- Nonlinear Effects in Asymmetric Synthesis. Examples in Asymmetric Oxidations and Aldolization Reactions
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It has been shown in three experiments that there is a strong departure from the linear relationship usually assumed between the enantiomeric excess of a chiral auxiliary and the extent of the asymmetric synthesis.This gives useful information on the reac
- Puchot, C.,Samuel, O.,Dunach, E.,Zhao, S.,Agami, C.,Kagan, H. B.
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- C2-symmetric bissulfoxides as organocatalysts in the allylation of benzoyl hydrazones: Spacer and concentration effects
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A comparative study on the allylation of a benzoyl hydrazone with allyl trichlorosilane using monosulfoxides, methylene-bridged (C2-symmetric bissulfoxides, and ethylene-bridged C2-symmetric bissulfoxides shows that the enantioselect
- Fernandez, Inmaculada,Valdivia, Victoria,Leal, Manuel Pernia,Khiar, Noureddine
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- Nonlinear effects as 'indicators' in the tuning of asymmetric catalysts
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Nonlinear effects (NLEs) have been used as a new tool to characterize the various modifications of a chiral titanium complex used in stoichiometric or catalytic mode in asymmetric sulfoxidation by cumyl hydroperoxide. Spectacular changes from (+)- to (-)-NLEs were observed for minor modifications of the experimental conditions.
- Brunel, Jean-Michel,Luukas, Timo O.,Kagan, Henri B.
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- Photoinversion of sulfoxides as a source of diversity in dynamic combinatorial chemistry
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Photochemical interconversion of the two diastereoisomers cis- and trans-thianthrene dioxide (1) can be considered an example of photodynamic combinatorial chemistry (PDCC) in which the interconversion among diastereomeric equilibrating species is brought
- Di Stefano, Stefano,Mazzonna, Marco,Bodo, Enrico,Mandolini, Luigi,Lanzalunga, Osvaldo
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- Using enzyme inhibition as a high throughput method to measure the enantiomeric excess of a chiral sulfoxide
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(Chemical Equation Presented) The enantiomeric excess of methyl p-tolyl sulfoxide can be determined in a high throughput format by measuring its ability to inhibit the alcohol dehydrogenase catalyzed oxidation of ethanol. The two enantiomers of the sulfox
- Sprout, Christopher M.,Seto, Christopher T.
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- Optically active polyoxotungstates bearing chiral organophosphonate substituents
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Divacant Keggin-type polyoxotungstates [γ-XW10O 36]8-with X = Si or Ge, were functionalized with chiral phosphoryl groups. The hybrid compounds [(RPO)2(γ-XW 10O36)]4- with R = N-
- Carraro, Mauro,Modugno, Gloria,Sartorel, Andrea,Scorrano, Gianfranco,Bonchio, Marcella
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- Enantiopure p,p'-disubstituted 1,2-diphenylethane-1,2-diols as chiral inducers in the Ti-mediated oxidation of sulfides: A case of reversal of asymmetric induction by fluorine substitution
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In the asymmetric oxidation of methyl p-tolyl sulfide, (2a), and benzyl phenyl sulfide (2b) by TBHP, mediated by a titanium complex with enantiopure (R,R)-p,p'-disubstituted-1,2-diphenylethane-1,2-diols, both the unsubstituted diol (R,R)-1a and the p-OMe
- Superchi, Stefano,Donnoli, Maria Irene,Rosini, Carlo
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- Asymmetric oxidation with furylhydroperoxides
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Chiral sulfoxides are accessible with very satisfactory enantiomeric excesses through a modified Sharpless procedure, based on the employment of furylhydroperoxides. Racemic hydroperoxides are found to undergo a kinetic resolution in the course of the asy
- Scettri, Arrigo,Bonadies, Francesco,Lattanzi, Alessandra
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- Biotransformation of organic sulfides. Predictive active site models for sulfoxidation catalysed by 2,5-diketocamphane 1,2-monooxygenase and 3,6- diketocamphane 1,6-monooxygenase, enantiocomplementary enzymes from Pseudomonas putida NCIMB 10007
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Growth of the bacterium Pseudomonas putida NCIMB 10007 on racemic camphor induces two enantiocomplementary diketocamphane monooxygenase isofunctional enzymes (isozymes) both able to catalyse electrophilic biooxidation of a wide range of prochiral sulfoxides to the corresponding chiral sulfoxides. Active site models to explain and predict the stereoselectivity of the sulfoxidations catalysed by both isozymes are proposed. The models are based on restrictive space descriptors derived from the optimised outcomes obtained with 23 different phenyl alkyl, benzyl alkyl, methyl alkyl and ethyl alkyl sulfides: consistency was maximised by using the same enzyme preparations throughout. The models, which are consistent with the recognised stereoselectivities of diketocamphane monooxygenase catalysed nucleophilic biooxidations of ketones to lactones, are the first to provide insight into the active site topography of FMN plus NADH-dependent Baeyer- Villiger monooxygenases. In addition, they are unique in providing a direct comparison of the active sites of two enantiocomplimentary isofunctional proteins that have evolved in the same cell line.
- Beecher, Jean,Willetts, Andrew
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- Preparative asymmetric deoxygenation of alkyl aryl sulfoxides by Rhodobacter sphaeroides f.sp. denitrificans
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Preparative enantioselective deoxygenation of racemic alkyl aryl sulfoxides by intact cells of Rhodobacter sphaeroides f.sp. denitrificans was examined. In methyl p-substituted phenyl sulfoxides, (S)-enantiomers were exclusively deoxygenated while enantio
- Abo, Mitsuru,Okubo, Akira,Yamazaki, Sunao
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- Acid promoted enantioselective oxygen-atom transfer from N-alkyl binaphthyl-derived oxaziridines onto sulfides
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Acid-promoted asymmetric sulfoxidations of prochiral sulfides using binaphthyl-derived oxaziridines have been studied. The reactions of dialkyl or aryl-alkyl sulfides gave good yields of the corresponding sulfoxides with enantiopurities ranging from 20% to 80%. The influence of temperature and strength of the acid catalyst on enantioselectivity was studied. The absolute configuration of the resulting major enantiomer varied with the structure of the sulfide.
- Akhatou, Abdeslam,Rahimi, Maryam,Cheboub, Karima,Ghosez, Léon,Hanquet, Gilles
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- 3,3'-Dinitro-octahydrobinaphthol: A new chiral ligand for metal-catalyzed enantioselective reactions
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Starting from R-configurated binaphthol the R-form of the title compound was readily prepared in two steps and characterized by X-ray structural analysis. It was used as the chiral ligand in the Ti-catalyzed asymmetric oxidation of methyl-p-tolylsulfide,
- Reetz, Manfred T.,Merk, Claudia,Naberfeld, Guido,Rudolph, Joachim,Griebenow, Nils,Goddard, Richard
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- Asymmetric oxidation of sulfide to sulfoxides on Ti-containing mesoporous silica catalysts with hydrogen peroxide in the presence of optically active tartaric acid
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On Ti-containing MCM-41 prepared by a template ion-exchange method, sulfide could be asymmetrically oxidized to sulfoxides in the presence of optically active tartaric acid (54% yield and 30% ee). The oxidation was composed of the asymmetric induction to sulfoxides and the subsequent kinetic resolution of sulfoxides.
