- Threitol-strapped manganese porphyrins as enantioselective epoxidation catalysts of unfunctionalized olefins
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Nine members of a family of new chiral porphyrins have been prepared from reactions between ditosylthreitol derivatives and 5,10,15,20-tetrakis(2-hydroxyphenyl)porphyrin. The assignment of the resultant isomers has been made from their 1H NMR s
- Collman, James P.,Lee, Virgil J.,Kellen-Yuen, Cynthia J.,Zhang, Xumu,Ibers, James A.,Brauman, John I.
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- Manganese-substituted carbonic anhydrase as a new peroxidase
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Carbonic anhydrase is a zinc metalloenzyme that catalyzes the hydration of carbon dioxide to bicarbonate. Replacing the active-site zinc with manganese yielded manganese-substituted carbonic anhydrase (CA[Mn]), which shows peroxidase activity with a bicar
- Okrasa, Krzysztof,Kazlauskas, Romas J.
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- Enantiomer Separation of Nitriles and Epoxides by Crystallization with Chiral Organic Salts: Chirality Switching Modulated by Achiral Acids
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Enantiomer separation of nitriles and epoxides by inclusion crystal formation with organic-salt type chiral hosts was achieved. The stereochemistry of the preferentially included nitrile could be switched only by changing the achiral carboxylic acid component. Crystallographic analysis of the inclusion crystals reveals that the hydrogen-bonding networks are controlled by the acidity of the phenol group of the acids, which results in chirality switching.
- Hirose, Takuji,Kodama, Koichi,Shimomura, Yuki
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p. 6552 - 6557
(2021/11/16)
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- A new clade of styrene monooxygenases for (R)-selective epoxidation
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Styrene monooxygenases (SMOs) are excellent enzymes for the production of (S)-enantiopure epoxides, but so far, only one (R)-selective SMO has been identified with a narrow substrate spectrum. Mining the NCBI non-redundant protein sequences returned a new distinct clade of (R)-selective SMOs. Among them,SeStyA fromStreptomyces exfoliatus,AaStyA fromAmycolatopsis albispora, andPbStyA fromPseudonocardiaceaewere carefully characterized and found to convert a spectrum of styrene analogues into the corresponding (R)-epoxides with up to >99% ee. Moreover, site 46 (AaStyA numbering) was identified as a critical residue that affects the enantioselectivity of SMOs. Phenylalanine at site 46 was required for the (R)-selective SMO to endow excellent enantioselectivity. The identification of new (R)-selective SMOs would add a valuable green alternative to the synthetic tool box for the synthesis of enantiopure (R)-epoxides.
- Xiao, Hu,Dong, Shuang,Liu, Yan,Pei, Xiao-Qiong,Lin, Hui,Wu, Zhong-Liu
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p. 2195 - 2201
(2021/04/12)
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- Structural and Biochemical Studies Enlighten the Unspecific Peroxygenase from Hypoxylon sp. EC38 as an Efficient Oxidative Biocatalyst
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Unspecific peroxygenases (UPOs) are glycosylated fungal enzymes that can selectively oxidize C-H bonds. UPOs employ hydrogen peroxide as the oxygen donor and reductant. With such an easy-to-handle cosubstrate and without the need for a reducing agent, UPOs are emerging as convenient oxidative biocatalysts. Here, an unspecific peroxygenase from Hypoxylon sp. EC38 (HspUPO) was identified in an activity-based screen of six putative peroxygenase enzymes that were heterologously expressed in Pichia pastoris. The enzyme was found to tolerate selected organic solvents such as acetonitrile and acetone. HspUPO is a versatile catalyst performing various reactions, such as the oxidation of prim- and sec-alcohols, epoxidations, and hydroxylations. Semipreparative biotransformations were demonstrated for the nonenantioselective oxidation of racemic 1-phenylethanol rac-1b (TON = 13 000), giving the product with 88% isolated yield, and the oxidation of indole 6a to give indigo 6b (TON = 2800) with 98% isolated yield. HspUPO features a compact and rigid three-dimensional conformation that wraps around the heme and defines a funnel-shaped tunnel that leads to the heme iron from the protein surface. The tunnel extends along a distance of about 12 ? with a fairly constant diameter in its innermost segment. Its surface comprises both hydrophobic and hydrophilic groups for dealing with substrates of variable polarities. The structural investigation of several protein-ligand complexes revealed that the active site of HspUPO is accessible to molecules of varying bulkiness with minimal or no conformational changes, explaining the relatively broad substrate scope of the enzyme. With its convenient expression system, robust operational properties, relatively small size, well-defined structural features, and diverse reaction scope, HspUPO is an exploitable candidate for peroxygenase-based biocatalysis.
- Ebner, Katharina,Glieder, Anton,Kroutil, Wolfgang,Mattevi, Andrea,Rinnofner, Claudia,Rotilio, Laura,Swoboda, Alexander
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p. 11511 - 11525
(2021/09/22)
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- Diastereoselective Alkene Hydroesterification Enabling the Synthesis of Chiral Fused Bicyclic Lactones
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Palladium-catalysed diastereoselective hydroesterification of alkenes assisted by the coordinative hydroxyl group in the substrate afforded a variety of chiral γ-butyrolactones bearing two stereocenters. Employing the carbonylation-lactonization products as the key intermediates, the route from the alkenes with single chiral center to chiral THF-fused bicyclic γ-lactones containing three stereocenters was developed.
