- Diketobile acids as new hosts in solid-state enantioselective resolutions
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New diketobile acid derivatives have been evaluated as hosts in the resolution of aryl methyl sulfoxides. The guest molecules are linked to the host ones via hydrogen bonds with the SO group. The 3,6-diketo derivative is also effective for the resolution of γ-lactames. Copyright
- Fantin, Giancarlo,Fogagnolo, Marco,Perrone, Daniela,Bortolini, Olga
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- Chiral: N, N ′-dioxide-iron(iii)-catalyzed asymmetric sulfoxidation with hydrogen peroxide
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A highly enantioselective sulfoxidation of various sulfides has been achieved by a N,N′-dioxide-iron(iii) complex with 35% aq. H2O2 as the oxidant. The utility of the current method was demonstrated by asymmetric gram-scale synthesis of drug molecule (R)-modafinil. Moreover, a possible working mode was provided to elucidate the chiral induction.
- Dong, Shunxi,Feng, Lili,Feng, Xiaoming,Liu, Xiaohua,Wang, Fang
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supporting information
p. 3233 - 3236
(2020/03/23)
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- Highly Efficient Access to (S)-Sulfoxides Utilizing a Promiscuous Flavoprotein Monooxygenase in a Whole-Cell Biocatalyst Format
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Chiral sulfoxides have gained attention as synthons and precursors for API synthesis. Flavoproteins such as Baeyer-Villiger or styrene monooxygenases mainly provide access to (R)-sulfoxides and often suffer from low selectivity, activity, and/or limited substrate scope. The flavoprotein monooxygenase AbIMO from Acinetobacter baylyi ADP1 initiates indole degradation. Here, AbIMO was expressed recombinantly in E. coli and characterized for its sulfoxidation activity and substrate spectrum. Next to indole and styrene, AbIMO was found to accept numerous alkyl aryl sulfides as substrates, transforming them to (S)-sulfoxides with high enantioselectivity (95 percent to '99 percent for most sulfides). The formulation as a whole-cell biocatalyst allowed specific production rates of up to 370 U gcdw?1 – the highest specific oxygenase activity achieved in whole cells so far – and the preparative synthesis of enantiopure (S)-aryl alkyl sulfoxides. With its extraordinarily high specific activity, high specificity, ease of handling, and high stability (catalyst is stable for '16 days at 4 °C), the designed whole-cell biocatalyst adds enormous value to the portfolio of chemical and biological catalysts for asymmetric sulfoxide synthesis.
- Willrodt, Christian,Gr?ning, Janosch A. D.,Nerke, Philipp,Koch, Rainhard,Scholtissek, Anika,Heine, Thomas,Schmid, Andreas,Bühler, Bruno,Tischler, Dirk
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p. 4664 - 4671
(2020/01/22)
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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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- Enzymatic kinetic resolution of chiral sulfoxides-an enantiocomplementary approach
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A new enzymatic assay for the preparation of chiral sulfoxides that is enantiocomplementary to the known (S)-enantiomer-reducing activity of methionine sulfoxide reductase A (MsrA) is described. To this end, we have utilized the enzyme DMSO reductase (DmsABC), recently discovered by us being highly upregulated in stationary phase E. coli bacteria.
- Nosek, Vladimír,Mí?ek, Ji?í
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supporting information
p. 10480 - 10483
(2019/09/07)
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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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- Method for catalyzing asymmetric oxidation of sulfur ether
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The invention provides a method for asymmetrically oxidizing sulfur ether. The sulfur ether is subjected to asymmetric catalytic oxidation reaction by taking a chiral complex formed by a four-tooth nitrogen organic ligand and a metal scandium compound as a catalyst and taking hydrogen peroxide as an oxidizing agent to obtain a corresponding chiral sulfoxide compound, and the yield and the enantioselectivity are more than 90 percent. The reaction has the advantages of cleanness, mild reaction condition, high conversion rate and high enantioselectivity. The method has an industrial prospect.
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Paragraph 0028; 0029; 0030; 0031
(2017/08/30)
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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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- Acid catalyzed alcoholysis of sulfinamides: Unusual stereochemistry, kinetics and a question of mechanism involving sulfurane intermediates and their pseudorotation
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The synthesis of optically active sulfinic acid esters has been accomplished by the acid catalyzed alcoholysis of optically active sulfinamides. Sulfinates are formed in this reaction with a full or predominant inversion of configuration at chiral sulfur or with predominant retention of configuration. The steric course of the reaction depends mainly on the size of the dialkylamido group in the sulfinamides and of the alcohols used as nucleophilic reagents. It has been found that bulky reaction components preferentially form sulfinates with retention of configuration. It has been demonstrated that the stereochemical outcome of the reaction can be changed from inversion to retention and vice versa by adding inorganic salts to the acidic reaction medium. The unusual stereochemistry of this typical bimolecular nucleophilic substitution reaction, as confirmed by kinetic measurements, has been rationalized in terms of the addition-elimination mechanism, A-E, involving sulfuranes as intermediates which undergo pseudorotations.
