- Biocatalytic oxidation by chloroperoxidase from Caldariomyces fumago in polymersome nanoreactors
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The encapsulation of chloroperoxidase from Caldariomyces fumago (CPO) in block copolymer polymersomes is reported. Fluorescence and electron microscopy show that when the encapsulating conditions favour self-assembly of the block copolymer, the enzyme is incorporated with concentrations that are 50 times higher than the enzyme concentration before encapsulation. The oxidation of two substrates by the encapsulated enzyme was studied: i) pyrogallol, a common substrate used to assay CPO enzymatic activity and ii) thioanisole, of which the product, (R)-methyl phenyl sulfoxide, is an important pharmaceutical intermediate. The CPO-loaded polymersomes showed distinct reactivity towards these substrates. While the oxidation of pyrogallol was limited by diffusion of the substrate into the polymersome, the rate-limiting step for the oxidation of thioansiole was the turnover by the enzyme.
- De Hoog,Nallani,Cornelissen,Rowan,Nolte,Arends
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- Preparation and Characterization of Optically Active Quadridentate Schiff Base-Titanium(IV) Complexes and the Catalytic Properties of These Complexes on Asymmetric Oxidation of Methyl Phenyl Sulfide with Organic Hydroperoxides
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Titanium(IV) complexes, 2O, with quadridentate Schiff base ligands derived from optically active 1,2-diamines and salicylaldehyde were prepared by treating TiCl4 with an equimolar amount of the Schiff base ligand in wet pyridine.The com
- Sasaki, Caori,Nakajima, Kiyohiko,Kojima, Masaaki,Fujita, Junnosuke
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- Enantioselective Sulfoxidation of Thioanisole by Cascading a Choline Oxidase and a Peroxygenase in the Presence of Natural Deep Eutectic Solvents
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A bienzymatic cascade for selective sulfoxidation is presented. The evolved recombinant peroxygenase from Agrocybe aegeritra catalyses the enantioselective sulfoxidation of thioanisole whereas the choline oxidase from Arthrobacter nicotianae provides the
- Li, Yongru,Ma, Yunjian,Li, Peilin,Zhang, Xizhen,Ribitsch, Doris,Alcalde, Miguel,Hollmann, Frank,Wang, Yonghua
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- Visible light-driven and chloroperoxidase-catalyzed oxygenation reactions
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Robust peroxidase-catalyzed enantiospecific oxyfunctionalizations can be achieved by simple light-driven in situ generation of hydrogen peroxide.
- Perez, Daniel I.,Grau, Maria Mifsud,Arends, Isabel W. C. E.,Hollmann, Frank
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- Application of various ionic liquids as cosolvents for chloroperoxidase- catalysed biotransformations
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Chloroperoxidase from Caldariomyces fumago catalyses oxidation of indole and thioanisole in reaction mixtures containing up to 40% (v/v) of different ionic liquids (ILs). Results indicate that ILs containing tosylate, trifluoroacetate, chloride, and methylsulfate anions are suitable cosolvents for these transformations, yielding high enantiomeric excess and good conversion rates.
- Lichtenecker, Roman J.,Schmid, Walther
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- Chiral separation materials based on derivatives of 6-amino-6-deoxyamylose
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In order to develop new type of chiral separation materials, in this study, 6-amino-6-deoxyamylose was used as chiral starting material with which 10 derivatives were synthesized. The amino group in 6-amino-6-deoxyamylose was selectively acylated and then the hydroxyl groups were carbamoylated yielding amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s, which were employed as chiral selectors (CSs) for chiral stationary phases of high-performance liquid chromatography. The resulted 6-amido-6-deoxyamyloses and amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s were characterized by IR, 1H NMR, and elemental analysis. Enantioseparation evaluations indicated that most of the CSs demonstrated a moderate chiral recognition capability. The 6-nonphenyl (6-nonPh) CS of amylose 6-cyclohexylformamido-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) showed the highest enantioselectivity towards the tested chiral analytes; the phenyl-heterogeneous (Ph-hetero) CS of amylose 6-(4-methylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) baseline separated the most chiral analytes; the phenyl-homogeneous (Ph-homo) CS of amylose 6-(3,5-dimethylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) also exhibited a good enantioseparation capability among the developed CSs. Regarding Ph-hetero CSs, the enantioselectivity depended on the combination of the substituent at 6-position and that at 2- and 3-positions; as for Ph-homo CSs, the enantioselectivity was related to the substituent at 2-, 3-, and 6-positions; with respect to 6-nonPh CSs, the retention factor of most analytes on the corresponding CSPs was lower than that on Ph-hetero and Ph-homo CSPs in the same mobile phases, indicating π–π interactions did occur during enantioseparation. Although the substituent at 6-position could not provide π–π interactions, the 6-nonPh CSs demonstrated an equivalent or even higher enantioselectivity compared with the Ph-homo and Ph-hetero CSs.
