- Asymmetric Epoxidation of Olefins Catalyzed by Substituted Aminobenzimidazole Manganese Complexes Derived from L-Proline
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A family of manganese complexes [Mn(Rpeb)(OTf)2] (peb=1-(1-ethyl-1H-benzo[d]imidazol-2-yl)-N-((1-((1-ethyl-1H-benzo[d]imidazol-2-yl)methyl) pyrrolidin-2-yl)methyl)-N-methylmethanamine)) derived from L-proline has been synthesized and characterized, where R refers to the group at the diamine backbone. X-ray crystallographic analyses indicate that all the manganese complexes [Mn(Rpeb)(OTf)2] exhibit cis-α topology. These types of complexes are shown to catalyze the asymmetric epoxidation of olefins employing H2O2 as a terminal oxidant with up to 96% ee. Obviously, the R group of the diamine backbone can influence the catalytic activity and enantioselectivity in the asymmetric epoxidation of olefins. In particular, Mn(i-Prpeb)(OTf)2 bearing an isopropyl arm, cannot catalyze the epoxidation reaction with H2O2 as the oxidant. However, when PhI(OAc)2 is used as the oxidant instead, all the manganese complexes including Mn(i-Prpeb)(OTf)2 can promote the epoxidation reactions efficiently. Taken together, these results indicate that isopropyl substitution on the Rpeb ligand inhibits the formation of active Mn(V)-oxo species in the H2O2/carboxylic acid system via an acid-assisted pathway.
- Tian, Jing,Lin, Jin,Zhang, Jisheng,Xia, Chungu,Sun, Wei
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supporting information
p. 593 - 600
(2021/11/16)
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- Enantioselective, Stereoconvergent Resolution Copolymerization of Racemic cis-Internal Epoxides and Anhydrides
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Unprecedented enantioselective resolution copolymerization of racemic cis-internal epoxides and anhydrides was mediated by dinuclear aluminum complexes with multiple chirality, affording optically active polyesters with two contiguous stereogenic centers, and the unreacted substrates in good enantioselectivity. Unexpected stereoconvergence is observed in this resolution copolymerization, where the selectivity factor for the enantioselective formation of copolymer significantly exceeds the kinetic resolution coefficient based on the unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho-substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol-linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi-crystalline polyesters and a concomitant kinetic resolution of the epoxide substrates.
- He, Guang-Hui,Ren, Bai-Hao,Chen, Shi-Yu,Liu, Ye,Lu, Xiao-Bing
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p. 5994 - 6002
(2021/02/11)
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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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- 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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- Regio- and stereoselective multi-enzymatic aminohydroxylation of β-methylstyrene using dioxygen, ammonia and formate
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We report an enzymatic route for the formal regio- and stereoselective aminohydroxylation of β-methylstyrene that consumes only dioxygen, ammonia and formate; carbonate is the by-product. The biocascade entails highly selective epoxidation, hydrolysis and hydrogen-borrowing alcohol amination. Thus, β-methylstyrene was converted into 1R,2R and 1S,2R-phenylpropanolamine in 59-63% isolated yields, and up to >99.5 : 0.5 dr and er.
- Corrado, Maria L.,Knaus, Tanja,Mutti, Francesco G.
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supporting information
p. 6246 - 6251
(2019/12/03)
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- Performance of chiral tetracarbonylmolybdenum pyrindanyl amine complexes in catalytic olefin epoxidation
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Tetracarbonylmolybdenum(0) complexes of the type cis-[Mo(CO)4(L)] containing chiral 7-(1-pyrindanyl) amine ligands were prepared and found to be effective precatalysts for the epoxidation of achiral (cis-cyclooctene) and prochiral (DL-limonene and trans-β-methylstyrene) olefins at 55 °C. Epoxides were the only products formed from cis-cyclooctene (100% yield) and trans-β-methylstyrene (100% selectivity at 82–85% conversion), and the main products formed from DL-limonene (80–82% 1,2-epoxide selectivity at 85% conversion). Characterization of recovered catalysts revealed that the precatalysts were transformed in situ to stable polyoxomolybdate salts containing the β-octamolybdate anion [β-Mo8O26]4?, which was responsible for the catalytic reaction.
- Neves, Patrícia,Nogueira, Lucie S.,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.,Sampaio-Dias, Ivo E.,Sousa, Carlos A.D.,Rizzo-Aguiar, Fabio,Rodríguez-Borges, José E.
