- Enantioselective Resolution Copolymerization of Racemic Epoxides and Anhydrides: Efficient Approach for Stereoregular Polyesters and Chiral Epoxides
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Herein we report an efficient strategy for preparing isotactic polyesters and chiral epoxides via enantioselective resolution copolymerization of racemic terminal epoxides with anhydrides, mediated by enantiopure bimetallic complexes in conjunction with a nucleophilic cocatalyst. The chirality of both the axial linker and the diamine backbones of the ligand are responsible for the chiral induction of this kinetic resolution copolymerization process. The catalyst systems exhibit exceptional levels of enantioselectivity with a kinetic resolution coefficient exceeding 300 for various racemic epoxides, affording highly isotactic copolymers (selectivity factors of more than 300) with a completely alternating structure and low polydispersity index. Most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures in the range from 77 to 160 °C.
- Li, Jie,Ren, Bai-Hao,Wan, Zhao-Qian,Chen, Shi-Yu,Liu, Ye,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 8937 - 8942
(2019/06/11)
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- Synthesis of an advanced intermediate enroute to thiomarinol antibiotics
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A stereoselective synthesis of the C1-C14 fragment of thiomarinols is disclosed. The key steps include the stereoselective preparation of an allylic sulfide via a chloro sulfide by 1,2-asymmetric induction, ring-closing metathesis reaction, Kirmse-Doyle reaction for the preparation of a γ,δ-unsaturated ester, Nozaki-Hiyama-Kishi coupling and Julia-Kocienski olefination reaction. Substrate controlled asymmetric induction has been advantageously employed for the creation of stereogenic centers. Noyori transfer hydrogenation and asymmetric hydrogenation reactions have been utilized for the creation of carbinol stereocenters.
- Raghavan, Sadagopan,Ravi, Anil
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p. 2814 - 2823
(2017/04/14)
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- Immobilized Aspergillus niger epoxide hydrolases: Cost-effective biocatalysts for the prepation of enantiopure styrene oxide, propylene oxide and epichlorohydrin
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This study aimed to prepare robust immobilized epoxide hydrolase (EH) preparations for asymmetric hydrolysis of racemic epoxides such as styrene oxide, propylene oxide and epichlorohydrin. For this purpose, Aspergillus niger EH was immobilized onto Lewatit VP OC 1600 support by adsorption, modified Florisil and Eupergit C supports by covalently. The suitability of the supports was examined for protein binding capacity and rate of racemic styrene oxide hydrolysis. The protein-activity recovery yields were 75-85%, 82-78% and 90-75%, respectively for EH immobilized onto Lewatit VP OC 1600, modified Florisil and Eupergit C supports. All A. niger EH preparations catalyzed preferentially hydrolysis of (R)-epoxides. Although enantiomeric excess values of all the tested epoxides were 99%, the highest enantiopure epoxide yields were obtained as 48% for (S)-styrene oxide by the immobilized EHs onto modified Florisil and Eupergit C. The highest diol yield was obtained as 78% for 3-chloro-1,2-propanediol, however, its enantiomeric excess value was 28.2%. Enantioselectivity of A. niger EH was improved with the preparation of mentioned immobilized forms. The highest enantioselectivity value was obtained as 95 toward styrene oxide by A. niger EH immobilized onto modified Florisil . The results of reusability studies show that the immobilized EH preparations offer feasible potentials for the preparation of enantiopure epoxides than that of free form.
- Yildirim, Deniz,Tuekel, S. Seyhan,Alptekin, Oezlem,Alagoez, Dilek
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- P-Tolyl glycerol ether: Is it possible to find more simple molecular organogelator with pronounced chirality driven properties?
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p-Tolyl glycerol ether not belonging to any of the known gelator families forms stable transparent gels in hydrocarbon media showing very good quantitative characteristics of gelling abilities, which are, in turn, strongly dependent on the chiral characteristics of the gelator. The crystal packing differences between the rac- and scal-substances could be the reason for such behaviour.