- Gao, Ya-Ya,Zhang, Yu-Hang,Zhang, Shan,Chen, Wei,Bai, Zheng-Wu
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supporting information
p. 899 - 914
(2021/10/07)
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- Ionic liquid-functionalized amphiphilic Janus nanosheets afford highly accessible interface for asymmetric catalysis in water
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High oil/water interfacial area together with accessible interfaces for regents is the key to achieving efficient asymmetric catalysis in water. Herein, by taking advantage of the excellent interfacial activity of Janus nanosheets (JNS), as well as the unique compatibility of imidazolium ionic liquid (IL), we developed a series of IL-functionalized amphiphilic Janus mesosilica nanosheets which afford highly accessible reaction interfaces for highly enantioselective sulfoxidation in water. The JNS-typed chiral salen TiIV catalysts were prepared by selectively decorating hydrophobic chiral salen TiIV complex on one side of Janus mesosilica nanosheets through the imidazolium-based IL linker. Benefiting from the two-dimensional porous Janus structure, as well as the compatible IL linker, the IL-tagged JNS catalysts afforded high oil/water interfacial areas and highly accessible reaction interface for sulfides and H2O2, significantly accelerating asymmetric sulfoxidation in water using H2O2 as an oxidant. In addition, they can be facilely recovered for stable reuse by simple centrifugation.
- Li, Chaoping,Liu, Su,Pi, Yibing,Feng, Jingwen,Liu, Zewei,Li, Shiye,Tan, Rong
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p. 236 - 245
(2021/02/16)
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- Two enantiocomplementary Baeyer-Villiger monooxygenases newly identified for asymmetric oxyfunctionalization of thioether
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Two enantiocomplementary Baeyer-Villiger monooxygenases RaBVMO and AmBVMO were identified by genome mining for the asymmetric sulfoxidation. Both recombinant BVMOs have optimal pH of 9.0 and temperature of 35 °C. The half-lives of RaBVMO and AmBVMO at 30 °C were 24.4 and 24.6 h. RaBVMO and AmBVMO exhibited broad substrate spectrum and could catalyze the oxidization of various compounds including fatty ketones, cyclic ketones, and thioethers. Kinetic parameters analysis revealed that both RaBVMO and AmBVMO displayed higher catalytic efficiency toward thioanisole than cyclohexanone. As much as 50 mM thioanisole could be completely oxidized by AmBVMO and RaBVMO with 99% (R) and 95% (S), respectively. Molecular docking analysis further provides evidence for the complementary enantioselectivity of RaBVMO and AmBVMO. Our results demonstrate the potential application of the two novel BVMOs in asymmetric synthesis of sulfoxides.
- Liu, Yafei,Ni, Ye,Wei, Shiyu,Xu, Guochao,Zhou, Jieyu
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- Efficient Synthesis of Sulfur-Stereogenic Sulfoximines via Ru(II)-Catalyzed Enantioselective C-H Functionalization Enabled by Chiral Carboxylic Acid
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Ru(II)-catalyzed enantioselective C-H functionalization involving an enantiodetermining C-H cleavage step remains undeveloped. Here we describe a Ru(II)-catalyzed enantioselective C-H activation/annulation of sulfoximines with α-carbonyl sulfoxonium ylides using a novel class of chiral binaphthyl monocarboxylic acids as chiral ligands, which can be easily and modularly prepared from 1,1′-binaphthyl-2,2′-dicarboxylic acid. A broad range of sulfur-stereogenic sulfoximines were prepared in high yields with excellent enantioselectivities (up to 99% yield and 99% ee) via desymmetrization, kinetic resolution, and parallel kinetic resolution. Furthermore, the resolution products can be easily transformed to chiral sulfoxides and key intermediates for kinase inhibitors.
- Zhou, Tao,Qian, Pu-Fan,Li, Jun-Yi,Zhou, Yi-Bo,Li, Hao-Chen,Chen, Hao-Yu,Shi, Bing-Feng
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supporting information
p. 6810 - 6816
(2021/05/29)
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- The mutagenesis of a single site for enhancing or reversing the enantio- or regiopreference of cyclohexanone monooxygenases
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The mutagenesis of a "second sphere"switch residue of CHMOAcineto could control its enantio- and regiopreference. Replacing phenylalanine (F) at position 277 of CHMOAcineto into larger tryptophan (W) enabled a significant enhancement of enantio- or regioselectivity toward structurally diverse substrates, moreover, a complete reversal of enantio- or regiopreference was realized by mutating F277 into a range of smaller amino acids (A/C/D/E/G/H/I/K/L/M/N/P/Q/R/S/T/V).
- Hu, Yujing,Xu, Weihua,Hui, Chenggong,Xu, Jian,Huang, Meilan,Lin, Xianfu,Wu, Qi
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supporting information
p. 9356 - 9359
(2020/11/02)
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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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- 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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- Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex
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An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OiPr)4 using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.