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- Enhanced Turnover for the P450 119 Peroxygenase-Catalyzed Asymmetric Epoxidation of Styrenes by Random Mutagenesis
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A randomized library is constructed based on pET30a-CYP119-T214V plasmid. This library of random mutants of CYP119-T214V was screened by means of the reduced CO difference spectra and epoxidation of styrene. By using directed evolution, a new CYP119 quadr
- Wang, Li,Wei, Siping,Pan, Xianchao,Liu, Pingxian,Du, Xi,Zhang, Chun,Pu, Lin,Wang, Qin
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p. 2741 - 2749
(2018/02/28)
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- Chiral Manganese Aminopyridine Complexes: the Versatile Catalysts of Chemo- and Stereoselective Oxidations with H2O2
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In the last decade, manganese(II) complexes with N-donor tetradentate aminopyridine ligands emerged as efficient catalysts of enantioselective epoxidation of olefins and direct selective oxidation of C?H groups in complex organic molecules, with environmentally benign oxidant hydrogen peroxide. In this personal account, we summarize the progress of these catalysts with regard to ligands design, structure-reactivity correlations, evaluation of the substrate scope, as well as mechanistic studies, shedding light on the nature of active sites and the mechanisms of selective oxygenations. Several practically promising catalytic syntheses with the aid of Mn aminopyridine catalysts are exemplified.
- Ottenbacher, Roman V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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- Manganes-Porphyrin as Efficient Enantioselective Catalyst for Aerobic Epoxidation of Olefins
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A chiral manganese porphyrin, [Mn(TCPP-Ind)Cl], was synthesized using cis-1-amino-2-indanol substituent. It showed remarkable catalytic activity and enantioselectivity in the epoxidation of olefins with O2/RCHO. Terminal olefins and styrene derivatives were successfully oxidized (> 99% ee). TON of 73,000 was achieved in the epoxidation of α-methylstyrene after five times recycling. Graphical Abstract: [Figure not available: see fulltext.].
- Farokhi, Afsaneh,Berijani, Kayhaneh,Hosseini-Monfared, Hassan
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p. 2608 - 2618
(2018/06/14)
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- Asymmetric Epoxidation of Olefins with H2O2 Catalyzed by a Bioinspired Aminopyridine N4 Iron Complex
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An iron complex with a chiral aminopyridine N4 ligand bearing strong electron-donating and bulky morpholine groups on the ligand is synthesized and characterized. The iron complex serves to efficiently catalyze the asymmetric epoxidation of various olefins by employing aqueous hydrogen peroxide as the green oxidant, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 93 % yield and 99.9 % ee). Owing to the introduction of morpholine functional groups on the ligand, the Fe-catalyzed reaction can proceed with a catalytic amount of the carboxylic acid partner (3 mol %).
- Wang, Wenfang,Sun, Qiangsheng,Xu, Daqian,Xia, Chungu,Sun, Wei
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p. 420 - 424
(2017/02/15)
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- Highly efficient asymmetric epoxidation of olefins with a chiral manganese-porphyrin covalently bound to mesoporous SBA-15: Support effect
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A chiral MnIII-porphyrin complex covalently bonded with mesoporous SBA-15 (SBA15-[Mn(TCPP-R?)Cl]) was synthesized and fully characterized. The heterogeneous SBA15-[Mn(TCPP-R?)Cl] exhibited remarkable catalytic activity toward enantioselective olefin epoxidation using O2 as terminal oxidant in the presence of isobutyraldehyde. The catalyst showed higher enantioselectivity than its homogeneous counterpart in the oxidation of α-methylstyrene. SBA15-[Mn(TCPP-R?)Cl] catalyzed epoxidation of styrene was achieved within 8?h and optically active styrene oxide was obtained in 89% ee and 90% yield. Likewise, styrene derivatives (trans-β-methylstyrene, indene), conjugated cis- and trans-disubstituted olefins (e.g. cis- and tans-stilbene) and terminal olefins were converted effectively to their corresponding epoxides in 63–99%?ee under the Mn(III)-catalyzed conditions. The catalyst could be recycled five times without any significant loss in activity.
- Farokhi, Afsaneh,Hosseini Monfared, Hassan
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p. 229 - 238
(2017/06/19)
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- A novel chiral manganese-tetraamide macrocycle complex covalently attached to magnetite as recyclable catalyst for aerobic asymmetric epoxidation of olefins
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A novel Mn complex containing N4-tetradentate tetraamide macrocyclic ligand (L) derived from chiral diethyl-2,3-benzylidene-L-tartrate and polyamidoamine dendrimer on Fe3O4@SiO2 surface was synthesized. The nanocomposite particles were investigated by SEM, XRD, VSM, EPR and FTIR. The nanocomposite showed high catalytic activity and selectivity for the epoxidation of linear terminal, cyclic and most of the aromatic olefins by O2 in the presence of isobutyraldehyde under mild conditions; epoxide selectivity 87–100%, enantiomeric excess 53–100%. The catalyst could be separated and recovered from the reaction system by applying an external magnetic field and reused for four cycles without the loss of activity after each cycle. Total TON of 16957 was obtained after four cycles.