- Bredikhin, Alexander A.,Bredikhina, Zemfira A.,Akhatova, Flyura S.,Gubaidullin, Aidar T.
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supporting information; experimental part
p. 3523 - 3525
(2010/08/06)
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- Cooperative activation in the hydrolytic kinetic resolution of epoxides by a bis-cobalt(III)salen-calix[4]arene hybrid
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A chiral, bimetallic cobalt(III)salen-calix[4]arene hybrid structure was prepared and tested in the hydrolytic kinetic resolution (HKR) of racemic epoxides. Kinetic studies have revealed that the two catalytic units on the upper rim of the calixarene scaffold are able to activate the reactants in a cooperative and primarily intramolecular mode. High enantioselective behaviour was observed and besides, a higher stability was found for the bimetallic catalyst as compared to a monometallic reference complex.
- Wezenberg, Sander J.,Kleij, Arjan W.
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supporting information; experimental part
p. 85 - 91
(2010/06/21)
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- Hydrolytic kinetic resolution of terminal epoxides catalyzed by novel bimetallic chiral Co (salen) complexes
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Novel bimetallic chiral Co (salen) complexes bearing transition-metal salts have been synthesized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity in hydrolytic kinetic resolution (HKR) of racemic terminal epoxides and consequently provided enantiomerically enriched epoxides (up to 99% ee). Copyright Taylor & Francis Group, LLC.
- Kawthekar, Rahul B.,Kim, Geon-Joong
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p. 1236 - 1248
(2008/09/18)
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- Iron-catalyzed asymmetric olefin cis-dihydroxylation with 97% enantiomeric excess
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Big cis-ster: The use of an (R,R)-bipyrrolidine backbone with two α-methylpyridine pendant arms affords a tetradentate N4 ligand that coordinates an iron center with cis-α topology (see picture; Fe purple, C gray, N blue, O red, S yellow, F green). This complex catalyzes the reaction between H2O2 and cis-2-heptene to afford a cis-diol product in very high enantioselectivity. (Figure Presented)
- Suzuki, Ken,Oldenburg, Paul D.,Que Jr., Lawrence
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p. 1887 - 1889
(2008/12/22)
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- 4(2)-Methoxyphenyl glycerol ethers in the synthesis of nonracemic di-O,O-acylglycerols
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Effective methods for the synthesis of nonracemic 4-and 2-methoxyphenyl glycerol ethers from nonracemic 3-chloropropanediols and by direct resolution of the racemate, respectively, were developed. Some existing discrepancies related to the to chiroptical properties of their derivatives were eliminated. Both ethers were used to synthesize nonracemic 3-O-aryloxy-1,2-di-O',O'-palmitoyl glycerols.
- Bredikhina,Novikova,Efremov,Sharafutdinova,Bredikhin
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experimental part
p. 2320 - 2323
(2010/02/15)
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- Continuous enantioselective kinetic resolution of terminal epoxides using immobilized chiral cobalt-salen complexes
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Jacobsen's cobalt-salen complex was covalently immobilized on polymer carriers that are part of different technical setups (polymer powder, composite Raschig rings, PASSflow microreactors) and employed for the enantioselective ring opening of terminal epoxides with water and phenols. The polymer-supported catalysts showed good activity and stereoselectivity and could be used repeatedly after a simple reactivation protocol in both batch as well as continuous-flow modes. Georg Thieme Verlag Stuttgart.