- Maddireddy, Narotham V.,Godbole, Himanshu M.,Singh, Girij P.,Kini, Suvarna G.,Shenoy, Gautham G.
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supporting information
p. 2810 - 2818
(2020/07/13)
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- Light-controlled cooperative catalysis of asymmetric sulfoxidation based on azobenzene-bridged chiral salen TiIVcatalysts
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Incorporation of azobenzene into the linker of bimetallic chiral salen TiIVcatalysts allowed the photoswitchable arrangement of the two Ti(salen) units throughcis/transphotoisomerization of azobenzene. The differently arranged Ti(salen) units changed their cooperative function to reflect the positional relationships, as a result, their efficiency as cooperative catalysts in asymmetric sulfoxidation could be readily controlled by light stimuli.
- Fu, Wenqin,Gao, Mengqiao,Li, Chaoping,Pi, Yibing,Tan, Rong,Wang, Weiying,Yin, Donghong
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supporting information
p. 5993 - 5996
(2020/06/04)
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- Accessing Enantiopure Epoxides and Sulfoxides: Related Flavin-Dependent Monooxygenases Provide Reversed Enantioselectivity
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Enantiopure organic compounds are of major importance for the chemical and pharmaceutical industry. Flavin-dependent group E monooxygenases, composed of monooxygenase and reductase, are known to perform epoxidation of substituted alkenes as well as sulfoxidation in a regio- and enantioselective fashion. Group E is divided into styrene monooxygenases (SMO) and indole monooxygenases (IMO). Hitherto mainly SMOs have been characterized. In this study, we assayed 31 monooxygenases from both types, while 23 of which showed activity. They almost exclusively produced (S)-styrene oxide at high enantiomeric excess with maximum activities of 0.73 μmol min?1 mg?1 (kcat=0.54 s?1). In case of sulfoxidation, we found that the enantioselectivity is contrary between both types. IMOs preferably produce the (S)-enantiomer while SMOs have a tendency to produce the (R)-enantiomer. Sequence analysis and molecular docking of substrates allowed identifying fingerprint motives: SMO N46-V48-H50-Y73-H76-S96 and IMO S46-Q48-M50-V/I73-I76-A96. These form an essential part of the active site while the loop (AS44-51) interacts with the co-substrate and other amino acids direct the substrate. The motives clearly distinguish group E monooxygenases and define the enantioselectivity and thus direct biotechnological applications. Two-hour biotransformations with several sulfides in conjunction with upscale experiments (10 and 100 mg scale) resulted in the identification of promising candidates for the realization of biocatalytic processes.
- Heine, Thomas,Scholtissek, Anika,Hofmann, Sarah,Koch, Rainhard,Tischler, Dirk
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p. 199 - 209
(2019/11/13)
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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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- Asymmetric sulfoxidation by C1-symmetric V(IV)O(ONO) (S)-NOBIN Schiff-base vanadyl complexes
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C1-symmetric vanadyl Schiff-base complexes were synthesized by reacting vanadium(IV) acetylacetonate with (S)-3-[(1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ylimino]methyl]-phenanthrene-4-ol and (S)-2-{[1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ylimino]methyl}tetraphene-1-ol. The complexes were characterized by MALDI-TOF-MS, UV-vis, and circular dichroism (CD) spectroscopy. The catalysts showed moderate activity for the oxidation of thioanisole to methyphenylsulfoxide with hydrogen peroxide, tert-butyl hydroperoxide, and cumene hydroperoxide as the oxidants.
- Barman, Sanmitra,Levy, Christopher J.
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supporting information
p. 637 - 641
(2019/09/06)
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- Enhanced Activity and Substrate Specificity by Site-Directed Mutagenesis for the P450 119 Peroxygenase Catalyzed Sulfoxidation of Thioanisole
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P450 119 peroxygenase was found to catalyze the sulfoxidation of thioanisole and the sulfonation of sulfoxide in the presence of tert-butyl hydroperoxide (TBHP) for the first time with turnover rates of 1549 min?1 and 196 min?1 respectively. Several mutants were designed to improve the peroxygenation activity and thioanisole specificity by site-directed mutagenesis. The F153G/T213G mutant gave an increase of sulfoxide yield and a decrease of sulfone yield. Moreover the S148P/I161T/K199E/T214V mutant and the K199E mutant with acidic Glu residue contributed to improving the product ratio of sulfoxide to sulfone. Addition of short-alkyl-chain organic acids to the P450 119 peroxygenase-catalyzed sulfur oxidation of thioanisole was investigated. Octanoic acid was found to induce a preferred sulfoxidation of thioanisole catalyzed by the F153G/T213G mutant to give approximately 2.4-fold increase in turnover rate with a kcat value of 3687 min?1 relative to that of the wild-type, and by the F153G mutant to give the R-sulfoxide up to 30 % ee. The experimental control and the proposed mechanism for the P450 119 peroxygenase-catalyzed sulfoxidation of thioanisole in the presence of octanoic acid suggested that octanoic acid could partially occupy the substrate pocket; meanwhile the F153G mutation could enhance the substrate specificity, which could lead to efficiently regulate the spatial orientation of thioanisole and facilitate the formation of Compound I. This is the most effective catalytic system for the P450 119 peroxygenase-catalyzed sulfoxidation of thioanisole.
