
- Zhang, Zhi-Jun,Cai, Rui-Feng,Xu, Jian-He
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p. 6047 - 6056
(2018/05/15)
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- Preparation method of DL-mandelic acid
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A preparation method of DL-mandelic acid comprises: using benzaldehyde, chloroform and sodium hydroxide as materials and beta-cyclodextrin as a catalyst, including the cyclodextrin via hydrophobic cavity structure that the beta-cyclodextrin has, forming d
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-
Paragraph 0012-0017
(2018/04/02)
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- Preparation method of mandelic acid
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The invention discloses a preparation method of mandelic acid. Benzaldehyde and Benzyltriethylammonium chloride are added into a trichloromethane solvent, a certain concentration of liquid alkali is dripped at a certain temperature, after the liquid alkal
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Paragraph 0018-0057
(2019/01/07)
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- Method for preparing mandelic acid from styrene oxide
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The invention provides a method for preparing mandelic acid from styrene oxide. The preparation method comprises the following steps: preparing phenyl glycol from styrene oxide through hydration under the catalysis of a NY-series catalyst; and introducing air for selective oxidation of mandelic acid from phenyl glycol under the action of an active carbon-loaded Pd-Au catalyst. The preparation method is characterized in that raw materials are mainly composed of styrene oxide, the NY-series catalyst and the active carbon-loaded Pd-Au catalyst. The preparation method for mandelic acid uses cheap and easily available raw materials and is simple in process, mild in conditions and high in product yield and product purity.
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-
Paragraph 0041; 0044; 0047; 0050; 0053; 0056
(2017/10/07)
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- Reductive carboxylation of aromatic esters by electron transfer from magnesium metal
-
Magnesium-promoted reductive carboxylation of ethyl benzoate in the presence of chlorotrimethylsilane in N,N-dimethylformamide brought about a new carbon-carbon bond formation between the carbonyl carbon atom and carbon dioxide to give the corresponding benzoylformic acid in good yield. It is noteworthy that only ethyl benzoates with substituents at the meta-position were converted into benzoylformic acid derivatives. Moreover, no mandelic acid was detected even under the reductive conditions. This result indicates that benzoylformic acid was obtained after hydrolysis of a carboxylated intermediate, which would be alive as a stabilized structure in the reaction media.
- Maekawa, Hirofumi,Okawara, Hikaru,Murakami, Taro
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p. 206 - 209
(2016/12/28)
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- Chemoenzymatic Preparation of Enantiomerically Enriched (R)-(–)-Mandelic Acid Derivatives: Application in the Synthesis of the Active Agent Pemoline
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The enantioselective resolution of several racemic derivatives of mandelic acid methyl ester catalyzed by lipases from Pseudomonas fluorescens (Amano AK) or Burkholderia cepacia (Amano PS-C II and Amano PS-IM) has been achieved. A gram-scale lipase-mediated kinetic resolution approach has been developed that allows the facile synthesis of the corresponding methyl (R)-(–)-mandelates with excellent enantiomeric excesses (up to >99 % ee) and reaction enantioselectivity (E values up to >200). The dopaminergic agent pemoline, used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy, was synthesized with 98 % ee in a straightforward route by condensing the prepared methyl (R)-(–)-mandelate with guanidine hydrochloride under basic conditions. The desired (R)-(+)-pemoline in optically pure form (>99 % ee) was obtained after two recrystallizations from ethanol. However, it was confirmed by chiral HPLC that optically active pemoline undergoes racemization in methanol solution.
- Potera?a, Marcin,Dranka, Maciej,Borowiecki, Pawe?
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p. 2290 - 2304
(2017/05/01)
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- The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
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A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
- Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
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p. 3665 - 3673
(2017/09/11)
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- Production Of Enantiopure alpha-Hydroxy Carboxylic Acids From Alkenes By Cascade Biocatalysis
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The invention provides compositions comprising an alkene epoxidase and a selective epoxide hydrolase, such as a recombinant microorganism comprising a first heterologous nucleic acid encoding an alkene epoxidase and a second heterologous nucleic acid encoding a selective epoxide hydrolase. Exemplary alkene epoxidases include StyAB, while exemplary selective epoxide hydrolases include epoxide hydrolases from Sphingomonas, Solanum tuberosum, or Aspergillus. The invention also provides non-toxic methods of making enantiomerically pure vicinal diols or enantiomerically pure alpha-hydroxy carboxylic acids using these compositions and microorganisms.