- Hadian-Dehkordi, Leila,Hosseini-Monfared, Hassan,Aleshkevych, Pavlo
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p. 142 - 151
(2017/03/29)
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- Umpolung Synthesis of 1,3-Amino Alcohols: Stereoselective Addition of 2-Azaallyl Anions to Epoxides
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We report the direct preparation of 1,3-amino alcohols that contain up to three contiguous stereogenic centers by the umpolung coupling of imines and epoxides. Nucleophilic 2-azaallyl anions, generated from imines, are stereoselectively added to epoxides to furnish 1,3-amino alcohols after hydrolysis of the product imine. Transformations afford amino alcohols with >98% site selectivity with respect to both reaction partners and in up to >98% yield and >20:1 dr.
- Daniel, Paige E.,Weber, Alexandria E.,Malcolmson, Steven J.
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supporting information
p. 3490 - 3493
(2017/07/15)
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- Increasing the Activity and Efficiency of Stereoselective Oxidations by using Decoy Molecules in Combination with Rate-Enhancing Variants of P450Bm3
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The use of rate-accelerating variants of P450Bm3 coupled with decoy molecules is described, resulting in improved catalytic activity for hydroxylation and epoxidation reactions. Prochiral substrates were investigated to ascertain the effect of the mutant enzymes and the decoy molecules on the regio- and enantioselectivity of the oxidations. For the alkyl and alkene substituted benzene substrates tested, large improvements in the product formation activity over the wild-type enzyme were obtained. The product formation rates for the substrates tested ranged from 660 to 2210 nmol (nmol P450)?1 min?1 for variants containing the R47L and Y51F mutations. Although the regioselectivity was not significantly altered in most of the turnovers, some adjustment in the enantioselectivity was observed with smaller substrates. The addition of decoy molecules often resulted in improved enantioselectivity and counteracted reductions arising from the rate-accelerating mutants.
- Munday, Samuel D.,Dezvarei, Shaghayegh,Bell, Stephen G.
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p. 2789 - 2796
(2016/09/13)
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- Ti-salalen mediated asymmetric epoxidation of olefins with H2O2: Effect of ligand on the catalytic performance, and insight into the oxidation mechanism
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The highly enantioselective epoxidation of several conjugated olefins with H2O2 in the presence of five chiral titanium(IV) salalen (dihydrosalen) complexes has been studied, with focus on the effects of substituents (electronic and
- Talsi, Evgenii P.,Rybalova, Tatyana V.,Bryliakov, Konstantin P.
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p. 131 - 137
(2016/06/09)
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- Photocatalytic Asymmetric Epoxidation of Terminal Olefins Using Water as an Oxygen Source in the Presence of a Mononuclear Non-Heme Chiral Manganese Complex
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Photocatalytic enantioselective epoxidation of terminal olefins using a mononuclear non-heme chiral manganese catalyst, [(R,R-BQCN)MnII]2+, and water as an oxygen source yields epoxides with relatively high enantioselectivities (e.g., up to 60% enantiomeric excess). A synthetic mononuclear non-heme chiral Mn(IV)-oxo complex, [(R,R-BQCN)MnIV(O)]2+, affords similar enantioselectivities in the epoxidation of terminal olefins under stoichiometric reaction conditions. Mechanistic details of each individual step of the photoinduced catalysis, including formation of the Mn(IV)-oxo intermediate, are discussed on the basis of combined results of laser flash photolysis and other spectroscopic methods.