- Wei, Xiaoyao,Zhang, Chun,Gao, Xiaowei,Gao, Yanping,Yang, Ya,Guo, Kai,Du, Xi,Pu, Lin,Wang, Qin
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p. 1076 - 1083
(2019/07/15)
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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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- A novel homochiral metal-organic framework with an expanded open cage based on (: R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl: synthesis, X-ray structure and efficient HPLC enantiomer separation
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A new homochiral metal-organic framework (MOF) with an expanded open cage based on the (R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl ligand was synthesized and utilized as a novel chiral stationary phase for high-performance liquid chromatography. Twelve racemates including sec-alcohols, sulfoxides, epoxides, lactone, 1,3-dioxolan-2-one, and oxazolidinone were used as analytes for evaluating the separation properties of the chiral-MOF-packed column. Experimentally, the homochiral MOF offered good molecular recognition ability, which suggests good prospects for the application of chiral MOFs as stationary phases for enantioseparation.
- Tanaka, Koichi,Kawakita, Tomohiro,Morawiak, Maja,Urbanczyk-Lipkowska, Zofia
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p. 487 - 493
(2019/01/21)
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- Facile synthesis of a 3D flower-like SiO2-MOF architecture with copper oxide as a copper source for enantioselective capture
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A facile self-template synthetic approach for the facile synthesis of a 3D flower-like SiO2-CuLBH architecture with copper oxide as a copper source has been demonstrated. The resulting composite as a sorbent showed a certain selective separation capability for phenyl methyl sulfoxide enantiomers (PMS) with an enantiomeric excess (ee) value of 31%.
- Li, Xinglin,Gao, Yu,Wang, Cuijie,Cui, Jiting,Yu, Ajuan,Zhang, Shusheng
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p. 16123 - 16126
(2019/11/03)
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- What to sacrifice? Fusions of cofactor regenerating enzymes with Baeyer-Villiger monooxygenases and alcohol dehydrogenases for self-sufficient redox biocatalysis
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A collection of fusion biocatalysts has been generated that can be used for self-sufficient oxygenations or ketone reductions. These biocatalysts were created by fusing a Baeyer-Villiger monooxygenase (cyclohexanone monooxygenase from Thermocrispum municipale: TmCHMO) or an alcohol dehydrogenase (alcohol dehydrogenase from Lactobacillus brevis: LbADH) with three different cofactor regeneration enzymes (formate dehydrogenase from Burkholderia stabilis: BsFDH; glucose dehydrogenase from Sulfolobus tokodaii: StGDH, and phosphite dehydrogenase from Pseudomonas stutzeri: PsPTDH). Their tolerance against various organic solvents, including a deep eutectic solvent, and their activity and selectivity with a variety of substrates have been studied. Excellent conversions and enantioselectivities were obtained, demonstrating that these engineered fusion enzymes can be used as biocatalysts for the synthesis of (chiral) valuable compounds.
- Mourelle-Insua, ángela,Aalbers, Friso S.,Lavandera, Iván,Gotor-Fernández, Vicente,Fraaije, Marco W.
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p. 1832 - 1839
(2019/02/24)
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- An ionic liquid-functionalized amphiphilic Janus material as a Pickering interfacial catalyst for asymmetric sulfoxidation in water
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Ionic liquid-functionalized amphiphilic Janus chiral salen TiIV catalysts were prepared by partial hydrophobic modification of silica with a chiral salen TiIV complex through an imidazolium ionic liquid (IL) linker. By optimizing their hydrophobic/hydrophilic balance, the IL-functionalized JNP materials exhibited excellent interfacial activity, significantly accelerating asymmetric sulfoxidation in water through the formation of stable Pickering emulsions. Moreover, catalyst recovery was readily achieved using centrifugation.
- Zhang, Mingjie,Tang, Zhiyang,Fu, Wenqin,Wang, Weiying,Tan, Rong,Yin, Donghong
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supporting information
p. 592 - 595
(2019/02/05)
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- Steric Tuning of Sulfinamide/Sulfoxides as Chiral Ligands with C1, Pseudo-meso, and Pseudo-C2 Symmetries: Application in Rhodium(I)-Mediated Arylation
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A new family of sulfinamide/sulfoxide derivatives was synthesized as chiral bidentate ligands by stereoselective additions of methylsulfinyl carbanions to N-tert-butylsulfinylimines. The new ligands, with C1, pseudo-meso, and pseudo-C2 symmetries, were successfully assayed in Rh-catalyzed additions of arylboronic acids to activated ketones. The sterically dissymmetric C1 ligand (RS,SC,RS)-N-[1-(phenylsulfinyl)-3-methylbut-2-yl] tert-butylsulfinamide turned out to be the optimal one, allowing the 1,4-additions of diverse arylboronic acids, on different α,β-unsaturated cyclic ketones with high chemical yields and enantioselectivities up to >99% ee.