- Shi, Zhanglin,Shen, Chaoren,Dong, Kaiwu
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p. 18039 - 18042
(2021/11/16)
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- Production of enantiopure chiral epoxides with e. Coli expressing styrene monooxygenase
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Styrene monooxygenases are a group of highly selective enzymes able to catalyse the epoxidation of alkenes to corresponding chiral epoxides in excellent enantiopurity. Chiral compounds containing oxirane ring or products of their hydrolysis represent key building blocks and precursors in organic synthesis in the pharmaceutical industry, and many of them are produced on an industrial scale. Two-component recombinant styrene monooxygenase (SMO) from Marinobacterium litorale was expressed as a fused protein (StyAL2StyB) in Escherichia coli BL21(DE3). By high cell density fermentation, 35 gDCW/L of biomass with overexpressed SMO was produced. SMO exhibited excellent stability, broad substrate specificity, and enantioselectivity, as it remained active for months and converted a group of alkenes to corresponding chiral epoxides in high enantiomeric excess (>95–99% ee). Optically pure (S)-4-chlorostyrene oxide, (S)-allylbenzene oxide, (2R,5R)-1,2:5,6-diepoxyhexane, 2-(3-bromopropyl)oxirane, and (S)-4-(oxiran-2-yl)butan-1-ol were prepared by whole-cell SMO.
- ?tadániová, Radka,Fischer, Róbert,Gyuranová, Dominika,Hegyi, Zuzana,Rebro?, Martin
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- Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
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Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
- Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
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p. 5077 - 5085
(2021/08/16)
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- The Stereoselective Oxidation of para-Substituted Benzenes by a Cytochrome P450 Biocatalyst
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The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol-CYP)?1.min?1) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S-oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.
- Chao, Rebecca R.,Lau, Ian C.-K.,Coleman, Tom,Churchman, Luke R.,Child, Stella A.,Lee, Joel H. Z.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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p. 14765 - 14777
(2021/09/14)
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- Chiral Separation of Styrene Oxides Supported by Enantiomeric Tetrahedral Neutral Pd(II) Cages
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The separation of enantiomers is of considerable importance in the preparation of the compounds of biological interests, catalysis, and drug development. Here, we report a novel enantioseparation of styrene epoxides (SOs) resolved in the presence of a pair of enantio-enriched tetrahedral cages. Chiral neutral cages of formula [(Pd3X*)4(C6O4Cl2)6] ([X*]3- = RRR- or SSS-[PO(N(*CH(CH3)Ph)3]3-) are constructed from Pd3 building units supported by tris(imido)phosphate trianions and chloranilate linkers. These cages exhibit considerable enantioselective separation capabilities toward a series of styrene epoxides via a crystallization inclusion method. A highest enantiomeric excess (ee) value of up to 80% is achieved for the (R)-4-fluorostyrene oxide.
- Rajasekar, Prabhakaran,Pandey, Swechchha,Ferrara, Joseph D.,Del Campo, Mark,Le Magueres, Pierre,Boomishankar, Ramamoorthy
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supporting information
(2019/11/19)
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- Olefins oxidation with molecular O2 in the presence of chiral Mn (III) salen complex supported on magnetic CoFe2O4@SiO2@CPTMS
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In the present study, CoFe2O4@SiO2@CPTMS nanocomposite was synthesized and the homogeneous chiral Mn-salen complex was anchored covalently onto the surface of CoFe2O4@SiO2@CPTMS nanocomposite. The heterogeneous Mn-salen magnetic nanocatalyst (CoFe2O4@SiO2@CPTMS@ chiral Mn (III) Complex) was characterized by different techniques including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Then, the aerobic enantioselective oxidation of olefins to the corresponding epoxide was investigated in the presence of magnetic chiral CoFe2O4@SiO2@Mn (III) complex at ambient conditions within 90?min. The results showed the corresponding products were synthesized with excellent yields and selectivity. In addition, the heterogeneous CoFe2O4@SiO2@ CPTMS@ chiral Mn (III) complex has benefits such as high selectivity and comparable catalytic reactivity with its homogeneous analog as well as mild reaction condition, facile recovery, and recycling of the heterogeneous catalyst.
- Hemmat, Kaveh,Nasseri, Mohammad A.,Allahresani, Ali
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- An effective strategy for creating asymmetric MOFs for chirality induction: A chiral Zr-based MOF for enantioselective epoxidation
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Recently the construction of chiral MOFs (CMOFs) has been very challenging and complex. For the first time, we synthesized a chiral Zr-based MOF with l-tartaric acid by solvent-assisted ligand incorporation (SALI). We show that a CMOF can be postsynthetically generated by a simple method: incorporating chiral carboxylic groups on the achiral NU-1000. The post-synthesized chiral NU-1000 was used as an asymmetric support for producing a chiral catalyst with molybdenum catalytic active centers as Lewis acid sites. Enantioselective epoxidation of various prochiral alkens to epoxids by using [C-NU-1000-Mo] is comparable to that using other asymmetric homogeneous and heterogeneous catalysts, along with high enantiomeric excess and selectivity to epoxide (up to 100%). The CMOF could be reused in the styrene oxidation after five cycles without substantial deterioration in the CMOF crystallinity or catalytic performance.
- Berijani, Kayhaneh,Morsali, Ali,Hupp, Joseph T.