- Solodenko, Wladimir,Jas, Gerhard,Kunz, Ulrich,Kirschning, Andreas
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p. 583 - 589
(2007/12/25)
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- Asymmetric ring-opening of epoxides on chiral Co(Salen) catalyst synthesized in SBA-16 through the "ship in a bottle" strategy
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Chiral Co(Salen) complex was synthesized in the mesoporous cage of SBA-16 through the "ship in a bottle" method. The pore entrance size of SBA-16 was precisely tailored by varying the autoclaving time and silylation with phenyltrimethoxysilane to trap Co(Salen) complex in the cage of SBA-16. Chiral Co(Salen) trapped in SBA-16 shows enantioselectivity (up to 87-96% ee) as high as that of the homogeneous catalyst for the asymmetric ring opening of terminal epoxides and can be recycled at least 10 times with no apparent loss of activity. The activity for the catalyst trapped inside SBA-16 can be significantly increased when the surface is modified with organic groups. This work extends the "ship in a bottle" synthesis from microporous materials to mesoporous cage-like materials and develops an effective strategy to trap metal complex catalyst with large molecular size into the nanopores or cavities of mesoporous materials.
- Yang, Hengquan,Zhang, Lei,Su, Weiguang,Yang, Qihua,Li, Can
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p. 204 - 212
(2007/10/03)
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- A simple and efficient approach to 1,3-aminoalcohols: application to the synthesis of (+)-negamycin
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A short and practical enantioselective synthesis of (+)-negamycin has been achieved in high enantio- and diastereomeric excess using an iterative Jacobsen's hydrolytic kinetic resolution as the key step.
- Naidu, S. Vasudeva,Kumar, Pradeep
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p. 3793 - 3796
(2008/02/06)
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- Asymmetric reactions on chiral catalysts entrapped within a mesoporous cage
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The encapsulation of homogeneous chiral catalysts, e.g. Co(Salen) and Ru-TsDPEN, in the mesoporous cage of SBA-16 is demonstrated; the encapsulated catalysts show performance as good as that of the homogeneous catalysts, and can be recycled for more than 10 times without significant loss of catalytic performance. The Royal Society of Chemistry.
- Yang, Hengquan,Li, Jun,Yang, Jie,Liu, Zhimin,Yang, Qihua,Li, Can
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p. 1086 - 1088
(2008/01/03)
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- Hydrolytic kinetic resolution of epoxides catalyzed by chromium(III)-endo, endo-2,5-diaminonorbornane-salen [Cr(III)-DIANANE-salen] complexes. Improved activity, low catalyst loading
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The hydrolytic kinetic resolution (HKR) of terminal epoxides, using chiral chromium(III)-salen catalysts based on DIANANE (endo,endo-2,5-diaminonorbornane) , was studied. A broad substrate scope was found for the chromium(III)-DIANANE catalysts, and very low loadings (down to 0.05 mol%) were needed to achieve high enantiomeric purities of both the remaining epoxides and the product diols (up to >99% ee). Besides monosubstituted epoxides, 2-methyl-2-n-pentyloxirane, which is an example for 2,2-disubstituted epoxides, could be ring-opened in an asymmetric fashion with water in the presence of an electronically tuned chromium-(III)-DIANANE complex.
- Berkessel, Albrecht,Ertuerk, Erkan
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p. 2619 - 2625
(2007/10/03)
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- Synthesis of optically pure terminal epoxide and 1,2-diol via hydrolytic kinetic resolution catalyzed by new heterometallic salen complexes
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The inactive chiral (salen)Co complex is easily activated by InCl 3 and TlCl3 Lewis acids by forming heterometallic salen complexes. These complexes show very high catalytic activity for the synthesis of enantiomerically enriched terminal epoxides (>99% ee) and 1,2-diols simultaneously via hydrolytic kinetic resolution. Strong synergistic effects of different Lewis acids, Co-In and Co-Tl, were exhibited in the catalytic process. The system described is very simple and efficient. Copyright Taylor & Francis Group, LLC.
