- Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
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Most ligands applied for asymmetric hydrogenation are synthesized via multistep reactions with expensive chemical reagents. Herein, a series of novel and easily accessed cinchona-alkaloid-based NNP ligands have been developed in two steps. By combining [Ir(COD)Cl]2, 39 ketones including aromatic, heteroaryl, and alkyl ketones have been hydrogenated, all affording valuable chiral alcohols with 96.0-99.9% ee. A plausible reaction mechanism was discussed by NMR, HRMS, and DFT, and an activating model involving trihydride was verified.
- Zhang, Lin,Zhang, Ling,Chen, Qian,Li, Linlin,Jiang, Jian,Sun, Hao,Zhao, Chong,Yang, Yuanyong,Li, Chun
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supporting information
p. 415 - 419
(2022/01/12)
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- Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes
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The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B2pin2) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me4NF to activate B2pin2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.
- Tran, Hai N.,Stanley, Levi M.
-
supporting information
p. 395 - 399
(2021/12/27)
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- Cobalt-catalyzed asymmetric hydrogenation of ketones: A remarkable additive effect on enantioselectivity
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A chiral cobalt pincer complex, when combined with an achiral electron-rich mono-phosphine ligand, catalyzes efficient asymmetric hydrogenation of a wide range of aryl ketones, affording chiral alcohols with high yields and moderate to excellent enantioselectivities (29 examples, up to 93% ee). Notably, the achiral mono-phosphine ligand shows a remarkable effect on the enantioselectivity of the reaction.
- Du, Tian,Wang, Biwen,Wang, Chao,Xiao, Jianliang,Tang, Weijun
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supporting information
p. 1241 - 1244
(2020/10/02)
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- A Cobalt(II) Complex Bearing the Amine(imine)diphosphine PN(H)NP Ligand for Asymmetric Transfer Hydrogenation of Ketones
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Novel chiral cobalt complex a containing amine(imine)diphosphine PN(H)NP ligand and complex b containing bis(amine)diphosphine PN(H)N(H)P ligand were synthesized. The structures of two complexes were characterized by X-ray crystallography and high resolution mass spectrometry. The catalytic performances of cobalt complexes a and b for asymmetric transfer hydrogenation (ATH) of ketones under mild conditions were evaluated using 2-propanolisopropanol as solvent and hydrogen source after being activated by 8 equivalents of base. Complex a showed a good reactivity for reduction of ketones, with a turnover number (TON) of up to 555, and a maximum enantiomeric excess (ee) value of up to 91 %. Complex b exhibited inertness for hydrogenation of ketones. Electronic structure studies on a and b were conducted to account for the function of ligands on the catalytic performances.
- Huo, Shangfei,Chen, Hong,Zuo, Weiwei
-
supporting information
p. 37 - 42
(2020/10/21)
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- Manganese catalyzed asymmetric transfer hydrogenation of ketones
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The asymmetric transfer hydrogenation (ATH) of a wide range of ketones catalyzed by manganese complex as well as chiral PxNy-type ligand under mild conditions was investigated. Using 2-propanol as hydrogen source, various ketones could be enantioselectively hydrogenated by combining cheap, readily available [MnBr(CO)5] with chiral, 22-membered macrocyclic ligand (R,R,R',R')-CyP2N4 (L5) with 2 mol% of catalyst loading, affording highly valuable chiral alcohols with up to 95% ee.
- Zhang, Guang-Ya,Ruan, Sun-Hong,Li, Yan-Yun,Gao, Jing-Xing
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supporting information
p. 1415 - 1418
(2020/11/20)
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- Mn(i) phosphine-amino-phosphinites: a highly modular class of pincer complexes for enantioselective transfer hydrogenation of aryl-alkyl ketones
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A series of Mn(i) catalysts with readily accessible and more π-accepting phosphine-amino-phosphinite (P′(O)N(H)P) pincer ligands have been explored for the asymmetric transfer hydrogenation of aryl-alkyl ketones which led to good to high enantioselectivities (up to 98%) compared to other reported Mn-based catalysts for such reactions. The easy tunability of the chiral backbone and the phosphine moieties makes P′(O)N(H)P an alternative ligand framework to the well-known PNP-type pincers.
- Jayaprakash, Harikrishnan
-
supporting information
p. 14115 - 14119
(2021/10/25)
-
- Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
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Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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p. 7652 - 7666
(2021/12/13)
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- Arene-Immobilized Ru(II)/TsDPEN Complexes: Synthesis and Applications to the Asymmetric Transfer Hydrogenation of Ketones
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The Noyori-Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAVISIL through the η6-coordinated arene ligand via a straightforward synthesis and the derived systems, (arene)Ru(II)/TsDPEN@silica and (arene)Ru(II)/TsDPEN@DAVISIL, form highly efficient catalysts for the asymmetric transfer hydrogenation of a range of electron-rich and electron-poor aromatic ketones, giving good conversion and excellent ee's under mild reaction conditions. Moreover, catalyst generated in situ immediately prior to addition of substrate and hydrogen donor, by reaction of silica-supported [(arene)RuCl2]2 with (S,S)-TsDPEN, was as efficient as that generated from its preformed counterpart [(arene)Ru{(S,S)-TsDPEN}Cl]@silica. Gratifyingly, the initial TOFs (up to 1085 h?1) and ee's (96–97 %) obtained with these catalysts either rivalled or outperformed those previously reported for catalysts supported by either silica or polymer immobilized through one of the nitrogen atoms of TsDPEN. While the high ee's were also maintained during recycle studies, the conversion dropped steadily over the first three runs due to gradual leaching of the ruthenium.