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p. 3388 - 3397
(2019/07/10)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Photoenzymatic epoxidation of styrenes
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Two-component-diffusible-flavomonooxygenases are versatile biocatalysts for selective epoxidation-, hydroxylation- or halogenation reactions. Their complicated molecular architecture can be simplified using photochemical regeneration of the catalytically
- Van Schie, Morten M. C. H.,Paul, Caroline E.,Arends, Isabel W. C. E.,Hollmann, Frank
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supporting information
p. 1790 - 1792
(2019/02/12)
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- Asymmetric synthesis of α-bromohydrins by carrot root as biocatalyst and conversion to enantiopure β-hydroxytriazoles and styrene oxides using click chemistry and SN2 ring-closure
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In this study we have combined the bioreduction of α-bromoketones using carrot root as biocatalyst and click chemistry for the preparation of enantiopure β-hydroxytriazoles in excellent enantiomeric excesses and yields. Moreover, we have utilized chiral α-halohydrins for the synthesis of enantiopure styrene oxides in very good yields and enantiomeric excesses. Structural assignments of the products were based on their 1H and 13C NMR data and their optical rotations. The enantiomeric excess of the chiral products was obtained by HPLC analysis.
- Hosseinzadeh, Rahman,Mohadjerani, Maryam,Mesgar, Sakineh
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p. 583 - 591
(2019/02/17)
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- Ultrafast Iron-Catalyzed Reduction of Functionalized Ketones: Highly Enantioselective Synthesis of Halohydrines, Oxaheterocycles, and Aminoalcohols
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A molecularly defined chiral boxmi iron alkyl complex catalyzes the hydroboration of various functionalized ketones and provides the corresponding chiral halohydrines, oxaheterocycles (oxiranes, oxetanes, tetrahydrofurans, and dioxanes) and amino alcohols with excellent enantioselectivities (up to >99 %ee) and conversion efficiencies at low catalyst loadings (as low as 0.5 mol %). Turnover frequencies of greater than 40000 h?1 at ?30 °C highlight the activity of this earth-abundant metal catalyst which tolerates a large number of functional groups.
- Blasius, Clemens K.,Vasilenko, Vladislav,Gade, Lutz H.
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supporting information
p. 10231 - 10235
(2018/07/31)
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- Multicore Artificial Metalloenzymes Derived from Acylated Proteins as Catalysts for the Enantioselective Dihydroxylation and Epoxidation of Styrene Derivatives
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Artificial metalloenzymes (AME′s) are an interesting class of selective catalysts, where the chiral environment of proteins is used as chiral ligand for a catalytic metal. Commonly, the active site of an enzyme is modified with a catalytically active metal. Here we present an approach, where the commercial proteins lysozyme (LYS) and bovine serum albumin (BSA) can be converted into highly active and enantioselective AME′s. This is achieved by acylation of the proteins primary amino groups, which affords the metal salts in the core of the protein. A series of differently acylated LYS and BSA were reacted with K2OsO2(OH)4, RuCl3, and Ti(OMe)4, respectively, and the conjugates were tested for their catalytic activity in dihydroxylation and epoxidation of styrene and its derivatives. The best suited system for dihydroxylation is fully acetylated LYS conjugated with K2OsO2(OH)4, which converts styrene to 1,2-phenylethanediol with an enantioselectivity of 95 % ee (S). BSA fully acylated with hexanoic acid and conjugated with three moles RuCl3 per mole protein shows the highest ee values for the conversion of styrene to the respective epoxide with enenatioselectivities of over 80 % ee (R), a TON of more than 2500 and a yield of up to 78 % within 24 h at 40 °C. LYS has two favored selective binding sites for the metal catalyst and BSA has even three. The AME′s with titanate in the active center invert the enantioselectivity of styrene epoxidation.
- Leurs, Melanie,Dorn, Bjoern,Wilhelm, Sascha,Manisegaran, Magiliny,Tiller, Joerg. C.
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p. 10859 - 10867
(2018/08/03)
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- Chiral Macrocyclic Organocatalysts for Kinetic Resolution of Disubstituted Epoxides with Carbon Dioxide
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Among chiral macrocycles 1 synthesized, 1m with the 3,5-bis(trifluoromethyl)phenylethynyl group was the best organocatalyst for the enantioselective synthesis of cyclic carbonates from disubstituted or monosubstituted epoxides and CO2. The X-ray crystal structure of 1m revealed a well-defined chiral cavity with multiple hydrogen-bonding sites that is suitable for the enantioselective activation of epoxides. A catalytic cycle proposed was supported by DFT calculations.
- Ema, Tadashi,Yokoyama, Maki,Watanabe, Sagiri,Sasaki, Sota,Ota, Hiromi,Takaishi, Kazuto
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supporting information
p. 4070 - 4073
(2017/08/15)
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- Bioinspired Manganese Complexes and Graphene Oxide Synergistically Catalyzed Asymmetric Epoxidation of Olefins with Aqueous Hydrogen Peroxide
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Bioinspired manganese complexes of N4ligands and graphene oxide (GO) synergistically catalyze the highly enantioselective epoxidation of olefins (up to 99% ee), which is a rare example with GO as a co-catalyst in asymmetric catalysis. GO as a new and key additive not only successfully functions in catalytic amounts, but also has a positive effect for improving the enantioselectivity of the asymmetric epoxidation compared with the traditional stoichiometric organic carboxylic acid method [e.g., chalcone, 95% ee (3.5 mg GO) vs. 84% ee (5 equiv., 75 mg acetic acid), ethyl cinnamate, 84% ee (3.5 mg GO) vs. 19% ee (5 equiv., 75 mg acetic acid)]. The X-ray photoelectron spectroscopy (XPS) spectra of GO before and after the reaction indicate that the intensities of C–O become stronger after the reaction, which may have a certain relationship with hydrogen peroxide (H2O2) and gives a reasonable rationale for the large consumption of H2O2. Also, part of the hydrogen peroxide was used for the oxidation of GO. (Figure presented.).