- Iwamoto, Masakazu,Tanaka, Yasuhiro,Hirosumi, Jiro,Kita, Nozomu
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- SULFOXIDES AS CHIRAL COMPLEXATION AGENTS. CONFORMATIONAL ENANTIOMER RESOLUTION AND INDUCED CIRCULAR DICHROISM OF BILIRUBINS
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Bilirubin-IXα, the end product of porphyrin metabolism in mammals and the neurotoxic yellow-orange pigment of jaundice, exhibits a strong tendency to fold like a book into either of two interconverting enantiomeric conformations, which are further stabilized by intramolecular hydrogen bonding.Bilirubin exhibits optical activity in R(-)-ethylmethylsulfoxide solvent, as seen by moderately strong bisignate circular dichroism Cotton effects (Δεmax452=+10.9, Δεmax404=-4.5), and in dichloromethane solution in the presence of 2M R-(+)-methyl-p-tolylsulfoxide its circular dichroism spectrum (Δεmax463=+11.2, Δεmax412=-7.1) is comparably strong.As observed earlier for chiral recognition of bilirubin by optically active amines and serum albumines, the optically active sulfoxide acts as a chiral complexation agent to induce an asymmetric transformation of bilirubin, whose bisignate circular dichroism spectra are characteristic of an exciton splitting arising from interaction of the two component dipyrrinone chromophores.
- Gawronski, J. K.,Polonski, T.,Lightner, D. A.
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- Kinetic resolution of racemic sulfoxides by a modified Sharpless procedure
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Kinetic resolution of racemic sulfoxides is achieved by enantioselective oxidation to sulfones under Sharpless-type conditions.
- Scettri, Arrigo,Bonadies, Francesco,Lattanzi, Alessandra,Senatore, Angela,Soriente, Annunziata
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- Discovery and application of methionine sulfoxide reductase B for preparation of (S)-sulfoxides through kinetic resolution
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Here we report a methionine sulfoxide reductase B (MsrB) enzymatic system for the preparation of (S)-sulfoxides through kinetic resolution of racemic (rac) sulfoxides. Eight MsrB homologue recombinant proteins were expressed and their activities on asymmetric reduction of rac-sulfoxides were analyzed. Among these MsrB homologue proteins, one protein from Acidovorax species showed good activity and enantioselectivity towards several aryl-alkyl sulfoxides. The (S)-sulfoxides were prepared with 93–98% enantiomeric excess through kinetic resolution at initial substrate concentration up to 50 mM. The establishment of MsrB catalytic kinetic resolution system provides a new efficient green strategy for preparation of (S)-sulfoxides.
- Wen, Yuanmei,Peng, Liaotian,Zhou, Yang,Peng, Tao,Chen, Yu,Cheng, Xiaoling,Chen, Yongzheng,Yang, Jiawei
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- Development of a simple high-throughput assay for directed evolution of enantioselective sulfoxide reductases
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We report on the development of high-throughput fluorogenic assay that can streamline directed evolution of enantioselective sulfoxide reductases. As a model, methionine sulfoxide reductase A (MsrA) has been evolved to expand its limited substrate scope. The resulting mutant MsrA can resolve a range of new challenging racemic sulfoxides with high efficiency including the pharmaceutically relevant albendazole sulfoxide. The simplicity and the level of throughput make this method also suitable for the screening of metagenomic libraries in future for the discovery of new enzymes with similar reactivities.
- Tarallo, Vincenzo,Sudarshan, Kasireddy,Nosek, Vladimír,Mí?ek, Jirí
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supporting information
p. 5386 - 5388
(2020/06/04)
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- Identification of MsrA homologues for the preparation of (R)-sulfoxides at high substrate concentrations
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Here we report a methionine sulfoxide reductase A (MsrA) homologue with extremely high substrate tolerance and a wide substrate scope for the biocatalytic preparation of enantiopure sulfoxides. This MsrA homologue which was obtained from Pseudomonas alcaliphila (named paMsrA) showed good activity and enantioselectivity towards a series of aryl methyl/ethyl sulfoxides 1a-1k, with electron-withdrawing or electron-donating substituents at the aromatic ring. Chiral sulfoxides in the R configuration were prepared with approximately 50% of yield and up to 99% enantiomeric excess through the asymmetric reductive resolution of racemic sulfoxide catalyzed by the recombinant paMsrA protein. More importantly, kinetic resolution has been successfully accomplished with high enantioselectivity (E > 200) at initial substrate concentrations up to 320 mM (approximately 45 g L-1), which represents a great improvement in the aspect of the substrate concentration for the biocatalytic preparation of chiral sulfoxides.
- Yang, Jiawei,Wen, Yuanmei,Peng, Liaotian,Chan, Yu,Cheng, Xiaoling,Chen, Yongzheng
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p. 3381 - 3388
(2019/04/01)
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- Chemoenzymatic Deracemization of Chiral Sulfoxides
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The highly enantioselective enzyme methionine sulfoxide reductase A was combined with an oxaziridine-type oxidant in a biphasic setup for the deracemization of chiral sulfoxides. Remarkably, high ee values were observed with a wide range of substrates, thus providing a practical route for the synthesis of enantiomerically pure sulfoxides.
- Nosek, Vladimír,Mí?ek, Ji?í
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supporting information
p. 9849 - 9852
(2018/07/31)
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- Molybdenum-catalyzed enantioselective sulfoxidation controlled by a nonclassical hydrogen bond between coordinated chiral imidazolium-based dicarboxylate and peroxido ligands
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Chiral alkyl aryl sulfoxides were obtained by molybdenum-catalyzed oxidation of alkyl aryl sulfides with hydrogen peroxide as oxidant in mild conditions with high yields and moderate enantioselectivities. The asymmetry is generated by the use of imidazoli
- Carrasco, Carlos J,Montilla, Francisco,Galindo, Agustín
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- Biocatalytic Preparation of Chiral Sulfoxides through Asymmetric Reductive Resolution by Methionine Sulfoxide Reductase A
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Here we report an environmentally friendly method for the preparation of chiral sulfoxides under high substrate concentration using recombinant methionine sulfoxide reductase A from Pseudomonas monteilii (pmMsrA) as a biocatalyst. Our results show that this enzyme can effectively accomplish the preparation of (R)-sulfoxides with approximately 50 % yield and 94–99 % enantiomeric excess through asymmetric reductive resolution of racemic sulfoxide. With the establishment of the enzyme regeneration system, the initial substrate concentration could be increased 40–100 times compared to our original report. The (R)-sulfoxides were obtained with high enantioselectivity under the substrate concentration up to 200 mm (approximately 32 g L?1), representing a quite high substrate concentration in biocatalytic preparation of chiral sulfoxides. Moreover, this system showed fairly good activity and enantioselectivity towards a series of ortho- and para-substituted phenyl methyl sulfoxides under high substrate concentration.