- Shen, Duyi,Saracini, Claudio,Lee, Yong-Min,Sun, Wei,Fukuzumi, Shunichi,Nam, Wonwoo
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supporting information
p. 15857 - 15860
(2016/12/23)
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- Proton-Promoted and Anion-Enhanced Epoxidation of Olefins by Hydrogen Peroxide in the Presence of Nonheme Manganese Catalysts
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We report a remarkable Br?nsted acid effect in the epoxidation of olefins by nonheme manganese catalysts and aqueous hydrogen peroxide. More specifically, a mononuclear nonheme manganese complex bearing a tetradentate N4 ligand, MnII(Dbp-MCP)(OTf)2 (Dbp-MCP = (1R,2R)-N,N′-dimethyl-N,N′-bis((R)-(3,5-di-tert-butyl-phenyl)-2-pyridinylmethyl)cyclohexane-1,2-diamine; OTf- = CF3SO3-), is a highly efficient catalyst in the epoxidation of olefins by aqueous H2O2 in the presence of H2SO4 (1-3 mol %). The yields of epoxide products as well as the chemo- and enantioselectivities increase dramatically in the presence of H2SO4; no formation of epoxides is observed in the absence of H2SO4. In addition, the product yields and enantioselectivities are dependent significantly on the manganese catalysts and Br?nsted acids. The catalytic epoxidation of olefins by other oxidants, such as peracids, alkyl hydroperoxides, and iodosylbenzene, is also affected by the presence of H2SO4; product yields and enantioselectivities are high and similar irrespective of the oxidants in the presence of H2SO4, suggesting that a common epoxidizing intermediate is generated in the reactions of [MnII(Dbp-MCP)]2+ and the oxidants. Mechanistic studies, performed with 18O-labeled water (H218O) and cumyl hydroperoxide, reveal that a high-valent manganese-oxo species is formed as an epoxidizing intermediate via O-O bond heterolysis of Mn-OOH(R) species. The role of H2SO4 is proposed to facilitate the formation of a high-valent Mn-oxo species and to increase the oxidizing power and enantioselectivity of the Mn-oxo oxidant in olefin epoxidation reactions. Density functional theory (DFT) calculations support experimental results such as the formation of a Mn(V)-oxo species as an epoxidizing intermediate.
- Miao, Chengxia,Wang, Bin,Wang, Yong,Xia, Chungu,Lee, Yong-Min,Nam, Wonwoo,Sun, Wei
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p. 936 - 943
(2016/02/05)
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- Engineering P450 Peroxygenase to Catalyze Highly Enantioselective Epoxidation of cis-β-Methylstyrenes
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P450 119 peroxygenase and its site-directed mutants are discovered to catalyze the enantioselective epoxidation of methyl-substituted styrenes. Two new site-directed P450 119 mutants, namely T213Y and T213M, which were designed to improve the enantioselectivity and activity for the epoxidation of styrene and its methyl substituted derivatives, were studied. The T213M mutant is found to be the first engineered P450 peroxygenase that shows highly enantioselective epoxidation of cis-β-methylstyrenes, with up to 91 % ee. Molecular modeling studies provide insights into the different catalytic activity of the T213M mutant and the T213Y mutant in the epoxidation of cis-β-methylstyrene. The results of the calculations also contribute to a better understanding of the substrate specificity and configuration control for the regio- and stereoselective peroxygenation catalyzed by the T213M mutant.
- Zhang, Chun,Liu, Ping-Xian,Huang, Lu-Yi,Wei, Si-Ping,Wang, Li,Yang, Sheng-Yong,Yu, Xiao-Qi,Pu, Lin,Wang, Qin
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p. 10969 - 10975
(2016/07/27)
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- Enantioselective aerobic oxidation of olefins by magnetite nanoparticles at room temperature: A chiral carboxylic acid strategy
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Asymmetric oxidations of organic compounds are limited in their synthetic scope and by practical factors, such as the use of complex catalyst synthesis. A simple and cheap nanostructured catalyst system comprising magnetite nanoparticles stabilized by l-(+)-tartaric acid (Fe3O4/tart-NPs) was successfully synthesized in diethylene glycol. The catalyst was characterized by FT-IR, TGA, ICP-AES, XRPD, SEM and dynamic light scattering (DLS). The catalytic activity of Fe3O4/tart-NPs dispersion in acetonitrile in the presence of isobutyraldehyde was studied in selective aerobic oxidation of olefins to form asymmetric epoxide, an important intermediate for the synthesis of biologically active compounds. In addition, the magnetically recoverable nanocatalyst Fe3O4/tart-NPs can be conveniently separated and recovered from the reaction system by applying an external magnetic field and reused for five cycles without the loss of activity after each cycle. These results demonstrate that the heterogeneous nanocatalysts possess potential applications for green and sustainable development. As synthesized nanoparticles of Fe3O4/tart-NPs are cheap and easy to synthesize asymmetric catalysts which were prepared without the involvement of difficult and cumbersome procedures for the synthesis of complicated asymmetric ligands. Possible reaction mechanisms were outlined.
- Hadian-Dehkordi, Leila,Hosseini-Monfared, Hassan
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p. 497 - 507
(2016/01/30)
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- Synergistic interplay of a non-heme iron catalyst and amino acid coligands in H2O2 activation for asymmetric epoxidation of α-alkyl-substituted styrenes
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Highly enantioselective epoxidation of α-substituted styrenes with aqueous H2O2 is described by using a chiral iron complex as the catalyst and N-protected amino acids (AAs) as coligands. The amino acids synergistically cooperate with the iron center in promoting an efficient activation of H2O2 to catalyze epoxidation of this challenging class of substrates with good yields and stereoselectivities (up to 97% ee) in short reaction times.