- Miao, Chengxia,Yan, Xingbin,Xu, Daqian,Xia, Chungu,Sun, Wei
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p. 476 - 484
(2017/02/10)
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- Immobilization of Amano lipase from Pseudomonas fluorescens on silk fibroin spheres: an alternative protocol for the enantioselective synthesis of halohydrins
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The search for a new, efficient, cheaper and sustainable matrix for lipase immobilization is a growing area in biotechnology. Amano lipase from Pseudomonas fluorescens was immobilized on silk fibroin spheres and used in the enzymatic kinetic resolution of halohydrins, to obtain optically active epoxides (up to 99% ee), important precursors in the synthesis of derivative antifungal azoles. This paper reinforces the versatility of silk fibroin as a support for heterogeneous catalysts.
- Ferreira, Irlon M.,Yoshioka, Sergio A.,Comasseto, Jo?o V.,Porto, André L. M.
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p. 12650 - 12658
(2017/03/11)
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- Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes
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Biocatalytic anti-Markovnikov alkene hydroamination and hydration were achieved based on two concepts involving enzyme cascades: epoxidation-isomerization-amination for hydroamination and epoxidation-isomerization-reduction for hydration. An Escherichia coli strain coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI), ω-transaminase (CvTA), and alanine dehydrogenase (AlaDH) catalyzed the hydroamination of 12 aryl alkenes to give the corresponding valuable terminal amines in high conversion (many ≥86%) and exclusive anti-Markovnikov selectivity (>99:1). Another E. coli strain coexpressing SMO, SOI, and phenylacetaldehyde reductase (PAR) catalyzed the hydration of 12 aryl alkenes to the corresponding useful terminal alcohols in high conversion (many ≥80%) and very high anti-Markovnikov selectivity (>99:1). Importantly, SOI was discovered for stereoselective isomerization of a chiral epoxide to a chiral aldehyde, providing some insights on enzymatic epoxide rearrangement. Harnessing this stereoselective rearrangement, highly enantioselective anti-Markovnikov hydroamination and hydration were demonstrated to convert α-methylstyrene to the corresponding (S)-amine and (S)-alcohol in 84-81% conversion with 97-92% ee, respectively. The biocatalytic anti-Markovnikov hydroamination and hydration of alkenes, utilizing cheap and nontoxic chemicals (O2, NH3, and glucose) and cells, provide an environmentally friendly, highly selective, and high-yielding synthesis of terminal amines and alcohols.
- Wu, Shuke,Liu, Ji,Li, Zhi
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p. 5225 - 5233
(2017/08/17)
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- Multistep Organic Transformations over Base-Rhodium/Diamine-Bifunctionalized Mesostructured Silica Nanoparticles
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The assembly of multiple catalytic functionalities within a single mesoporous silica as a catalyst for multistep enantioselective organic transformations in an environmentally friendly medium is a significant challenge in heterogeneous asymmetric catalysis. Herein, we took advantage of a BF4 ? anion hydrogen bonding strategy to anchor a chiral cationic rhodium/diamine complex within base-functionalized mesostructured silica nanoparticles conveniently to construct a bifunctional heterogeneous catalyst. The solid-state 13C NMR spectrum discloses the well-defined chiral Rh/diamine active species, and we used XRD, N2 adsorption–desorption, and electron microscopy to reveal the ordered mesostructure. The combination of bifunctionality in the silica nanoparticles enables two kinds of efficient enantioselective organic transformations with high yields and enantioselectivities, in which the asymmetric transfer hydrogenation of α-haloketones followed by epoxidation provides various chiral aryloxiranes, and the amination of α-haloketones with anilines followed by asymmetric transfer hydrogenation produces various β-amino alcohols. Furthermore, the catalyst can be recovered and recycled for seven times without a loss of catalytic activity, which is an attractive feature for multistep organic transformations in a sustainable benign process.
- Liao, Hang,Chou, Yajie,Wang, Yu,Zhang, Han,Cheng, Tanyu,Liu, Guohua
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p. 3197 - 3202
(2017/08/29)
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- The Activation of Carboxylic Acids via Self-Assembly Asymmetric Organocatalysis: A Combined Experimental and Computational Investigation
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The heterodimerizing self-assembly between a phosphoric acid catalyst and a carboxylic acid has recently been established as a new activation mode in Br?nsted acid catalysis. In this article, we present a comprehensive mechanistic investigation on this activation principle, which eventually led to its elucidation. Detailed studies are reported, including computational investigations on the supramolecular heterodimer, kinetic studies on the catalytic cycle, and a thorough analysis of transition states by DFT calculations for the rationalization of the catalyst structure-selectivity relationship. On the basis of these investigations, we developed a kinetic resolution of racemic epoxides, which proceeds with high selectivity (up to s = 93), giving the unreacted epoxides and the corresponding protected 1,2-diols in high enantiopurity. Moreover, this approach could be advanced to an unprecedented stereodivergent resolution of racemic α-chiral carboxylic acids, thus providing access to a variety of enantiopure nonsteroidal anti-inflammatory drugs and to α-amino acid derivatives.
- Monaco, Mattia Riccardo,Fazzi, Daniele,Tsuji, Nobuya,Leutzsch, Markus,Liao, Saihu,Thiel, Walter,List, Benjamin
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supporting information
p. 14740 - 14749
(2016/11/18)
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- A Robust Metal-Metalloporphyrin Framework Based upon a Secondary Building Unit of Infinite Nickel Oxide Chain
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Herein we report the construction of a robust metal-metalloporphyrin framework that is based upon a rare secondary building unit of infinite nickel oxide chain. The constructed MMPF-20 exhibits permanent porosity and selective adsorption of CO2 over CH4 as well as demonstrates interesting catalytic performances in the context of olefin epoxidation.