- Peng, Liaotian,Wen, Yuanmei,Chen, Yu,Yuan, Zhimei,Zhou, Yang,Cheng, Xiaoling,Chen, Yongzheng,Yang, Jiawei
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p. 3284 - 3290
(2018/06/04)
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- Ultrafast chiral separations for high throughput enantiopurity analysis
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Recent developments in fast chromatographic enantioseparations now make high throughput analysis of enantiopurity on the order of a few seconds achievable. Nevertheless, routine chromatographic determinations of enantiopurity to support stereochemical investigations in pharmaceutical research and development, synthetic chemistry and bioanalysis are still typically performed on the 5-20 min timescale, with many practitioners believing that sub-minute enantioseparations are not representative of the molecules encountered in day to day research. In this study we develop ultrafast chromatographic enantioseparations for a variety of pharmaceutically-related drugs and intermediates, showing that sub-minute resolutions are now possible in the vast majority of cases by both supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RP-LC). Examples are provided illustrating how such methods can be routinely developed and used for ultrafast high throughput analysis to support enantioselective synthesis investigations.
- Barhate, Chandan L.,Joyce, Leo A.,Makarov, Alexey A.,Zawatzky, Kerstin,Bernardoni, Frank,Schafer, Wes A.,Armstrong, Daniel W.,Welch, Christopher J.,Regalado, Erik L.
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supporting information
p. 509 - 512
(2017/01/13)
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- Enantioselective Aromatic Sulfide Oxidation and Tandem Kinetic Resolution Using Aqueous H2O2 and Chiral Iron–Bis(oxazolinyl)bipyridine Catalysts
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An efficient method for the oxidation of aromatic sulfides has been developed by using aqueous H2O2, catalyzed by the in situ generated chiral Fe/6,6′-bis(4-isopropyloxazolin-2-yl)-2,2′-bipyridine (bipybox-iPr) complex. The corresponding sulfoxides were obtained with high enantioselectivities (up to 98.5:1.5 er) and in good yields (up to 61 %) when the mono-oxidation of the sulfides was performed in combination with the kinetic resolution of the sulfoxide into the sulfone.
- Jalba, Angela,Régnier, Noémie,Ollevier, Thierry
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p. 1628 - 1637
(2017/04/06)
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- An efficient silica supported Chitosan@vanadium catalyst for asymmetric sulfoxidation and its application in the synthesis of esomeprazole
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A new type of silica supported Chitosan@vanadium complex was used as a highly active heterogeneous catalyst for asymmetric oxidation of aryl alkyl sulfides. With the economic aqueous H2O2(30%) as the oxidant, the oxidation products were obtained in high yields (up to 95%) with good enantioselectivities (up to 68% ee). It is noted that the marketed drug Nexium (first proton-pump inhibitor, esomeprazole) could be synthesized easily by the newly developed asymmetric sulfoxidation reaction. In addition, the highly active catalyst can be reused five times without losing its catalytic activity.
- Shen, Chao,Qiao, Jun,Zhao, Linwei,Zheng, Kai,Jin, Jianzhong,Zhang, Pengfei
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p. 114 - 118
(2017/01/25)
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- Stereoselective sulfoxidation catalyzed by achiral Schiff base complexes in the presence of serum albumin in aqueous media
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Four coordination complexes ML derived from an achiral Schiff base ligand (H2L = 2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol) have been synthesized and characterized. A method is described for the enantioselective oxidation of a series of aryl alkyl sulfides using the coordination complexes in the presence of serum albumins (SAs) in an aqueous medium at ambient temperature. The mixture of metal complexes with serum albumins is useful for inducing asymmetric catalysis. The complex, albumin source and substrate influence stereoselective sulfoxidation. At optimal pH with the appropriate oxidant, some of ML/SA systems are identified as very efficient catalysts, giving the corresponding sulfoxides in excellent chemical yield (up to 100%) and good enantioselectivity (up to 94% ee) in certain cases. UV–visible spectroscopic data provide evidence that stronger binding between the complex and serum albumin lead to higher enantioselectivity.
- Tang, Jie,Yao, Pengfei,Huang, Fuping,Luo, Meiyi,Wei, Yi,Bian, Hedong
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supporting information
p. 1700 - 1707
(2017/11/17)
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- Peroxygenase-Catalyzed Enantioselective Sulfoxidations
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The performances of the unspecific peroxigenase from Agrocybe aegerita (AaeUPO) in the asymmetric sulfoxidation of substituted aryl alkyl sulfides were here investigated. A small library of differently substituted aryl alkyl sulfoxides was successfully synthesized from the corresponding sulfides in the presence of AaeUPO and H2O2. All the sulfoxides were obtained as (R)-enantiomers, regardless the substitution pattern both on the aromatic ring and the alkyl chain, in up to > 99 % conversion and > 99 % ee. An overview about the biocatalytic entries to chiral sulfoxides is also presented here in form of a comparison between the results obtained with AaeUPO and performances of the chloroperoxidase from Caldariomyces fumago, and three different Baeyer–Villiger monooxygenases. To the best our knowledge, this is the first example of a systematic investigation of the AaeUPO synthetic potential in the asymmetric oxidation of hetero atoms, i.e., the pro-stereogenic sulfur of sulfides.
- Bassanini, Ivan,Ferrandi, Erica Elisa,Vanoni, Marta,Ottolina, Gianluca,Riva, Sergio,Crotti, Michele,Brenna, Elisabetta,Monti, Daniela
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supporting information
p. 7186 - 7189
(2017/12/28)
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- Kinetic resolution of phenyl methyl sulfoxides by mammalian methionine sulfoxide reductase A
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Chiral sulfoxides are widely used in organic synthesis as chiral auxiliaries. There are numerous strategies for the preparation of enantiomerically pure sulfoxides, based either on the enantioselective oxidation of sulphides or the enantiospecific reduction of sulfoxides. For both cases, bioconversion techniques have been developed and proposed for large-scale synthesis. Methionine sulfoxide reductase enzymes (MsrA and MsrB) catalyse the stereoselective conversion of methionine sulfoxide to methionine. MsrA can also catalyse the reduction of other exogenous sulfoxides, including p-tolyl methyl sulfoxide. However, the stereoselectivity towards this type of substrate is not yet well characterized. The activity and enantioselectivity of MsrA toward several aryl methyl sulfoxides is presented in this paper.