- Borrego, Lorenzo G.,Recio, Rocío,álvarez, Eleuterio,Sánchez-Coronilla, Antonio,Khiar, Noureddine,Fernández, Inmaculada
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supporting information
p. 6513 - 6518
(2019/08/20)
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- Diastereoselective Synthesis and Catalytic Activity of Two Chiral cis-Dioxidomolybdenum(VI) Complexes
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Two enantiomerically pure chiral dioxidomolybdenum(VI) complexes (1 and 2) of the type [MoO2L] (L = dianionic, tetradentate ONNO-ligand) were synthesized and investigated in enantioselective oxidation reactions. The solid-state structures of complex 1 and 2, determined via single-crystal X-ray diffraction analysis revealed two fundamentally different coordination geometries: a C1-symmetric cis-β isomer (Λ-1), and a C2-symmetric cis-α isomer (Δ-2). In both cases, only one of the two possible helical enantiomers (Λ- or Δ-helix) was formed. The complexes were examined as precatalysts in the epoxidation of the challenging prochiral substrate trans-stilbene, using either tert-butyl hydroperoxide (TBHP) or cumyl hydroperoxide (CHP) as oxidants. The asymmetric cis-β complex 1 was found to be significantly more active in the epoxidation than its cis-α counterpart 2, asymmetric induction was, however, negligible for both complexes. The complexes were also tested in catalytic enantioselective sulfoxidation reactions where chiral induction could be achieved, albeit small. The observed putative molybdenum oxido-peroxido intermediate 1-O2 could be identified as an important precomplex before formation of the active catalyst in sulfoxidation.
- Haghdoost, Mohammad Mehdi,Zwettler, Niklas,Golbaghi, Golara,Belaj, Ferdinand,Bagherzadeh, Mojtaba,Schachner, J?rg A.,M?sch-Zanetti, Nadia C.
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p. 2549 - 2556
(2018/06/04)
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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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- Enantioselective Separation over a Chiral Biphenol-Based Metal-Organic Framework
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A chiral porous 3D metal-organic framework (MOF) is constructed from an enantiopure carboxylate ligand of 1,1′-biphenol, which can be utilized as adsorbent for the separation of aromatic alcohols and sulfoxides with enantioselectivity of up to 99.4%. Single-crystal X-ray diffraction analysis reveals the binding sites and host-guest interactions clearly, providing microscopic insight into the origin of the enantiosorption in the framework.
- Abbas, Anees,Wang, Zhao-Xi,Li, Zijian,Jiang, Hong,Liu, Yan,Cui, Yong
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supporting information
p. 8697 - 8700
(2018/08/17)
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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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- Biocatalytical Asymmetric Sulfoxidation by Identifying Cytochrome P450 from Parvibaculum Lavamentivorans DS-1
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Cytochrome P450 monooxygenases (P450s) catalyzed asymmetric sulfoxidation represents a green route for the synthesis of valuable enantiopure sulfoxides, which are potentially interesting synthons in synthetic and pharmaceutical chemistry. Here the potential P450 and redox partner genes from Parvibaculum lavamentivorans DS-1 are screened and co-expressed in Escherichia coli host to construct twenty recombinant P450 strains. By testing the whole-cell biooxidation of thioanisole, P450PL2 (CYP278A4) and P450PL7 (CYP108G3) are identified with excellent S enantioselectivity while P450PL1 (CYP111B1) and P450PL9 (CYP153A26) exhibit the complementary R enantioselectivity. Asymmetric sulfoxidation of sulfides 1 a–1 m is further investigated using the recombinant E. coli strain P450PL2-2 based on the optimal conditions, producing the corresponding enantioenriched sulfoxides with up to 82 % isolated yield and 99 % ee.
- Wu, Kailin,Tang, Linchao,Cui, Haibo,Wan, Nanwei,Liu, Ziyan,Wang, Zhongqiang,Zhang, Shimin,Cui, Baodong,Han, Wenyong,Chen, Yongzheng
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p. 5410 - 5413
(2018/11/23)
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- Panel of New Thermostable CYP116B Self-Sufficient Cytochrome P450 Monooxygenases that Catalyze C?H Activation with a Diverse Substrate Scope
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The ability of cytochrome P450 monooxygenases to catalyse a wide variety of synthetically challenging C?H activation reactions makes them highly desirable biocatalysts both for the synthesis of chiral intermediates and for late-stage functionalisations. However, P450s are plagued by issues associated with poor expression, solubility and stability. Catalytically self-sufficient P450s, in which the haem and reductase domains are fused in a single protein, obviate the need for additional redox partners and are attractive as biocatalysts. Here we present a panel of natural self-sufficient P450s from thermophilic organisms (CYP116B65 from A. thermoflava, CYP116B64 from A. xiamenense, CYP116B63 from J. thermophila, CYP116B29 from T. bispora and CYP116B46 from T. thermophilus). These P450s display enhanced expression and stability over their mesophilic homologues. Activity profiling of these enzymes revealed that each P450 displayed a different fingerprint in terms of substrate range and reactivity that cover reactions as diverse as hydroxylation, demethylation, epoxidation and sulfoxidation. The productivity of the bio-transformation of diclofenac to produce the 5-hydroxy metabolite increased 42-fold using the thermostable P450-AX (>0.5 g L?1 h?1) compared to the P450-RhF system reported previously. In conclusion, we have generated a toolkit of thermostable self-sufficient P450 biocatalysts with a broad substrate range and reactivity.