- Zhang, Weijie,Gao, Wenyang,Pham, Tony,Jiang, Pingping,Ma, Shengqian
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p. 1005 - 1009
(2016/02/18)
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- Synthesis of enantiopure 1,2-azido and 1,2-amino alcohols via regio- and stereoselective ring-opening of enantiopure epoxides by sodium azide in hot water
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A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring-opening of enantiopure styryl and pyridyl (S)-epoxides by N3- in hot water takes place preferentially at the internal position with complete inversion of configuration to produce (R)-2-azido ethanols with up to 99% enantio- and regioselectivity, while the (S)-adamantyl oxirane provides mainly the (S)-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh3 in water/THF, and then converted into the Boc or acetamide derivatives.
- Wang, Hai-Yang,Huang, Kun,De Jesús, Melvin,Espinosa, Sandraliz,Pi?ero-Santiago, Luis E.,Barnes, Charles L.,Ortiz-Marciales, Margarita
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- Asymmetric epoxidation of alkenes catalyzed by novel chiral porphyrin metal complexes
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Novel chiral porphyrin ligands were synthesized from four different chiral aldehydes. In situ transition metal complexes of these novel chiral porphyrin ligands were found to catalyze asymmetric epoxidation reaction of styrene possessing various substituents. The chiral epoxides were formed in excellent yield and ee.
- Sakthipriya, Pachiannan,Ananthi, Nallamuthu
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p. 730 - 737
(2016/08/30)
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- Azidolysis of epoxides catalysed by the halohydrin dehalogenase from Arthrobacter sp. AD2 and a mutant with enhanced enantioselectivity: an (S)-selective HHDH
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Halohydrin dehalogenase from Arthrobacter sp. AD2 catalysed azidolysis of epoxides with high regioselectivity and low to moderate (S)-enantioselectivity (E?=?1–16). Mutation of the asparagine 178 to alanine (N178A) showed increased enantioselectivity towards styrene oxide derivatives and glycidyl ethers. Conversion of aromatic epoxides was catalysed by HheA-N178A with complete enantioselectivity, however the regioselectivity was reduced. As a result of the enzyme-catalysed reaction, enantiomerically pure (S)-β-azido alcohols and (R)-α-azido alcohols (ee???99%) were obtained.
- Mikleu?evi?, Ana,Primo?i?, Ines,Hrenar, Tomica,Salopek-Sondi, Branka,Tang, Lixia,Elenkov, Maja Majeri?
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p. 930 - 935
(2016/09/13)
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- A method for producing an optically active epoxy compound
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PROBLEM TO BE SOLVED: To provide a new method for producing an optically active epoxy compound.SOLUTION: The method includes a step of reacting an oxidizing agent with an unsaturated compound that has a double bond within the molecule in the presence of a
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Paragraph 0083-0085; 0088-0093
(2019/01/05)
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- Self-supported chiral polymeric MnIII salen complexes as highly active and recyclable catalysts for epoxidation of nonfunctionalized olefins
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Abstract A series of self-supported chiral polymeric MnIII N,N′-ethylenebis(salicylimine) (salen) complexes were synthesized through metalation of the corresponding salen ligands obtained by condensation of several bis/tris-aldehydes with (1R,2
- Roy, Tamal,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 1038 - 1044
(2015/06/08)
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- Nonenzymatic Regeneration of Styrene Monooxygenase for Catalysis
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Styrene monooxygenase (SMO) is a two-component flavoprotein catalyzing the selective epoxidation of various C=C double bonds. For cell-free catalysis, traditionally a cascade of NAD(P)H:flavin oxidoreductase, nicotinamide cofactor (NADH), and NADH regener
- Paul, Caroline E.,Tischler, Dirk,Riedel, Anika,Heine, Thomas,Itoh, Nobuya,Hollmann, Frank
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p. 2961 - 2965
(2015/09/08)
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- Grafting of a chiral Mn(iii) complex on graphene oxide nanosheets and its catalytic activity for alkene epoxidation
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A chiral Mn(iii) complex supported by a covalent grafting method on modified graphene oxide was synthesized using 3-chloropropyltrimethoxysilane as a reactive surface modifier. The heterogeneous catalyst was characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, ultraviolet-visible spectra, nitrogen adsorption-desorption isotherms, transmission electron microscopy and atomic absorption spectroscopy. The catalytic potential of the heterogeneous catalyst and comparison with its homogeneous counterpart were studied for enantioselective epoxidation of various alkenes using m-chloroperbenzoic acid as an oxidant and it showed high selectivity and comparable catalytic reactivity with its homogeneous analogue. In addition, higher enantioselectivity and higher yield were observed in the presence of 4-methylmorpholine N-oxide and pyridine N-oxide, respectively. The catalyst was reused for several runs without significant loss of activity and selectivity.