- Achilli, Cesare,Ciana, Annarita,Minetti, Giampaolo
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supporting information
p. 4781 - 4782
(2017/11/29)
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- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
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The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
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p. 21293 - 21301
(2016/03/08)
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- Efficient HPLC enantiomer separation using a pillared homochiral metal-organic framework as a novel chiral stationary phase
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HPLC enantioseparation of racemates using novel pillared homochiral metal-organic framework-silica composite as chiral stationary phase has been successfully demonstrated.
- Tanaka, Koichi,Hotta, Naoki,Nagase, Shohei,Yoza, Kenji
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supporting information
p. 4891 - 4894
(2016/07/06)
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- Chiral DHIP-Based Metal-Organic Frameworks for Enantioselective Recognition and Separation
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Two chiral porous 2,3-dihydroimidazo[1,2-a]pyridine (DHIP)-based metal-organic frameworks (MOFs) are assembled from an enantiopure dipyridyl-functionalized DHIP bridging ligand. The Zn-DHIP MOF shows a good enantioseparation performance toward aromatic sulfoxides, and the heterogeneous adsorbent can be readily recovered and reused without significant degradation of the separation performance.
- Zhang, Jie,Li, Zijian,Gong, Wei,Han, Xing,Liu, Yan,Cui, Yong
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supporting information
p. 7229 - 7232
(2016/08/09)
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- Method for preparing chiral sulfoxide through catalysis of asymmetric oxidation of thioether
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The invention provides a method for preparing chiral sulfoxide. According to the method, in a mixed solvent, thioether is used as a substrate, a complex produced by chiral tetradentate organic ligand and a metal manganese compound in situ is used as a cat
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Paragraph 0058; 0059; 0060; 0061; 0062
(2016/10/10)
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- Bovine serum albumin-cobalt(II) Schiff base complex hybrid: An efficient artificial metalloenzyme for enantioselective sulfoxidation using hydrogen peroxide
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An artificial metalloenzyme (BSA-CoL) based on the incorporation of a cobalt(ii) Schiff base complex {CoL, H2L = 2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol} with bovine serum albumin (BSA) has been synthesized and characterized. Attention is focused on the catalytic activity of this artificial metalloenzyme for enantioselective oxidation of a variety of sulfides with H2O2. The influences of parameters such as pH, temperature, and the concentration of catalyst and oxidant on thioanisole as a model are investigated. Under optimum conditions, BSA-CoL as a hybrid biocatalyst is efficient for the enantioselective oxidation of a series of sulfides, producing the corresponding sulfoxides with excellent conversion (up to 100%), chemoselectivity (up to 100%) and good enantiomeric purity (up to 87% ee) in certain cases.
- Tang, Jie,Huang, Fuping,Wei, Yi,Bian, Hedong,Zhang, Wei,Liang, Hong
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p. 8061 - 8072
(2016/06/06)
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- Molybdenum-catalyzed asymmetric sulfoxidation with hydrogen peroxide and subsequent kinetic resolution, using an imidazolium-based dicarboxylate compound as chiral inductor
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A catalytic system based on simple and economic molybdenum compounds and a straightforwardly prepared imidazolium-based dicarboxylate compound, as chirality inductor, was developed for the catalytic asymmetric oxidation of sulfides with hydrogen peroxide. High yields of chiral methyl phenyl sulfoxide and good enantioselectivities (up to 40% ee) were achieved utilizing one equivalent of oxidant in 1?h. By combination of the enantioselective sulfoxidation and the concomitant kinetic resolution an 83% ee was obtained, an excellent enantioselectivity value for a molybdenum catalyst.
- Carrasco, Carlos J.,Montilla, Francisco,Galindo, Agustín
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p. 134 - 136
(2016/07/11)
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- Asymmetric catalytic sulfoxidation by a novel v IV 8 cluster catalyst in the presence of serum albumin: A simple and green oxidation system
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A novel VIV8 cluster formulated as [V8O12(OH)4(CH3O)4(DAC)4]·7CH3OH (1) (DAC = 1,2-diaminocyclohexane) has been constructed successfully. Enantioselective oxidation of a series of alkyl aryl sulfides catalyzed by 1 is tested in an aqueous medium in the presence of serum albumin. The catalytic procedure is found to be simple and environmentally friendly. The influences of the parameters such as concentration of catalyst and oxidant, pH, and reaction time on the thioanisole as models are investigated. Under optimum conditions, 1 exhibits high conversion (up to 99%), excellent chemoselectivity (≥90% in all cases) and moderate enantioselectivity (up to 75% ee). After binding with serum albumin, the catalytic activity of 1 is promoted. The bovine serum albumin (BSA) and pig serum albumin (PSA) molecules have a more positive effect on the catalytic activity.
- Tang, Jie,Yao, Peng-Fei,Xu, Xiao-Ling,Li, Hai-Ye,Huang, Fu-Ping,Nie, Qing-Qing,Luo, Mei-Yi,Yu, Qing,Bian, He-Dong
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p. 44154 - 44162
(2016/06/09)
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- Enantioselective sulfoxidation reaction catalyzed by a G-quadruplex DNA metalloenzyme
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Enantioselective sulfoxidation reaction is achieved for the first time by a DNA metalloenzyme assembled with the human telomeric G-quadruplex DNA and Cu(ii)-4,4′-bimethyl-2,2′-bipyridine complex, and the mixed G-quadruplex architectures are responsible for the catalytic enantioselectivity and activity.
- Cheng, Mingpan,Li, Yinghao,Zhou, Jun,Jia, Guoqing,Lu, Sheng-Mei,Yang, Yan,Li, Can
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p. 9644 - 9647
(2016/08/04)
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- Biotransformation of prochiral sulfides into (R)-sulfoxides using immobilized Gordonia terrae IEGM 136 cells
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Biotransformation of methyl phenyl sulfide (MPS) into optically active (R)-sulfoxide was optimized using Gordonia terrae IEGM 136 cells immobilized into cryogel of polyvinyl alcohol. Biotransformation time of 0.5 g/L MPS was shortened from 144 to 24 h in comparison with free cells. Immobilized Gordonia cells were resistant to high (up to 1.5 g/L) sulfide concentrations and catalyzed its complete bioconversion into (R)-sulfoxide (95% ee) within 72 h. Using a sequential addition method, the total load of MPS reached 4.25 g/L. At that, MPS bioconversion was 96.9% and the enantiomeric excess (ee) value of the target (R)-sulfoxide was as high as 96%. Possible reuse of immobilized cells for MPS biotransformation was experimentally proved. The obtained biocatalyst showed a high activity towards ethyl phenyl sulfide, benzyl methyl sulfide, methyl p-tolyl sulfide and formed corresponding (R)-sulfoxides with 77-95% ee. Putative pathways for sulfide oxidation by Gordonia cells were proposed.