- Tavanti, Michele,Porter, Joanne L.,Sabatini, Selina,Turner, Nicholas J.,Flitsch, Sabine L.
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p. 1042 - 1051
(2018/03/21)
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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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- Sulfoxidation inside a C3-vanadium(V) bowl-shaped catalyst
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The confined enantiopure oxido-vanadium complex SSS-RRR-1 was synthesized and tested as a catalyst for the oxidation of sulfides into sulfoxides. This catalyst is very efficient with a reaction rate more than 300 times higher than that of the model compound SSS-RRR-3, and a turnover number (TON) close to 105 was reached in combination with a good selectivity (more than 90%) in the sulfoxide product. Moreover, enantiomerically enriched sulfoxide can be obtained, breaking through the major limitation of the previous chiral vanatrane catalysts that show no detectable enantiomeric excess (ee). Further investigations revealed that the complex SSS-RRR-1 adopts a bowl-shaped structure with an open hydrophobic pocket. The microenvironment of the chiral pocket above the metal center accounts for the strong improvement in catalytic activity and enantioselectivity.
- Zhang, Dawei,Dutasta, Jean-Pierre,Dufaud, Veronique,Guy, Laure,Martinez, Alexandre
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p. 7340 - 7345
(2017/11/09)
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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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- Bio-inspired single-chain polymeric nanoparticles containing a chiral salen TiIV complex for highly enantioselective sulfoxidation in water
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A series of bio-inspired single-chain polymeric nanoparticles (SCPNs) containing a chiral salen TiIV complex in their hydrophobic cavity were constructed from the synthesized amphiphilic copolymers of poly(NIPAAm-co-IL/Ti(salen)) (NIPAAm, N-isopropylacrylamide; IL/Ti(salen), vinylimidazolium ionic liquid-modified chiral salen TiIV complex). These SCPNs behaved as enzyme-mimetic catalysts due to compartmentalization and site isolation, mediating enantioselective oxidation of various sulfides in water with excellent yields (90-99%) and enantioselectivities (ee, 88-99%). In particular, the ee values observed for electron-rich substrates (>95% ee) represented the best results so far in titanium-salen systems. Moreover, the catalysts could be easily recovered for steady reuse by thermo-controlled separation due to thermo-responsive properties. This work first constructed titanium-containing biomimetic SCNPs for biocatalysis of enantioselective sulfoxidation in water.
- Zhang, Yaoyao,Tan, Rong,Gao, Mengqiao,Hao, Pengbo,Yin, Donghong
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p. 1182 - 1193
(2017/08/14)
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- Cooperative chiral salen TiIV catalyst supported on ionic liquid-functionalized graphene oxide accelerates asymmetric sulfoxidation in water
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A cooperative chiral salen TiIV catalyst was prepared by covalently appending multiple chiral salen TiIV complexes on a graphene oxide (GO) surface through a flexible ionic liquid (IL) linker. Characterization results confirmed the decoration of intact Ti(salen) units on the edges and planes of exfoliated GO with the imidazolium-IL spacer. The IL-functionalized GO nanosheets endowed the chiral salen TiIV catalyst with high water-dispersion, diminished diffusion limitation, and particularly a reinforced intramolecular cooperative effect. The cooperative catalyst was thus highly efficient and universally applicable in the catalysis of asymmetric sulfoxidation in water, affording high yields of various chiral sulfoxides with excellent enantioselectivities, while traditional chiral salen TiIV complex was far less active. More importantly, the heterogeneous catalyst was perfectly stable and could be reused several times without significant loss of activity and selectivity.