- Nasseri, Mohammad Ali,Allahresani, Ali,Raissi, Heidar
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p. 26087 - 26093
(2014/07/08)
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- Enhanced turnover rate and enantioselectivity in the asymmetric epoxidation of styrene by new T213G mutants of CYP 119
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New CYP 119 T213G mutants were constructed and characterized. Introduction of the T213G mutation into the wild-type CYP 119 significantly enhances the turnover rate for the peroxide-dependent styrene epoxidation 4.4-fold to 346.2 min-1, and the
- Zhang, Chun,Li, Jing,Yang, Bo,He, Fang,Yang, Sheng-Yong,Yu, Xiao-Qi,Wang, Qin
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p. 27526 - 27531
(2014/07/21)
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- A mononuclear manganese complex of a tetradentate nitrogen ligand - Synthesis, characterizations, and application in the asymmetric epoxidation of olefins
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A new chiral manganese complex (C1) bearing a tetradentate nitrogen ligand containing chiral bipyrrolidine and benzimidazole moieties was prepared. The structure of C1 was confirmed by ESI-MS and crystallography. This manganese complex is an active catalyst for the asymmetric epoxidation of various olefins with excellent conversion (up to 99%) and high enantiomeric excess (up to 96%ee) with hydrogen peroxide as the oxidant in the presence of 2-ethylhexanoic acid or acetic acid. Compared with previous structurally similar manganese complexes with different diamine backbones (C2, cyclohexanediamine; C3, diamine from L-proline), C1 showed improved asymmetric induction, especially for simple olefins such as styrene derivatives and substituted chromene. The possible reasons for the improvement of the ee values are discussed in the text on the basis of the crystal structures of the manganese complexes.
- Shen, Duyi,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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supporting information
p. 5777 - 5782
(2015/02/19)
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- Nitration of Halterman porphyrin: A new route for fine tuning chiral iron and manganese porphyrins with application in epoxidation and hydroxylation reactions using hydrogen peroxide as oxidant
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A methodology is reported for the regioselective nitration of the phenyl groups of Halterman porphyrin, using NaNO2. These nitro-porphyrins can be reduced to aminoporphyrins and then N-dimethylated to give new optically active porphyrins. Applications to the asymmetric epoxidation of styrene derivatives by H2O2 to give optically active epoxides (ee up to 60%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 69%) were carried out in organic solvents (dichloromethane/methanol) using chiral iron and manganese porphyrins as catalysts.
- Amiri, Nesrine,Le Maux, Paul,Srour, Hassan,Nasri, Habib,Simonneaux, Gérard
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p. 8836 - 8842
(2015/03/04)
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- A magnetically recyclable Fe3O4@SiO2/Mn(III) chiral salen complex as a highly selective and versatile heterogeneous nanocatalyst for the oxidation of olefins and sulfides
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In this study, a new magnetically recoverable heterogeneous Mn(iii) nanocatalyst (MHMC) was developed by covalent grafting of a homogeneous chiral Mn(iii) salen complex (HMC) onto the surface of a Fe3O4/SiO2 core-shell. The structural and chemical nature of MHMC was characterized by different techniques. The catalytic activity of the MHMC and comparison with its homogeneous analogue were studied for the enantioselective epoxidation of various alkenes to epoxide compounds using tert-butyl hydroperoxide (TBHP) as an oxidant. The MHMC showed higher enantioselectivity and comparable catalytic reactivity to its homogeneous analogue with benefits such as facile recovery and recycling of the heterogeneous catalyst. The results showed that a higher enantioselectivity and yield were observed in the presence of N-methylmorpholine N-oxide (NMNO). The catalytic activity of this complex was also tested in the oxidation of sulfides using aqueous 30% H2O2 in excellent yields. The catalyst was reused for several runs without significant loss in activity and selectivity.
- Allahresani, Ali,Nasseri, Mohammad Ali
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p. 60702 - 60710
(2015/02/19)
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- Asymmetric synthesis of 2-arylpiperazines
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An asymmetric synthesis of 2-arylpiperazines starting from phenacyl bromides, a variety of which are easily available, has been established. The synthesis features a CBS reduction of phenacyl bromide to provide optically enriched compounds, an SN2 reaction of 1,2,3-oxathiazolidine 2-oxides with an azide anion with invert of configuration, and construction of the piperazine ring via reduction of piperazine-2,3-diones.
- Yokoshima, Satoshi,Watanabe, Kazutoshi,Uehara, Fumiaki,Usui, Yoshihiro,Tanaka, Hiroshi
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p. 5749 - 5751
(2015/02/19)
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- Enantioselective hydrolysis of racemic and meso -epoxides with recombinant escherichia coli expressing epoxide hydrolase from Sphingomonas sp. HXN-200: Preparation of epoxides and vicinal diols in high ee and high concentration
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A unique epoxide hydrolase (SpEH) from Sphingomonas sp. HXN-200 was identified and cloned based on genome sequencing and expressed in Escherichia coli. The engineered E. coli (SpEH) showed the same selectivity and substrate specificity as the wild type strain and 172 times higher activity than Sphingomonas sp. HXN-200 for the hydrolysis of styrene oxide 1. Hydrolysis of racemic styrene oxide 1, substituted styrene oxides 3, 5-7, and N-phenoxycarbonyl-3,4-epoxypiperidine 8 (200-100 mM) with resting cells of E. coli (SpEH) gave (S)-epoxides 1, 3, 5-7 and (-)-8 in 98.0-99.5% enantiomeric excess (ee) and 37.6-46.5% yield. Hydrolysis of cyclopentene oxide 9, cyclohexene oxide 10, and N-benzyloxycarbonyl-3,4-epoxypyrrolidine 11 (100 mM) afforded the corresponding (R, R)-vicinal trans-diols 12-14 in 86-93% ee and 90-99% yield. The ee of (1R, 2R)-cyclohexane-1,2-diol 13 was improved to 99% by simple crystallization. These biotransformations showed high specific activity (0.28-4.3 U/mg cdw), product concentration, product/cells ratio, and cell-based productivity. Hydrolysis at even higher substrate concentration was also achieved: (S)-1 was obtained in 430 mM (51 g/Lorg) and 43% yield; (1R, 2R)-13 was obtained in 500 mM (58 g/L) and >99% yield. Gram-scale preparation of epoxides (S)-1, (S)-3, (S)-6 and diols (1R, 2R)-12, (1R, 2R)-13, (3R, 4R)-14 were also demonstrated. E. coli (SpEH) cells showed the highest enantioselectivity to produce (S)-1 (E of 39) among all known EHs in the form of whole cells or free enzymes and the highest enantioselectivities to produce (S)-3, 5, 6, 7, (-)-8, and (R, R)-14 (E of 36, 35, 28, 57, 22, and 28) among all known EHs. The easily available and highly active E. coli (SpEH) cells are the best biocatalysts known thus far for the practical preparation of these useful and valuable enantiopure epoxides and vicinal diols via hydrolysis.
