- A new clade of styrene monooxygenases for (R)-selective epoxidation
-
Styrene monooxygenases (SMOs) are excellent enzymes for the production of (S)-enantiopure epoxides, but so far, only one (R)-selective SMO has been identified with a narrow substrate spectrum. Mining the NCBI non-redundant protein sequences returned a new distinct clade of (R)-selective SMOs. Among them,SeStyA fromStreptomyces exfoliatus,AaStyA fromAmycolatopsis albispora, andPbStyA fromPseudonocardiaceaewere carefully characterized and found to convert a spectrum of styrene analogues into the corresponding (R)-epoxides with up to >99% ee. Moreover, site 46 (AaStyA numbering) was identified as a critical residue that affects the enantioselectivity of SMOs. Phenylalanine at site 46 was required for the (R)-selective SMO to endow excellent enantioselectivity. The identification of new (R)-selective SMOs would add a valuable green alternative to the synthetic tool box for the synthesis of enantiopure (R)-epoxides.
- Xiao, Hu,Dong, Shuang,Liu, Yan,Pei, Xiao-Qiong,Lin, Hui,Wu, Zhong-Liu
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p. 2195 - 2201
(2021/04/12)
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- Enantiomer Separation of Nitriles and Epoxides by Crystallization with Chiral Organic Salts: Chirality Switching Modulated by Achiral Acids
-
Enantiomer separation of nitriles and epoxides by inclusion crystal formation with organic-salt type chiral hosts was achieved. The stereochemistry of the preferentially included nitrile could be switched only by changing the achiral carboxylic acid component. Crystallographic analysis of the inclusion crystals reveals that the hydrogen-bonding networks are controlled by the acidity of the phenol group of the acids, which results in chirality switching.
- Hirose, Takuji,Kodama, Koichi,Shimomura, Yuki
-
p. 6552 - 6557
(2021/11/16)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
-
Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
-
-
- Asymmetric synthesis of α-bromohydrins by carrot root as biocatalyst and conversion to enantiopure β-hydroxytriazoles and styrene oxides using click chemistry and SN2 ring-closure
-
In this study we have combined the bioreduction of α-bromoketones using carrot root as biocatalyst and click chemistry for the preparation of enantiopure β-hydroxytriazoles in excellent enantiomeric excesses and yields. Moreover, we have utilized chiral α-halohydrins for the synthesis of enantiopure styrene oxides in very good yields and enantiomeric excesses. Structural assignments of the products were based on their 1H and 13C NMR data and their optical rotations. The enantiomeric excess of the chiral products was obtained by HPLC analysis.
- Hosseinzadeh, Rahman,Mohadjerani, Maryam,Mesgar, Sakineh
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p. 583 - 591
(2019/02/17)
-
- A new enantioselective synthesis of antiobesity drug lorcaserin
-
A simple and efficient enantioselective synthesis of anti-obesity drug lorcaerin starting from easily accessible 3-chlorostyrene oxide has been described for the first time employing hydrolytic kinetic resolution as a source of chirality. The protocol might also be useful in the synthesis of structural variants of lorcaserin.
- Ghotekar, Ganesh S.,More, Devidas A.,Nalla, Viswanadh,Muthukrishnan
-
p. 16876 - 16880
(2019/11/14)
-
- Multistep Organic Transformations over Base-Rhodium/Diamine-Bifunctionalized Mesostructured Silica Nanoparticles
-
The assembly of multiple catalytic functionalities within a single mesoporous silica as a catalyst for multistep enantioselective organic transformations in an environmentally friendly medium is a significant challenge in heterogeneous asymmetric catalysis. Herein, we took advantage of a BF4 ? anion hydrogen bonding strategy to anchor a chiral cationic rhodium/diamine complex within base-functionalized mesostructured silica nanoparticles conveniently to construct a bifunctional heterogeneous catalyst. The solid-state 13C NMR spectrum discloses the well-defined chiral Rh/diamine active species, and we used XRD, N2 adsorption–desorption, and electron microscopy to reveal the ordered mesostructure. The combination of bifunctionality in the silica nanoparticles enables two kinds of efficient enantioselective organic transformations with high yields and enantioselectivities, in which the asymmetric transfer hydrogenation of α-haloketones followed by epoxidation provides various chiral aryloxiranes, and the amination of α-haloketones with anilines followed by asymmetric transfer hydrogenation produces various β-amino alcohols. Furthermore, the catalyst can be recovered and recycled for seven times without a loss of catalytic activity, which is an attractive feature for multistep organic transformations in a sustainable benign process.