- Doherty, Simon,Knight, Julian G.,Alshaikh, Hind,Wilson, James,Waddell, Paul G.,Wills, Corinne,Dixon, Casey M.
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supporting information
p. 226 - 235
(2020/12/31)
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- Tridentate nitrogen phosphine ligand containing arylamine NH as well as preparation method and application thereof
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The invention discloses a tridentate nitrogen phosphine ligand containing arylamine NH as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. The tridentate nitrogen phosphine ligand disclosed by the invention is the first case of tridentate nitrogen phosphine ligand containing not only a quinoline amine structure but also chiral ferrocene at present, a noble metal complex of the type of ligand shows good selectivity and extremely high catalytic activity in an asymmetric hydrogenation reaction, meanwhile, a cheap metal complex of the ligand can also show good selectivity and catalytic activity in the asymmetric hydrogenation reaction, and is very easy to modify in the aspects of electronic effect and space structure, so that the ligand has huge potential application value. A catalyst formed by the ligand and a transition metal complex can be used for catalyzing various reactions, can be used for synthesizing various drugs, and has important industrial application value.
- -
-
Paragraph 0095-0102; 0105-0109
(2021/06/26)
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- Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
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Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
-
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- Boron containing chiral Schiff bases: Synthesis and catalytic activity in asymmetric transfer hydrogenation (ATH) of ketones
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Asymmetric Transfer Hydrogenation (ATH) has been an attractive way for the reduction of ketones to chiral alcohols. A great number of novel and valuable synthetic pathways have been achived by the combination usage of organometallic and coordination chemistry for the production of important class of compounds and particularly optically active molecules. For this aim, four boron containing Schiff bases were synthesized by the reaction of 4-formylphenylboronic acid with chiral amines. The boron containing structures have been found as stable compounds due to the presence of covalent B–O bonds and thus could be handled in laboratory environment. They were characterized by 1H NMR and FT-IR spectroscopy and elemental analysis and they were used as catalyst in the transfer hydrogenation of ketones to the related alcohol derivatives with high conversions (up to 99%) and low enantioselectivities (up to 22% ee).
- Pa?a, Salih,Arslan, Nevin,Meri??, Nermin,Kayan, Cezmi,Bingül, Murat,Durap, Feyyaz,Aydemir, Murat
-
-
- Asymmetric Hydrogenation of Ketones and Enones with Chiral Lewis Base Derived Frustrated Lewis Pairs
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The concept of frustrated Lewis pairs (FLPs) has been widely applied in various research areas, and metal-free hydrogenation undoubtedly belongs to the most significant and successful ones. In the past decade, great efforts have been devoted to the synthesis of chiral boron Lewis acids. In a sharp contrast, chiral Lewis base derived FLPs have rarely been disclosed for the asymmetric hydrogenation. In this work, a novel type of chiral FLP was developed by simple combination of chiral oxazoline Lewis bases with achiral boron Lewis acids, thus providing a promising new direction for the development of chiral FLPs in the future. These chiral FLPs proved to be highly effective for the asymmetric hydrogenation of ketones, enones, and chromones, giving the corresponding products in high yields with up to 95 % ee. Mechanistic studies suggest that the hydrogen transfer to simple ketones likely proceeds in a concerted manner.
- Du, Haifeng,Feng, Xiangqing,Gao, Bochao,Meng, Wei
-
supporting information
p. 4498 - 4504
(2020/02/05)
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- Cationic NHC-Phosphine Iridium Complexes: Highly Active Catalysts for Base-Free Hydrogenation of Ketones
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Novel bidentate N-heterocyclic carbene-phosphine iridium complexes have been synthesized and evaluated in the hydrogenation of ketones. Reported catalytic systems require base additives and, if excluded, need elevated temperature or high pressure of hydrogen gas to achieve satisfactory reactivity. The developed catalysts showed extremely high reactivity and good enantioselectivity under base-free and mild conditions. In the presence of 1 mol % catalyst under 1 bar hydrogen pressure at room temperature, hydrogenation was complete in 30 minutes giving up to 96 % ee. Again, this high reactivity was achieved in additive-free conditions. Mechanistic experiments demonstrated that balloon pressure of hydrogen was sufficient to form the activate species by reducing and eliminating the 1,5-cyclooctadiene ligand. The pre-activated catalyst was able to hydrogenate acetophenone with 89 % conversion in 5 min.
- Quan, Xu,Kerdphon, Sutthichat,Peters, Bram B. C.,Rujirawanich, Janjira,Krajangsri, Suppachai,Jongcharoenkamol, Jira,Andersson, Pher G.