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Paragraph 0074-0076
(2016/05/02)
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- A high-throughput screening method for determining the substrate scope of nitrilases
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Nitrile compounds are intermediates in the synthesis of pharmaceuticals such as atorvastatin. We have developed a chromogenic reagent to screen for nitrilase activity as an alternative to Nessler's reagent. It produces a semi-quantifiable blue colour and hydrolysis of 38 nitrile substrates by 23 nitrilases as cell-free extracts has been shown. This journal is
- Black, Gary W.,Brown, Nicola L.,Perry, Justin J. B.,Randall, P. David,Turnbull, Graeme,Zhang, Meng
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supporting information
p. 2660 - 2662
(2015/03/05)
-
- Solid phase behavior in the chiral systems of various 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives
-
The solid phase behavior of a series of monosubstituted F-, Cl-, Br-, I-, and CH3- and two 2,4-halogen-disubstituted 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives was investigated. The study includes detailed information about melting temperature, melting enthalpy, X-ray diffraction data, as well as selected binary phase diagrams of the respective chiral systems. Aside from the known metastable conglomerate 2-chloromandelic acid, evidence for two more metastable conglomerates was found.
- Von Langermann, Jan,Temmel, Erik,Seidel-Morgenstern, Andreas,Lorenz, Heike
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p. 721 - 728
(2015/03/30)
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- Improved performance of lipases immobilized on heterofunctional octyl-glyoxyl agarose beads
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A new heterofunctional support, octyl-glyoxyl agarose, is proposed in this study. The supports were prepared by simple periodate oxidation of the commercial octyl-agarose, introducing 25 μmol of glyoxyl groups per wet gram of support. This support was assayed with three different lipases (those from Candida antarctica (form B), Thermomyces lanuginosus (TLL) or Rhizomucor miehei) and the artificial phospholipase Lecitase Ultra. Used at pH 7, the new support maintained as first immobilization step the lipase interfacial activation. Thus, it was possible to have the purification and immobilization of the enzyme in one step. Moreover, stabilization of the open form of the lipase was achieved. The covalent enzyme/support bonds cannot be obtained if the immobilized enzyme was not incubated at alkaline pH value. This incubation at pH 10 of the previously immobilized enzymes produced a smaller decrease in enzyme activity when compared to the direct immobilization of the enzymes on glyoxyl-agarose at pH 10, because the immobilization via interfacial activation promoted a stabilization of the lipases. Except in the case of TLL (covalent attachment involved 70% of the enzyme molecules), covalent immobilization yield was over 80%. The non-covalent attached enzyme molecules were discarded by washings with detergent solutions and the new biocatalysts were compared to the octyl-agarose immobilized enzymes. While the stability in thermal and organic solvents inactivations was increased for Lecitase Ultra, CALB and RML, TLL improved its stability in organic media but its thermal stability decreased after covalent attachment of the interfacially activated enzyme. This stabilization resulted in octyl-glyoxyl-lipase preparations which presented higher activity in the presence of organic solvents. Finally, while octyl-agarose released enzyme molecules after incubation at high temperatures or in the presence of organic solvents and detergents, the covalently immobilized enzyme remained attached to the support even after boiling the enzyme in SDS, eliminating the risks of product contamination.
- Rueda, Nazzoly,Dos Santos, Jose C. S.,Torres, Rodrigo,Ortiz, Claudia,Barbosa, Oveimar,Fernandez-Lafuente, Roberto
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p. 11212 - 11222
(2015/02/05)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
-
- Evaluation of styrene-divinylbenzene beads as a support to immobilize lipases
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A commercial and very hydrophobic styrene-divinylbenzene matrix, MCI GEL CHP20P, has been compared to octyl-Sepharose beads as support to immobilize three different enzymes: lipases from Thermomyces lanuginosus (TLL) and from Rhizomucor miehie (RML) and Lecitase Ultra, a commercial artificial phospholipase. The immobilization mechanism on both supports was similar: interfacial activation of the enzymes versus the hydrophobic surface of the supports. Immobilization rate and loading capacity is much higher using MCI GEL CHP20P compared to octyl-Sepharose (87.2 mg protein/g of support using TLL, 310 mg/g using RML and 180 mg/g using Lecitase Ultra). The thermal stability of all new preparations is much lower than that of the standard octyl-Sepharose immobilized preparations, while the opposite occurs when the inactivations were performed in the presence of organic co-solvents. Regarding the hydrolytic activities, the results were strongly dependent on the substrate and pH of measurement. Octyl-Sepharose immobilized enzymes were more active versus p-NPB than the enzymes immobilized on MCI GEL CHP20P, while RML became 700-fold less active versus methyl phenylacetate. Thus, the immobilization of a lipase on this matrix needs to be empirically evaluated, since it may present very positive effects in some cases while in other cases it may have very negative ones.