- Xing, Chen,Deng, Jiang,Tan, Rong,Gao, Mengqiao,Hao, Pengbo,Yin, Donghong,Yin, Dulin
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p. 5944 - 5952
(2017/12/26)
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- Ultraviolet-responsive self-assembled metallomicelles for photocontrollable catalysis of asymmetric sulfoxidation in water
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Self-assembled metallomicelles with ultraviolet (UV)-controlled morphologies were constructed from a synthesized azobenzene-containing amphiphilic chiral salen TiIV catalyst. The morphologies of the metallomicelles could be well adjusted by changing the UV irradiation time, and this was confirmed by TEM analyses. The UV-induced change in morphology potentially adjusted the catalyst concentration and/or accessibility in real-time, allowing photocontrollable catalysis of asymmetric sulfoxidation in water. UV-responsive catalytic activities with excellent selectivities were observed over the metallomicelles for a wide range of alkyl aryl sulfides. Moreover, a thermo-responsive NIPAAm block in the catalyst enables it to be easily recovered for steady reuse by thermo-controlled separation. This work constructed a photo-responsive metallomicellar system to carry out metallomicellar catalysis in a controllable way.
- Gao, Mengqiao,Tan, Rong,Hao, Pengbo,Zhang, Yaoyao,Deng, Jiang,Yin, Donghong
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p. 54570 - 54580
(2017/12/12)
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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 0019; 0020; 0021; 0022; 0023; 0024; 0025-0027
(2017/08/30)
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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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- Enantiopure 24-armed dendritic polyoxometalates: Synthesis and evaluation as recoverable catalysts for asymmetric sulfide oxidation
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Enantiopure 24-armed dendritic polyoxometalate (DENDRI-POM) hybrids were prepared by ionic coupling of enantiopure 8-armed n-propyl dendritic ammoniums with a catalytically active peroxophosphotungstate trianion {PO4[WO(O2)2]4}3-. The catalytic properties of these DENDRI-POM hybrids were evaluated in the oxidation of thioanisole as a model reaction and compared to those of the 12-armed n-propyl analogous previously reported in our group. Up to 10% enantiomeric excess (ee) was obtained, indicating a negative effect on the reaction rate and the enantioselectivity, whereas the selectivity to the chiral sulfoxide versus sulfone was improved. This study AIDS understanding of how the structure and size of the dendritic wedge around the POM can influence its catalytic properties, especially regarding enantioselectivity. Four catalytic cycles were performed without any obvious change in the activity, selectivity and enantioselectivity.
- Jahier, Claire,Touzani, Rachid,El Kadiri, Sghir,Nlate, Sylvain
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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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- Cooperative chiral salen TiIV catalysts with built-in phase-transfer capability accelerate asymmetric sulfoxidation in water
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A series of cooperative chiral salen TiIV catalysts with inherent phase-transfer capability were prepared by covalently bridging double chiral salen TiIV units with various polyethylene glycol (PEG)-based dicationic ionic liquid (IL) linkers. Characterization results suggested the presence of polyether-based IL spacers and intact active sites in the catalysts. The polyether-based dicationic IL spacer not only enforced an intramolecular, cooperative reaction pathway favored for the asymmetric suloxidation, but also endowed the bimetallic catalysts with built-in phase transfer capability. High yields of chiral sulfoxides (in the range of 74-90%) with excellent ee values (in the range of 85-91%) were achieved within 45 min when the asymmetric oxidation of methyl phenyl sulfide, methyl p-methoxyphenyl sulfide, and methyl o-methoxyphenyl sulfide were performed in water. The catalytic efficiency was significantly higher than that over neat complex (yields, 10-16% and ee values, 77-79%). More attractively, the phase transfer catalysts could be facilely recovered by solvent precipitation for efficient reuse.
- Zhao, Guangwu,Tan, Rong,Zhang, Yaoyao,Luo, Xuanfeng,Xing, Chen,Yin, Donghong
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p. 24704 - 24711
(2016/03/15)
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- Double- [...] macrocyclic metal complex and its synthetic method and application (by machine translation)
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The invention discloses a series of double- [...] macrocyclic metal complex and its synthetic method and application. The double- [...] method for synthesizing a macrocyclic metal complex for: heating 5, 5-diamino -1H, 1H -3, 3 the [...] -bi -1, 2, 4-tria
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Page/Page column 10-11
(2016/10/09)
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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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- 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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- Thermo-responsive self-assembled metallomicelles accelerate asymmetric sulfoxidation in water
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A series of novel chiral salen TiIV catalysts with thermo-responsive surfactant properties were prepared by covalently appending a chiral salen TiIV complex on the hydrophobic block of thermo-responsive amphiphilic copolymers of poly(N-isopropylacrylamide-co-N,N-dimethyl acrylamide) (poly (NIPAAM-co-DMAAM)). Characterization results suggested self-assembly behavior of the catalysts in water at room temperature. The self-assembled metallomicelles induced a micellar catalytic approach in asymmetric sulfoxidation in water using H2O2 as an oxidant, leading to significant rate acceleration and remarkable high selectivity. Quantitative conversion (>99%) of methyl phenyl sulfide with up to 96% chemoselectivity and 95% enantioselectivity was achieved over 0.5 mol% of PN70D7-C even within 30 min, whereas neat complex was far less efficient (9% conversion with 72% chemoselectivity and 79% enantioselectivity). Moreover, the catalysts could be easily recovered by thermo-controlled separation and be efficiently reused for several cycles.