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supporting information
p. 13311 - 13316
(2020/09/22)
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- ANTICANCER COMBINATION THERAPY
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The invention describes anti-cancer therapies comprising using a SOS1 inhibitor in combination with a MEK inhibitor, each as described herein.
- -
-
Page/Page column 155
(2021/01/22)
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- RETRACTED ARTICLE: The Manganese(I)-Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege
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The bis(carbonyl) manganese(I) complex [Mn(CO)2(1)]Br (2) with a chiral (NH)2P2 macrocyclic ligand (1) catalyzes the asymmetric transfer hydrogenation of polar double bonds with 2-propanol as the hydrogen source. Ketones (43 substrates) are reduced to alcohols in high yields (up to >99 %) and with excellent enantioselectivities (90–99 % ee). A stereochemical model based on attractive CH–π interactions is proposed.
- Passera, Alessandro,Mezzetti, Antonio
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supporting information
p. 187 - 191
(2019/12/11)
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- An iron variant of the Noyori hydrogenation catalyst for the asymmetric transfer hydrogenation of ketones
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We report the design of a new iron catalyst for the asymmetric transfer hydrogenation of ketones. This type of iron catalyst combines the structural characteristics of the Noyori hydrogenation catalyst (an axially chiral 2,2′-bis(phosphino)-1,1′-binaphthyl fragment and the metal-ligand bifunctional motif) and an ene(amido) group that can activate the iron center. After activation by 8 equivalents of potassiumtert-butoxide, (SA,RP,SS)-7aand (SA,RP,SS)-7bare active but nonenantioselective catalysts for the transfer hydrogenation of acetophenone and α,β-unsaturated aldehydes at room temperature in isopropanol. A maximum turnover number of 14480 was observed for (SA,RP,SS)-7ain the reduction of acetophenone. The right combination of the stereochemistry of the axially chiral 2,2′-bis(phosphino)-1,1′-binaphthyl group and the carbon-centered chiral amine-imine moiety in (SA,RP,RR)-7b′afforded an enantioselective catalyst for the preparation of chiral alcohols with moderate to good yields and a broad functional group tolerance.
- Huo, Shangfei,Wang, Qingwei,Zuo, Weiwei
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supporting information
p. 7959 - 7967
(2020/06/26)
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- Highly Enantioselective Transfer Hydrogenation of Prochiral Ketones Using Ru(II)-Chitosan Catalyst in Aqueous Media
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Unprecedentedly high enantioselectivities are obtained in the transfer hydrogenation of prochiral ketones catalyzed by a Ru complex formed in situ with chitosan chiral ligand. This biocompatible, biodegradable chiral polymer obtained from the natural chitin afforded good, up to 86 % enantioselectivities, in the aqueous-phase transfer hydrogenation of acetophenone derivatives using HCOONa as hydrogen donor. Cyclic ketones were transformed in even higher, over 90 %, enantioselectivities, whereas further increase, up to 97 %, was obtained in the transfer hydrogenations of heterocyclic ketones. The chiral catalyst precursor prepared ex situ was examined by scanning electron microscopy, FT-mid- and -far-IR spectroscopy. The structure of the in situ formed catalyst was investigated by 1H NMR spectroscopy and using various chitosan derivatives. It was shown that a Ru pre-catalyst is formed by coordination of the biopolymer to the metal by amino groups. This precursor is transformed in water insoluble Ru-hydride complex following hydrogen donor addition. The practical value of the developed method was verified by preparing over twenty chiral alcohols in good yields and optical purities. The catalyst was applied for obtaining optically pure chiral alcohols at gram scale following a single crystallization.
- Sz?ll?si, Gy?rgy,Kolcsár, Vanessza Judit
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p. 820 - 830
(2018/12/13)
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- Catalysts for the asymmetric transfer hydrogenation of various ketones from [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] and [Ru(η6-arene)(μ-Cl)Cl]2, Ir(η5-C5Me5)(μ-Cl)Cl]2 or [Rh(μ-Cl)(cod)]2
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The combination of [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] with [Ru(η6-arene)(μ-Cl)Cl]2, Ir(η5-C5Me5)(μ-Cl)Cl]2 or [Rh(μ-Cl)(cod)]2, in the presence of KOH/isoPrOH, has been found to generate catalysts that are capable of enantioselectively reducing alkyl, aryl ketones to the corresponding (R)-alcohols. Under optimized conditions, when the catalysts were applied to the asymmetric transfer hydrogenation, we obtained the secondary alcohol products in high conversions and enantioselectivities using only 0.5 mol% catalyst loading. In addition, [3-[(2S)-2-{[(chloro(?4-1,5-cyclooctadiene)rhodium)diphenyl phosphanyl] oxy}-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride], (6) complex is much more active than the other analogous complexes in the transfer hydrogenation. Catalyst 6 acts as excellent catalysts, giving the corresponding (R)-1-phenyl ethanol in 99% conversion in 30 min (TOF ≤ 396 h?1) and in high enantioselectivity (92% ee).