- Garcia-Galan, Cristina,Barbosa, Oveimar,Hernandez, Karel,Dos Santos, Jose C. S.,Rodrigues, Rafael C.,Fernandez-Lafuente, Roberto
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p. 7629 - 7645
(2014/07/08)
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- A combination of phase transfer catalyst and ultrasonic irradiation promotes synthesis of mandelic acid
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A combination of phase transfer catalyst and ultrasonic irradiation used to promotes synthesis of mandelic acid from benzaldehyde with chloroform. The main advantages of this method are that the reaction time is much shorter and the yield is higher than t
- Zhang, Yu-Quan,Zheng, Xu-Dong,Gai, Ke,Li, Yan-Chun,Cheng, Dong-Ping
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p. 455 - 457
(2014/06/09)
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- Carboxylation with CO2 via brook rearrangement: Preparation of α-hydroxy acid derivatives
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In the presence of CsF, a wide range of α-substituted α-siloxy silanes were carboxylated under a CO2 atmosphere (1 atm) via Brook rearrangement. A variety of α-substituents including aryl, alkenyl, and alkyl groups were tolerated to afford α-hydroxy acids in moderate-to-high yields. One-pot synthesis from aldehydes using PhMe2SiLi and CO 2 was also possible, providing α-hydroxy acids without the isolation of an α-hydroxy silane.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
-
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- The preparation of various new heterocyclic compounds via cyclization of substituted derivatives of phenacyl esters of hydrazonoacetic acid
-
A procedure for the preparation of derivatives of phenacyl hydrazonopropanoates and their application in the synthesis of various heterocycles has been developed. Not only is the preparation of indole derivatives described, but also a new method for the preparation of previously unknown pyridazine derivatives.
- Melnicky, Radek,Grepl, Martin,Lycka, Antonin,Bertolasi, Valerio,Kvapil, Lubomir,Dvorakova, Barbora,Hradil, Pavel
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p. 2447 - 2457
(2013/09/23)
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- The combi-CLEA approach: Enzymatic cascade synthesis of enantiomerically pure (S)-mandelic acid
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Enantiomerically pure (S)-mandelic acid was synthesised from benzaldehyde by sequential hydrocyanation and hydrolysis in a bienzymatic cascade at starting concentrations up to 0.25 M. A cross-linked enzyme aggregate (CLEA) composed of the (S)-selective oxynitrilase from Manihot esculenta and the non-selective nitrilase from Pseudomonas fluorescens EBC 191 was employed as the biocatalyst. The nitrilase produces approx. equal amounts of (S)-mandelic acid and (S)-mandelic amide from (S)-mandelonitrile under standard conditions, but we surprisingly found that high (up to 0.5 M) concentrations of HCN induced a marked drift towards amide production. By including the amidase from Rhodococcus erythopolis in the CLEA we obtained (S)-mandelic acid as the sole product in 90% yield and >99% enantiomeric purity.
- Chmura, Andrzej,Rustler, Sven,Paravidino, Monica,Van Rantwijk, Fred,Stolz, Andreas,Sheldon, Roger A.
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p. 1225 - 1232
(2013/10/22)
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- Amberlyst A-26: An efficient and reusable heterogeneous catalyst for a one-pot oxidation-Cannizarro reaction
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Amberlyst A-26 catalyses the efficient synthesis of α-hydroxy- arylacetic acids from aryl methyl ketones in the presence of SeO2. After simple separation, the catalyst does not lose its activity and can be reused without significant loss in activity for at least four cycles.