- Liao, Hang,Chou, Yajie,Wang, Yu,Zhang, Han,Cheng, Tanyu,Liu, Guohua
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p. 3197 - 3202
(2017/08/29)
-
- Photocatalytic Asymmetric Epoxidation of Terminal Olefins Using Water as an Oxygen Source in the Presence of a Mononuclear Non-Heme Chiral Manganese Complex
-
Photocatalytic enantioselective epoxidation of terminal olefins using a mononuclear non-heme chiral manganese catalyst, [(R,R-BQCN)MnII]2+, and water as an oxygen source yields epoxides with relatively high enantioselectivities (e.g., up to 60% enantiomeric excess). A synthetic mononuclear non-heme chiral Mn(IV)-oxo complex, [(R,R-BQCN)MnIV(O)]2+, affords similar enantioselectivities in the epoxidation of terminal olefins under stoichiometric reaction conditions. Mechanistic details of each individual step of the photoinduced catalysis, including formation of the Mn(IV)-oxo intermediate, are discussed on the basis of combined results of laser flash photolysis and other spectroscopic methods.
- Shen, Duyi,Saracini, Claudio,Lee, Yong-Min,Sun, Wei,Fukuzumi, Shunichi,Nam, Wonwoo
-
supporting information
p. 15857 - 15860
(2016/12/23)
-
- Asymmetric epoxidation of alkenes and benzylic hydroxylation with P450tol monooxygenase from Rhodococcus coprophilus TC-2
-
P450tol monooxygenase was discovered as a unique and highly enantioselective enzyme for asymmetric epoxidation of some terminal alkenes containing electron-withdrawing groups and benzylic hydroxylation of several ethylbenzenes giving the corresponding useful and valuable products, such as (R)-2- and 3-substituted styrene oxides, (S)-4-substituted styrene oxides, and (S)-benzylic alcohols, in high ee.
- Li, Aitao,Wu, Shuke,Adams, Joseph P.,Snajdrova, Radka,Li, Zhi
-
supporting information
p. 8771 - 8774
(2014/07/22)
-
- NEW CHIRAL SALEN CATALYSTS AND METHODS FOR THE PREPARATION OF CHIRAL COMPOUNDS FROM RACEMIC EPOXIDES BY USING THEM
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The present invention relates to new chiral salen catalysts and the preparation method of chiral compounds from racemic epoxides using the same. More specifically, it relates to new chiral salen catalysts that have high catalytic activity due to new molecular structures and have no or little racemization of the generated target chiral compounds even after the reaction is completed and can be also reused without catalyst regeneration treatment, and its economical preparation method to mass manufacture chiral compounds of high optical purity, which can be used as raw materials for chiral food additives, chiral drugs, or chiral crop protection agents, etc., using the new chiral salen catalysts.
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Page/Page column 40
(2009/01/24)
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- A novel method for the synthesis of chiral epoxides from styrene derivatives using chiral acids in presence of Pseudomonas lipase G6 [PSL G6] and hydrogen peroxide
-
Chiral epoxidation of styrene and its derivatives was carried out using series of chiral acids and urea hydrogen peroxide (UHP) or aqueous hydrogen peroxide (50%) in two phases under the catalytic influence of immobilized Pseudomonas lipase G6 [PSL G6] at 25-55 °C. A moderate to good yield and enantioselectivities of chiral epoxides were obtained.