- Kylosova,Elkin,Grishko,Ivshina
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- Compound and application of compound in preparation of orseolia oryzae sex attractant
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The invention discloses a compound and an application of the compound in preparation of an orseolia oryzae sex attractant. The compound is (6S)-6-acetoxyl-2-heptanone, and a structural formula of the compound is represented as a formula I. The compound can cooperate with (6S)-6-acetoxyl-2-heptanone to be taken as the orseolia oryzae sex attractant or can be independently taken as the orseolia oryzae sex attractant, and the compound can be used for performing population monitoring and comprehensive control of orseolia oryzae. The orseolia oryzae sex attractant prepared from the compound and a lure of the orseolia oryzae sex attractant can be applied to: (1) orseolia oryzae population monitoring and prediction; (2), mass trapping; (3), mating disruption. The sex attractant prepared from the sex pheromone (namely, the compound) and the lure of the sex attractant can be used for performing population monitoring and comprehensive control on the orseolia oryzae, and the sex attractant has the advantages of low cost and high efficiency and is suitable for predicting the occurrence rule of pests hiding in insect galls.
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Paragraph 0083; 0084
(2016/12/22)
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- Rice gall midge sex attractant and application thereof
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The invention discloses rice gall midge sex attractant and application thereof.The rice gall midge sex attractant is prepared from two rice gall midge sex pheromone effective components, namely, (2S,6S)-2,6-Diacetoxyheptane and (6S)-6-acetoxyl group-2-hep
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Paragraph 0036-0037
(2017/04/03)
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- Compound and application thereof to preparation of orseolia oryzae wood-mason sex attractant
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The invention discloses a compound and application thereof to preparation of orseolia oryzae wood-mason sex attractant. The compound is (2S, 6S)-2, 6-2 acetoxyl group heptanes, and the structural formula of the compound is as shown in the formula I. The compound can be matched with (6S)-6-acetoxyl group-2-heptanone or used independently to serve as the orseolia oryzae wood-mason sex attractant and can be used for conducting population monitoring and comprehensive prevention and control over orseolia oryzae wood-mason. The orseolia oryzae wood-mason sex attractant prepared from the compound and a lure of the sex attractant can be used for population monitoring and predication of orseolia oryzae wood-mason, mass trapping and interference with mating. The sex attractant prepared from sex pheromone (compound) and the lure of the sex attractant can be used for population monitoring and comprehensive prevention and control over orseolia oryzae wood-mason, and the sex attractant is low in cost, high in efficiency and suitable for predicating occurrence regularity of pests hiding in insect galls.
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Paragraph 0078-0079
(2017/04/03)
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- Bimetallic titanium complex catalyzed enantioselective oxidation of thioethers using aqueous H2O2 as a terminal oxidant
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A series of dimeric amino alcohol derived Schiff bases with various chiral amino alcohols and their corresponding bimetallic titanium complex were generated in situ. Thereafter with the in situ generated complexes, the asymmetric oxidation of prochiral aryl alkyl sulfides has been investigated using aqueous H2O2 as a terminal oxidant. During the study we found that the use of methanol or tert-butanol as an additive improved the catalytic activity in terms of both conversion and enantioselectivity. Moreover we observed a co-operative effect of the two reactive units of the bimetallic complex, which results in high reactivity as well as enantioselectivity compared to the corresponding monomeric complex. With this improved catalytic system several aryl alkyl sulfides and 1,3-dithianes were oxidised to the corresponding sulfoxides with good to high enantioselectivity (ee 78-99%) and conversion (70-99%). Unlike the monomer, oxidation of substrates like benzyl phenyl sulfide was achieved with high enantioselectivity as well as high yield.
- Bera, Prasanta Kumar,Gupta, Naveen,Abdi, Sayed H. R.,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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p. 47732 - 47739
(2015/06/16)
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- A click chemistry approach towards flavin-cyclodextrin conjugates-bioinspired sulfoxidation catalysts
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A click chemistry approach based on the reaction between alkynylflavins and mono(6-azido-6-deoxy)-β-cyclodextrin has proven to be a useful tool for the synthesis of flavin-cyclodextrin conjugates studied as monooxygenase mimics in enantioselective sulfoxi
- Tomanová, Petra,?turala, Ji?í,Budě?ínsky, Milo?,Cibulka, Radek
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p. 19837 - 19848
(2015/12/23)
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- A Non-Aldol Preparation of Enantiopure Propionate-Derived Motifs with the Assistance of Chiral Sulfoxides: Application to a Convergent Synthesis of the Lactone Core of Octalactins
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Propionate-derived fragments were prepared by a non-aldol method using chiral sulfoxide chemistry. A methacrylate ester, assisted by a chiral sulfoxide as an auxiliary agent, was easily transformed into an optically pure allylic alcohol, which was then su
- Bauder, Claude
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p. 5402 - 5413
(2015/08/24)
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- In situ-generated chiral iron complex as efficient catalyst for enantioselective sulfoxidation using aqueous H2O2 as oxidant
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A series of amino alcohol-derived, Schiff-base ligands L1-L4 were synthesised and characterized. Iron complexes of these ligands [FeL1(acac)], [FeL2(acac)], [FeL3(acac)] and [FeL4(acac)] were generated in situ to catalyze the asymmetric oxidation of prochiral sulfides using aqueous H2O2 as a terminal oxidant. One of these complexes [FeL1(acac)] was identified as a very efficient catalyst for the enantioselective oxidation of a series of alkyl aryl sulfides with excellent enantioselectivity (75-96% ee), conversion (up to 92%) and chemo selectivity (up to 98%). During the optimization process, a series of electron-donating benzoic acid derivatives were found to favour both conversion and enantioselectivity.
- Bera, Prasanta Kumar,Kumari, Prathibha,Abdi, Sayed H. R.,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Subramanian,Bajaj, Hari C.