- Shen, Ming-Gui,Shang, Shi-Bin,Song, Zhan-Qian,Wang, Dan,Rao, Xiao-Ping,Gao, Hong,Liu, He
-
-
- Efficient and selective oxidation of primary and secondary alcohols using an iron(III)/phenanthroline complex: Structural studies and catalytic activity
-
An efficient catalytic system for the oxidation of alcohols has been developed by using iron(III) catalyst [Fe(phen)2Cl 2]NO3 (1) (phen = 1,10-phenanthroline) and H 2O2 as terminal oxidant. A series of primary and secondary alcohols were oxidized into aldehydes and ketones in good yields and excellent selectivities after a short reaction time. The mononuclear iron(III) complex [Fe(phen)2Cl2]NO3 was characterized by several independent methods. The X-ray structure shows distorted octahedral geometry around the FeIII center, which is in a high-spin state (S = 5/2) according to Moessbauer study. Copyright
- Biswas, Bhaskar,Kole, Niranjan,Al-Hunaiti, Afnan,Raeisaenen, Minna T.,Ansalone, Simone,Leskelae, Markku,Repo, Timo,Chen, Yen-Tung,Tsai, Hui-Lien,Naik, Anil D.,Railliet, Antoine P.,Garcia, Yann,Ghosh, Rajarshi
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p. 4479 - 4485,7
(2020/08/24)
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- Ultrasonically-promoted synthesis of mandelic acid by phase transfer catalysis in an ionic liquid
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An efficient and facile process to synthesize mandelic acid through phase transfer catalysis (PTC; also phase transfer catalyst) using ultrasound in an ionic liquid has been developed. Mandelic acid was synthesized from benzaldehyde with chloroform in an
- Hua, Qian,Dabin, Liu,Chunxu, Lv
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experimental part
p. 1035 - 1037
(2012/03/12)
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- Synthesis of racemic mandelic acids with the composite phase transfer catalyst β-cyclodextrin-[bmim]PF6
-
Ionic liquids were employed as a part of composite phase transfer catalyst to synthesise mandelic acid, and it is found that [bmim]PF6 coupled with β-cyclodextrin is the most effective catalyst, which was also applicable to other reactions used to synthesise mandelic acid derivatives. Reaction conditions were optimized and the products were characterised by 1H NMR and IR.
- Yang, Ben-Yong,Yang, De-Hong
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experimental part
p. 484 - 485
(2011/11/29)
-
- Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate
-
Propylene carbonate can be used as a green solvent for the asymmetric synthesis of cyanohydrin trimethylsilyl ethers from aldehydes and trimethylsilyl cyanide catalysed by VO(salen)NCS, though reactions are slower in this solvent than the corresponding re
- North, Michael,Omedes-Pujol, Marta
-
experimental part
p. 1043 - 1055
(2011/03/22)
-
- Biocatalytic racemization of α-hydroxycarboxylic acids using a stereo-complementary pair of α-hydroxycarboxylic acid dehydrogenases
-
Biocatalytic racemization of aliphatic, (aryl)aliphatic and aromatic α-hydroxycarboxylic acids was achieved via a reversible oxidation-reduction sequence using a pair of stereo-complementary Prelog- and anti-Prelog d- and l-α-hydroxyisocaproate dehydrogenases from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008, resp., overexpressed in Escherichia coli. The mild reaction conditions ensured essential 'clean' isomerization, undesired 'over-oxidation' of the substrate forming the α-ketoacid could be suppressed by exclusion of O2 and adjustment of the NAD+/NADH-ratio.
- Bodlenner, Anne,Glueck, Silvia M.,Nestl, Bettina M.,Gruber, Christian C.,Baudendistel, Nina,Hauer, Bernhard,Kroutil, Wolfgang,Faber, Kurt
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experimental part
p. 7752 - 7755
(2009/12/04)
-
- Exploring the biocatalytic scope of alditol oxidase from Streptomyces coelicolor
-
The substrate scope of the flavoprotein alditol oxidase (AldO) from Streptomyces coelicolor A3(2), recombinantly produced in Escherichia coli, was explored. While it has been established that AldO efficiently oxidizes alditols to D-aldoses, this study revealed that the enzyme is also active with a broad range of aliphatic and aromatic alcohols. Alcohols containing hydroxy groups at the C-1 and C-2 positions like 1,2,4-butanetriol (Km=170 mM, k cat -4.4s-1), 1,2-pentanediol (Km=52 mM, k cat=0.85 s-1) and 1,2-hexanediol (Km=97 mM, kcat=2.0s-1) were readily accepted by AldO. Furthermore, the enzyme was highly enantioselective for the oxidation of 1,2-diols [e.g., for l-phenyl-1,2-ethanediol the (R)-enantiomer was preferred with an Is-value of 74]. For several diols the oxidation products were determined by GC-MS and NMR. Interestingly, for all tested 1,2-diols the products were found to be the a-hydroxy acids instead of the expected α-hydroxy aldehydes. Incubation of (R)-1-phenyl-1,2-ethanediol with 18O-labelled water (H 218O) revealed that a second enzymatic oxidation step occurs via the hydrate product intermediate. The relaxed substrate specificity, excellent enantioselectivity, and independence of coenzymes make AldO an attractive enzyme for the preparation of optically pure 1,2-diols and α-hydroxy acids.