- Sarma, Kuladip,Bhati, Nishi,Borthakur, Naleen,Goswami, Amrit
-
p. 8735 - 8741
(2008/02/09)
-
- Enantioconvergent hydrolysis of styrene epoxides by newly discovered epoxide hydrolases in mung bean
-
Two novel epoxide hydrolases were discovered in mung bean (Phaseolus radiatus L.) for the first time, either of which can catalyze enantioconvergent hydrolysis of styrene epoxides. Their regioselectivity coefficients are more than 90% for the p-nitrostyrene oxide. Furthermore, the crude mung bean powder was also shown to be a cheap and practical biocatalyst, allowing a one-step asymmetric synthesis of chiral (R)-diols from racemic epoxides, in up to >99% ee and 68.7% overall yield (after recrystallization).
- Xu, Wei,Xu, Jian-He,Pan, Jiang,Gu, Qing,Wu, Xin-Yan
-
p. 1737 - 1740
(2007/10/03)
-
- METHOD FOR PRODUCING SINGLE ENANTIOMER EPOXIDES BY THE ADH REDUCTION OF ALPHA-LEAVING GROUP-SUBSTITUTED KETONES AND CYCLISATION
-
The invention relates to a method for producing single enantiomer epoxides by reducing a-leaving group-substituted ketones with (R)- or (S)-selective alcohol dehydrogenases in the presence of a cofactor and optionally a suitable system for regenerating the oxidised cofactor, to produce the corresponding single enantiomer alcohols and subsequently, by means of cyclisation induced by a base, the corresponding single enantiomer epoxides (EQUATION 1 ), wherein in EQUATION 1 LG may stand for F, CI, Br, I, OSO2Ar, OSO2CH3, OSO2R or OP(O)OR2, and R1, R2 and R3, independently of one another, stand for hydrogen, a branched or unbranched, optionally substituted C1-C2O- alkyl radical, symbolise an optionally randomly substituted C3-C10- cycloalkyl or alkenyl radical or a randomly substituted carbo- or heterocyclic aryl radical, or corresponds to a radical from the group CO2R, CONR2, COSR, CS2R, C(NH)NR2, CN, CHaI3, ArO, ArS, RO, RS, CHO, OH, NHR, NR2, Cl, F, Br, I or SiR3.
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Page/Page column 8
(2008/06/13)
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- Effective asymmetric epoxidation of styrenes by chiral dioxirane
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High enantioselectivity (80-92% enantiomeric excess (ee)) has been obtained for the epoxidation of various styrenes using an easily prepared ketone (4) catalyst.
- Goeddel, David,Shu, Lianhe,Yuan, Yi,Wong, O. Andrea,Wang, Bin,Shi, Yian
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p. 1715 - 1717
(2007/10/03)
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- Direct catalytic synthesis of enantiopure 5-substituted oxazolidinones from racemic terminal epoxides
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(Chemical Equation Presented) A venerable scaffold for asymmetric synthesis and drug development, chiral 5-substituted oxazolidinones are obtained in almost enantiomerically pure form (up to 99.9% ee) starting from racemic terminal epoxides. The salient features of this process include the very simple and convenient experimental protocol and the employment of a readily accessible catalyst and inexpensive, easily handled starting materials. An enantioconvergent approach for the total conversion of racemic epoxide into a single stereoisomeric oxazolidinone is also described.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Locatelli, Manuela,Melchiorre, Paolo,Sambri, Letizia
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p. 1983 - 1985
(2007/10/03)
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- Nitrite-mediated hydrolysis of epoxides catalyzed by halohydrin dehalogenase from Agrobacterium radiobacter AD1: A new tool for the kinetic resolution of epoxides
-
Halohydrin dehalogenase obtained from Agrobacterium radiobacter AD1, has been tested for the nitrite-mediated ring opening of epoxides. This reaction mainly leads to the formation of unstable hydroxynitrite ester intermediates, which can be further hydrolyzed to the corresponding diols. This conversion proceeds with high enantioselectivity and high regioselectivity towards styrene oxide derivatives. It has been concluded that halohydrin dehalogenase can serve as an attractive alternative to epoxide hydrolases in the preparation of enantiopure epoxides by kinetic resolution.