- Thakur, Santosh Singh,Chen, Shu-Wei,Li, Wenji,Shin, Chang-Kyo,Koo, Yoon-Mo,Kim, Geon-Joong
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p. 2371 - 2383
(2007/10/03)
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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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- Modular approach for the development of supported, monofunctionalized, salen catalysts
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We report a modular approach toward polymer-supported, metalated, salen catalysts. This strategy is based on the synthesis of monofunctionalized Mn- and Co-salen complexes attached to a norbornene monomer via a stable phenylene-acetylene linker. The resulting functionalized monomers can be polymerized in a controlled fashion using ring-opening metathesis polymerization. This polymerization method allows for the synthesis of copolymers, resulting in an unprecedented control over the catalyst density and catalytic-site isolation. The obtained polymeric manganese and cobalt complexes were successfully used as supported catalysts for the asymmetric epoxidation of olefins and the hydrolytic kinetic resolution of epoxides. All polymeric catalysts showed outstanding catalytic activities and selectivities comparable to the original catalysts reported by Jacobsen. Moreover, the copolymer-supported catalysts are more active and selective than their homopolymer analogues, providing further proof that catalyst density and site isolation are key toward highly active and selective supported salen catalysts.
- Holbach, Michael,Weck, Marcus
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p. 1825 - 1836
(2007/10/03)
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- Highly reactive and enantioselective kinetic resolution of terminal epoxides with H2O and HCl catalyzed by new chiral (salen)Co complex linked with Al
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The asymmetric hydrolytic kinetic resolution (HKR) of racemic terminal epoxides by new easily synthesized dimeric chiral (salen)Co bearing Al, provides a practical and straightforward method for the synthesis of enantiomerically enriched terminal epoxides (>99% ee) and diols. An inorganic acid, HCl is applied first time for the asymmetric ring opening reaction of terminal epoxides. Reactions are conveniently carried out at room temperature under an air atmosphere.
- Thakur, Santosh Singh,Li, Wenji,Kim, Seong-Jin,Kim, Geon-Joong
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p. 2263 - 2266
(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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- PROCESS FOR PRODUCING OPTICALLY ACTIVE HALOPROPANEDIOL DERIVATIVE
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The present invention provides a method capable of simply producing optically active halopropanediol derivatives useful as pharmaceutical intermediates from inexpensive raw materials.Monohalohydroxyacetone derivatives can be produced by reacting propargyl alcohol derivatives available at low cost and a hypohalogenous acid to convert the propargyl alcohol derivatives to di- or tri-halohydroxyacetone derivatives, and then hydrogenating the derivatives in the present of a transition metal catalyst. Also, optically active halopropanediol derivatives can be produced by stereoselectively reducing the halohydroxyacetone derivatives with an enzyme source having the ability to stereoselectively reduce the carbonyl groups of the halohydroxyacetone derivatives.
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- General catalytic synthesis of highly enantiomerically enriched terminal aziridines from racemic epoxides
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If life deals you a lemon ...: Low selectivity in the [Co(salen)]-catalyzed kinetic resolution of terminal epoxides with N-Boc sulfonamides is parlayed into an efficient one-pot synthesis of enantiopure amino alcohol derivatives. This provides the foundation for a general route to the title compounds (see scheme; Boc = tertbutoxycarbonyl; Ns = 2-nitrobenzenesulfonyl).
- Kim, Sang Kyun,Jacobsen, Eric N.
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p. 3952 - 3954
(2007/10/03)
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- Mechanistic Investigation Leads to a Synthetic Improvement in the Hydrolytic Kinetic Resolution of Terminal Epoxides
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The mechanism of the hydrolytic kinetic resolution (HKR) of terminal epoxides was investigated by kinetic analysis using reaction calorimetry. The chiral (salen)Co-X complex (X = OAc, OTs, Cl) undergoes irreversible conversion to (salen)Co-OH during the course of the HKR and thus serves as both precatalyst and cocatalyst in a cooperative bimetallic catalytic mechanism. This insight led to the identification of more active catalysts for the HKR of synthetically useful terminal epoxides. Copyright
- Nielsen, Lars P. C.,Stevenson, Christian P.,Blackmond, Donna G.,Jacobsen, Eric N.