- Van Hellemond, Erik W.,Vermote, Linda,Koolen, Wilma,Sonke, Theo,Zandvoort, Ellen,Heuts, Dominic P. H. M.,Janssen, Dick B.,Fraaije, Marco W.
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experimental part
p. 1523 - 1530
(2011/03/22)
-
- Racemic Separation of 2,6-Trans-Dimethymorpholine
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A process for preparing optically active trans-2,6-dimethylmorpholine by (i) reacting racemic trans-2,6-dimethylmorpholine with D-mandelic acid, (ii) removing the salt formed from D-mandelic acid and one enantiomer of trans-2,6-dimethylmorpholine from the other enantiomer of trans-2,6-dimethylmorpholine and (iii) isolating the desired optically active trans-2,6-dimethylmorpholine.
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Page/Page column 2
(2009/01/24)
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- Enantioselective conversion of α-arylnitriles by Klebsiella oxytoca
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A new bacterial isolate Klebsiella oxytoca 38.1.2 with stereoselective nitrile hydratase activity against rac-2-phenylglycine nitrile, rac-2-phenylpropionitrile and rac-mandelonitrile was investigated. The cultivation conditions for growth and nitrile hydratase formation were studied. An intracellular (S)-enantioselective nitrile hydratase and a putative (S)-selective amidase were found to be induced in the presence of rac-2-phenylpropionitrile. The temperature dependence on the enantioselectivity of the nitrile hydratase active cells was studied in more detail for the biotransformation of rac-2-phenylpropionitrile and rac-mandelonitrile. By increasing the temperature from 15 °C to 37 °C, the apparent enantiomeric ratio of the conversion of rac-2-phenylpropionitrile to (S)-2-phenylpropionamide increased from 16 to 35 at nearly 50% conversion rate. rac-Mandelonitrile was converted to (S)-mandelamide with an enantiomeric excess of up to 95% in a 80% yield without further conversion to mandelic acid.
- Ewert, Christian,Lutz-Wahl, Sabine,Fischer, Lutz
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body text
p. 2573 - 2578
(2009/04/06)
-
- Stereoselective insertion of rhodium carbenoid to water under control with intramolecular participation of hydroxy group
-
A chiral diazo ester having a hydroxy group in the proper geometry produces an adduct with water up to 92% de upon treatment with a rhodium catalyst. This high stereoselectivity is attributable to the intramolecular hydrogen bond between the internal hydroxy group and the rhodium carbenoid. Copyright
- Sugimura, Takashi,Nagai, Takao
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p. 286 - 287
(2008/09/20)
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- Medium effects on Zwitterionic-biradicaloid intermediates from two phenyl-α-oxoamides. Irradiations in fluid and solid protic media, neat solid phases, and the solid, smectic and isotropic phases of a completely saturated phosphonium salt at different tem
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The photochemical processes of two N,N-dialkyl phenyl-α-oxoamides, N,N-diisopropyl phenyl-α-oxoamide (1) and N,N-dibenzyl phenyl-α-oxoamide (2), are investigated at different temperatures in methanol and ethylene glycol (to probe the influences of H-bondi
- Chesta, Carlos A.,George, Mathew,Luo, Chuping,Weiss, Richard G.