- Wu, Shuke,Li, Aitao,Chin, Yit Siang,Li, Zhi
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p. 752 - 759
(2013/06/05)
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- Synthesis of new binol based [1+1] macrocyclic chiral manganese(III) Schiff bases as catalysts for asymmetric epoxidation
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A series of new chiral binol based [1+1] macrocyclic Schiff bases have been synthesized in high yields in short reaction times via cyclo-condensation of dialdehydes with long tethers and chiral diamines. Macrocyclic Mn(salen) complexes containing N2
- Suresh, Paulsamy,Srimurugan, Sankareswaran,Dere, Ravindra T.,Ragavan, R. Venkat,Gopinath, Vadiraj Suphala
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p. 669 - 676
(2013/07/11)
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- Engineered P450pyr monooxygenase for asymmetric epoxidation of alkenes with unique and high enantioselectivity
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A triple mutant of P450pyr monooxygenase (P450pyrTM) catalysed the epoxidation of several para-substituted styrenes as the first enzyme showing high (R)-enantioselectivity and high conversion, demonstrated a broad substrate range, and showed high enantioselectivity for the epoxidation of an unconjugated 1,1-disubstituted alkene, 2-methyl-3-phenyl-1-propene, and a cyclic alkene, N-phenoxycarbonyl-1,2,5,6-tetrahydropyridine, respectively.
- Li, Aitao,Liu, Ji,Pham, Son Q.,Li, Zhi
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supporting information
p. 11572 - 11574
(2013/12/04)
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- Highly stereoselective epoxidation with H2O2 catalyzed by electron-rich aminopyridine manganese catalysts
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Fast, efficient, and highly stereoselective epoxidation with H 2O2 is reached by manganese coordination complexes with e-rich aminopyridine tetradentate ligands. It is shown that the electronic properties of these catalysts vary systematically with the stereoselectivity of the O-atom transfer event and exert fine control over the activation of hydrogen peroxide, reducing the amount of carboxylic acid co-catalyst necessary for efficient operation.
- Cusso, Olaf,Garcia-Bosch, Isaac,Font, David,Ribas, Xavi,Lloret-Fillol, Julio,Costas, Miquel
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supporting information
p. 6158 - 6161
(2014/01/17)
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- Directed evolution of metagenome-derived epoxide hydrolase for improved enantioselectivity and enantioconvergence
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We performed a directed evolution study with a metagenome-derived epoxide hydrolase (EH), termed Kau2. Homology models of Kau2 were built; we selected one of them and used it as a guide for saturation mutagenesis experiments targeted at specific residues within the large substrate binding pocket. During the molecular evolution process, we found several enzyme variants with higher enantioselectivity or enhanced enantioconvergence toward para-Chlorostyrene oxide. Improved enantioselectivities by up to a factor of 5, reaching an E-value of up to 130 with the R-enantiomer as the residual epoxide, were achieved by replacing amino acid pairs at the positions 110 and 113, or 290 and 291, which are positions located in the vicinity of two presumed binding sites for the epoxide enantiomers. The (R)-para-Chlorophenylethane-1,2-diol product exhibited a high enantiomeric excess (ee) of 97% at 50% conversion of the racemic epoxide for the most enantioselective variant. Further, five amino acid substitutions were sufficient to substantially increase the degree of enantioconvergence and to lower the E-value to 17 for the final evolved EH variant, enabling the production of the R-diol with an ee-value of 93% at 28 °C in a complete conversion of the racemic epoxide. Higher eep-values of up to 97% were determined in enantioconvergent reactions using lower temperatures. The EH activities of whole cells were found to be within the range of 74-125% of the wild-type activity for all investigated variants. We show in this report that the metagenome-derived Kau2 EH is amenable to the redesign of its enantioselectivity and regioselectivity properties by directed evolution using a homology model as a guide. The generated enzyme variants should be useful for the production of the chiral building blocks (R)-para-Chlorostyrene oxide and (R)-para-Chlorophenylethane-1,2-diol.
- Kotik, Michael,Zhao, Wei,Iacazio, Gilles,Archelas, Alain
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- Highly enantioselective ylide-mediated synthesis of terminal epoxides
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The highly efficient asymmetric epoxidation of aldehydes by methylene transfer is now possible using new sulfonium salts. This journal is
- Piccinini, Alessandro,Kavanagh, Sarah A.,Connon, Stephen J.
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supporting information; experimental part
p. 7814 - 7816
(2012/09/05)
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- Stereoselective epoxidation of alkenes with hydrogen peroxide using a bipyrrolidine-based family of manganese complexes
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Novel manganese complexes containing N4-tetradentate ligands derived from chiral bipyrrolidinediamines catalyze the stereoselective epoxidation of a wide array of alkenes using low catalyst loadings (0.1 mol%) and hydrogen peroxide (1.2 equiv.) as terminal oxidant. This family of catalysts affords good to excellent yields (80-100%) and moderate to good ees (40-73%) in short reaction times (30 min) making efficient use of hydrogen peroxide.