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p. 1360 - 1362
(2007/10/03)
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- Chiral Co(III)(salen)-catalysed hydrolytic kinetic resolution of racemic epoxides in ionic liquids
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In the chiral Co(III)(salen)-catalysed HKR of racemic epoxides, in the presence of ionic liquids, Co(II)(salen) complex is oxidised without acetic acid to catalytically active Co(III)(salen) complex during reaction and, moreover, this oxidation state is stabilised against reduction to Co(II) complex which enables the reuse of the recovered catalyst for consecutive reactions without extra reoxidation.
- Oh, Chun Rim,Choo, Dong Joon,Shim, Woo Ho,Lee, Dong Hoon,Roh, Eun Joo,Lee, Sang-Gi,Song, Choong Eui
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p. 1100 - 1101
(2007/10/03)
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- Hydrolytic kinetic resolution of epoxides
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The present invention provides a process for the preparation of an enantiomerically enriched non-racemic chiral diol and an enantiomerically enriched non-racemic chiral epoxy compound by a hydrolytic kinetic resolution reaction. The process includes the step of contacting oxygen and mixture including a racemic chiral epoxy compound, a non-racemic Co(II) complex catalyst, an aromatic carboxylic acid and water, at a temperature and length of time sufficient to produce a mixture of said non-racemic chiral diol and said non-racemic chiral epoxy compound. The present invention also provides a process for the preparation of an enantiomerically enriched non-racemic chiral diol and an enantiomerically enriched non-racemic chiral epoxy compound by a hydrolytic kinetic resolution reaction. This process includes the step of: contacting a racemic chiral epoxy compound and water in the presence of a non-racemic complex of Co(III) having an aryl carboxylate counter-anion, at a temperature and length of time sufficient to produce a mixture of said non-racemic chiral diol and said non-racemic chiral epoxy compound.
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- Commercialization of the hydrolytic kinetic resolution of racemic epoxides: Toward the economical large-scale production of enantiopure epichlorohydrin
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The hydrolytic kinetic resolution of racemic terminal epoxides utilizing chiral (salen)Co(III) catalysts provides practical access to enantiopure epoxides and diols. However, general issues surrounding catalyst activation combined with the specific problem of racemization of epichlorohydrin served to make the large-scale production of (R)- or (S)-epichlorohydrin difficult and uneconomical. A process for the large-scale production and isolation of active (salen)Co(III)OAc catalyst and a method of catalyst reduction after reaction using ascorbic acid have been developed to overcome these issues.
- Larrow, Jay F.,Hemberger, Karl E.,Jasmin, Serge,Kabir, Hocine,Morel, Phillipe
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p. 3589 - 3592
(2007/10/03)
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- PROCESS FOR THE PREPARATION OF PROTECTED 3-AMINO-1,2-DIHYDROXYPROPANE ACETAL AND DERIVATIVES THEREOF
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A process for producing protected 3-amino-1,2-dihydroxypropane acetal, particularly in chiral forms, for use as an intermediate in the preparation of various 3-carbon compounds which are chiral. In particular, the present invention relates to the process for preparation of 3-amino-1,2-dihydroxypropane isopropylidene acetal. The protected 3-amino-1,2-dihydroxypropane acetal is a key intermediate to the preparation of chiral 3-carbon compounds which in turn are intermediates to various pharmaceuticals.
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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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- Highly enantioselective resolution of terminal epoxides using polymeric catalysts
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Poly-salen-Co(III) complexes were employed in the hydrolytic kinetic resolution (HKR) of terminal epoxides and ee's up to 98% were obtained. In the HKR of epichlorohydrin, the polymeric catalysts can be recovered and modified for recycling. The recovered
- Song, Yuming,Yao, Xiaoquan,Chen, Huilin,Bai, Changmin,Hu, Xinquan,Zheng, Zhuo
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p. 6625 - 6627
(2007/10/03)
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- Process for the preparation of protected 3-amino-1,2-dihydroxypropane acetal and derivatives thereof
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A process for producing protected 3-amino-1,2-dihydroxypropane acetal, particularly in chiral forms, for use as an intermediate in the preparation of various 3-carbon compounds which are chiral. In particular, the present invention relates to the process for preparation of 3-amino-1,2-dihydroxypropane isopropylidene acetal. The protected 3-amino-1,2-dihydroxypropane acetal is a key intermediate to the preparation of chiral 3-carbon compounds which in turn are intermediates to various pharmaceuticals.