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p. 61550 - 61556
(2015/02/19)
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- Exploring nicotinamide cofactor promiscuity in NAD(P)H-dependent flavin containing monooxygenases (FMOs) using natural variation within the phosphate binding loop. Structure and activity of FMOs from Cellvibrio sp. BR and Pseudomonas stutzeri NF13
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Flavin-containing monooxygenases (FMOs) catalyse asymmetric oxidation reactions that have potential for preparative organic synthesis, but most use the more expensive, phosphorylated nicotinamide cofactor NADPH to reduce FAD to FADH2 prior to f
- Jensen, Chantel N.,Ali, Sohail T.,Allen, Michael J.,Grogan, Gideon
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p. 191 - 198
(2015/01/09)
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- Enhancing enantioselectivity and productivity of P450-catalyzed asymmetric sulfoxidation with an aqueous/ionic liquid biphasic system
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Biocatalytic asymmetric sulfoxidation represents a green method to prepare the useful and valuable enantiopure sulfoxides, but this method sometimes suffers from unsatisfied enantioselectivity and low productivity due to substrate and product inhibitions. Here we developed an aqueous/ionic liquid (IL) biphasic system for simultaneously enhancing the enantioselectivity and productivity of P450 monooxygenase-catalyzed asymmetric sulfoxidations of sulfides 1, 3, 5, 7, and 9, as the first example of this kind for a biooxidation. Escherichia coli (P450pyrI83H-GDH) coexpressing P450pyrI83H monooxygenase and glucose dehydrogenase was engineered for the asymmetric sulfoxidations with cofactor recycling, giving higher R-enantioselectivity than any other known P450 monooxygenases and showing high specific activities. The inhibition to the reactions and the toxicity to the cells of the substrates and products were investigated and mostly avoided by using a KP buffer/[P6,6,6,14][NTf2] biphasic reaction system, in which the IL showed excellent biocompatibility to the cells and high solubility to the substrates and products. Sulfoxidations of 1, 3, 5, 7, and 9 with the resting E. coli cells in the biphasic system increased the product concentration from 9.4 to 20 mM for (R)-phenyl methyl sulfoxide 2, from 1.9 to 9.9 mM for (R)-4-fluorophenyl methyl sulfoxide 4, from 5.4 to 16 mM for (R)-ethyl phenyl sulfoxide 6, from 4.2 to 22 mM for (R)-methyl p-tolyl sulfoxide 8, and from 5.7 to 24 mM for (R)-methyl p-methoxyphenyl sulfoxide 10, respectively, and improved the product ee from 85 to 99% for (R)-2, from 80 to 98% for (R)-4, from 88 to 96% for (R)-6, from 35 to 62% for (R)-8, and from 53 to 67% for (R)-10, respectively. The enhancements in enantioselectivity are possibly caused by the low substrate concentrations in the aqueous phase of the biphasic system. Preparative sulfoxidations to produce the useful and valuable sulfoxides (R)-2, (R)-4, and (R)-6 in 99%, 98%, and 96% ee, respectively, were demonstrated.
- Gao, Pengfei,Li, Aitao,Lee, Heng Hiang,Wang, Daniel I. C.,Li, Zhi
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p. 3763 - 3771
(2015/02/19)
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- Iron-catalyzed imidative kinetic resolution of racemic sulfoxides
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Kinetic resolution of racemic sulfoxides requires either custom substrates or shows moderate enantioselectivity, leading to achiral coproducts (such as sulfones) as an intrinsic part of the process. A new strategy is demonstrated that allows the resolution of racemic sulfoxides through catalytic asymmetric nitrene-transfer reactions. This approach gives rise to both optically active sulfoxides and highly enantioenriched sulfoximines. By using a chiral iron catalyst and a readily available iodinane reagent, high selectivity factors have been achieved under very practical reaction conditions. With respect to the substrate scope, it is noteworthy that this unprecedented imidative kinetic resolution of racemic sulfoxides provides access to both aryl-alkyl and dialkyl sulfoximines in highly enantioenriched forms. Copyright
- Wang, Jun,Frings, Marcus,Bolm, Carsten
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supporting information
p. 966 - 969
(2014/02/14)
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- PROCESS FOR THE ASYMMETRIC OXIDATION OF ORGANIC COMPOUNDS WITH PEROXIDES IN THE PRESENCE OF A CHIRAL ACID CATALYST
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The present invention relates to a process for the asymmetric oxidation of nucleophilic organic compounds, particularly metal-free, with peroxide compounds in the presence of a chiral Bronsted acid catalyst. In one detail, the present invention relates to a process for enantioselective sulfoxidation of thiocompounds with peroxide compounds in the presence of a chiral imidodiphosphate catalyst. In another detail, the present invention relates to a process for enantioselective sulfoxidation of thiocompounds with peroxide compounds in the presence of a chiral phosphoric acid catalyst.
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Page/Page column 19-21
(2013/07/25)
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- Flexible C2-symmetric bis-sulfoxides as ligands in enantioselective 1,4-addition of boronic acids to electron-deficient alkenes
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The application of acyclic C2-symmetric chelating bis-sulfoxide ligands in the Rh(I)-catalyzed enantioselective 1,4-addition of boronic acids to electron-deficient alkenes is reported. Among the acyclic ethane-bridged bis-sulfoxides tested, the
- Khiar, Noureddine,Salvador, Alvaro,Valdivia, Victoria,Chelouan, Ahmed,Alcudia, Ana,Alvarez, Eleuterio,Fernandez, Inmaculada
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p. 6510 - 6521
(2013/07/26)
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- A chiral porous metallosalan-organic framework containing titanium-oxo clusters for enantioselective catalytic sulfoxidation
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A chiral porous zeolite-like metal-organic framework is constructed by using mixed ligands of dipyridyl-functionalized chiral Ti(salan) and biphenyl-4,4′-dicarboxylate. The framework containing salan-bound Ti 4O6 clusters consists of both hydrophobic and amphiphilic mesocages and is shown to be an efficient and recyclable heterogeneous catalyst for the oxidation of thioethers to sulfoxides by aqueous H2O 2 (up to 82% ee), displaying markedly enhanced enantioselectivity over the homogeneous catalyst by providing a cavity confinement effect. This work highlights the potential of significantly improving enantioselectivity of homogeneous catalysts by using MOFs as support structures.
- Xuan, Weimin,Ye, Chengcheng,Zhang, Mengni,Chen, Zhijie,Cui, Yong
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p. 3154 - 3159
(2013/07/26)
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- Titanium-salan-catalyzed asymmetric sulfoxidations with H2O 2: Design of more versatile catalysts
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Titanium-salan complexes with 3,3'-diphenyl substituents in the salicylidene rings of the salan ligand are efficient sulfoxidation catalysts, capable of catalyzing the asymmetric oxidation of bulky aryl benzyl sulfides with H2O2 with good to high enantioselectivities. In this paper, substituent effects on titanium-salan-catalyzed enantioselective oxidation of sulfides to sulfoxides have been systematically investigated. Titanium-salan catalysts with halogen substituents at the 5,5'-positions (3,3'-H2dihydrogen substituted) have been found to catalyze the oxidation of both bulky aryl benzyl sulfides and small alkyl phenyl sulfides with good to high enantioselectivities. Kinetic data witness a direct attack of the sulfide to the electrophilic active oxygen species; a consistent reaction mechanism is proposed. Copyright 2013 John Wiley & Sons, Ltd. Titanium-salan complexes with halogen substituents at the 5,5'-positions are versatile catalysts for the oxidation of both bulky aryl benzyl sulfides and small alkyl phenyl sulfides, demonstrating good to high chemoselectivity (up to 92 %) and enantioselectivity (up to 93 % ee). Copyright
- Talsi, Evgenii P.,Bryliakov, Konstantin P.
