- Benzocycloarene hydroxylation by P450 biocatalysis
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Experimental and theoretical studies of the hydroxylation of a family of benzocycloarene compounds [benzocyclobutene, benzocyclopentene (indan), benzocyclohexene (tetralin), and benzocycloheptene] by wild type and Y96F mutant P450cam were performed in order to understand the factors affecting product distribution, catalytic rate and cofactor utilization. The products of all reactions except that of benzocycloheptene were regiospecifically hydroxylated in the 1-position. Reaction energetics predominated over active site steric constraints in this case so that quantum mechanical calculations (B3LYP/6-31G*) comparing the energetics of all possible radical intermediates successfully predicted hydroxylation at the 1- and 3-positions of benzocycloheptene, and at the 1-position for the other three compounds. However, the fact that the ratio of 1-alcohol to 3-alcohol changes significantly between wild type and Y96F mutant P450cam indicates that active site geometry and composition also play a significant role in determining BCA7 product regiospecificity. The indan and tetralin reaction products were stereoselective for the R enantiomer (88 and 94%, respectively). Steric constraints of the active site were confirmed by molecular dynamics calculations (locally enhanced sampling dynamics) to control enantiomer distribution for tetralin hydroxylation. NADH coupling, binding affinity, and product turnover rates were dramatically higher for Y96F P450cam, showing that the removal of the active site hydroxyl group on tyrosine makes the enzyme better suited for oxidation of these hydrophobic compounds. NADH coupling, binding affinity and product turnover rate for each enzyme generally increased with arene ring size. For both enzymes, NADH coupling and product turnover rates were correlated with the extent of high-spin shift upon substrate binding as determined by the shift in Soret absorption bands at 417 and 391 nm.
- Mayhew, Martin P.,Roitberg, Adrian E.,Tewari, Yadu,Holden, Marcia J.,Vanderah, David J.,Vilker, Vincent L.
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- Improving the enantioselectivity of artificial transfer hydrogenases based on the biotin-streptavidin technology by combinations of point mutations
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Artificial metalloenzymes based on the incorporation of biotinylated ruthenium piano-stool complexes within streptavidin can be readily optimized by chemical or genetic means. We performed genetic modifications of such artificial metalloenzymes for the tr
- Pordea,Creus,Letondor,Ivanova,Ward
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- Enantioselective benzylic hydroxylation of indan and tetralin with Pseudomonas monteilii TA-5
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A set of 22 toluene- and ethylbenzene-degrading strains were screened for the enantioselective benzylic hydroxylation of indan and tetralin, and Pseudomonas monteilii TA-5 was discovered as an active and selective biocatalyst for such hydroxylations. Cells of P. monteilii TA-5 can be easily grown to a high density and demonstrated a specific hydroxylation activity of 24 U/g cdw (cell dry weight). Conditions for the hydroxylation of indan 1a and tetralin 1b with resting cells of this strain were optimized, to give the corresponding (R)-1-indanol 2a and (R)-1-tetralol 2b in 99% ee and 62-67% yields, respectively. No significant product inhibition was observed, and biohydroxylation with cell-free extracts suggested that the responsible hydroxylase is a soluble enzyme depending on either NADH or NADPH. Preparative biohydroxylation was demonstrated with resting cells as biocatalysts, affording (R)-2a in 99% ee and 65% yield, and (R)-2b in 99% ee and in 63% yield, respectively.
- Lie, Felicia,Chen, Yongzheng,Wang, Zunsheng,Li, Zhi
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- Concurrent oxidations with tandem biocatalysts in one pot: Green, selective and clean oxidations of methylene groups to ketones
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A novel tandem-biocatalysts system consisting of a monooxygenase-containing microorganism and an alcohol dehydrogenase is developed for the concurrent oxidations of methylene groups to ketones in one pot, providing green, clean and simple access to valuable ketones with high yield, excellent selectivity and efficient cofactor recycling.
- Zhang, Wei,Tang, Weng Lin,Wang, Daniel I. C.,Li, Zhi
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- CH-activating oxidative hydroxylation of 1-tetralones and related compounds with high regio- and stereoselectivity
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Mutants of P450-BM3 evolved by directed evolution are excellent catalysts in the CH-activating oxidative hydroxylation of 1-tetralone derivatives and of indanone, with unusually high regio- and enantioselectivity being observed. Similar results were achieved in the oxidative hydroxylation of tetralin and indane. The products are useful building blocks in the synthesis of a number of biologically active compounds.
- Roiban, Gheorghe-Doru,Agudo, Rubn,Ilie, Adriana,Lonsdale, Richard,Reetz, Manfred T.
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- Designer Outer Membrane Protein Facilitates Uptake of Decoy Molecules into a Cytochrome P450BM3-Based Whole-Cell Biocatalyst
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We report an OmpF loop deletion mutant, which improves the cellular uptake of external additives into an Escherichia coli whole-cell biocatalyst. Through co-expression of the OmpF mutant with wild-type P450BM3 in the presence of decoy molecules, the yield
- Karasawa, Masayuki,Shoji, Osami,Stanfield, Joshua Kyle,Suzuki, Kazuto,Yonemura, Kai
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supporting information
(2021/12/16)
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- A NEW TEMPLATE of MITSUNOBU ACYLATE CLEAVABLE in NONALKALINE CONDITIONS
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The Mitsunobu inversion is one of the reliable methods for stereospecific substitution of chiral alcohols, but its deacylation step has limited the substrate scope. Here, we propose a new template of the Mitsunobu acylate that can be deacylated in non-alkaline treatments. The 3,4-dihydroxy-2-methylenebutanoate was selected as a template structure, and its acetonide- or bisTBS derivatives were synthesized. The latter especially showed excellent inversion efficiency (up to >99% ee) and good elimination performance for a series of secondary alcohols in near-neutral conditions. The results demonstrated the applicability of the new template for the substrates labile in alkaline conditions, such as a-hydroxyesters.