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- Polymer-supported chiral Co(salen) complexes: Synthetic applications and mechanistic investigations in the hydrolytic kinetic resolution of terminal epoxides
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This paper describes the synthesis of polystyrene- and silica-bound chiral Co(salen) complexes and their application in asymmetric catalysis. A general method for the covalent attachment of salen complexes to both types of support has been devised, and the corresponding immobilized cobalt derivatives are shown to be efficient and highly enantioselective catalysts for the hydrolytic kinetic resolution (HKR) of terminal epoxides. These systems provide practical solutions to certain technical difficulties associated with the isolation of reaction products from the HKR. Removal of the supported catalyst by filtration and repeated recycling is demonstrated with no loss of reactivity or enantioselectivity. The enantioselective addition of phenols to terminal epoxides mediated by this catalyst system provides a facile, high-yielding synthesis of the corresponding enantioenriched aryl ethers. The immobilized catalysts have been adapted to a continuous flow process for the generation of reaction products in high yield and ee, requiring only very simple techniques for product purification. The mechanism by which these catalysts perform highly efficient and enantioselective epoxide ring opening has been addressed using a silica- bound Co(salen) complex. A dramatic correlation between the degree of catalyst site-isolation and reaction rate has been observed, consistent with a cooperative bimetallic mechanism in these reactions.
- Annis, D. Allen,Jacobsen, Eric N.
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p. 4147 - 4154
(2007/10/03)
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- A tandem enzyme reaction to produce optically active halohydrins, epoxides and diols
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The recombinant halohydrin dehalogenase from Agrobacterium radiobacter AD1 was used to obtain enantiomerically pure halohydrins and epoxides by kinetic resolution. By adding an excess of the recombinant epoxide hydrolase from the same organism the reversible conversion was drawn to completion. Halohydrins such as (S)-2,3-dichloro-1-propanol (E>100) and (S)-2-chloro-1-phenylethanol (E=73) were obtained with an enantiomeric excess of higher than 99%. This is a novel biocatalytic route for obtaining enantiomerically pure aromatic halohydrins and epoxides.
- Lutje Spelberg, Jeffrey H.,Van Hylckama Vlieg, Johan E. T.,Bosma, Tjibbe,Kellogg, Richard M.,Janssen, Dick B.
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p. 2863 - 2870
(2007/10/03)
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- Kinetic chiral resolutions of 1,2-diols and desymmetrization of glycerol catalyzed by glycerol kinase
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Enantioselective phosphorylation catalyzed by glycerol kinase (EC 2.7.1.30) facilitated the kinetic chiral resolution of 3-chloro-1,2- propanediol, 3-fluoro-1,2-propanediol, 3-butene-1,2-diol, and 1,2,4- butanetriol. Both enantiomers of each compound were isolated is free diol or triol form, in excellent enantiomeric purity (91 to > 99.5% ee) and in moderate to good yield (60-94% of theoretical). The enantioselectivities of glycerol kinase from different sources were compared using 1,2,4-butanetriol as the substrate. The effect of elevated temperatures on enzymatic activity, stability, and enantioselectivity were studied, and procedures for the isolation of diol and triol products were optimized. Glycerol kinase- catalyzed phosphorylation facilitated the three-step chemoenzymatic conversion of glycerol to (S)-1,2-O-isopropylideneglycerol in 83% yield and > 99.5% ee).