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p. 239 - 244
(2013/06/04)
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- Chiral microporous Ti(salan)-based metal-organic frameworks for asymmetric sulfoxidation
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Chiral porous metal-metallosalan frameworks are constructed from an unsymmetrical chiral pyridinecarboxylate ligand derived from Ti(salan) and are shown to be heterogeneous catalysts for asymmetric oxidation of thioethers to sulfoxides.
- Zhu, Chengfeng,Chen, Xu,Yang, Zhiwei,Du, Xia,Liu, Yan,Cui, Yong
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p. 7120 - 7122
(2013/08/23)
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- Asymmetric oxidation of sulfides by hydrogen peroxide catalyzed by chiral manganese porphyrins in water/methanol solution
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An efficient asymmetric oxidation of sulfides catalyzed by water-soluble chiral manganese porphyrin was carried out in presence of cheap and environmentally benign oxidant H2O2 at 25 °C. Prochiral sulfides were converted to respective sulfoxides with up to 100% conversion and up to 57% enantiomeric excess. The present study demonstrated the necessity of water as solvent and imidazole as co-catalyst. Application to the preparation of the optically drug, sulindac, was demonstrated.
- Srour, Hassan,Jalkh, Joanna,Le Maux, Paul,Chevance, Soizic,Kobeissi, Marwan,Simonneaux, Gérard
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- Synthesis of novel β-amino alcohols and their application in the catalytic asymmetric sulfoxidation of sulfides
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Novel chiral norephedrine-based β-amino alcohol ligands containing a thiophene ring were prepared from norephedrine and substituted furan carbaldehydes (methyl- or ethyl-substituted) and used in combination with VO(acac)2 for the asymmetric oxidation of aryl methyl sulfides using H2O2 as an oxidant. Amino alcohol derived Schiff bases 4,5a-b gave higher enantiomeric excesses than amino alcohol-derived reduced Schiff based ligands 6,7a-b. Of these chiral ligands, (1S,2R)-5b and (1S,2R)-7b gave high yields (90%) with moderate to high enantioselectivities (78%, 96% ee, respectively). The oxidation of other aryl methyl sulfides with (1S,2R)-5b and (1S,2R)-7b as ligands afforded the corresponding sulfoxides in 60-89% yields and with 92-99% ee.
- Aydin, A. Ebru
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p. 444 - 448
(2013/06/26)
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- Investigation of steric and electronic effects in the copper-catalysed asymmetric oxidation of sulfides
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Steric and electronic effects in the copper-catalysed asymmetric oxidation of aryl benzyl, aryl alkyl and alkyl benzyl sulfides have been investigated. The presence of an aryl group directly attached to the sulfur is essential to afford sulfoxides with high enantioselectivities, with up to 97% ee for 2-naphthyl benzyl sulfoxide, the highest enantioselectivity achieved to date for copper-catalysed asymmetric sulfoxidation. In contrast, the benzyl substituent can be replaced by sterically comparable groups with no effect on enantioselectivity. Copper-mediated oxidation of substituted aryl benzyl sulfides display modest steric and electronic effects resulting in comparable or lower enantioselectivities to those obtained with the unsubstituted benzyl phenyl sulfide.
- O'Mahony, Graham E.,Eccles, Kevin S.,Morrison, Robin E.,Ford, Alan,Lawrence, Simon E.,Maguire, Anita R.
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supporting information
p. 10168 - 10184
(2013/11/06)
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- Asymmetric oxidation catalysis by a porphyrin-inspired manganese complex: Highly enantioselective sulfoxidation with a wide substrate scope
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The first genuinely promising porphyrin-inspired manganese-catalyzed asymmetric sulfoxidation method using hydrogen peroxide has been successfully developed, allowing for rapidly oxidizing (0.5-1.0 h) a wide variety of sulfides in high yields with excellent enantioselectivities (up to >99% ee).
- Dai, Wen,Li, Jun,Chen, Bo,Li, Guosong,Lv, Ying,Wang, Lianyue,Gao, Shuang
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supporting information
p. 5658 - 5661
(2013/12/04)
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- Sequential deracemization of sulfoxides via whole-cell resolution and heterogeneous oxidation
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A new concept for the synthesis of asymmetric sulfoxides exploiting sequential deracemization of racemic (rac) sulfoxides using a two-stage protocol had been developed. Enantio-pure sulfoxide was obtained using Escherichia coli (E. coli) cells to catalyze the reduction of (R)-sulfoxide to the thioether, and then using a heterogeneous Ta2O5-SiO2 catalyst for catalyzing the oxidation of the ethers to the rac-sulfoxide. The performance of E. coli depended on the strain and the conditions under which the bacteria growth was carried out (e.g. source of carbon, presence of vitamins, and concentration of dimethyl sulfoxide, DMSO). Under optimized conditions, the E. coli cells performed the rac-sulfoxide resolution for different sufoxides leading to the best enantiomeric excess (ee) of around 62% (S)-MTSO (methyl tolyl sulfoxide) with 49% conversion of the rac-MTSO. The sequential deracemization process applied for rac-MTSO was cyclically performed leading to 97.5% ee of (S)-sulfoxide and a 56% yield in (S)-sulfoxide after three deracemization cycles of rac-MTSO.
- Tudorache, Madalina,Nica, Simona,Bartha, Emerich,Lupan, Iulia,Parvulescu, Vasile I.
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- A tetradentate ligand for the enantioselective Ti(IV)-promoted oxidation of sulfides to sulfoxides: Origin of enantioselectivity
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A detailed stereomechanistic analysis has led to the design of a new tetradentate ligand for the enantioselective Ti(IV)-catalyzed oxidation of unsymmetrical sulfides to sulfoxides with high selectivity. The pathway of this oxidation and the closely related and long-known Kagan-Modena oxidation have been clarified to identify the likely origin of the enantioselectivity.
- Newhouse, Timothy R.,Li, Xin,Blewett, Megan M.,Whitehead, Clare M. C.,Corey
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supporting information
p. 17354 - 17357
(2013/01/15)
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- Application of a novel 1,3-diol with a benzyl backbone as chiral ligand for asymmetric oxidation of sulfides to sulfoxides
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A chiral 1,3-diol with a benzyl backbone has been used for the asymmetric oxidation of sulfides to sulfoxides. Moderate to good yields and enantioselectivity (upto 87% ee) have been observed.