- Sai, Yusuke,Sakakibara, Yoshimichi,Shigetomi, Kengo,Ubukata, Makoto,Uraki, Yasumitsu
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p. 140 - 158
(2022/01/08)
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- Chiral Yolk-Shell MOF as an Efficient Nanoreactor for Asymmetric Catalysis in Organic-Aqueous Two-Phase System
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It remains a great challenge to introduce large and efficient homogeneous asymmetric catalysts into MOFs and other microporous materials as well as retain their degrees of freedom. Herein, a new heterogeneous strategy of homogeneous chiral catalysts is proposed, that is, to construct a yolk-shell MOFs-confined, large-size, and highly efficient homogeneous chiral catalyst, which can be used as a nanoreactor for asymmetric catalytic reactions.
- Shi, Shunli,Zhong, Yicheng,Hu, Zhuo,Wang, Lei,Yuan, Mingwei,Ding, Shunmin,Wang, Shuhua,Chen, Chao
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supporting information
p. 12714 - 12718
(2021/09/11)
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- Enantioselective Hydroxylation of Benzylic C(sp3)-H Bonds by an Artificial Iron Hydroxylase Based on the Biotin-Streptavidin Technology
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The selective hydroxylation of C-H bonds is of great interest to the synthetic community. Both homogeneous catalysts and enzymes offer complementary means to tackle this challenge. Herein, we show that biotinylated Fe(TAML)-complexes (TAML = Tetra Amido Macrocyclic Ligand) can be used as cofactors for incorporation into streptavidin to assemble artificial hydroxylases. Chemo-genetic optimization of both cofactor and streptavidin allowed optimizing the performance of the hydroxylase. Using H2O2 as oxidant, up to ~300 turnovers for the oxidation of benzylic C-H bonds were obtained. Upgrading the ee was achieved by kinetic resolution of the resulting benzylic alcohol to afford up to >98% ee for (R)-tetralol. X-ray analysis of artificial hydroxylases highlights critical details of the second coordination sphere around the Fe(TAML) cofactor.
- Barnet, Maxime,Peterson, Ryan L.,Rebelein, Johannes G.,Rumo, Corentin,Serrano-Plana, Joan,Ward, Thomas R.
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supporting information
p. 10617 - 10623
(2020/07/04)
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- Identification of an Esterase Isolated Using Metagenomic Technology which Displays an Unusual Substrate Scope and its Characterisation as an Enantioselective Biocatalyst
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Evaluation of an esterase annotated as 26D isolated from a marine metagenomic library is described. Esterase 26D was found to have a unique substrate scope, including synthetic transformations which could not be readily effected in a synthetically useful manner using commercially available enzymes. Esterase 26D was more selective towards substrates which had larger, more sterically demanding substituents (i. e. iso-propyl or tert-butyl groups) on the β-carbon, which is in contrast to previously tested commercially available enzymes which displayed a preference for substrates with sterically less demanding substituents (e.g. methyl group) at the β-carbon. (Figure presented.).
- Gavin, Declan P.,Murphy, Edel J.,Foley, Aoife M.,Castilla, Ignacio Abreu,Reen, F. Jerry,Woods, David F.,Collins, Stuart G.,O'Gara, Fergal,Maguire, Anita R.
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p. 2466 - 2474
(2019/03/11)
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- Asymmetric aerobic oxidation of secondary alcohols catalyzed by poly(: N-vinyl-2-pyrrolidone)-stabilized gold clusters modified with cyclodextrin derivatives
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Surface modification of poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters (1.8 ± 0.6 nm) with aminated cyclodextrins induced aerobic oxidative kinetic resolution of racemic secondary alcohols (krel = 1.2).
- Hirano, Koto,Takano, Shinjiro,Tsukuda, Tatsuya
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supporting information
p. 15033 - 15036
(2020/01/03)
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
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A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
- Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
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p. 663 - 666
(2019/05/21)
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- Combining Photo-Organo Redox- and Enzyme Catalysis Facilitates Asymmetric C-H Bond Functionalization
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In this study, we combined photo-organo redox catalysis and biocatalysis to achieve asymmetric C–H bond functionalization of simple alkane starting materials. The photo-organo catalyst anthraquinone sulfate (SAS) was employed to oxyfunctionalise alkanes to aldehydes and ketones. We coupled this light-driven reaction with asymmetric enzymatic functionalisations to yield chiral hydroxynitriles, amines, acyloins and α-chiral ketones with up to 99 % ee. In addition, we demonstrate functional group interconversion to alcohols, esters and carboxylic acids. The transformations can be performed as concurrent tandem reactions. We identified the degradation of substrates and inhibition of the biocatalysts as limiting factors affecting compatibility, due to reactive oxygen species generated in the photocatalytic step. These incompatibilities were addressed by reaction engineering, such as applying a two-phase system or temporal and spatial separation of the catalysts. Using a selection of eleven starting alkanes, one photo-organo catalyst and 8 diverse biocatalysts, we synthesized 26 products and report for the model compounds benzoin and mandelonitrile > 97 % ee at gram scale.
