- Enhanced catalytic activity of lipase in situ encapsulated in electrospun polystyrene fibers by subsequent water supply
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Rhizopus oryzae lipase prepared was immobilized in polystyrene electrospun fibers from a suspension of crude lipase powder in an N,N-dimethylformamide solution of polystyrene. The performance of the enzyme was enhanced by supplying water onto the resultant non-woven fabric. The electrospun fibers supplied with water by spraying showed 47-fold faster initial transesterification rate measured as conversion of (S)-glycidol to glycidyl n-butyrate with vinyl n-butyrate compared with a non-encapsulated crude lipase control. Before being moistened with water, the initial transesterification rate was slower than non-encapsulated lipase. The encapsulated and moistened lipase showed 77% of residual activity after 10 cycles of use.
- Sakai, Shinji,Yamaguchi, Tetsu,Watanabe, Rie,Kawabe, Masaaki,Kawakami, Koei
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Read Online
- Synthesis and enzymatic resolution of racemic 2,3-epoxy propyl esters obtained from glycerol
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A method is described for the synthesis of (±)-2,3-epoxy propyl esters from glycerol, involving reaction of epichlorohydrin with sodium or potassium salts of carboxylic acids in the presence of TBAB as catalyst, with moderate to excellent yields. Kinetic resolution of glycidyl butyrate by lipase of Thermomyces lanuginosa has been achieved with remarkable enantiomeric excess (ee >99%) using 1,4-dioxane as a co-solvent in pure buffer solution (30 and 50 °C, pH = 7.0).
- Araujo, Yara Jaqueline Kerber,Avvari, Naga Prasad,Paiva, Derisvaldo Rosa,De Lima, Dênis Pires,Beatriz, Adilson
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supporting information
p. 1696 - 1698
(2015/03/14)
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- Dinuclear salen cobalt complex incorporating Y(OTf)3: enhanced enantioselectivity in the hydrolytic kinetic resolution of epoxides
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The activation of inactive Jacobsen's chiral salen Co(ii) (salen = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine) compound is attained by dinuclear chiral salen Co(iii)-OTf complex formation with yttrium triflate. The yttrium metal not only displays a promoting effect on electron transfer, but also assists in forming two stereocentres of a Lewis acid complex with Co(iii)-OTf. We found that the binuclear Co-complex significantly enhanced reactivity and enantioselectivity in the hydrolytic kinetic resolution of terminal epoxides compared to its analogous monomer and kinetic data are also consistent with these results.
- Patel, Deepak,Kurrey, Ganesh Ram,Shinde, Sandip S.,Kumar, Pradeep,Kim, Geon-Joong,Thakur, Santosh Singh
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p. 82699 - 82703
(2015/10/19)
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- Chemoselective CaO-mediated acylation of alcohols and amines in 2-methyltetrahydrofuran
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Calcium oxide is proposed as an innocuous acid scavenger for the chemoselective synthesis of amide- and ester-type compounds. Although these molecules have wide spread applications in organic and pharmaceutical chemistry, and a large number of routes have been designed for their synthesis, the development of more efficient and environmentally friendly acylation strategies remains an ongoing challenge. The use of CaO allows for the stoichiometric acylation of primary alcohols in the presence of phenols or tertiary alcohols; amines can also be subjected to acylation reactions in the presence of hydroxyl groups. Chirality is obtained through acylation if the starting material is an optically pure alcohol or if a chiral acylating agent is used. Furthermore, the use of 2-methyltetrahydrofuran (2-MeTHF), a more ecofriendly solvent, leads to maximized yields. This protocol is successfully applied to the synthesis of an interesting N-aryloxazolidin-2-one intermediate for the preparation of linezolid-type compounds.
- Pace, Vittorio,Hoyos, Pilar,Alcántara, Andrés R.,Holzer, Wolfgang
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p. 905 - 910
(2013/07/27)
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- Stereoselective synthesis of (R)-glycidyl butyrate from racemic glycidyl butyrate or epichlorohydrin via hydrolytic kinetic resolution
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The differences of (R)-glycidyl butyrate synthesis via hydrolytic kinetic resolution of glycidyl butyrate directly or regioselective opening epichlorohydrin as key steps by using Jacobsen's hydrotic kinetic resolution are compared. In the view of separation problem, it is hard to get the pure (R)-glycidyl butyrate by kinetic resolution of glycidyl butyrate directly. Via kinetic resolution of epichlorohydrin, treatment with butyric acid in the presence of CrCl3 and then epoxidation with NaOH, the total yield of 38.5% and optical purity of 99% are obtained.
- Jiang, Chengjun,Yan, Jianbo
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scheme or table
p. 242 - 243
(2012/05/19)
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- PROCESS FOR THE PREPARATION OF GLYCIDYL DERIVATIVES
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There is provided a process for preparing a glycidyl derivative from 3-chloro-1,2-propanediol, comprising i) adding a phosphate salt to a solution into which 3-chloro-1,2-propanediol is dissolved into a solvent to produce glycidol, and ii) adding to the solution of step i) a base capable of releasing a glycidyl group from the glycidol and a substrate susceptible to nucleophilic attack to produce the desired glycidyl derivative by nucleophilic attack of the glycidyl group to the substrate.