- Cuss, Olaf,Ribas, Xavi,Lloret-Fillol, Julio,Costas, Miquel
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supporting information
p. 2729 - 2733
(2015/03/04)
-
- 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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- 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 0098-0100; 0102-0107
(2019/01/05)
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- Asymmetric epoxidation of olefins with hydrogen peroxide by an in situ-formed manganese complex
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Asymmetric epoxidation of a variety of cis, trans, terminal, and trisubstituted olefins in excellent yields (up to 94%) and enantioselectivities (>99% ee) by an in situ-formed manganese complex using H2O 2 has been developed. A relationship between the hydrophobicity of the catalyst imposed by ligand and the catalytic activity has been observed. The influence of the amount and identity of the acid additive was examined, and improved enantioselectivities were achieved through the use of a catalytic amount of a carboxylic acid additive.
- Dai, Wen,Shang, Sensen,Chen, Bo,Li, Guosong,Wang, Lianyue,Ren, Lanhui,Gao, Shuang
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p. 6688 - 6694
(2014/08/05)
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- Manganese complexes with non-porphyrin N4 ligands as recyclable catalyst for the asymmetric epoxidation of olefins
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New chiral manganese complexes of N4 ligands derived from 2-acetylpyridine were prepared and used as catalysts in the enantioselective epoxidation of olefins, using H2O2 as an oxidant to give epoxides, with excellent conversions (up to 99%) and enantiomeric excess (up to 88%) within 1 h at 0°C. A detailed mechanistic study was undertaken based on the information obtained by single crystal X-ray, optical rotation, UV-Vis, CD spectra and kinetic studies, and revealed that the reaction is first order with respect to the concentration of catalyst and oxidant and independent of substrate concentration. The complex (0.1 mol%) was successfully subjected to recyclability experiments over 3 cycles in the epoxidation of styrene with H2O2 as an oxidant and acetic acid as an additive at 0°C with retention of performance.
- Maity, Nabin Ch.,Kumar Bera, Prasanta,Ghosh, Debashis,Abdi, Sayed H. R.,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Bajaj, Hari C.,Suresh
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p. 208 - 217
(2014/01/06)
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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)
-
- Novel chiral (salen)Mn(iii) complexes containing a calix[4]arene unit in 1,3-alternate conformation as catalysts for enantioselective epoxidation reactions of (Z)-aryl alkenes
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Two new chiral calix[4]arene-salen ligands 1a,b, based on calix[4]arene platforms in 1,3-alternate conformation, have been prepared by a new general synthetic pathway. Their Mn(iii) complexes, 3a,b, have shown fairly good efficiency in the asymmetric epoxidation of styrene and substituted styrenes, whereas excellent catalytic activity and selectivity were observed with rigid bicyclic alkenes, namely 1,2-dihydro-naphthalene and substituted 2,2′-dimethyl-chromene. The higher catalytic properties of 3a may be ascribed to the more rigid and inherently chiral structure as proved by molecular modelling, NMR spectroscopy and X-ray data of the similarly structured UO2 complexes 2a,b.
- Bonaccorso, Carmela,Brancatelli, Giovanna,Ballistreri, Francesco P.,Geremia, Silvano,Pappalardo, Andrea,Tomaselli, Gaetano A.,Toscano, Rosa M.,Sciotto, Domenico
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p. 2183 - 2193
(2014/01/17)
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- Oxygen-atom transfer from iodosylarene adducts of a manganese(IV) salen complex: Effect of arenes and anions on I(III) of the coordinated iodosylarene
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This paper reports preparation, characterization, and reactivity of iodosylarene adducts of a manganese(IV) salen complex. In order to systematically investigate steric and electronic factors that control reactivity and selectivity, we prepared iodosylare
- Wang, Chunlan,Kurahashi, Takuya,Inomata, Kensuke,Hada, Masahiko,Fujii, Hiroshi
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p. 9557 - 9566
(2013/09/12)
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- Titanium salalen catalysts based on cis-1,2-diaminocyclohexane: Enantioselective epoxidation of terminal non-conjugated olefins with H 2O2
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Terminal, non-conjugated olefins, such as 1-octene, are difficult to epoxidize asymmetrically. Ti salalen complexes based on cis-1,2- diaminocyclohexane catalyze this demanding reaction giving high yields and enantioselectivities (up to 95 % ee), with H2O2 as the oxidant. The X-ray structures of the μ-oxo and peroxo complexes shed light on the coordination behavior of this novel class of ligands.
- Berkessel, Albrecht,Guenther, Thomas,Wang, Qifang,Neudoerfl, Joerg-M.