- Zhang, Wuyuan,Fueyo, Elena Fernandez,Hollmann, Frank,Martin, Laura Leemans,Pesic, Milja,Wardenga, Rainer,H?hne, Matthias,Schmidt, Sandy
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- Design and Assembly of a Chiral Metallosalen-Based Octahedral Coordination Cage for Supramolecular Asymmetric Catalysis
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Supramolecular containers featuring both high catalytic activity and high enantioselectivity represent a design challenge of practical importance. Herein, it is demonstrated that a chiral octahedral coordination cage can be constructed by using twelve enantiopure Mn(salen)-derived dicarboxylic acids as linear linkers and six Zn4-p-tert-butylsulfonylcalix[4]arene clusters as tetravalent four-connected vertices. The porous cage features a large hydrophobic cavity (≈3944 ?3) decorated with catalytically active metallosalen species and is shown to be an efficient and recyclable asymmetric catalyst for the oxidative kinetic resolution of racemic secondary alcohols and the epoxidation of olefins with up to >99 % enantiomeric excess. The cage architecture not only prevents intermolecular deactivation and stabilizes the Mn(salen) catalysts but also encapsulates substrates and concentrates reactants in the cavity, resulting in enhanced reactivity and enantioselectivity relative to the free metallosalen catalyst.
- Tan, Chunxia,Jiao, Jingjing,Li, Zijian,Liu, Yan,Han, Xing,Cui, Yong
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supporting information
p. 2085 - 2090
(2018/02/06)
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- Engineering P450LaMO stereospecificity and product selectivity for selective C-H oxidation of tetralin-like alkylbenzenes
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The P450-mediated asymmetric hydroxylation of inert C-H bonds is a chemically challenging reaction. Self-sufficient P450LaMO from the CYP116B subfamily could catalyze the transformation of 1,2,3,4-tetrahydronaphthalene to (S)-tetralol, despite its poor enantioselectivity (er 66:34) and product selectivity (the ratio of alcohol and ketone, ak, 76:24). To improve the selectivity, phenylalanine scanning and further protein engineering were performed to reshape the active pocket of P450LaMO, resulting in a mutant (T121V/Y385F/M391L) with not only improved (S)-enantioselectivity (er 98:2) but also excellent product selectivity (ak 99:1), in contrast to another mutant L97F/T121F/E282V/T283Y with complementary (R)-enantioselectivity (er 23:77). Moreover, the enantiopure (S)-alcohols formed by the P450LaMO-catalyzed oxidation of a series of alkylbenzenes are potentially important building blocks in the pharmaceutical industry. This Phe-based enantioselectivity engineering used for reshaping the active pocket of P450s could provide a guide to the protein evolution of other CYP116B members.
- Li, Ren-Jie,Li, Aitao,Zhao, Jing,Chen, Qi,Li, Ning,Yu, Hui-Lei,Xu, Jian-He
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p. 4638 - 4644
(2018/09/29)
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- Asymmetric Autoamplification in the Oxidative Kinetic Resolution of Secondary Benzylic Alcohols Catalyzed by Manganese Complexes
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Herein, chiral Mn–aminopyridine complexes have been shown to catalyze the oxidation of alkylarenes to enantiomerically enriched 1-arylalkanols with hydrogen peroxide. The observed enantiomeric excess values result from the direct enantioselective benzylic C?H hydroxylation, accompanied by stereoconvergent oxidative kinetic resolution of the resulting alcohol. Testing several (S,S)-bipyrrolidine derived Mn complexes has revealed a novel catalyst (6) that exhibits the best kinetic resolution in the series (krel up to 8.8), along with sufficient reactivity and efficiency (>1000 catalytic turnovers). The mechanistic study of the Mn-mediated alcohol oxidation witnesses electrophilic active species (ρ=?1.2), with rate-limiting H abstraction (kH/kD=2.2), followed by oxygen rebound and dehydration of the resulting gem-diol to form the ketone. Intriguingly, while for the resolution of the relatively bulky 1,2-diphenylethanol, krel is virtually constant throughout the reaction, for less bulky alcohols, krel increases with increasing conversion, in line with the rising optical purity of the 1-arylalkanol. The latter participates in the oxidation as an auxiliary ligand, assisting the chiral recognition. This effect is related to the previously described asymmetric autocatalysis and asymmetric autoinduction, but is not identical with either of those, with the differences being discussed. To unambiguously identify this effect, the term asymmetric autoamplification (chiral autoamplification) is proposed.
- Talsi, Evgenii P.,Samsonenko, Denis G.,Bryliakov, Konstantin P.
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p. 2599 - 2607
(2017/07/12)
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- A heterogenized chiral imino indanol complex of manganese as an efficient catalyst for aerobic epoxidation of olefins
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Herein, a new heterogenized chiral catalyst, GFC-[Mn(L)(OH)], was synthesized by grafting the complex [Mn(L)(OH)] on carbon-coated magnetic Fe3O4 nanoparticle-decorated reduced graphene oxide sheets (GFC) through an amine linkage (L = (1R,2S)-1-(N-salicylideneamino)-2-indanol). The catalyst was characterized via FT-IR, UV/vis, XRD, SEM, and vibrating sample magnetometer (VSM) techniques. It exhibited excellent activity and selectivity in the epoxidation of olefins with oxygen in the presence of isobutyraldehyde under mild conditions (conversion 38-98%; selectivity 65-98%; and enantioselectivity 58-100%, except for alpha-methylstyrene). Furthermore, the synergistic effect of the reduced graphene oxide support was observed on the increasing activity, epoxide selectivity, and enantioselectivity. The catalyst can be recovered via magnetic separation from the reaction mixture and recycled five times without any significant loss in its activity. The advantage of this development is the use of both the synergic effect of reduced graphene oxide and the magnetite nanoparticles to obtain an easily recyclable heterogeneous green catalyst. In addition, high asymmetric induction of a rigid indanol-based unit of the ligand results in high enantioselectivity.