- Bujnicki, Bogdan,Drabowicz, Jzef,Mikolajczyk, Marian
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p. 2949 - 2972
(2015/09/21)
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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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- Chain Extension of Boronic Esters with Lithiooxiranes Generated by Sulfoxide-Metal Exchange - Stereocontrolled Access to 2°/2°, 2°/3°, and 3°/3° Vicinal Diols and Related Compounds
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Lithiooxiranes [LiCR1(O)CR2R3, R1 = H, Me; R2/R3 = H/Ph, H/tBu, Me/Ph], generated by sulfoxide-lithium exchange from stereodefined sulfinyl epoxides (with use of PhLi or tBuLi, THF, at or below -90 °C), were employed for the stereospecific reagent-controlled homologation of boronic esters R0-Bpin (R0 = BnCH2, allyl, cHex, Ph). Addition of TBSOTf to the intermediate ate complexes gave β-silyloxyboronates that were converted to vicinal diol monosilyl ethers by oxidative work-up with aq. NaOOH. The 2°/2° (4-32 %, dr > 98:2), 2°/3° (21-66 %, dr ≥ 65:35), and 3°/3° (59-68 %, dr ≥ 95:5) contiguous stereodiad-containing compounds created in this manner were typically obtained in a highly stereocontrolled manner. In general, cis-sulfinyl epoxides afforded anti-like stereodiads, whereas trans-sulfinyl epoxides afforded syn-like stereodiads; however, as a result of its suspected configurational instability, LiCMe(O)CHPh gave anti-like 2°/3° motifs regardless of sulfinyl epoxide stereochemistry.
- Alwedi, Embarek,Zakharov, Lev N.,Blakemore, Paul R.
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supporting information
p. 6643 - 6648
(2016/02/19)
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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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- 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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- 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 25-27
(2013/07/25)
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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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- A new methodology for the oxidation of sulfides with Fe(III) catalysts
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A variety of sulfides were converted to the corresponding sulfoxide derivatives with 70% t-BuOOH (water) as the oxidant in the presence of catalytic quantity of Fe2(SO4)3. The method described has a wide range of applicati
- Chakraborty, Debashis,Malik, Payal,Goda, Vinod Kumar
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experimental part
p. 21 - 26
(2012/03/11)
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- Bi2O3 catalyzed asymmetric oxidation of sulfides
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Bismuth based catalytic system for the asymmetric oxidation of alkyl and aryl benzyl sulfides using t-BuOOH as the oxidant has been investigated. This method affords sulfoxides with high enantioselectivities (up to 98% ee) and good yields in reasonable time. The over oxidized product namely the sulfone was not observed. The described method has wide range of applications, exhibits chemoselectivity/enantioselectivity, and proceeds under mild and environmentally friendly reaction conditions.
- Malik, Payal,Chakraborty, Debashis
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supporting information
p. 5652 - 5655
(2012/11/07)
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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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- 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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- 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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- Titanium complexes of chiral amino alcohol derived Schiff bases as efficient catalysts in asymmetric oxidation of prochiral sulfides with hydrogen peroxide as an oxidant
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An efficient asymmetric oxidation of prochiral sulfides catalyzed by a series of simple in situ generated complexes based on chiral amino alcohol derived Schiff bases with Ti(Oi-Pr)4 was carried out in presence of cheap and environmentally benign oxidant H2O2 at 0 °C. Prochiral sulfides were converted to respective chiral sulfoxides efficiently (conversion, 93%; up to ee, 98%) with this system in 10 h at 0 °C. The present study demonstrated a significant role of steric influence of the substituent attached on both aryl and alkyl moiety on the enantioselectivity. Kinetic studies of the catalytic reaction showed first order dependence on substrate and catalyst whereas it is zero for the oxidant. Kinetic studies in combination with UV-vis. spectral studies were used to propose a catalytic cycle for the sulfoxidation reaction.