- Meri?, Nermin,Arslan, Nevin,Kayan, Cezmi,Rafikova, Khadichakhan,Zazybin, Alexey,Kerimkulova, Aygul,Aydemir, Murat
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p. 108 - 118
(2019/04/17)
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- NOVEL BENZYLAMINO SUBSTITUTED PYRIDOPYRIMIDINONES AND DERIVATIVES AS SOS1 INHIBITORS
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The present invention encompasses compounds of formula (I) wherein the groups R1 to R4, A and p have the meanings given in the claims and specification, their use as inhibitors of SOS1, pharmaceutical compositions which contain compounds of this kind and their use as medicaments/medical uses, especially as agents for treatment and/or prevention of oncological diseases.
- -
-
Paragraph 0868
(2019/07/10)
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- Iridium and Rhodium Complexes Containing Enantiopure Primary Amine-Tethered N-Heterocyclic Carbenes: Synthesis, Characterization, Reactivity, and Catalytic Asymmetric Hydrogenation of Ketones
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The imidazolium salt [(S,S)-tBuNC3H3NCHPhCHPhNH2]PF6, (S,S)-11·HPF6 is a precursor to the enantiopure "Kaibene" ligand, tBu-Kaibene, (S,S)-11 featuring a tert-butyl group on the N-heterocyclic carbene (NHC) ring-nitrogen atoms. It has been prepared in high yield and purity by refluxing a chiral cyclic sulfamidate with 1-tert-butylimidazole. Similarly (S,S)-12·HPF6 with a mesityl group at the imidazolium ring-nitrogen atom has been prepared in the same fashion and serves as a source of Mes-Kaibene, (S,S)-12. These bidentate Kaibene ligands feature an NHC and a primary amine separated by a chiral linker. Salts (S,S)-11·HPF6 or (S,S)-12·HPF6 react with base and AgI or CuI to give a total of four M(Kaibene)2I compounds (M = Ag or Cu). At 22 °C, the amine-functionalized imidazolium cations undergo oxidative addition to iridium(I) in [IrCl(cod)]2 (cod = 1,5-cyclooctadiene) to generate iridium(III) hydride R-Kaibene compounds [IrHCl(cod)((S,S)-11)](PF6) (17) and [IrHCl(cod)((S,S)-12)](PF6) (18), respectively, each as a mixture of six configurational isomers. In contrast, the salt (S,S)-11·HPF6 reacts with [Ir(OtBu)(cod)]2 to produce a bimetallic iridium compound with (S,S)-11 as the bridging ligand. This compound contains interesting NH···Cl and NH···Ir noncovalent intramolecular interactions. Salt (S,S)-12·HPF6 reacts with silver oxide to yield [Ag2((S,S)-12)2](PF6)2 (20). Reagent 20 serves as an efficient transmetalation reagent to deliver to each rhodium in [RhCl(cod)]2 1 equiv of (S,S)-12 as a bidentate ligand to give [Rh(cod)((S,S)-12)](PF6). In the reaction between [IrCl(cod)]2 and 20, (S,S)-12 ends up coordinated in an iridium(III) hydride complex (22) as a tridentate ligand via the NHC, NH2, and a cyclometalated phenyl group. The two iridium hydride compounds, 18 and 22, are catalysts for the hydrogenation of a range of ketones (turnover number up to 499, turnover frequency up to 249 h-1, with er (enantiomeric ratio) up to 35:65 R:S).
- Wan, Kai Y.,Roelfes, Florian,Lough, Alan J.,Hahn, F. Ekkehardt,Morris, Robert H.
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supporting information
p. 491 - 504
(2018/02/17)
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- A new class of well-defined ruthenium catalysts for enantioselective transfer hydrogenation of various ketones
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A pair of novel optically pure phosphinite ligands were synthesized by ring opening reaction of chiral amines with (R)-styrene oxide or (S)-glycidyl phenyl ether oxide using a straightforward method in high yields and their ruthenium complexes were described in detail. The ruthenium complexes proved to be highly efficient catalysts for the enantioselective hydrogenation of ketones, affording products up to 99% ee. The results showed that the corresponding chiral alcohols could be obtained with high activity and excellent enantioselectivities at the desired temperature. (2S)-1-{benzyl[(1S)-1-(naphthalen-1-yl)ethyl]amino}-3-phenoxypropan-2-yl diphenylphosphinito[dichloro(η6-benzene)ruthenium (II)] acts an excellent catalyst in the reduction of ketones, giving the corresponding alcohol up to 99% ee.
- Kayan, Cezmi,Meri?, Nermin,Rafikova, Khadichakhan,Zazybin, Alexey,Gürbüz, Nevin,Karakaplan, Mehmet,Aydemir, Murat
-
-
- A comparative study on asymmetric reduction of ketones using the growing and resting cells of marine-derived fungi
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Whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to optically active alcohols. Currently, most of the whole-cell catalytic performance involves resting cells rather than growing cell biotransformation, which is one-step process that benefits from the simultaneous growth and biotransformation, eliminating the need for catalysts preparation. In this paper, asymmetric reduction of 14 aromatic ketones to the corresponding enantiomerically pure alcohols was successfully conducted using the growing and resting cells of marine-derived fungi under optimized conditions. Good yields and excellent enantioselectivities were achieved with both methods. Although substrate inhibition might be a limiting factor for growing cell biotransformation, the selected strain can still completely convert 10-mM substrates into the desired products. The resting cell biotransformation showed a capacity to be recycled nine times without a significant decrease in the activity. This is the first study to perform asymmetric reduction of ketones by one-step growing cell biotransformation.