- Abbasi, Vahideh,Hosseini-Monfared, Hassan,Hosseini, Seyed Majid
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p. 9866 - 9874
(2017/09/18)
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- CO2-expanded bio-based liquids as novel solvents for enantioselective biocatalysis
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For the first time, CO2-expanded bio-based liquids were reported as novel and sustainable solvents for biocatalysis. Herein, it was found that by expansion with CO2, 2-methyltetrahydrofuran (MeTHF), and other bio-based liquids, which were not favorable solvents for immobilized Candida antarctica lipase B (Novozym 435) catalyzed transesterification, were tuned into excellent reaction media. Especially, for the kinetic resolution of challenging bulky secondary substrates such as rac-1-adamantylethanol, the lipase displayed very high activity with excellent enantioselectivity (E value > 200) in CO2-expanded MeTHF (MeTHF concentration 10% v/v, 6 MPa), whereas there was almost no activity observed in conventional organic solvents.
- Hoang, Hai Nam,Nagashima, Yoshihiro,Mori, Shuichi,Kagechika, Hiroyuki,Matsuda, Tomoko
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p. 2984 - 2989
(2017/04/26)
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- Ultrafast chiral separations for high throughput enantiopurity analysis
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Recent developments in fast chromatographic enantioseparations now make high throughput analysis of enantiopurity on the order of a few seconds achievable. Nevertheless, routine chromatographic determinations of enantiopurity to support stereochemical investigations in pharmaceutical research and development, synthetic chemistry and bioanalysis are still typically performed on the 5-20 min timescale, with many practitioners believing that sub-minute enantioseparations are not representative of the molecules encountered in day to day research. In this study we develop ultrafast chromatographic enantioseparations for a variety of pharmaceutically-related drugs and intermediates, showing that sub-minute resolutions are now possible in the vast majority of cases by both supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RP-LC). Examples are provided illustrating how such methods can be routinely developed and used for ultrafast high throughput analysis to support enantioselective synthesis investigations.
- Barhate, Chandan L.,Joyce, Leo A.,Makarov, Alexey A.,Zawatzky, Kerstin,Bernardoni, Frank,Schafer, Wes A.,Armstrong, Daniel W.,Welch, Christopher J.,Regalado, Erik L.
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supporting information
p. 509 - 512
(2017/01/13)
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- Selective Activation of C?H Bonds in a Cascade Process Combining Photochemistry and Biocatalysis
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Selective oxyfunctionalizations of inert C?H bonds can be achieved under mild conditions by using peroxygenases. This approach, however, suffers from the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Herein, we demonstrate that inorganic photocatalysts such as gold–titanium dioxide efficiently provide H2O2 through the methanol-driven reductive activation of ambient oxygen in amounts that ensure that the enzyme remains highly active and stable. Using this approach, the stereoselective hydroxylation of ethylbenzene to (R)-1-phenylethanol was achieved with high enantioselectivity (>98 % ee) and excellent turnover numbers for the biocatalyst (>71 000).
- Zhang, Wuyuan,Burek, Bastien O.,Fernández-Fueyo, Elena,Alcalde, Miguel,Bloh, Jonathan Z.,Hollmann, Frank
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p. 15451 - 15455
(2017/11/13)
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- A recyclable Mn-porphyrin catalyst for enantioselective epoxidation of unfunctionalized olefins using molecular dioxygen
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A magnetically separable chiral catalyst, Fe3O4/tart/Mn(TCPP)Cl, was prepared by the synthesis and immobilization of manganese-tetra(4-carboxyphenyl)porphyrin, Mn(TCPP)Cl, onto the chiral surface of magnetite nanoparticles (Fe3O4/tart-NPs; tart = l-tartaric acid) through the carboxylate groups. The solid catalyst was characterized by a variety of methods including XRD, FE-SEM, FT-IR and UV-Vis spectroscopy. The catalytic activity was tested in the epoxidation reactions of prochiral olefins with molecular oxygen. The reactions were carried out in acetonitrile as solvent with molecular oxygen in the presence of isobutyraldehyde as the stoichiometric oxidant. The catalyst showed consistently high conversion, selectivity and enantioselectivity to epoxide formation in the oxidation of a variety of terminal, cyclic and aromatic olefins. The catalyst showed little deactivation with time and it is easily recovered by magnetic filtration and could be reused four times with little or no loss in activity and selectivity.
- Farokhi, Afsaneh,Hosseini-Monfared, Hassan
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p. 5032 - 5043
(2016/07/06)
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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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- Linear free-energy relationship and rate study on a silylation-based kinetic resolution: Mechanistic insights
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The substituent effect of different p-substituted triphenylsilyl chlorides on silylation-based kinetic resolutions was explored. Electron-donating groups slow down the reaction rate and improve the selectivity, while electron-withdrawing groups increase the reaction rate and decrease the selectivity. Linear free-energy relationships were found correlating both selectivity factors and initial rates to the σpara Hammett parameters. A weak correlation of selectivity factors to Charton values was also observed when just alkyl substituents were employed but was nonexistent when substituents with more electronic effects were incorporated. The rate data suggest that a significant redistribution of charge occurs in the transition state, with an overall decrease in positive charge. The linear free-energy relationship derived from selectivity factors is best understood by the Hammond postulate. Early and late transition states describe the amount of substrate participation in the transition state and therefore the difference in energy between the diastereomeric transition states of the two enantiomers. This work highlights our efforts toward understanding the mechanism and origin of selectivity in our silylation-based kinetic resolution.
- Akhani, Ravish K.,Moore, Maggie I.,Pribyl, Julia G.,Wiskur, Sheryl L.