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Page/Page column 6-7; 9
(2008/06/13)
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- A new dinuclear chiral salen complexes for asymmetric ring opening and closing reactions: Synthesis of valuable chiral intermediates
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A new dinuclear chiral Co(salen) complexes bearing group 13 metals have been synthesized and characterized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity for the asymmetric ring opening of epoxides with H2O, chloride ions and carboxylic acids and consequently provide enantiomerically enriched terminal epoxides (>99% ee). It also catalyzes the asymmetric cyclization of ring opened product, to prepare optically pure terminal epoxides in one step. The homogeneous dinuclear chiral Co(salen) have been covalently immobilized on MCM-41. The potential benefits of heterogenization include facilitation of catalyst separation and recyclability requiring very simple techniques. The system described is very efficient.
- Thakur, Santosh Singh,Chen, Shu-Wei,Li, Wenji,Shin, Chang-Kyo,Kim, Seong-Jin,Koo, Yoon-Mo,Kim, Geon-Joong
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p. 1862 - 1872
(2007/10/03)
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- Synthesis of optically active 2-hydroxy monoesters via-kinetic resolution and asymmetric cyclization catalyzed by heterometallic chiral (salen) Co complex
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The binuclear chiral (salen) Co complexes bearing Lewis acids of Al and Ga catalyze regio- and enantioselective ring opening of terminal epoxides with carboxylic acids. The ring opened product of epichlorohydrin with carboxylic acids followed by cyclization step in the presence of catalyst and base represent straightforward, efficient methods for the synthesis of enatiomerically enriched (>99% ee) valuable terminal epoxides. Strong synergistic effects of different Lewis acid of Co-Al and Co-Ga were exhibited in the catalytic process.
- Li, Wenji,Thakur, Santosh Singh,Chen, Shu-Wei,Shin, Chang-Kyo,Kawthekar, Rahul B.,Kim, Geon-Joong
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p. 3453 - 3457
(2007/10/03)
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- Synthesis of enantiomerically pure glycidol via a fully enantioselective lipase-catalyzed resolution
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The efficient enzymatic synthesis of enantiopure 2,3-epoxypropanol (glycidol) has been achieved. The racemic glycidyl butyrate was successfully resolved by enzymatic hydrolysis using a strategy that combines different immobilization protocols and different experimental reaction conditions. A new enzyme (25 kDa lipase)-which is a lipase-like enzyme purified from the pancreatic porcine lipase (PPL) extract-immobilized on DEAE-Sepharose was selected as the optimal biocatalyst. The optimal results were obtained at pH 7, 25°C and 10% dioxane using this biocatalyst and a very high enantioselectivity for the enzyme was displayed, obtaining both (R)-(-)-glycidyl butyrate and (R)-(+)-glycidol with enantiomeric excesses >99% (E >100). The hydrolysis of (R)-(-)-glycidyl butyrate produced pure (S)-(-)-glycidol.
- Palomo, Jose M.,Segura, Rosa L.,Mateo, Cesar,Terreni, Marco,Guisan, Jose M.,Fernandez-Lafuente, Roberto
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p. 869 - 874
(2007/10/03)
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- Process for preparation of optically active halogeno hydroxypropyl compound and glycidyl compound
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A process for preparing regioselectively an optically active 1-halogeno-2-hydroxypropyl compound of the following formula; wherein X is halogen atom and Nu is a heteroatom having a substituent, and an optically active glycidyl compound of the formula; which comprises reacting an optically active epihalohydrin of the formula; with a neucleophilic agent, in the presence of a metal complex of the formula; wherein n is an integer of 0, 1 or 2, Y1, Y2 and Y3 are hydrogen atom, etc., and Y2 and Y3 may form a ring such as benzene, A is a counterion and M is a metal ion, and further subjecting the compound (4) to reaction with a base to prepare the optically active glycidyl compound (5).
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- Enzymatic resolution of (±)-glycidyl butyrate in aqueous media. Strong modulation of the properties of the lipase from Rhizopus oryzae via immobilization techniques
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The enantioselectivity of the lipase from Rhizopus oryzae for the small yet highly interesting (±)-glycidyl butyrate have been greatly modulated by the use of different immobilization techniques. Thus, the enzyme immobilized by interfacial adsorption on an octyl-agarose support presented a very low enantioselectivity (E=2). This value could be improved up to an E=17 by covalently immobilizing the enzyme on the cyanogen bromide agarose. However, the best results were achieved by immobilizing the enzyme via ionic adsorption on supports coated with dextran sulfate, with an E value of 51 (ee99% at 55% conversion).
- Palomo, Jose M.,Segura, Rosa L.,Fernandez-Lorente, Gloria,Guisan, Jose M.,Fernandez-Lafuente, Roberto
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p. 1157 - 1161
(2007/10/03)
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- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
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The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
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p. 1307 - 1315
(2007/10/03)
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