- Liu, Hui,Chen, Bi-Shuang,Ribeiro de Souza, Fayene Zeferino,Liu, Lan
-
-
- Easy Access to Enantiopure (S)- and (R)-Aryl Alkyl Alcohols by a Combination of Gold(III)-Catalyzed Alkyne Hydration and Enzymatic Reduction
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Chemoenzymatic one-pot processes based on the combination of metal catalysis and biocatalysis open up highly attractive perspectives regarding the production of enantiopure compounds. By combining a gold-catalyzed hydration reaction with an enzymatic reduction, we present a straightforward and atom-economical chemoenzymatic method for the synthesis of secondary alcohols with excellent optical purity. Efficient cofactor recycling exploits the solvent of the metal-catalyzed step as an auxiliary substrate for the enzymatic step.
- Schaaf, Patricia,Gojic, Vladimir,Bayer, Thomas,Rudroff, Florian,Schnürch, Michael,Mihovilovic, Marko D.
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p. 920 - 924
(2018/02/23)
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- NHTs Effect on the Enantioselectivity of Ru(II) Complex Catalysts Bearing a Chiral Bis(NHTs)-Substituted Imidazolyl-Oxazolinyl-Pyridine Ligand for Asymmetric Transfer Hydrogenation of Ketones
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Pincer-type ruthenium(II)-NNN complex catalysts bearing a chiral bis(NHTs)-substituted imidazolyl-oxazolinyl-pyridine ligand were synthesized and structurally characterized by NMR, IR, elemental analysis, and X-ray single-crystal crystallographic determinations. The two NHTs groups substituted on the imidazolyl moiety of the chiral NNN ligand exhibited a remarkable effect on the enantioselectivity of the Ru(II)-NNN complexes for the asymmetric transfer hydrogenation (ATH) of ketones. The Ru(II)-NNN complex bearing a chiral (NHTs)2-substituted imidazolyl-(isopropyl)oxazolinyl-pyridine ligand exhibited excellent catalytic activity, reaching an enantioselectivity up to 99.9% ee for the target alcohol products.
- Chai, Huining,Liu, Tingting,Yu, Zhengkun
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p. 4136 - 4144
(2017/11/21)
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- New functional chiral P-based ligands and application in ruthenium-catalyzed enantioselective transfer hydrogenation of ketones
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Metal-catalyzed asymmetric transfer hydrogenation is a powerful and practical method for the reduction of ketones to produce the corresponding secondary alcohols, which are valuable building blocks in the pharmaceutical, perfume, and agrochemical industries. Hence, a series of novel chiral β-amino alcohols were synthesized by chiral amines with regioselective ring opening of (S)-propylene oxide or reaction with (S)-(+)-2-hydroxypropyl p-toluenesulfonate by a straightforward method. The chiral ruthenium catalytic systems generated from [Ru(arene)(μ-Cl)Cl]2 complexes and chiral phosphinite ligands based on amino alcohol derivatives were employed in asymmetric transfer hydrogenation of ketones to give the corresponding optically active alcohols; (2S)-1-{[(2S)-2-[(diphenylphosphanyl)oxy]propyl][(1R)-1-phenylethyl]amino}propan-2-yldiphenylphosphinitobis[dichol-oro(η6-benzene)ruthenium(II)] acts an excellent catalyst in the reduction of α-naphthyl methyl ketone, giving the corresponding alcohol with up to 99% ee. The substituents on the backbone of the ligands were found to have a remarkable effect on both the conversion and enantioselectivity of the catalysts. Furthermore, this transfer hydrogenation is characterized by low reversibility under these conditions.
- Meri?, Nermin,Kayan, Cezmi,Gürbüz, Nevin,Karakaplan, Mehmet,Binbay, Nil Ertekin,Aydemir, Murat
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p. 1739 - 1749
(2017/10/26)
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- Chirality dihydrogen silane compound and synthetic method and application thereof
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The invention discloses a chirality dihydrogen silane compound. The chirality dihydrogen silane compound is as shown in the formula IV. In the formula IV, X represents a chiral carbon atom. The invention further discloses a synthetic method for the chirality dihydrogen silane compound. The method comprises the following steps: using olefin shown in the formula I and silane shown in the formula II as raw materials, and using a chiral CoX2-OIP complex compound as a catalyst, in the existence of a reducing agent, reacting to obtain the chirality dihydrogen silane compound shown in the formula IV. The synthetic method is suitable for different types of the olefins, the reaction condition is moderate, the operation is simple and convenient, and the atomic economy is high. The reaction does not need to be added with any other toxic transition metal ions, the reaction yield is better and is 53%-97% generally, and the enantio-selectivity is higher and is 81%-99% and gt generally. The provided chirality dihydrogen silane compound shown in the formula IV can be used for synthesizing a chiral alcohol compound, a chiral silicon alcohol compound, a chiral polysubstituted silane compound and so on.