- Garcia-Bosch, Isaac,Gomez, Laura,Polo, Alfonso,Ribas, Xavi,Costas, Miquel
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supporting information; experimental part
p. 65 - 70
(2012/03/27)
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- Enantioselective manganese-porphyrin-catalyzed epoxidation and C-H hydroxylation with hydrogen peroxide in water/methanol solutions
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The asymmetric epoxidation of alkene and hydroxylation of arylalkane derivatives by H2O2 to give optically active epoxides (enantiomeric excess (ee) up to 68%) and alcohols (ee up to 57%), respectively, were carried out in water/methanol solutions using chiral water-soluble manganese porphyrins as catalysts.
- Srour, Hassan,Maux, Paul Le,Simonneaux, Gerard
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experimental part
p. 5850 - 5856
(2012/07/14)
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- Enantioselective water-soluble iron-porphyrin-catalyzed epoxidation with aqueous hydrogen peroxide and hydroxylation with iodobenzene diacetate
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The asymmetric epoxidation of styrene derivatives by H2O 2 (or UHP) to give optically active epoxides (ee up to 81%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 78%) were carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts.
- Maux, Paul Le,Srour, Hassan F.,Simonneaux, Gérard
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experimental part
p. 5824 - 5828
(2012/09/11)
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- Retention of stereochemistry in gold-catalyzed formal [4+3] cycloaddition of epoxides with arenynamides
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Golden opportunity: [4+3] Cycloaddition reactions of arenynamides and epoxides are enabled under gold catalysis and have a broad substrate scope (see scheme; Ms=methanesulfonyl). An SN2-type front-side attack of phenyl at the oxiranyl ring is expected to cause the retention of stereochemistry. Copyright
- Karad, Somnath Narayan,Bhunia, Sabyasachi,Liu, Rai-Shung
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supporting information; scheme or table
p. 8722 - 8726
(2012/10/18)
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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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- Non-heme manganese complexes catalyzed asymmetric epoxidation of olefins by peracetic acid and hydrogen peroxide
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Chiral non-heme aminopyridine manganese complexes catalyze the enantioselective epoxidation of olefins with peracetic acid or hydrogen peroxide with moderate to high yields and ee valuess up to 89% (peracetic acid, AcOOH) and 84% (hydrogen peroxide, H2O2), performing as many as 1000 turnovers.
- Ottenbacher, Roman V.,Bryliakov, Konstantin P.,Talsi, Evgenii P.
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supporting information; scheme or table
p. 885 - 889
(2011/06/27)
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- A novel layered organic polymer-inorganic hybrid zinc poly (styrene-phenylvinylphosphonate)-phosphate immobilized chiral salen Mn(III) catalyst large-scale asymmetric epoxidation of unfunctionalized olefins
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A novel layered organic polymer-inorganic hybrid zinc poly (styrene-phenylvinylphosphonate)-phosphate (ZnPS-PVPA) has been synthesized under mild conditions and diphenol-modified ZnPS-PVPA was used to successfully immobilize the chiral salen Mn(III) by axial coordination. The obtained heterogeneous chiral catalysts exhibited excellent activities and enantioselectivities using sodium periodate as an oxidant for asymmetric epoxidation of unfunctionalized olefins, especially for the epoxidation of α-methylstyrene (conversion: up to 97%; ee: exceed 99%). Moreover, these synthesized catalysts were relatively stable and could be expediently separated from the reaction system, and could be recycled at least ten times without obvious loss of activity and enantioselectivity. These novel catalysts could be efficiently used in large-scale reactions with the enantioselectivity being maintained at the same level, which offer a great possibility for application in industry.
- Hu, Xiaoyan,Fu, Xiangkai,Xu, Jiangwei,Wang, Changwei
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experimental part
p. 2797 - 2804
(2011/08/10)
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- Chiral epoxides via borane reduction of 2-haloketones catalyzed by spiroborate ester: Application to the synthesis of optically pure 1,2-hydroxy ethers and 1,2-azido alcohols
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An enantioselective borane-mediated reduction of a variety of 2-haloketones with 10% spiroaminoborate ester 1 as catalyst is described. By a simple basic workup of 2-halohydrins, optically active epoxides are obtained in high yield and with excellent enantiopurity (up to 99% ee). Ring-opening of oxiranes with phenoxides or sodium azide is investigated under different reaction conditions affording nonracemic 1,2-hydroxy ethers and 1,2-azido alcohols with excellent enantioselectivity (99% ee) and in good to high chemical yield. 2011 American Chemical Society.
- Huang, Kun,Wang, Haiyang,Stepanenko, Viatcheslav,De Jesus, Melvin,Torruellas, Carilyn,Correa, Wildeliz,Ortiz-Marciales, Margarita
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supporting information; experimental part
p. 1883 - 1886
(2011/06/20)
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- Biaryl-bridged salalen ligands and their application in titanium-catalyzed asymmetric epoxidation of olefins with aqueous H2O2
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A series of biaryl-bridged salalen ligands together with their titanium complexes have been designed and synthesized. The Ti complexes could serve as highly efficient catalysts for the asymmetric epoxidation of a wide range of olefins, giving the corresponding epoxides with high ee values. A biaryl-bridged salalen titanium complex was developed and used in the enantioselective epoxidation of a range of olefins with aqueous hydrogen peroxide as the oxidant. Notably, the intramolecular dinuclear Ti catalyst possessing a biaryl bridge is highly efficient for the reaction, especially using terminal aromatic olefins as substrates.
- Xiong, Donglu,Hu, Xiaoxue,Wang, Shoufeng,Miao, Cheng-Xia,Xia, Chungu,Sun, Wei
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experimental part
p. 4289 - 4292
(2011/09/15)
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