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p. 570 - 583
(2008/09/17)
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- Modulation of immobilized lipase enantioselectivity via chemical amination
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The aspartic and glutamic carboxylic groups of the surface of three different immobilized lipases (those from Candida antarctica (form B) (CAL-B), Thermomyces lanuginose (TLL) and Pseudomonas fluorescens (PFL) have been modified with ethylenediamine (after activation of the carboxylic function with carbodiimide). The exchange of groups with a negative charge for positively charged groups permitted us to greatly alter the activity, specificity and stereoselectivity of the lipase. Thus, in some cases, the activity of the lipases increased after the chemical modification while in other cases the activity was strongly reduced. Moreover, the effect of the experimental conditions on the activity was also strongly altered. Remarkably, the enantioselectivity of the enzymes in the hydrolysis of different mandel ic acid derivatives was strongly modulated. For example, amination of the CNBr-CAL-B preparation greatly increased the enantioselectivity of the enzyme in the hydrolysis of (±)-2-hydroxyphenylacetic acid methyl ester, from an E value of 2 without modification up to E>100, affording (R)-mandelic acid in high purity (ee>99% at 50% conversion) at pH 7 and 4°C. Thus, the chemical modification of lipases seems to be a very powerful tool to improve their performance as enantioselective biocatalvsts.
- Palomo, Jose M.,Fernandez-Lorente, Gloria,Guisan, Jose M.,Fernandez-Lafuente, Roberto
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p. 1119 - 1127
(2008/09/17)
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- Exploring the synthetic applicability of a cyanobacterium nitrilase as catalyst for nitrile hydrolysis
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The substrate specificity and synthetic applicability of the nitrilase from cyanobacterium Synechocystis sp. strain PCC 6803 have been examined. This nitrilase catalyzed the hydrolysis of both aromatic and aliphatic nitriles to the corresponding acids in high yields. Furthermore, the stereoselective hydrolysis of phenyl-substituted β-hydroxy nitriles to (S)-enriched β-hydroxy carboxylic acids and selective hydrolysis of α,ω- dinitriles with five or less methylene groups to ω-cyano carboxylic acids have been achieved. This suggested that nitrilase from Synechocystis sp. PCC 6803 could be a useful enzyme catalyst for the "green" nitrile hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Hua, Ling
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p. 5238 - 5242
(2007/10/03)
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- Aerial oxidation of the glucocorticoid side-chain under pH control
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The outcome of aerial oxidation of the glucocortico-steroid side-chain (as exemplified by dexamethasone) has been shown to be subject to strict pH control. At pH 7.4 the glyoxal is the only product; at pH values of 8 and 9.2 the etioacid is formed, and at
- Edmonds, John S.,Morita, Masatoshi,Turner, Peter,Skelton, Brian W.,White, Allan H.
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- A photocatalytic acid- and base-free Meerwein-Ponndorf-Verley-type reduction using a [Ru(bpy)3]2+/viologen couple
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A photocatalytic system to effect the Meerwein-Ponndorf-Verley reduction of carbonylic compounds to alcohols has been developed. The system comprises [Ru(bpy)3]2+ as a photosensitizer, triethanolamine as a sacrificial electron donor,
- Herance, Jose Raul,Ferrer, Belen,Bourdelande, Jose Luis,Marquet, Jordi,Garcia, Hermenegildo
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p. 3890 - 3895
(2008/02/06)
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- Novel catalytic tandem isomerisation/cyclisation reaction of α-methallyloxy carboxylic acids
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A new tandem isomerisation/cyclisation of α-methallyloxy carboxylic acids leading to substituted 1,3-dioxolan-4-ones in 60-70 % yields was catalysed by Cu(OTf)2 or Al(OTf)3. Extension to the synthesis of oxathiolanones and oxathianon
- Chaminade, Xavier,Coulombel, Lydie,Olivero, Sandra,Dunach, Elisabet
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p. 3554 - 3557
(2007/10/03)
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- Inhibition of mandelate racemase by the substrate-intermediate-product analogue 1,1-diphenyl-1-hydroxymethylphosphonate
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Mandelate racemase has been studied as a paradigm for enzyme-catalyzed abstraction of a proton from carbon acids with relatively high pKa values. 1,1-Diphenyl-1-hydroxymethylphosphonate is a substrate-intermediate- product analogue and is a mod
- Burley, Rodney K. M.,Bearne, Stephen L.