- -
-
Paragraph 0208; 0209; 0210; 0211; 0212; 0213; 0214
(2017/10/22)
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- Third-Generation Amino Acid Furanoside-Based Ligands from d-Mannose for the Asymmetric Transfer Hydrogenation of Ketones: Catalysts with an Exceptionally Wide Substrate Scope
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A modular ligand library of α-amino acid hydroxyamides and thioamides was prepared from 10 different N-tert-butyloxycarbonyl-protected α-amino acids and three different amino alcohols derived from 2,3-O-isopropylidene-α-d-mannofuranoside. The ligand library was evaluated in the half-sandwich ruthenium- and rhodium-catalyzed asymmetric transfer hydrogenation of a wide array of ketone substrates, including simple as well as sterically demanding aryl alkyl ketones, aryl fluoroalkyl ketones, heteroaromatic alkyl ketones, aliphatic, conjugated and propargylic ketones. Under the optimized reaction conditions, secondary alcohols were obtained in high yields and in enantioselectivities up to >99%. The choice of ligand/catalyst allowed for the generation of both enantiomers of the secondary alcohols, where the ruthenium-hydroxyamide and the rhodium-thioamide catalysts act complementarily towards each other. The catalytic systems were also evaluated in the tandem isomerization/asymmetric transfer hydrogenation of racemic allylic alcohols to yield enantiomerically enriched saturated secondary alcohols in up to 98% ee. Furthermore, the catalytic tandem α-alkylation/asymmetric transfer hydrogenation of acetophenones and 3-acetylpyridine with primary alcohols as alkylating and reducing agents was studied. Secondary alcohols containing an elongated alkyl chain were obtained in up to 92% ee. (Figure presented.).
- Margalef, Jèssica,Slagbrand, Tove,Tinnis, Fredrik,Adolfsson, Hans,Diéguez, Montserrat,Pàmies, Oscar
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p. 4006 - 4018
(2016/12/30)
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- Enzymatic reduction of acetophenone derivatives with a benzil reductase from Pichia glucozyma (KRED1-Pglu): electronic and steric effects on activity and enantioselectivity
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A recombinant ketoreductase from Pichia glucozyma (KRED1-Pglu) was used for the enantioselective reduction of various mono-substituted acetophenones. Reaction rates of meta- and para-derivatives were consistent with the electronic effects described by σ-Hammett coefficients; on the other hand, enantioselectivity was determined by an opposite orientation of the substrate in the binding pocket. Reduction of ortho-derivatives occurred only with substrates bearing substituents with low steric impact (i.e., F and CN). Reactivity was controlled by stereoelectronic features (C=O length and charge, shape of LUMO frontier molecular orbitals), which can be theoretically calculated.
- Contente, Martina L.,Serra, Immacolata,Palazzolo, Luca,Parravicini, Chiara,Gianazza, Elisabetta,Eberini, Ivano,Pinto, Andrea,Guidi, Benedetta,Molinari, Francesco,Romano, Diego
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supporting information
p. 3404 - 3408
(2016/04/09)
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- Highly Enantioselective Transfer Hydrogenation of Polar Double Bonds by Macrocyclic Iron(II)/(NH)2P2 Catalysts
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We describe herein a new protocol for the synthesis of 2,2′-((1S,1′S)-ethane-1,2-diylbis(phenylphosphanediyl))dibenzaldehyde ((SP,SP)-5), which is the key intermediate in the synthesis of macrocyclic iron(II)/(NH)2P2 catalysts for the highly enantioselective transfer hydrogenation of polar double bonds. The dialdehyde (SP,SP)-5 was obtained as a single diastereoisomer and enantiomer from an optically pure H-phosphinate in 33% yield over five steps. It was further converted to afford multigram quantities of the macrocyclic iron(II)/(NH)2P2 complexes, which were tested in the asymmetric transfer hydrogenation of aryl alkyl ketones and imines in 2-propanol on a 100 mmol scale. Ten substrates, including challenging ones such as tert-butyl phenyl ketone and industrially relevant molecules such as 3,5-bis(trifluoromethyl)acetophenone, were reduced in high yield (89.0-99.7%), excellent enantioselectivity (95.8-99.4% ee), and with low catalyst loadings (S/C up to 10 000/1).
- Bigler, Raphael,Mezzetti, Antonio
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supporting information
p. 253 - 261
(2016/03/04)
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- Iminophenyl Oxazolinylphenylamine for Enantioselective Cobalt-Catalyzed Hydrosilylation of Aryl Ketones
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A new family of chiral iminophenyl oxazolinylphenylamines (IPOPA) was designed and synthesized through three steps from commercially available starting materials. An efficient cobalt-catalyzed asymmetric hydrosilylation of simple ketones with a low catalyst loading of CoCl2 and IPOPA was developed to afford chiral alcohols in good yields with high enantioselectivities.