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supporting information
p. 8467 - 8471
(2013/09/02)
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- Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins
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Organic carbonates, e.g., dimethyl carbonate and propylene carbonate were used as reaction media in enantioselective epoxidation of non-functionalized alkenes by using a series of chiral macrocyclic Mn(III) salen complexes (5 mol%) as catalyst with pyridi
- Maity, Nabin Ch.,Rao, Ganga V.S.,Prathap,Abdi, Sayed H.R.,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Bajaj, Hari C.
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p. 380 - 389
(2013/02/22)
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- The elpaN-salen series: Multifunctional ligands based on D-glucose for the Mn(III)-catalyzed enantioselective epoxidation of styrenes
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It is described the simple design of a series of N,N′,O,O′- chiral ligands (elpaN-salen-H2), which represent a subset of the elpaN-type library of ligands based on β-1,2-D-glucodiamine. The corresponding Mn(III) complexes were examined in the asymmetric epoxidation of styrenes with satisfactory results, e.g. cis-β-methylstyrene was functionalised in ees up to 88%.
- Ruffo, Francesco,Bismuto, Alessandro,Carpentieri, Andrea,Cucciolito, Maria E.,Lega, Matteo,Tuzi, Angela
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p. 288 - 294
(2013/10/22)
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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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- Structure and reactivity of an iodosylarene adduct of a manganese(IV)-salen complex
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O transfer: The X-ray crystal structure of an iodosylarene adduct of a manganese(IV)-salen complex shows bis-iodosylarene coordination with a stepped conformation of the salen ligand. Spectroscopic characterization suggests that the complex maintains the
- Wang, Chunlan,Kurahashi, Takuya,Fujii, Hiroshi
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supporting information; experimental part
p. 7809 - 7811
(2012/09/21)
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- Asymmetric epoxidation of conjugated olefins with dioxygen
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A complex situation: Asymmetric epoxidation of conjugated olefins was achieved at room temperature using ruthenium complex 1 as the catalyst and air as the oxidant to give epoxides in up to 95 % ee (see scheme). When the product was acid sensitive, the reaction was carried out at 0 °C under oxygen. Copyright
- Koya, Shota,Nishioka, Yota,Mizoguchi, Hirotaka,Uchida, Tatsuya,Katsuki, Tsutomu
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supporting information; experimental part
p. 8243 - 8246
(2012/09/08)
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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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- 3- and 4-uloses derived from N-acetyl- D -glucosamine: A unique pair of complementary organocatalysts for asymmetric epoxidation of alkenes
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The 4-ulose and the 3-ulose, both derived in two steps from the α-methyl glycoside of N-acetyl-D-glucosamine (GlcNAc), act as organocatalysts in the asymmetric epoxidation of alkenes, with unprecedented complementary enantioselectivity. The best results are found with α,β-unsaturated esters as substrates, with enantiomeric ratios up to 90:10 and 11:89, respectively. Copyright
- Schoeberl, Christof,Jaeger, Volker
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supporting information; experimental part
p. 790 - 796
(2012/05/04)
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- Asymmetric vanadium- and iron-catalyzed oxidations: New mild (R)-modafinil synthesis and formation of epoxides using aqueous H2O2 as a terminal oxidant
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The enantioselective oxidation of thioanisole to methyl phenyl sulfoxide and the epoxidation of several alkenes, including terminal ones, have been realized by using new iron(III) complexes, generated in situ from primary amine-derived non-symmetrical Schiff base ligands and aqueous H 2O2 as environmentally benign oxidant. Further investigations on vanadium catalysis and the application of both catalytic systems in the synthesis of enantiomerically-enriched chiral drug (R)-modafinil were undertaken. It was found that the vanadium-based catalytic system (VO(acac)2/ligand 6), is able to provide (R)-modafinil in quantitative yield and acceptable enantiomeric excess within a very short reaction time (15 min).
- Stingl, Kerstin A.,Wei?, Katharina M.,Tsogoeva, Svetlana B.
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experimental part
p. 8493 - 8501
(2012/10/08)
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- Immobilized dimeric chiral Mn(III) salen complex on short channel ordered mesoporous silica as an effective catalyst for the epoxidation of non-functionalized alkenes
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Chiral dimeric Mn(III) salen complex with 1R, 2R-(-)-diaminocyclohexane collar was immobilized on short channel large pore sized silica through a long linker of {(CH2)3-NH-melamine-piperazine} to investigate its performance in enanti
- Roy, Tamal,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Abdi, Sayed H.R.,Sadhukhan, Arghya,Bajaj, Hari C.