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p. 2384 - 2396
(2014/04/17)
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- Enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complex with sodium hypochlorite as oxidant
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Chiral Mn(III)-salen complex catalyzed oxidative kinetic resolution (OKR) of secondary alcohols has been achieved with cheap and easily available sodium hypochlorite (NaClO) as oxidant. The novel protocol is very efficient for the OKR of a variety of secondary alcohols at room temperature.
- Zhang, Yuecheng,Zhou, Qiao,Ma, Wenchan,Zhao, Jiquan
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p. 114 - 117
(2014/01/06)
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- Organocatalytic oxidation of secondary alcohols using 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA)
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Diamine, 1,2-di(1-naphthyl)-1,2-ethanediamine (NEDA), efficiently catalyzes the oxidation of alcohols by using TBHP as an oxidant. Notably, secondary benzyl alcohols are oxidized in almost quantitative yields, and the catalyst also displays high activity towards even hindered cycloaliphatic secondary alcohols. With enantiopure (R,R)-NEDA, oxidative kinetic resolution can be realized and depending on the alcohol ee up to 99% are achieved.
- Al-Hunaiti, Afnan,R?is?nen, Minna,Pihko, Petri,Leskel?, Markku,Repo, Timo
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supporting information
p. 6141 - 6144
(2015/03/30)
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- Carbohydrate-based N-heterocyclic carbenes for enantioselective catalysis
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Versatile syntheses of C2-linked and C2-symmetric carbohydrate-based imidazol(in)ium salts from functionalised amino-carbohydrate derivatives are reported. The novel NHCs were ligated to [Rh(COD)Cl]2 and evaluated in Rh-catalysed asymmetric hydrosilylation of ketones with good yields and promising enantioselectivities.
- Henderson, Alexander S.,Bower, John F.,Galan, M. Carmen
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supporting information
p. 9180 - 9183
(2015/02/19)
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- Escherichia coli/ADH-A: An all-inclusive catalyst for the selective biooxidation and deracemisation of secondary alcohols
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The nicotinamide adenine dinucleotide regeneration system present in Escherichia coli cells was exploited for the oxidation and deracemisation of secondary alcohols with the overexpressed alcohol dehydrogenase from Rhodococcus ruber DSM 44541 (E. coli/ADH-A). Thus, various racemic alcohols were selectively oxidised with lyophilised or resting E. coli/ADH-A cells without need for an external cofactor or co-substrate. The addition of these substrates to the E. coli/ADH-A cells in buffer afforded the corresponding ketones and the remaining enantioenriched (R)-alcohols. This methodology was used for the desymmetrisation of a meso-diol and for the synthesis of the highly valuable raspberry ketone. Moreover, a biocatalytic concurrent process was developed with the resting cells of E. coli/ADH-A, ADH from Lactobacillus brevis, and glucose dehydrogenase for the deracemisation of various secondary alcohols, which afforded the desired enantiopure alcohols in more than 99 % ee starting from the racemic mixture. The reaction time of deracemisation of 1-phenylethanol was estimated to be less than 30 min. The stereoinversion of (S)-1-phenylethanol to its pure (R)-enantiomer was also achieved, which provided a biocatalytic alternative to the chemical Mitsunobu inversion reaction. An integrated recycling system: A nicotinamide adenine dinucleotide regeneration system present in Escherichia coli cells is exploited for the oxidation of secondary alcohols with E. coli/alcohol dehydrogenase (ADH-A). Racemic alcohols are oxidized selectively without need for an external cofactor or cosubstrate, which affords the remaining enantioenriched (R)-alcohols. Deracemization, desymmetrization, and stereoinversion processes are developed, which leads to optically pure high value-added compounds. Copyright
- Paul, Caroline E.,Lavandera, Ivan,Gotor-Fernandez, Vicente,Kroutil, Wolfgang,Gotor, Vicente
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p. 3875 - 3881
(2014/01/06)
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- Separation of enantiopure m-substituted 1-phenylethanols in high space-time yield using Bacillus subtilis esterase
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A recombinant Bacillus subtilis esterase (BsE) expressed in E. coli was found to exhibit excellent enantioselectivity (E was always greater than 100) towards m-substituted 1-phenylethanol acetates in the enantioselective hydrolysis reaction. An explanation for the high enantioselectivity observed towards these substrates was provided by molecular modeling. Moreover, the BsE also showed strong tolerance towards a high concentration of m-substituted 1-phenylethanol acetates (up to 1 M). Based on these excellent catalytic properties of BsE, a kind of m-substituted 1-phenylethanols, (R)-1-(3-chlorophenyl)ethanol, was efficiently synthesized in space-time yield of 920 g per L per day and 97% ee, indicating that the BsE was considered as a potentially ideal and promising biocatalyst for large-scale production of optically active m-substituted 1-phenylethanols. The Royal Society of Chemistry 2013.
- Zheng, Gao-Wei,Liu, Xu-Yun,Zhang, Zhi-Jun,Tian, Ping,Lin, Guo-Qiang,Xu, Jian-He
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p. 20446 - 20449
(2013/11/06)
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- Use of tridentate TsDPEN/pyridine ligands in ruthenium-catalysed asymmetric reduction of ketones
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A series of enantiomerically pure tridentate ligands based on the 1,2-diphenylethane-1,2-diamine structure, containing additional pyridine groups, was prepared and tested in asymmetric transfer hydrogenation of ketones using Ru3(CO)12 as a metal source. Alcohols were formed in up to 93% ee in the best cases, and good results were obtained with ortho-haloarylketones.