- Chen, Xu,Lu, Zhan
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supporting information
p. 4658 - 4661
(2016/09/28)
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- I86A/C295A mutant secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus has broadened substrate specificity for aryl ketones
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Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase (SADH) reduces aliphatic ketones according to Prelog's Rule, with binding pockets for small and large substituents. It was shown previously that the I86A mutant SADH reduces acetophenone, which is not a substrate of wild-type SADH, to give the anti-Prelog R-product (Musa, M. M.; Lott, N.; Laivenieks, M.; Watanabe, L.; Vieille, C.; Phillips, R. S. ChemCatChem 2009, 1, 89–93.). However, I86A SADH did not reduce aryl ketones with substituents larger than fluorine. We have now expanded the small pocket of the active site of I86A SADH by mutation of Cys-295 to alanine to allow reaction of substituted acetophenones. As predicted, the double mutant I86A/C295A SADH has broadened substrate specificity for meta-substituted, but not para-substituted, acetophenones. However, the increase of the substrate specificity of I86A/C295A SADH is accompanied by a decrease in the kcat/Km values of acetophenones, possibly due to the substrates fitting loosely inside the more open active site. Nevertheless, I86A/C295A SADH gives high conversions and very high enantiomeric excess of the anti-Prelog R-alcohols from the tested substrates.
- Nealon, Christopher M.,Welsh, Travis P.,Kim, Chang Sup,Phillips, Robert S.
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p. 151 - 156
(2016/08/15)
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- Iron(II)/(NH)2P2 Macrocycles: Modular, Highly Enantioselective Transfer Hydrogenation Catalysts
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A generalized protocol for the synthesis of chiral (NH)2P2 macrocycles allows changing the linker between the phosphines and gives access to a family of such ligands, as demonstrated for the propane-1,3-diyl analogue. The corresponding complexes based on earth-abundant and nontoxic iron were applied as catalysts in the asymmetric transfer hydrogenation of polar double bonds. Thanks to the ligand modularity and to the use of tunable isonitriles as ancillary ligands, the catalyst system can be individually optimized for each substrate to give high enantioselectivity (up to 99.9% conversion and 99.6% ee, TOF up to >3950 h-1) for a broad scope of 26 substrates.
- Bigler, Raphael,Huber, Raffael,St?ckli, Marco,Mezzetti, Antonio
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p. 6455 - 6464
(2016/10/18)
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- METHOD FOR PREPARING CHIRAL ALCOHOLS FROM RACEMIC OR MESO ALCOHOLS
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Disclosed is a method for producing a chiral alcohol compound. According to the present invention, a stereoselective reaction between a racemic alcohol compound or a mesoalcohol compound and a silylation agent can be performed in the presence of a chiral catalyst compound to produce a chiral alcohol compound. In this case, a compound obtained by derivatizing oligo ethylene glycol including a hydroxy functional group of a binol derivative, which is an acid portion, and an oligo ethylene glycol functional group, which is an alkali portion, can be used as the chrial catalyst compound.COPYRIGHT KIPO 2016
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Paragraph 0189-0190
(2016/10/10)
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- METHOD FOR PREPARING CHIRAL ALCOHOLS FROM RACEMIC OR MESO ALCOHOLS
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A method for manufacturing a chiral alcohol compound is disclosed. A racemic alcohol compound or a meso alcohol compound and a silylation agent in the presence of a chiral catalyst compound can be reacted in a stereoselective manner to manufacture the chiral alcohol compound. In this case, a compound derivatized with an oligoethylene glycol including an oligoethylene glycol functional group as a base part and a hydroxy functional group of a binol derivative as an acid part can be used as the chiral catalyst compound.COPYRIGHT KIPO 2016
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Paragraph 0189; 0190; 0191; 0438
(2016/10/10)
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- Chiral terpene auxiliaries III: Spiroborate esters from (1R,2S,3R,5R)-3-amino-apopinan-2-ol as highly effective catalysts for asymmetric reduction of ketones with borane
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New spiroborate esters, derived from terpene amino alcohols, (S)-prolinol, and 2-aminoethanol, were employed as catalysts in the borane reduction of acetophenone and other aryl alkyl and halogenated ketones. The corresponding alcohols were obtained in high yields and with enantioselectivities up to 98% ee. The influence of the amino alcohol and the diol moieties of spiroborate on the reaction selectivity was examined. The catalyst load, the nature of the solvent, the borane source, and the reaction conditions were also investigated.
- ?wiklińska, Marta,Krzemiński, Marek P.,Tafelska-Kaczmarek, Agnieszka
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p. 1453 - 1458
(2015/12/09)
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- Alternative Hydrogen Source for Asymmetric Transfer Hydrogenation in the Reduction of Ketones
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cis-1,4-Butenediol is shown to be a highly active hydrogen source for asymmetric transfer hydrogenation in the reduction of ketones. With the use of a ruthenium catalyst, cis-1,4-butenediol is isomerised and subsequently oxidised to a lactone as an irreversible step, which provides the driving force for the asymmetric reduction of ketones.