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p. 4342 - 4344
(2007/10/03)
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- The dimethyldioxirane-mediated oxidation of phenylethyne
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The product pattern found for the dimethyldioxirane-mediated oxidation of phenylethyne strongly depends on the reaction conditions. Dimethyldioxirane generated in situ from caroate (HSO5) and acetone in acetonitrile-water furnishes phenylacetic acid as the main product. With solutions of dimethyldioxirane in acetone, mandelic acid and phenylacetic acid are mainly formed. The relative abundances of the two acids depend on the residual water present in the dimethyldioxirane-acetone solution. Application of thoroughly dried solutions of the reagent effects increased formation of mandelic acid. When phenylethyne is oxidized by dimethyldioxirane transferred into tetrachloromethane, to minimize traces of water even further, oligomeric mandelic acid is obtained. The results are rationalized by the initial formation of phenyloxirene, which is known to equilibrate with phenylformylcarbene and bcnzoylcarbene. Subsequent Wolff rearrangement produces intermediate phenylketene, which can be trapped by water as phenylacetic acid or suffer from further oxidation to the α-lactone of mandelic acid. The α-lactone can either react with water to yield mandelic acid or, under anhydrous conditions, to yield oligomeric mandelic acid. In addition to mandelic acid and phenylacetic acid phenylglyoxylic acid, benzoic acid and benzaldehyde are observed as reaction products. The formation of phenylglyoxylic acid by transfer of two oxygen atoms to the in rear ranged carbon skeleton of phenylethyne followed by oxygen insertion into the aldehydic C-H bond of the intermediately formed phenylglyoxal is discussed. In a second pathway this acid is formed by partial oxidation of mandelic acid. Benzaldehyde and benzoic acid are explained as products of the oxidative degradation of the α-lactone by dimethyldioxirane. Under in situ conditions benzoic acid is also formed by caroate initiated oxidative decarboxylation of phenylglyoxylic acid and/or intermediate phenylglyoxal. The Royal Society of Chemistry 2005.
- Zeller, Klaus-Peter,Kowallik, Meike,Haiss, Peter
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p. 2310 - 2318
(2007/10/03)
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- Facile deoxygenation of dicarbonyl compounds using a samarium diiodide-additive system
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The reduction of α- and β-dicarbonyl compounds was investigated with samarium diiodide in the presence of additive. Diketones and ketocarboxylic acids were easily reduced at room temperature to give the mono-alcohols in good to excellent yield, and ketoester afforded the saturated ester as the major product in moderate yield. These reductions containing the reductive deoxygenation can be rapidly performed under the facile and mild conditions by this method.
- Kamochi, Yasuko,Kudo, Tadahiro,Masuda, Toshinobu,Takadate, Akira
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p. 1017 - 1020
(2007/10/03)
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- Improved solution- and solid-phase preparation of hydroxamic acids from esters
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The addition of small amounts of solid KCN to solution and solid-phase esters in THF/MeOH/50% aqueous NH2OH increases the efficiency of their transformation to the corresponding hydroxamic acids.
- Ho, Chih Y.,Strobel, Eric,Ralbovsky, Janet,Galemmo Jr., Robert A.
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p. 4873 - 4875
(2007/10/03)
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- Synthetic utility of bowl-shaped tris(2,6-diphenyl-benzyl)silyl glyoxylate as a stable glyoxylate: Application to highly diastereoselective aldol reactions
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A stable glyoxylate can be successfully applied to both syn- and anti-selective aldol reactions by using two different kinds of ordinary Lewis acids. Thus, treatment of bowl-shaped tris(2,6-diphenylbenzyl)silyl glyoxylate 1 with enol silyl ether under the influence of BF3·OEt2 gave syn-aldol product, while the use of TiCl4 afforded anti-aldol product with >97% selectivity.
- Shirakawa, Seiji,Maruoka, Keiji
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p. 281 - 284
(2007/10/03)
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- Chemo-enzymatic synthesis of enantiomerically pure (R)-2-naphthylmethoxyacetic acid
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Enantiomerically pure (R)-2-naphthylmethoxyacetic acid (2-NMA) was synthesized from 2-naphthaldehyde via an integrated chemo-enzymatic procedure. The one-pot, successive use of SnBr2-TMSCN and AcBr worked effectively to give a racemic cyanohydrin acetate. Lipase from Burkholderia cepacia then mediated the highly enantioselective hydrolysis of the (S)-enantiomer of the racemate, leaving the (R)-acetate with an e.e. of >99.9%. The resulting product of this enzyme-catalyzed hydrolysis, an (S)-cyanohydrin, spontaneously decomposed into naphthaldehyde, the starting material of this synthetic route, which could be recycled. The hydration of nitrile to amide as well as the hydrolysis of the acetate was performed with a microorganism, Rhodococcus rhodochrous, under very mild conditions without any loss of the enantiomeric purity. The amide group was hydrolyzed with nitrosylsulfuric acid, and the product was isolated as an α-hydroxy ester. The α-hydroxyl group was methylated with diazomethane-silica gel and the final task, hydrolysis of the ester, was accomplished under conditions as mild as neutral pH with an esterase from Krebsiella oxytoca to give enantiomerically pure 2-NMA.