- Hasnaoui, Ghannia,Lutje Spelberg, Jeffrey H.,De Vries, Erik,Tang, Lixia,Hauer, Bernhard,Janssen, Dick B.
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p. 1685 - 1692
(2007/10/03)
-
- Purification and characterization of a yeast carbonyl reductase for synthesis of optically active (R)-styrene oxide derivatives
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Optically active styrene oxide derivatives are versatile chiral building blocks. Stereoselective reduction of phenacyl halide to chiral 2-halo-1-phenylethanol is the key reaction of the most economical synthetic route. Rhodotorula glutinis var. dairenensis IFO415 was discovered on screening as a potent microorganism reducing a phenacyl halide to the (R)-form of the corresponding alcohol. An NADPH-dependent carbonyl reductase was purified to homogeneity through four steps from this strain. The relative molecular mass of the enzyme was estimated to be 40,000 on gel filtration and 30,000 on SDS-polyacrylamide gel electrophoresis. This enzyme reduced a broad range of carbonyl compounds in addition to phenacyl halides. Some properties of the enzyme and preparation of a chiral styrene oxide using the crude enzyme are reported herein.
- Kizaki, Noriyuki,Sawa, Ikuo,Yano, Miho,Yasohara, Yoshihiko,Hasegawa, Junzo
-
-
- A METHOD FOR THE PRODUCTION OF CHIRAL SUBSTITUTED EPOXIDES
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A method for the production of chiral substituted epoxides of formula (I) wherein R represents a substituted C5-C20-aryl-, C5-C20-heterocycle or C1-C20-alkyl radical, R1 represents H or is
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Page/Page column 17
(2008/06/13)
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- Bacterial monooxygenase mediated preparation of nonracemic chiral oxiranes: Study of the effects of substituent nature and position
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Monooxygenation of styrene derivatives using recombinant E. coli biocatalyst is an efficient way to prepare the corresponding oxiranes. The electronic and geometric effects of the ring substituents are described and show the relaxed specificity of the enzyme and its high stereoselectivity.
- Bernasconi, Silvana,Orsini, Fulvia,Sello, Guido,Di Gennaro, Patrizia
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p. 1603 - 1606
(2007/10/03)
-
- Enzymatic transformations. Part 58: Enantioconvergent biohydrolysis of styrene oxide derivatives catalysed by the Solanum tuberosum epoxide hydrolase
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The biohydrolysis of four racemic styrene oxide derivatives has been explored, using the (recombinant) Solanum tuberosum epoxide hydrolase. Interestingly, this enzyme showed a marked tendency to operate a so-called enantioconvergent process, thus affording the corresponding (R)-diol in a nearly quantitative yield and good to excellent ee. We have demonstrated that this is due to the fact that the (S)-enantiomer of these epoxides was preferably attacked at the (benzylic) more substituted carbon atom, whereas the (R)-epoxide was attacked at the (terminal) less substituted carbon atom. The thus obtained meta- and para-chlorostyrene diol derivatives are important building blocks in the synthesis of various biologically active molecules. A nine cycles repeated batch reactor was performed starting from racemic meta-chlorostyrene oxide and afforded a 100% analytical yield (88% preparative) of the corresponding diol, obtained with ees as high as 97%.
- Monterde, Maria I.,Lombard, Murielle,Archelas, Alain,Cronin, Annette,Arand, Michael,Furstoss, Roland
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p. 2801 - 2805
(2007/10/03)
-
- A Unique Binaphthyl Strapped Iron-Porphyrin Catalyst for the Enantioselective Epoxidation of Terminal Olefins
-
A new chiral binaphthyl-strapped iron-porphyrin 4b that exhibits unprecedented catalytic activity toward the enantioselective epoxidation of terminal olefins was synthesized. Typical enantiomeric excesses (ee) of 90% were measured with a maximum of 97% fo
- Rose, Eric,Ren, Qi-Zhi,Andrioletti, Bruno
-
p. 224 - 230
(2007/10/03)
-
- Acetalsulfonate derivative, process for producing the same, and process for producing styrene oxide derivative
-
There are provided an acetalsulfonate derivative useful as an intermediate for medicines and agricultural chemicals, a process for industrially producing the derivative, and a process for industrially producing a styrene oxide derivative from the acetalsulfonate derivative or from a mandelic acid derivative. A process for producing an acetalsulfonate derivative which comprises a first step of esterifying a mandelic acid derivative to form a mandelic ester derivative, a second step of protecting the mandelic ester derivative by an acetal to form an acetal derivative, a third step of reducing the acetal derivative to form an ethanediol derivative and a fourth step of reacting the ethanediol derivative with a sulfonyl chloride derivative. A process for producing a styrene oxide derivative which comprises a deprotecting step of deacetalizing the acetalsulfonate derivative and a step of epoxidizing the sulfonate derivative obtained in the deprotecting step with the aid of a base catalyst.