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experimental part
p. 6314 - 6322
(2012/08/28)
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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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- Stereoselective benzylic hydroxylation of alkylbenzenes and epoxidation of styrene derivatives catalyzed by the peroxygenase of Agrocybe aegerita
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Here we report on the stereoselective benzylic hydroxylation and C1-C2 epoxidation of alkylbenzenes and styrene derivatives, respectively, by a heme-thiolate peroxygenase (EC 1.11.2.1) from the fungus Agrocybe aegerita. Benzylic hydroxylation led exclusively to the (R)-1-phenylalkanols. For (R)-1-phenylethanol, (R)-1-phenylpropanol and (R)-1-tetralol, the ee reached >99%. For longer chain lengths, the enantiomeric excesses (ee) and total turnover numbers (TTN) decreased while the number of by-products, e.g. 1-phenylketones, increased. Epoxidation of straight chain and cyclic styrene derivatives gave a heterogeneous picture and resulted in moderate to excellent ee values and TTN: e.g., in the case of (1R,2S)-cis-β-methylstyrene oxide formation, an ee >99% and a TTN of 110000 was achieved. Hydroxylation and epoxidation were true peroxygenations, which was demonstrated by the incorporation of 18O from H218O2 into the products. The use of fed-batch devices and varying feeding strategies for the substrate and co-substrate turned out to be a suitable approach to optimize peroxygenase catalysis.
- Kluge, Martin,Ullrich, Rene,Scheibner, Katrin,Hofrichter, Martin
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supporting information; experimental part
p. 440 - 446
(2012/04/10)
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- A peptide-embedded trifluoromethyl ketone catalyst for enantioselective epoxidation
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The development of peptide-based oxidation catalysts that use a transiently generated dioxirane as the chemically active species is reported. The active catalyst is a chiral trifluoromethyl ketone (Tfk) with a pendant carboxylic acid that can be readily incorporated into a peptide. These peptides were capable of epoxidizing alkenes in high yield (up to 89%) and enantiomeric ratios (er) ranging from 69.0:31.0 to 91.0:9.0, depending on the alkene substitution pattern.
- Romney, David K.,Miller, Scott J.
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supporting information; experimental part
p. 1138 - 1141
(2012/05/04)
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- Asymmetric epoxidation using iminium salt organocatalysts featuring dynamically controlled atropoisomerism
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Introduction of a pseudoaxial substituent at a stereogenic center adjacent to the nitrogen atom in binaphthyl- and biphenyl-derived azepinium salt organocatalysts affords improved enantioselectivities and yields in the epoxidation of unfunctionalized alkenes. In the biphenyl-derived catalysts, the atropoisomerism at the biphenyl axis is controlled by the interaction of this substituent with the chiral substituent at nitrogen.
- Bulman Page, Philip C.,Bartlett, Christopher J.,Chan, Yohan,Day, David,Parker, Phillip,Buckley, Benjamin R.,Rassias, Geracimos A.,Slawin, Alexandra M. Z.,Allin, Steven M.,Lacour, Jerome,Pinto, Andre
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experimental part
p. 6128 - 6138
(2012/10/08)
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- Synthesis of new carbohydrate-derived ketones as organocatalysts in the enantioselective epoxidation of arylalkenes. Part 2: Chiral ketones from sugars
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A range of new, somewhat complex, stereochemically varied, and structurally related carbohydrate-derived ketones were synthesised by a simple method from the carbohydrate precursor (d-gluco and d-galacto derivatives). The common skeleton possesses the keto function sited on a seven-membered ring fused to positions 2 and 3 of the sugar moiety. Their chirality transfer capability in the dioxirane-mediated epoxidation of arylalkenes was evaluated. Copyright
- Vega-Pérez, José M.,Vega-Holm, Margarita,Peri?án, Ignacio,Palo-Nieto, Carlos,Iglesias-Guerra, Fernando
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experimental part
p. 364 - 372
(2011/03/20)
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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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- Asymmetric epoxidation of styrene derivatives by styrene monooxygenase from Pseudomonas sp. LQ26: Effects of α- And β-substituents
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Recombinant Escherichia coli expressing a styrene monooxygenase, StyAB2, from Pseudomonas sp. LQ26 was applied to synthesize a range of chiral epoxides from conjugated styrene derivatives with excellent (>99%) enantioselectivity in most cases. The substrate preference was studied with a special focus on the steric effect of α- and β-substituents.