- Darwish, Moftah O.,Wallace, Alistair,Clarkson, Guy J.,Wills, Martin
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supporting information
p. 4250 - 4253
(2013/07/26)
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- β-Hydroxyamide derivatives of salicylic acid as organocatalysts for enantioselective reductions of prochiral ketones
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In order to find the most effective catalyst for the enantioselective reduction of a prochiral ketone, a series of novel β-hydroxyamide derivatives of salicylic acid and chiral amino alcohols were synthesized. Different substituted prochiral ketones have been reduced in high yield (up to 99%) and the corresponding secondary alcohols are formed with good enantiomeric excess (up to 86%). The mechanism of this type of catalyst can be explained by considering the reaction mechanism for the CBS catalyst.
- Turgut, Yilmaz,Azizoglu, Murat,Erdogan, Asli,Arslan, Nevin,Hosgoren, Halil
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p. 853 - 859
(2013/08/23)
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- HYDROGENATION OF ESTERS OR CARBONYL GROUPS WITH TETRADENTATE AMINO/IMINO-THIOETHER BASED RUTHENIUM COMPLEXES
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The present invention relates to the field of catalytic hydrogenation and, more particularly, to the use of specific ruthenium catalysts, or pre-catalysts, in hydrogenation processes for the reduction of ketones and/or aldehydes into the corresponding alcohol respectively. Said catalysts are ruthenium complexes comprising a tetradentate ligand (L4) coordinating the ruthenium with: two nitrogen atoms, each in the form of a primary or secondary amine (i.e. a NH2 or NH group) or N-alkyl imine functional groups (i.e. a C═N group), and two sulfur atoms, each in the form of thioether functional groups.
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Paragraph 0113; 0114
(2013/10/22)
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- CHIRAL SPIRO-PYRIDYLAMIDOPHOSPHINE LIGAND COMPOUND, SYNTHESIS METHOD THEREFOR AND APPLICATION THEREOF
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The present invention relates to a chiral spiro-pyridylamidophosphine ligand compound, synthesis method therefor and application thereof. The chiral spiro-pyridylamidophosphine compound is a compound having a structure of Formula (I), a racemate or optical isomer thereof, or a catalytically acceptable salt thereof, and is mainly characterized by having a chiral spiro-dihydro-indene skeleton in its structure. The chiral spiro-pyridylamidophosphine compound may be synthesized with optical active 7-diaryl/alkylphosphino-7'-amino-1,1'-spiro-dihydro-indene or substituted 7-diaryl/alkylphosphino-7'-amino-1,1'-spiro-dihydro-indene having a spiro-skeleton as chiral starting material. The chiral spiro-pyridylamidophosphine compound may be used as a chiral ligand in asymmetric hydrogenation of a carbonyl compound catalyzed by iridium, in which the reaction activity is very high, the amount of the catalyst may be 0.0001 mol%, and the enantioselectivity of the reaction is up to 99.9%ee.
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Paragraph 0059; 0060
(2013/10/08)
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- Asymmetric hydrogenation of ketones with H2 and ruthenium catalysts containing chiral tetradentate S2N2 ligands
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Getting more for less: In the presence of H2 and a base, air- and moisture-tolerant RuII complexes catalyze the hydrogenation of ketones and aldehydes with excellent activity and chemoselectivity, and with enantioselectivity of up to 95 % under mild conditions. The ratio of substrate to catalyst can be lowered to 106:1. The reactions tolerate scale-up and can be carried out with almost no solvent. A base-free method is available for base-sensitive substrates. Copyright
- Patchett, Ruth,Magpantay, Iris,Saudan, Lionel,Schotes, Christoph,Mezzetti, Antonio,Santoro, Francesco
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supporting information
p. 10352 - 10355
(2013/10/21)
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- Efficient Ru(II)-catalyzed asymmetric hydrogenation of simple ketones with C2-symmetric planar chiral metallocenyl phosphinooxazoline ligands
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C2-symmetric metallocenyl planar phosphinooxazoline ligands (2 and 3) have been applied in the Ru(II)-catalyzed asymmetric hydrogenation of simple ketones. This type of ligands enjoys the advantages of dual reaction sites as well as larger steric hindrance than their corresponding C 1-symmetric counterparts. As a result, almost quantitative conversions and excellent enantioselectivities were obtained for a series of simple ketones. Under the optimal reaction conditions, up to 99.7% ee was obtained in many cases. It was also confirmed that hydrogen rather than reaction solvent i-PrOH is at work in the hydrogenation procedure.
- Guo, Hui,Liu, Delong,Butt, Nicholas A.,Liu, Yangang,Zhang, Wanbin
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experimental part
p. 3295 - 3299
(2012/07/03)
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- Obtaining enriched compounds via a tandem enantioselective reaction and kinetic resolution polishing sequence
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Herein we describe a tandem method of coupling an enantioselective reaction with a nonenzymatic kinetic resolution to prepare highly enantioenriched compounds. The procedure employs a moderately selective enantioselective reaction on a ketone or aldehyde to form an enriched alcohol followed by a kinetic resolution of the alcohol to generate ee's of >99% in yields greater than what is possible with a kinetic resolution. This method highlights an avenue to quickly acquire highly enriched compounds without developing and optimizing a new methodology.
- Klauck, Maggie I.,Patel, Sachin G.,Wiskur, Sheryl L.
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experimental part
p. 3570 - 3575
(2012/06/15)
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- Oxidative kinetic resolution of racemic secondary alcohols in water with chiral PNNP/Ir catalyst
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Using water as solvent, the oxidative kinetic resolution of a wide range of racemic secondary alcohols with a chiral PNNP/Ir catalyst was investigated. The catalytic reaction proceeded smoothly with excellent enantioselectivity (up to 97% ee) under mild conditions, providing an environmentally benign process to achieve optically active alcohols.