- Keith Chenault,Chafin, Laura F.,Liehr, Sebastian
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p. 4039 - 4045
(2007/10/03)
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- Eine neue Ligandenklasse fuer die asymmetrische Dihydroxylierung von Olefinen
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Keywords: Asymmetrische Dihydroxylierungen; Chirale Liganden; Chinchonaalkaloide; Katalyse; Osmiumverbindungen
- Becker, Heinrich,Sharpless, K. Barry
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p. 447 - 449
(2007/10/03)
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- A novel generation of optically active 1,2-diols from the racemates by using halohydrin dehydro-dehalogenase
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A novel enzyme dehalogenating halohydrins, designated as halohydrin dehydo-dehalogenase (HDDase), was purified from Alcaligenes sp. DS-S-7G. The enzyme catalyzed oxidative dehalogenation of (R)-3-chloro-1,2-propanediol [monochlorohydrin (MCH)] to acetic acid and formaldehyde via hydroxyacetone stereoselectively by the addition of artificial electron acceptors. The dehalogenating activity was much higher in the presence of 2,6- dichlorophenolindophenol (DCIP) and phenazine methosulfate (PMS). The resulting stereoselective dehydro-dehalogenation was applicable to preparation of various optically active halohydrins and 1,2-diols so that the respective residual isomers had excellent enantiomeric excesses (ee) (60-99% ee).
- Suzuki,Kasai,Minamiura
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p. 239 - 246
(2007/10/02)
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- Lipase-Catalyzed Enantiomer Selective Hydrolysis of 1,2-Diol Diacetates
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Enantiomer selective hydrolysis of racemic 1,2-diol diacetates (rac-2a-h) was investigated by using the inexpensive commercial porcine pancreatic lipase.The hydrolysis proceeds with variable regioselectivity but with moderate to good enantioselectivity yielding a mixture of isomeric monoacetates (3a-h and 4a-h) and unchanged diacetate enantiomers (2a-h).Evidence was found that both monoacetates (3a-h and 4a-h) are formed with the same sense of enantiomer selectivity.
- Poppe, Laszlo,Novak, Lajos,Kajtar-Peredy, Maria,Szantay, Csaba
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p. 2211 - 2218
(2007/10/02)
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- Degradation of 2,3-Dichloro-1-propanol by a Pseudomonas sp.
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A bacterium that assimilates 2,3-dichloro-1-propanol was isolated from soil by enrichment culture.The strain was identified as Pseudomonas sp. by the taxonomic studies.The strain converted 2,3-dichloro-1-propanol to 3-chloro 1,2-propanediol, releasing chloride ions.The conversion was stereospecific because the residual 2,3-dichloro-1-propanol and formed 3-chloro-1,2-propanediol gave optical rotation.The resting cells converted various halohydrins to the dehalogenated alcohols, and cell-free extracts had strong epoxyhydrolase activity.These results indicated that the strain assimilated 2,3-dichloro-1-propanol via 3-chloro-1,2-propanediol, glycidol and glycerol.The possibility to manufacture optically active 2,3-dichloro-1-propanol is discussed.
- Kasai, Naoya,Tsujimura, Kazuya,Unoura, Kinya,Suzuki, Toshio
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p. 3185 - 3190
(2007/10/02)
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- Enzymic Synthesis of Glycosides of Racemic Alcohols Using β-Galactosidase and Separation of the Diastereomers by High-Performance Liquid Chromatography Using a Conventional Column
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β-Glycosides of phenylethylene glycol, propylene glycol, 3-chloropropylene glycol and 1-phenylethyl alcohol were synthesized by transglycosidation using β-galactosidase from Aspergillus oryzae, and the diastereomers were resolved by high-performance liquid chromatography on a conventional column.Keywords--enzymic transglycosidation; β-galactosidase; Aspergillus oryzae; racemic alcohol resolution; HPLC
- Ooi, Yasuhiro,Mitsuo, Naoki,Satoh, Toshio
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p. 5547 - 5550
(2007/10/02)
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- Synthesis of S-3-chloro-1,2-propanediol
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The S-enantiomer of 3-chloro-1,2-propanediol is prepared by reaction of a chlorodeoxy-D-saccharide having the partial structure. STR1 to cleave the glycol, reduce the aldehyde so formed to an alcohol, and hydrolyse the alcohol under mild acidic conditions.
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