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Page/Page column 15
(2010/01/31)
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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
-
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)
-
- Practical synthesis of optically active styrene oxides via reductive transformation of 2-chloroacetophenones with chiral rhodium catalysts
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(equation presented) A practical method for the synthesis of optically active styrene oxides has been developed via formation of optically active 2-chloro-1-phenylethanols generated by reductive transformation of ring-substituted 2-chloroacetophenones. Th
- Hamada, Takayuki,Torii, Takayoshi,Izawa, Kunisuke,Noyori, Ryoji,Ikariya, Takao
-
p. 4373 - 4376
(2007/10/03)
-
- Designing new chiral ketone catalysts. Asymmetric epoxidation of cis-olefins and terminal olefins
-
This paper describes a new class of chiral oxazolidinone ketone catalyst for asymmetric epoxidation. High ee values have been obtained for a number of cyclic and acyclic cis-olefins. The epoxidation was stereospecific with no isomerization observed in the epoxidation of acyclic systems. Encouragingly high ee values have also been obtained for a number of terminal olefins. Mechanistic studies show that electronic interactions play an important role in stereodifferentiation.
- Tian, Hongqi,She, Xuegong,Yu, Hongwu,Shu, Lianhe,Shi, Yian
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p. 2435 - 2446
(2007/10/03)
-
- Stereo- and enantioselective alkene epoxidations: A comparative study of D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins
-
The mechanism of stoichiometric enantioselective alkene epoxidations by the D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins, [RuVI(D4-Por*)O2] (1) and [RuVI(D2-Por*)O2] (2a), in the presence of pyrazole (Hpz) was studied by UV/ Vis spectrophotometry and analysis of the organic products. The enantioselectivity of styrene oxidations is more susceptible to steric effects than to substituent electronic effects. Up to 72% ee was achieved for epoxidation of 3-substituted and cis-disubstituted styrenes by employing 1 as the oxidant, whereas entantioselectivities of only 20-40 % were obtained in the reactions with 2-substituted and trans-disubstituted styrenes. Complex 2a oxidized 2-substituted styrenes to their epoxides in up to 88% ee. Its reactions with transalkenes are more enantioselective (67 % ee) than with the cis-alkenes (40 % ee). Based on a two-dimensional NOESY NMR study, 2a was found to adopt a more open conformation in benzene than in dichloromethane, which explains the observed solvent-dependent enantioselectivity of its reactions with alkenes. The oxidation of aromatic alkenes by the chiral dioxoruthenium(VI) porphyrins proceeds through the ratelimiting formation of a benzylic radical intermediate; the observed enantioselectivity (eeobs) depends on both the facial selectivity of the first C-O bond formation step and the diastereoselectivity of the subsequent epoxide ring closure. To account for the observed facial selection, "side-on" and "top-on" approach transition state models are examined (see: B. D. Brandes, E. N. Jacobsen, Tetrahedron Lett. 1995, 36, 5123).
- Zhang, Rui,Yu, Wing-Yiu,Sun, Hong-Zhe,Liu, Wei-Sheng,Che, Chi-Ming
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p. 2495 - 2507
(2007/10/03)
-
- Stereoselective ring opening reactions
-
The present invention relates to a process for stereoselective or regioselective chemical synthesis which generally comprises reacting a nucleophile and a chiral or prochiral cyclic substrate in the presence of a non-racemic, chiral catalyst to produce a stereoisomerically- and/or regioisomerically-enriched product. The present invention also relates to hydrolytic kinetic resolutions of racemic and diastereomeric mixtures of epoxides.