- Zhang, Juanni,Yang, Xiangren,Zhou, Han,Li, Yanyun,Dong, Zhenrong,Gao, Jingxing
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supporting information; experimental part
p. 1289 - 1292
(2012/06/18)
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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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- Enantioseparation of typical pesticides using cellulose carbamate stationary phases by capillary liquid chromatography
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Cellulose-tris(3,5-dimethylphenylcarbamate) was initially synthesized as the chiral selector, then stable coated and bonded chiral stationary phases were prepared, respectively, using aminopropyl-functionalized silica gel as the support media. The prepared stationary phases were used for micro-column chiral separation by self-installed capillary high performance liquid chromatography system. Eighteen kind of chiral compounds including some typical pesticides were tested on both prepared chiral stationary phases and different chromatographic parameters such as resolution and retention time were comparatively investigated.
- Bai, Lian-Yang,Zhang, Yu-Ping,Deng, Pu-Hong,Zhang, Yi-Jun,Chen, Jun
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experimental part
p. 4917 - 4922
(2012/10/08)
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- P/S ligands derived from carbohydrates in Rh-catalyzed hydrosilylation of ketones
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Reported is the synthesis of a number of diastereomerically pure cationic Rh(i)-complexes I starting from phosphinite thioglycosides. These complexes were used in the asymmetric hydrosilylation of prochiral ketones. The reactivity and enantioselectivity o
- Khiar, Noureddine,Leal, Manuel Pernia,Navas, Raquel,Moya, Juan Francisco,Perez, Maria Victoria Garcia,Fernandez, Inmaculada
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experimental part
p. 355 - 360
(2012/02/05)
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- Enantioselective zinc-catalyzed hydrosilylation of ketones using pybox or pybim ligands
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The combination of ZnEt2 and chiral pyridinebisoxazoline (pybox) or pyridinebisimidazoline (pybim) ligands catalyzed the asymmetric hydrosilylation of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones. Under mild conditions, high yields and good enantioselectivities were achieved. ESI measurements allowed for the characterization of the active catalyst. Zincing outside of the pybox: A ZnEt2/pybox catalyst promotes the hydrosilylation of carbonyl compounds under mild conditions to afford high yields and good ee values for a broad range of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones.
- Junge, Kathrin,Moeller, Konstanze,Wendt, Bianca,Das, Shoubhik,Goerdes, Dirk,Thurow, Kerstin,Beller, Matthias
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experimental part
p. 314 - 320
(2012/04/18)
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- A new chiral sulfinyl-NH-pyridine ligand for Ir-catalyzed asymmetric transfer hydrogenation reaction
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A new flexible C1-symmetric tridentate ligand (S)-N-(2-(tert-butylsulfinyl)benzyl)-1-(pyridin-2-yl)methanamine sulfoxide (L1) was successfully prepared and utilized as a chiral ligand for Ir(I)-catalyzed ATH (asymmetric transfer hydrogenation) reactions. Without any cooperation of other chiral center, encouraging ee and conversion values have been achieved, which provide us a better understanding on these types of ligands and a new strategy to develop new high-efficiency chiral catalysts for asymmetric reaction.
- Tang, Lei,Wang, Qiwei,Wang, Juanjuan,Lin, Zechao,Wang, Xiaobei,Cun, Linfeng,Yuan, Weicheng,Zhu, Jin,Liao, Jian,Deng, Jingen
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scheme or table
p. 3839 - 3842
(2012/08/14)
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- Ruthenium complexes of phosphino-substituted ferrocenyloxazolines in the asymmetric hydrogenation and transfer hydrogenation of ketones: A comparison
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Three novel routes have been developed for the synthesis of ferrocenyl-based phosphino-oxazolines in which the phosphino unit is attached to a ferrocenylmethyl or a ferrocenylethyl side chain. In two of the routes the phosphino-substituted ethyl side chain was built up diastereoselectively. Ruthenium complexes of the type [RuCl2PPh3(L)] of 12 bidentate phosphine-oxazoline ligands were synthesized, characterized, and tested in the transfer hydrogenation of acetophenone. For the best performing complexes a total of 12 additional ketones were screened in transfer hydrogenations and hydrogenations under transfer hydrogenation conditions. Two catalyst precursors in particular delivered products with an enantiomeric excess of up to 98% in transfer hydrogenations and 99% ee in hydrogenations. The transfer hydrogenation results obtained with all novel ligands were compared to those of two well-established FOXAP ligands. Furthermore, a qualitative comparison with the hydrogenation data was carried out. In both cases surprising similarities in product enantiomeric excess and product absolute configuration were found. Attempts were made to rationalize some of the observed features by considering a transition-state model. The molecular structures of one synthesis intermediate, two catalyst precursors, and two corresponding acetonitrile complexes were studied by X-ray diffraction.
- Zirakzadeh, Afrooz,Schuecker, Raffael,Gorgas, Nikolaus,Mereiter, Kurt,Spindler, Felix,Weissensteiner, Walter
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experimental part
p. 4241 - 4250
(2012/08/08)
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- Homogeneous enantioselective catalysis in a continuous-flow microreactor: Highly enantioselective borohydride reduction of Ketones catalyzed by optically active cobalt complexes
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Highly enantioselective homogeneous catalysis under continuous-flow conditions was established for the cobalt-catalyzed borohydride reduction of tetralone derivatives. A microreactor allowed higher reaction temperature with the residence time of 12 min than the corresponding batch system to maintain enantioselectivity as well as reactivity. The present system was directly applied to gram-scale synthesis to afford the reduced product with 92% ee.