- Zhang, Yaoyao,Tan, Rong,Zhao, Guangwu,Luo, Xuanfeng,Xing, Chen,Yin, Donghong
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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
(2016/10/10)
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- Characterization and Crystal Structure of a Robust Cyclohexanone Monooxygenase
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Cyclohexanone monooxygenase (CHMO) is a promising biocatalyst for industrial reactions owing to its broad substrate spectrum and excellent regio-, chemo-, and enantioselectivity. However, the low stability of many Baeyer–Villiger monooxygenases is an obstacle for their exploitation in industry. Characterization and crystal structure determination of a robust CHMO from Thermocrispum municipale is reported. The enzyme efficiently converts a variety of aliphatic, aromatic, and cyclic ketones, as well as prochiral sulfides. A compact substrate-binding cavity explains its preference for small rather than bulky substrates. Small-scale conversions with either purified enzyme or whole cells demonstrated the remarkable properties of this newly discovered CHMO. The exceptional solvent tolerance and thermostability make the enzyme very attractive for biotechnology.
- Romero, Elvira,Castellanos, J. Rubén Gómez,Mattevi, Andrea,Fraaije, Marco W.
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supporting information
p. 15852 - 15855
(2016/12/16)
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- Method for realizing asymmetric oxidation reaction of thioether under aqueous-phase catalysis of chiral Salen Ti complex catalyst based on temperature-sensitive type ionic liquid
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The invention discloses a method for realizing an asymmetric oxidation reaction of thioether under aqueous-phase catalysis of a chiral Salen Ti complex catalyst based on a temperature-sensitive type ionic liquid. According to the method, a chiral thioether compound and hydrogen peroxide are subjected to an asymmetric oxidation reaction under the catalytic action of the chiral Salen Ti complex catalyst based on the temperature-sensitive type ionic liquid in a water medium, and a chiral sulfoxide compound is obtained; the chiral Salen Ti complex catalyst based on the temperature-sensitive type ionic liquid also contains a chiral Salen Ti complex catalyst unit and a temperature-sensitive material unit. Compared with a conventional chiral Salen Ti catalyst, the catalyst has good water solubility, can be subjected to a catalytic reaction in the water medium and is easily recycled; the catalyst is applicable to the aqueous-phase catalytic oxidation reaction of chiral thioether and has the characteristics of high catalysis efficiency and good chiral sulfoxide selectivity.
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Paragraph 0075-0079
(2017/02/24)
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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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- On the nature of the chain-extending species in organolithium initiated stereospecific reagent-controlled homologation reactions using α-chloroalkyl aryl sulfoxides
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The reaction of an organolithium with an α-chloroalkyl aryl sulfoxide ostensibly generates an α-chloroalkyllithium by sulfoxide-lithium exchange, but the actual identity of the chain-extending species in chlorosulfoxide-based StReCH reactions is not certain. To explore this issue, racemic 2-cyclohexyl (4R?,5R?)-4,5-diphenyl-1,3,2-dioxaborolane was homologated by treatment with scalemic (S)-chloromethyl phenyl sulfoxide and n-BuLi (THF, -78 °C). The reaction proceeded without a detectable level of kinetic resolution, a finding consistent with chloromethyllithium being the active chain-extending species rather than a chiral sulfurane intermediate.
- Hoyt, Amanda L.,Blakemore, Paul R.
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supporting information
p. 2980 - 2982
(2015/06/02)
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- A highly efficient, enantioselective and recyclable mesoporous silica-based Mn(ii) catalyst for asymmetric oxidation of thioanisole
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The development of environmentally benign reactions is an important goal in synthetic organic chemistry and chemical engineering. However, catalytic enantioselective oxidations using transition-metal complexes are limited when the oxidant is hydrogen peroxide. A hydrazone based asymmetric ligand (H2L) was used to prepare a heterogeneous catalyst by the immobilization of its manganese complex, [{Mn(H2O)2Cl2}2(H2Btar)] (1), on mesoporous support SBA-15 via the post grafting method (H2L = 2,3-O-4-hydroxybenzhydrazidebenzylidene-d-tartrate). The heterogeneous asymmetric catalyst 1-SBA15 was characterized by elemental analysis; small angle X-ray diffraction (SAX), scanning electron microscopy (SEM), nitrogen sorption measurement, Fourier transform infrared spectroscopy and EPR spectroscopy. The asymmetric oxidation of thioanisole (PhSMe) was achieved with hydrogen peroxide in the presence of 1-SBA15 in excellent conversion and enantioselectivity (>99% ee). Compared to a homogeneous catalyst, the heterogenized catalyst is more stable and can be recycled four times without any significant loss of activity. Immobilization of complex 1 onto SBA-15 increased the selectivity toward sulfone in the oxidation.
- Alavi, Sohaila,Hosseini-Monfared, Hassan,Aleshkevych, Pavlo
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p. 48827 - 48835
(2015/01/08)
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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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