- Gogoi, Paramartha,Kotipalli, Trimurthulu,Indukuri, Kiran,Bondalapati, Somasekhar,Saha, Pipas,Saikia, Anil K.
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supporting information; experimental part
p. 2726 - 2729
(2012/07/17)
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- Asymmetric counteranion-directed iron catalysis: A highly enantioselective sulfoxidation
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A highly active and enantioselective ion-pair sulfoxidation catalyst, consisting of an achiral iron(III)-salen cation and a chiral phosphate counteranion, mediates the oxidization of various sulfides with high yields and enantioselectivities. The enantioselectivities observed, especially for electron-poor substrates, represent the best results so far in manganese and iron-salen systems. This work represents the first application of our concept of asymmetric counteranion-directed catalysis (ACDC) to iron catalysis. Copyright
- Liao, Saihu,List, Benjamin
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supporting information
p. 2363 - 2367
(2012/10/30)
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- Supramolecular assembly of chiral polyoxometalate complexes for asymmetric catalytic oxidation of thioethers
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In this paper, a chiral amphiphilic cation with two stereocenters has been employed to encapsulate a well-known catalytically activated sandwich-type polyoxometalate, Na12[WZn3(H2O) 2(ZnW9O34)2], through electrostatic interaction. The prepared chiral organic cation-encapsulated polyoxometalate complexes were found to self-aggregate into spherical supramolecular assemblies with a diameter of ca. 100 nm in the reaction solution. These assemblies, serving as microreactors, exhibited an efficient asymmetric catalytic activity for the oxidation of sulfide with up to 72% enantiomeric excess. The coverage density of chiral organic cations enwrapped on the polyoxometalate surface was proved to have an important influence on the enantioselectivity. Detailed kinetic study of the catalytic process showed that the enantioselectivity of sulfide oxidation was derived from the combination of an ineffective asymmetric sulfoxidation and an effective kinetic resolution of the sulfoxide. The present research strategically offers an understanding for the direct and efficient construction of polyoxometalate based supramolecular catalysts for asymmetric reactions through controlling the surface microenvironment.
- Wang, Yizhan,Li, Haolong,Qi, Wei,Yang, Yang,Yan, Yi,Li, Bao,Wu, Lixin
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p. 9181 - 9188
(2013/01/13)
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- Copper-catalyzed asymmetric oxidation of sulfides
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Copper-catalyzed asymmetric sulfoxidation of aryl benzyl and aryl alkyl sulfides, using aqueous hydrogen peroxide as the oxidant, has been investigated. A relationship between the steric effects of the sulfide substituents and the enantioselectivity of th
- O'Mahony, Graham E.,Ford, Alan,Maguire, Anita R.
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experimental part
p. 3288 - 3296
(2012/05/20)
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- Chiral phosphoric acid-catalyzed asymmetric oxidation of aryl alkyl sulfides and aldehyde-derived 1,3-dithianes: Using aqueous hydrogen peroxide as the terminal oxidant
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(R)-1,1'-Binaphthyl-2,2'-diol (R-BINOL) derived chiral phosphoric acids have been explored as organocatalysts for the asymmetric oxidation of a series of aryl alkyl sulfides and 1,3-dithianes derived from aldehydes with aqueous hydrogen peroxide (H2O2) as the terminal oxidant. The enantiomerically enriched sulfoxides are obtained in moderate to excellent yield (up to 99%) with excellent diastereoselectivity (up to >99:1 dr) and moderate to good enantioselectivity (up to 91:9 er). In particular, the present protocol stereoselectively provides an efficient access to enantiomerically enriched aryl alkyl sulfoxides and dithioacetal mono-sulfoxides, which strictly restrains the formation of the undesirable by-products: sulfones or disulfoxides. The tracking experiments also verify that this approach proceeds via a direct sulfoxidation process, instead of a kinetic resolution route by overoxidation of the resulting sulfoxides. Copyright
- Liu, Zhao-Min,Zhao, Hua,Li, Mei-Qiu,Lan, Yu-Bao,Yao, Qi-Bo,Tao, Jing-Chao,Wang, Xing-Wang
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supporting information; experimental part
p. 1012 - 1022
(2012/05/20)
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- Efficient biocatalysis for the production of enantiopure (S)-epoxides using a styrene monooxygenase (SMO) and Leifsonia alcohol dehydrogenase (LSADH) system
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Herein we report the production of enantiopure epoxides through biocatalysis using recombinant Escherichia coli cells expressing Rhodococcus sp. ST-10 styrene monooxygenase (SMO) and Leifsonia sp. S749 alcohol dehydrogenase (LSADH) genes are described. Rhodococcus sp. ST-10 SMO catalyzed the epoxidation of various alkenes, including styrene derivatives, vinyl pyridines, and linear alkenes, to give (S)-epoxides. NADH was regenerated by the reduction of NAD + by LSADH with 2-propanol. The E. coli biocatalyst was used in an aqueous/organic biphasic reaction system and the reaction conditions were optimized. Under the optimized conditions, 170 mM of (S)-styrene oxide was obtained from styrene in the organic phase with excellent enantiomeric excess (99.8%). This biocatalytic process was used to synthesize various (S)-epoxides.
- Toda, Hiroshi,Imae, Ryouta,Itoh, Nobuya
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p. 1542 - 1549
(2013/02/21)
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- Activation of H2O2 by chiral confined Bronsted acids: A highly enantioselective catalytic sulfoxidation
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Confined chiral Bronsted acids are shown to catalyze asymmetric oxidations of sulfides to sulfoxides with hydrogen peroxide. The wide generality and high enantioselectivity of the developed method compare even to the best metal-based systems and suggest utility in other asymmetric oxidations.
- Liao, Saihu,Coric, Ilija,Wang, Qinggang,List, Benjamin
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supporting information; experimental part
p. 10765 - 10768
(2012/08/28)
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- Diastereoselective synthesis of the C17-C30 fragment of amphidinol 3
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The diastereoselective synthesis of the C17-C30 fragment of amphidinol 3 (AM3) 1 was achieved from the enantio-enriched aldehyde 20, Weinreb amide 14 and 2-bromo-3-(trimethylsilyl)propene, which was used as a bifunctional conjunctive reagent. The absolute configuration of the stereogenic centers, in both aldehyde 20 and Weinreb amide 14, were efficiently controlled by using (+)-(R)-methyl-p-tolylsulfoxide as the unique source of chirality.
- Rival, Nicolas,Hazelard, Damien,Hanquet, Gilles,Kreuzer, Thomas,Bensoussan, Charlelie,Reymond, Sébastien,Cossy, Janine,Colobert, Fran?oise
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supporting information
p. 9418 - 9428
(2013/01/15)
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