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-
- Benzamide therapeutics for the treatment of inflammatory bowel disease
-
Benzamides are disclosed to be useful for treating and preventing inflammatory bowel disease.
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- Enantioselective epoxidation of terminal olefins by chiral dioxirane.
-
[see reaction]. This paper describes an enantioselective epoxidation of terminal olefins using chiral ketone 3 as catalyst and Oxone as oxidant. Up to 85% ee has been obtained.
- Tian,She,Xu,Shi
-
p. 1929 - 1931
(2007/10/03)
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- Highly efficient asymmetric epoxidation of alkenes with a D4-symmetric chiral dichlororuthenium(IV) porphyrin catalyst
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A dichlororuthenium(IV) complex of 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,2: 5,8-dimethanoanthrance-9-yl] porphyrin, [RuIV(D4-Por*)Cl2] (1), was prepared by heating [RuII-(D4-Po
- Zhang, Rui,Yu, Wing-Yiu,Wong, Kwok-Yin,Che, Chi-Ming
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p. 8145 - 8153
(2007/10/03)
-
- Alternative synthesis of the chiral atypical β-adrenergic phenylethanolaminotetraline agonist SR58611A using enantioselective hydrogenation
-
We have developed an alternative synthesis of the atypical β-adrenergic phenylethanolaminotetraline agonist SR58611A. Two key intermediates have been synthesised involving enantioselective hydrogenation of an aminoketone and an enamide providing the corre
- Devocelle, Marc,Mortreux, Andre,Agbossou, Francine,Dormoy, Jean-Robert
-
p. 4551 - 4554
(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)
-
- Asymmetric catalysis by a chiral ruthenium porphyrin: Epoxidation, hydroxylation, and partial kinetic resolution of hydrocarbons
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matrix presented A new member of our D2 symmetry ruthenium porphyrins is shown to be a most selective catalyst for asymmetric epoxidation of terminal and trans-disubstituted olefins. The same catalyst displays some selectivity in kinetic resolution of secondary alcohols and in what appears to be the first example of catalytic enantioselective hydroxylation of tertiary alkanes.
- Gross, Zeev,Ini, Santiago
-
p. 2077 - 2080
(2008/02/10)
-
- Process for the preparation of optically active 2-halo-1-(substituted phenyl) ethanol
-
The present invention provides an industrially advantageous process for the preparation of an optically active 2-halo-1-(substituted phenyl)ethanol useful as medicines, agricultural chemicals or as intermediates thereof; and a simple process for the prepa
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- Process for producing (R)-styrene oxides
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The present invention provides a process for producing (R)-styrene oxides represented by the formula (1): STR1 wherein R1, R2, R3 and X are as defined in the specification, which comprises treating a mixture of (R)- and (S)-phenylhalogenomethylcarbinols with a lipase in the presence of a carboxylate to preferentially convert the (S)-phenylhalogenomethylcarbinols, and treating a mixture of the formed carbinol alkylates (3) and (R)-phenylhalogenomethylcarbinols with a base to cyclize the (R)-phenylhalogenomethylcarbinols, and also provides an industrially excellent process for producing (R)-styrene oxides (1) which comprises using a mixture enriched with (R)-phenylhalogenomethylcarbinols as the mixture of (R)- and (S)-phenylhalogenomethylcarbinols (2).
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- A practical synthesis of (R)-3-chlorostyrene oxide starting from 3- chloroethylbenzene
-
A novel and practical synthesis of (R)-3-chlorostyrene oxide (-)-1 was achieved starting from commercially available 3-chloroethylbenzene 3. Enantiopure (-)-3-chlorostyrene bromohydrin (-)-5 was obtained by the treatment of racemic (±)-5 with lipase QL in the presence of acylating reagents. 3-Chloro-α,β-dibromoethylbenzene 4, a precursor of (±)-5, was synthesized via the expeditious bromination of 3 which was developed by these authors.