- Lin, Hui,Liu, Yan,Wu, Zhong-Liu
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experimental part
p. 134 - 137
(2011/04/27)
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- Synthesis of enantiopure β-amino alcohols via AKR/ARO of epoxides using recyclable macrocyclic Cr(III) salen complexes
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A series of chiral macrocyclic Cr(III) salen complexes 1-8 were synthesized and characterized. These complexes were found to be highly active, regio-, diastereo-, and enantioselective catalysts in aminolytic kinetic resolution (AKR) of racemic trans-epoxides as well as asymmetric ring opening (ARO) of prochiral meso-epoxides with various anilines as nucleophiles at room temperature in 18-24 h. Excellent yields (>99% with respect to the nucleophile) with high enantioselectivity (ee, >99%) of chiral anti-β-amino alcohols was achieved with concomitant recovery of corresponding epoxides in high ee (up to >99%). The complex 1 also catalyzed the ARO of meso-epoxides to provide corresponding syn-β-amino alcohols in high yield (99%) and ee (up to 91%). Due to built-in basic sites in the catalyst, no external base (as an additive) was required to promote AKR and ARO reactions. The catalyst 1 was conveniently recycled several times with retention of its performance. The AKR of trans-stilbene oxide with aniline was successfully demonstrated at relatively higher scale (10 mmol) using the catalyst 1.
- Kureshy, Rukhsana Ilays,Prathap, K. Jeya,Kumar, Manish,Bera, Prasanta Kumar,Khan, Noor-Ul Hasan,Abdi, Sayed Hasan Razi,Bajaj, Hari Chandra
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supporting information; experimental part
p. 8300 - 8307
(2011/11/12)
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- Asymmetric counteranion-directed transition-metal catalysis: Enantioselective epoxidation of alkenes with Manganese(III) salen phosphate complexes
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(Figure Presented) Figure Presentation Paired up: A highly active and enantioselective ion-pair epoxidation catalyst, consisting of an achiral Mn |||-salen complex and a chiral phosphate counteranion, mediates the epoxidization of a wide range of alkenes with high yields and enantioselectivities (see scheme). The unique role of the counteranion is to stabilize an enantiomorphic conformation of the cationic Mn catalyst.
- Liao, Saihu,List, Benjamin
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supporting information; experimental part
p. 628 - 631
(2010/04/06)
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- Catalytic enantioselective alkene epoxidation using novel spirocyclic N-carbethoxy-azabicyclo[3.2.1]octanones
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A general synthetic route allowing access to several spirocyclic N-carbethoxy-azabicyclo[3.2.1]octanones is developed. These novel ketones efficiently catalyse alkene epoxidation using Oxone with up to 91.5% ee.
- Armstrong, Alan,Bettati, Michela,White, Andrew J.P.
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experimental part
p. 6309 - 6320
(2010/10/19)
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- Photopromoted Ru-catalyzed asymmetric aerobic sulfide oxidation and epoxidation using water as a proton transfer mediator
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Ru(NO)-salen complexes were found to catalyze asymmetric aerobic oxygen atom transfer reactions such as sulfide oxidation and epoxidation in the presence of water under visible light irradiation at room temperature. Oxidation of sulfides including alkyl aryl sulfides and 2-substituted 1,3-dithianes using complex 2 as the catalyst proceeded with moderate to high enantioselectivity of up to 98% ee, and epoxidation of conjugated olefins using complex 3 as the catalyst proceeded with good to high enantioselectivity of 76-92% ee. Unlike biological oxygen atom transfer reactions that need a proton and electron transfer system, this aerobic oxygen atom transfer reaction requires neither such a system nor a sacrificial reductant. Although the mechanism of this oxidation has not been completely clarified, some experimental results support the notion that an aqua ligand coordinated with the ruthenium ion serves as a proton transfer agent for the oxygen activation process, and it is recycled and used as the proton transfer mediator during the process. Thus, we have achieved catalytic asymmetric oxygen atom transfer reaction using molecular oxygen that can be carried out under ambient conditions.
- Tanaka, Haruna,Nishikawa, Hiroaki,Uchida, Tatsuya,Katsuki, Tsutomu
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supporting information; experimental part
p. 12034 - 12041
(2010/11/04)
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- Organocatalysis of asymmetric epoxidation by iminium salts using sodium hypochlorite as the stoichiometric oxidant
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Iminium salts can provide high selectivity and high efficiency when used as organocatalysts for asymmetric epoxidation. For this purpose, they are normally used in conjunction with Oxone as the stoichiometric oxidant. Oxone, however, has limited stability
- Page, Philip C. Bulman,Parker, Phillip,Buckley, Benjamin R.,Rassias, Gerasimos A.,Bethell, Donald
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experimental part
p. 2910 - 2915
(2009/06/28)
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- A diacetate ketone-catalyzed asymmetric epoxidation of olefins
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(Chemical Equation Presented) A fructose-derived diacetate ketone has been shown to be an effective catalyst for asymmetric epoxidation. High ee values have been obtained for a variety of trans and trisubstituted olefins including electron-deficient α,β-unsaturated esters as well as certain cis olefins.
- Wang, Bin,Wu, Xin-Yan,Wong, O. Andrea,Nettles, Brian,Zhao, Mei-Xin,Chen, Dajun,Shi, Yian
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experimental part
p. 3986 - 3989
(2009/09/30)
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