- Kimura, Mayumi,Kuboki, Atsuhito,Sugai, Takeshi
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p. 1059 - 1068
(2007/10/03)
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- Enantiomerically pure substituted oxaaza compounds, salts of the same, and processes for the preparation of both
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This invention provides a method for conveniently obtaining a compound of formula (Ia) which is a production intermediate of antimicrobial compounds, in which a salt of optically active acid of formula (IIIa) is obtained by allowing a compound of formula (I), a ketone compound and an optically active acid to react with one another, converted into its free form and then hydrolyzed. In the formula, R1: hydrogen atom or alkyl, aryl or aralkyl group; R2: hydrogen atom or alkyl, aryl, aralkyl, acyl, alkyloxycarbonyl, aralkyloxycarbonyl or substituted sulfonyl; these may further have substituents.)
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- Mapping the substrate selectivity of new hydrolases using colorimetric screening: Lipases from Bacillus thermocatenulatus and Ophiostoma piliferum, esterases from Pseudomonas fluorescens and Streptomyces diastatochromogenes
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Recent advances in biochemistry and molecular biology have simplified the discovery and preparation of new hydrolases. Although these hydrolases might solve problems in organic synthesis, measuring their selectivity, especially enantioselectivity, remains tedious and time consuming. Recently, we developed a colorimetric screening method to measure the enantioselectivity of hydrolases. Here we apply this rapid screening method to map the substrate selectivity of four new hydrolases: lipases from the thermophilic Bacillus thermocatenulatus (DSM 730, BTL2) and a filamentous fungus Ophiostoma piliferum (NRRL 18917, OPL) and esterases from two bacteria, Pseudomonas fluorescens (SIK-W1, esterase I, PFE) and Streptomyces diastatochromogenes (Tue 20, SDE). We screened a general library of 29 substrates and a chiral library of 23 pairs of enantiomers. All four hydrolases catalysed the hydrolysis of unnatural substrates, but the two lipases accepted a broader range of substrates than the two esterases. As expected, the two lipases favoured more hydrophobic substrates, while the two esterases showed a preference for smaller substrates. Several moderately enantioselective reactions were identified for the solketal esters: BTL2, butyrate, E = 7.9 (R); octanoate, E = 4.9 (R) and 3-bromo-2-methyl propionate methyl esters, PFE, E = 12 (S); SDE, E = 5.6 (S). OPL showed low enantioselectivity toward all substrates tested. The current colorimetric screen could not measure the selectivity for several slow-reacting substrates. Traditional screening identified high enantioselectivity of BTL2 and PFE toward one of these slow substrates, 1-phenylethyl acetate (E>50).
- Liu, Andrew Man Fai,Somers, Neil A.,Kazlauskas, Romas J.,Brush, Terry S.,Zocher, Frank,Enzelberger, Markus M.,Bornscheuer, Uwe T.,Horsman, Geoff P.,Mezzetti, Alessandra,Schmidt-Dannert, Claudia,Schmid, Rolf D.
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p. 545 - 556
(2007/10/03)
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- Process for the separation of a mixture of enantiomers
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A diastereomer complex obtained via a process for the separation of enantiomers is disclosed, wherein separation can be rapidly effected such that enantiomers are obtained with high e.e. values. The process pets the separation of mixtures of enantiomers in which more than one resolving agent is used, of which at least one resolving agent is optically active, and which yields a diastereomer complex containing at least two resolving agents in optically active form. The process provides for, inter alia, a diastereomer complex having at least three compounds of which at least two compounds are resolving agents in optically active form, and at least one compound is an onantiomer in optically active form. Also provided is a diastereomer complex having at least three compounds of which at lea one compound is a resolving agent in optically active form, and at least two compounds which are enantiomers in optically active form.
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