- Tanaka, Ken,Yasuda, Mari
-
p. 3275 - 3282
(2007/10/03)
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- Synthesis of enantiopure 3-chlorostyrene oxide via an asymmetric epoxidation-hydrolytic kinetic resolution sequence
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3-Chlorostyrene oxide was prepared in >99% ee employing the (salen)Co- catalyzed hydrolytic kinetic resolution (HKR) reaction. The HKR was performed successfully on both racemic and enantiomerically enriched epoxides, the latter was obtained via (salen)Mn
- Brandes, Bridget D.,Jacobsen, Eric N.
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p. 3927 - 3933
(2007/10/03)
-
- Aminobenzamide compounds for the treatment of neurodegenerative disorders
-
A group of benzamide compounds are disclosed which are useful for treating neurodegenerative disorders. Methods for making these compounds are provided. These materials are formed into pharmaceutical compositions for oral or intravenous administration to patients suffering from conditions such as Parkinson's disease which can exhibit themselves as progressive loss of central nervous system function. The compounds can arrest or slow the progressive loss of function.
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- Enantioselective Epoxidation of Styrene Derivatives by Chloroperoxidase Catalysis
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Chloroperoxidase catalysed epoxidation of styrene derivatives by t-BuOOH preferentially gives (R) oxides with ee values between 28 and 68percent.The data support the view of oxygen delivery from the ferryl oxygen directly to the substrate.
- Colonna, Stefano,Gaggero, Nicoletta,Casella, Luigi,Carrea, Giacomo,Pasta, Piero
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p. 1325 - 1330
(2007/10/02)
-
- Phenylethanolaminomethyltetralins and pharmaceutical use
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New phenylethanolaminomethyltetralins of formula (I) STR1 wherein E represents hydrogen, (C1 -C4)alkyl, (C1 -C4)alkoxy, phenyl, nitro, halogen, or trifluoromethyl, L represents hydrogen, (C1 -C4)alkyl, (C1 -C4)alkyoxy, phenyl, nitro, or halogen, or E and L taken together represent a group --CH=CH--CH=CH-- or --CH2 --CH2 --CH2 --CH2 --, and G represents hydrogen, chloro, hydroxy or an --OG' group wherein G' represents a (C1 -C4 (alkyl group either unsubstituted or substituted with hydroxy, (C1 -C4)alkoxy, (C1 -C4)alkoxycarbonyl, carboxy, or (C3 -C7)cycloalkyl; a (C3 -C7)cycloalkyl group; or a (C2 -C4)alkanoyl group; and salts thereof, are described which showed to be active as intestinal motility modulating agents and intraocular hypertension lowering agents. Also described is a process for the preparation of the new compounds and the intermediates of formula (III) STR2 employed in said process.
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- Synthesis of Chiral Square Planar Cobalt(III) Complexes and Catalytic Asymmetric Epoxidations with these Complexes
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The chiral square planar cobalt(III) complexes, Na4-(R)-HMBA-DMP)> (2), -2,4-dimethylpentan-3-one> and complexes with two or four chiral centres, Co2L> have been prepared and characterized by 1H NMR spectroscopy, solution magnetic properties, and X-ray crystallography.Asymmetric epoxidations of styrenes with these chiral cobalt(III) complexes and iodosylbenzene have been investigated.Various substituted styrenes were epoxidized with chemical yields of (25-86percent) and enantiomeric excess between 0 and 17percent.
- Ozaki, Shigeko,Mimura, Hisashi,Yasuhara, Naoko,Masui, Masaichiro,Yamagata, Yuriko,et al.
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p. 353 - 360
(2007/10/02)
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- 3-Chlorophenyl anti-obesity agents
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Compounds of formula (III): STR1 and esters, amides and pharmaceutically acceptable salts thereof, wherein A1 is hydrogen or methyl; A2 is hydrogen or methyl; and n is 1, 2 or 3 have anti-obesity activity. Methods for their preparation pharmaceutical formulations of the compounds and their use in medicine are described.
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