- Bera, Prasanta Kumar,Ghosh, Debashis,Abdi, Sayed Hasan Razi,Khan, Noor-Ul Hasan,Kureshy, Rukhsana Ilays,Bajaj, Hari Chandra
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experimental part
p. 36 - 44
(2012/08/07)
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- Optically active tripodal dendritic polyoxometalates: Synthesis, characterization and their use in asymmetric sulfide oxidation with hydrogen peroxide
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A series of structurally well-defined enantiopure tripodal allyl dendritic structures bearing three amine groups have been synthesized. The hydrogenation of the allyl groups in the presence of a Pd/C catalyst gave the corresponding enantiopure n-propyl counterparts. Treatment of these n-propyl amino dendrimers with heteropolyacid H3PW12O40 and excess H 2O2 gave the enantiopure n-propyl {PO 4[WO(O2)2]4}3- salts. Characterization of these dendritic POM hybrids in solution by NMR spectroscopy, elemental analysis, UV/Vis spectrophotometry, circular dichroism (CD), vibrational circular dichroism (VCD) and fluorimetry indicates the presence of POM-ligand interactions and confirms their optical and chiroptical properties. The hybrid compounds selectively oxidized sulfides to the corresponding chiral sulfoxides with up to 13% enantiomeric excess (ee), highlighting the transfer of chirality from the dendritic wedges to the inorganic cluster. The properties of the POM anion, especially its solubility and regio-and stereoselectivity, are sensitive to the structure of the cation. The catalyst was recovered by precipitation without any discernible loss in activity, selectivity or enantioselectivity over three catalytic cycles at-50 °C. Interestingly, a dendritic effect was noted in the enantioselectivity as the dendritic-POM hybrids are more selective than their non-dendritic counterparts. The ee resulting from chirality transfer to the anionic POM unit is comparable to that obtained in our previous work with monopodal dendritic polyoxometalates (14%) despite the polyvalency of the highly charged tripodal ligand, which is rationalized by different spectroscopic methods. Copyright
- Jahier, Claire,Coustou, Marie-Flora,Cantuel, Martine,McClenaghan, Nathan D.,Buffeteau, Thierry,Cavagnat, Dominique,Carraro, Mauro,Nlate, Sylvain
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experimental part
p. 727 - 738
(2011/04/26)
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- Catalytic enantioselective oxidation of bulky alkyl aryl thioethers with H2O2 over titanium-salan catalysts
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A simple and efficient catalytic procedure for the oxidation of bulky (preferably aryl benzyl substituted) thioethers with hydrogen peroxide in good to high yields and enantioselectivities (up to 98.5%ee) is reported. The high optical yields are achieved in a tandem stereoconvergent enantioselective oxidation and kinetic resolution process. A reasonable balance between the sulfoxide yield and enantioselectivity could be found by varying the concentration and temperature. An improved synthesis of the titanium-salan catalysts for the preparation of a more stereoselective catalyst is reported.
- Bryliakov, Konstantin P.,Talsi, Evgenii P.
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experimental part
p. 4693 - 4698
(2011/10/03)
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- First enantioselective iron-porphyrin-catalyzed sulfide oxidation with aqueous hydrogen peroxide
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The asymmetric oxidation of sulfides by H2O2 to give optically active sulfoxides (ee up to 90%) was carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts.
- Le Maux, Paul,Simonneaux, Gerard
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supporting information; experimental part
p. 6957 - 6959
(2011/08/08)
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- Enantiopure Ti(IV) amino triphenolate complexes as NMR chiral solvating agents
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Enantiopure Ti(IV) complexes bearing pseudo-C3 amino triphenolate ligands have been synthesized and characterized. The complexes bearing ortho phenyl groups act as 1H NMR chiral solvating agent (CSA) for the stereochemical analysis of a series of sulfoxides. The coordination of a Lewis base coligand (sulfoxide) and the presence of aromatic rings are the key structural factors for the efficiency of the CSA. Chirality, 2011. 2011 Wiley-Liss, Inc. Copyright
- Zonta, Cristiano,Kolarovic, Andrej,Mba, Miriam,Pontini, Marta,KUendig, E. Peter,Licini, Giulia
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body text
p. 796 - 800
(2012/01/19)
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- Exploring the biocatalytic scope of a bacterial flavin-containing monooxygenase
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A bacterial flavin-containing monooxygenase (FMO), fused to phosphite dehydrogenase, has been used to explore its biocatalytic potential. The bifunctional biocatalyst could be expressed in high amounts in Escherichia coli and was able to oxidize indole and indole derivatives into a variety of indigo compounds. The monooxygenase also performs the sulfoxidation of a wide range of prochiral sulfides, showing moderate to good enantioselectivities in forming chiral sulfoxides. The Royal Society of Chemistry 2011.
- Rioz-Martinez, Ana,Kopacz, Malgorzata,De Gonzalo, Gonzalo,Torres Pazmino, Daniel E.,Gotor, Vicente,Fraaije, Marco W.
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experimental part
p. 1337 - 1341
(2011/04/23)
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- New chiral molybdenum complex catalyzed sulfide oxidation with hydrogen peroxide
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Six new cis-dioxomolybdenum(VI) complexes of chiral Schiff-base ligands, derived from condensation of various amino alcohols and substituted salicylaldehydes, have been prepared and characterized by NMR, IR, ESI-MS and single crystal X-ray diffraction techniques. The geometry around the molybdenum center is distorted octahedral in which a tridentate Schiff-base ligand with two anionic oxygens and one neutral imine nitrogen occupies meridional position. The octahedral geometry of the cis-dioxomolybdenum center is additionally completed by a coordinated labile solvent molecule. In some complexes the sixth site is found to be vacant where the relatively bulky substituents hinder the coordination of the solvent. These complexes are tested for catalytic enantioselective sulfoxidation reactions using hydrogen peroxide as oxidant at low temperature which shows high selectivity along with good to moderate enantiomeric excess. ESI-MS study of the reaction mixture indicates the formation of oxoperoxoMo(VI) complexes during catalysis. The steric effect originated from the substituent on chiral ligand on the catalytic reaction is also discussed. It is found that the substituents at the β position of the amino alcohol seem to greatly influence the enantioselectivity of the oxidation reactions.
- Chakravarthy, Rajan Deepan,Suresh, Kotapati,Ramkumar, Venkatachalam,Chand, Dillip Kumar
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experimental part
p. 57 - 63
(2011/10/30)
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