- Hayashi, Takuo,Kikuchi, Satoshi,Asano, Yukako,Endo, Yoshishige,Yamada, Tohru
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experimental part
p. 1235 - 1240
(2012/09/21)
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- Asymmetric hydrosilylation of ketones catalyzed by complexes formed from trans-diaminocyclohexane-based diamines and diethylzinc
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Chiral acyclic and macrocyclic amines derived from trans-1,2- diaminocyclohexane in complexes with diethylzinc efficiently catalyze asymmetric hydrosilylation of aryl-alkyl and aryl-aryl ketones with enantiomeric excess of the product up to 86 %. A trianglamine ligand with a cyclic structure or the presence of an additional coordinating group increases the enantioselectivity of the reaction, in comparison with catalysis by a simple acyclic N,N′-dibenzyl-1,2-diaminocyclohexane ligand. In addition, the effect of the asymmetric activation of the catalyst by a variety of alcohols and diols is studied.
- Gajewy, Jadwiga,Gawronski, Jacek,Kwit, Marcin
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experimental part
p. 1045 - 1054
(2012/09/22)
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- Application of ruthenium complexes of triazole-containing tridentate ligands to asymmetric transfer hydrogenation of ketones
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The synthesis of a series of tridentate ligands based on a homochiral 1,2-diamine structure attached to a triazole group and their subsequent applications to the asymmetric transfer hydrogenation of ketones are described. In the best cases, alcohols of up to 93% ee were obtained. Although base is not required, the use of Ru3(CO)12 as metal source is essential, indicating a unique mechanism for the formation of the active catalyst.
- Johnson, Tarn C.,Totty, William G.,Wills, Martin
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supporting information
p. 5230 - 5233,4
(2012/12/12)
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- Application of ruthenium complexes of triazole-containing tridentate ligands to asymmetric transfer hydrogenation of ketones
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The synthesis of a series of tridentate ligands based on a homochiral 1,2-diamine structure attached to a triazole group and their subsequent applications to the asymmetric transfer hydrogenation of ketones are described. In the best cases, alcohols of up to 93% ee were obtained. Although base is not required, the use of Ru3(CO)12 as metal source is essential, indicating a unique mechanism for the formation of the active catalyst.
- Johnson, Tarn C.,Totty, William G.,Wills, Martin
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supporting information
p. 5230 - 5233
(2013/01/15)
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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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- Evaluation of snake venom phospholipase A2: Hydrolysis of non-natural esters
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Phospholipase A2 from the rattlesnake Crotalus durissus terrificus was employed for the first time to test its enantioseletivity on the hydrolysis of different non-natural esters. It was observed that the structure of this small enzyme is restrictive in the choice of its lipase action with non-natural substrates. Two forms of the enzyme were used; free and as its cross-linked enzyme aggregate (CLEA). With all substrates, the free enzyme showed activity similar to the CLEA preparation. The advantage of the CLEA phospholipase is the possibility to reuse it in several consecutive reactions without a decrease of activity and selectivity with good but higher yields and ee than with the free enzyme.
- Pirolla, Renan A. S.,Baldasso, Paulo A.,Marangoni, Se?rgio,Moran, Paulo J. S.,Rodrigues, Jose? Augusto R.
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experimental part
p. 300 - 307
(2011/10/05)
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- Silylation-based kinetic resolution of monofunctional secondary alcohols
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The nucleophilic small molecule catalyst (-)-tetramisole was found to catalyze the kinetic resolution of monofunctional secondary alcohols via enantioselective silylation. Optimization of this new methodology allows for selectivity factors up to 25 utilizing commercially available reagents and mild reaction conditions.
- Sheppard, Cody I.,Taylor, Jessica L.,Wiskur, Sheryl L.
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supporting information; experimental part
p. 3794 - 3797
(2011/10/02)
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- Aerobic oxidative kinetic resolution of secondary alcohols with naphthoxide-bound iron(salan) complex
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The first general method for iron-catalyzed aerobic oxidative kinetic resolution of secondary alcohols was achieved with good to high enantiomeric differentiation (krel = 7-50). Although iron(salan) complex 1 does not catalyze alcohol oxidation, the naphthoxide-bound iron(salan) complex does.
- Kunisu, Takashi,Oguma, Takuya,Katsuki, Tsutomu
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experimental part
p. 12937 - 12939
(2011/10/02)
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- Specific photobiocatalytic oxyfunctionalization reactions
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Turn a light on: Enantiospecific hydroxylation of nonactivated C-H bonds as well as epoxidations of C=C bonds are reported using a novel peroxidase from Agrocybe aegerita (AaeAPO). AaeAPO represents a more active and more versatile alternative to the current gold standard, chloroperoxidase. H2O 2 was produced in situ by photocatalytic reduction of O2 using simple flavin adenine mononucleotide (FMN) catalysts. Copyright
- Churakova, Ekaterina,Kluge, Martin,Ullrich, Rene,Arends, Isabel,Hofrichter, Martin,Hollmann, Frank
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supporting information; experimental part
p. 10716 - 10719
(2011/12/22)
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- Practical synthesis of optically active alcohols via asymmetric transfer hydrogenation of aromatic ketones using chiral Rh(III)-monosulfonamide ligand complex in aqueous media
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A series of monosulfonamide derivatives were synthesized and tested as chiral ligands in the Ru(II),Rh(III)-catalyzed transfer hydrogenation of aromatic ketones in aqueous sodium formate and isopropanol/potassium hydroxide. Possible secondary Cp*methyl- s
- Cortez, Norma A.,Aguirre, Gerardo,Parra-Hake, Miguel,Somanathan, Ratnasamy,Arita, Amy J.,Cooksy, Andrew L.,De Parrodi, Cecilia Anaya,Huelgas, Gabriela
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experimental part
p. 73 - 84
(2011/03/19)
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