- Wakeham, Russell J.,Morris, James A.,Williams, Jonathan M. J.
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p. 4039 - 4041
(2015/12/26)
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- Cobalt-catalyzed asymmetric hydroboration of aryl ketones with pinacolborane
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The highly enantioselective cobalt-catalyzed hydroboration reaction of aryl ketones with HBpin was developed using iminopyridine oxazoline ligands. Halides, amines, ethers, sulfides, esters and amides are well tolerated under the mild reaction conditions, demonstrating its synthetic advantage. Substituted diaryl ketones could also be hydroborated with high enantioselectivity.
- Guo, Jun,Chen, Jianhui,Lu, Zhan
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supporting information
p. 5725 - 5727
(2015/03/30)
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- Screening of a library of hemisalen ligands in asymmetric H-transfer: Reduction of aromatic ketones in water
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A library of chiral hemisalen ligands (30) was realized. The ligands were synthesized by the condensation of salicylaldehyde derivatives with amino-alcohols (amino-indanol or substituted amino-ethanol) and characterized. These ligands associated with ruthenium (II) precursors were tested on the asymmetric transfer hydrogenation (ATH) of aromatic ketones by sodium formate in water. The different substituent pattern on the ligand (electronic and hindrance effects on different positions) as well as the ruthenium precursor were investigated. The best compromise in terms of conversion and chiral induction led to the complex [RuCl2(mesitylene)]2 coordinated to (1S,2R)-1-((E)-(3-(dimethyl(phenyl)silyl)-2-hydroxy-5-methoxy benzylidene) amino)-2,3-dihydro-1H-inden-2-ol (L25). It reduces acetophenone in 95% yield and 91% ee in 18 h at 30°C.
- Boukachabia, Mourad,Vriamont, Nicolas,Lambin, Dominique,Riant, Olivier,Aribi-Zouioueche, Louisa
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p. 403 - 412
(2014/05/06)
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- Stereochemistry and mechanism of enzymatic and non-enzymatic hydrolysis of benzylic sec-sulfate esters
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The substrate scope of inverting alkylsulfatase Pisa1 was extended towards benzylic sec-sulfate esters by suppression of competing non-enzymatic autohydrolysis by addition of dimethyl sulfoxide as co-solvent. Detailed investigation of the mechanism of autohydrolysis in 18O-labeled buffer by using an enantiopure sec-benzylic sulfate ester as substrate revealed that from the three possible pathways (i) inverting SN2-type nucleophilic attack of [OH-] at the benzylic carbon represents the major pathway, whereas (ii) SN1-type formation of a planar benzylic carbenium ion leading to racemization was a minor event, and (iii) Retaining SN2-type nucleophilic attack at sulfur took place at the limits of detection. The data obtained are interpreted by analysis of Hammett constants of meta substituents. The enzymatic hydrolysis of benzylic sec-sulfate esters by alkylsulfatase Pisa1 proceeded with clean inversion of configuration and with excellent stereoselectivities when the competing non-enzymatic hydrolysis was suppressed by addition of dimethyl sulfoxide as co-solvent. Copyright
- Toesch, Michael,Schober, Markus,Breinbauer, Rolf,Faber, Kurt
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supporting information
p. 3930 - 3934
(2014/06/24)
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- Modular hydroxyamide and thioamide pyranoside-based ligand library from the sugar pool: New class of ligands for asymmetric transfer hydrogenation of ketones
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A large library of pyranoside-based hydroxyamide and thioamide ligands has been synthesized for asymmetric transfer hydrogenation in an attempt to expand the scope of the substrates to cover a broader range of challenging heteroaromatic and aryl/fluoroalkyl ketones. These ligands have the advantage that they are prepared from commercial D-glucose, D-glucosamine and α-amino acids, inexpensive natural chiral feedstocks. By carefully selecting the ligand components (substituents/configurations at the amide/thioamide moiety, the position of amide/thioamide group and the configuration at C-2), we found that pyranoside-based thioamide ligands provided excellent enantioselectivities (in the best cases, ees of >99% were achieved) in a broad range of ketones, including the less studied heteroaromatics and challenging aryl/fluoroalkyls. Note that both enantiomers of the reduction products can be obtained with excellent enantioselectivities by simply changing the absolute configuration of the thioamide substituent.
- Coll, Mercè,Pàmies, Oscar,Diéguez, Montserrat
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p. 2293 - 2302
(2014/07/21)
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- Iron catalyzed asymmetric hydrogenation of ketones
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Chiral molecules, such as alcohols, are vital for the manufacturing of fine chemicals, pharmaceuticals, agrochemicals, fragrances, and novel materials. These molecules need to be produced in high yield and high optical purity and preferentially catalytically. Among all the asymmetric catalytic reactions, asymmetric hydrogenation with H2 (AH) is the most widely used in the industry. With few exceptions, these AH processes use catalysts based on the three critical metals, rhodium, ruthenium, and iridium. Herein we describe a simple, industrially viable iron catalyst that allows for the AH of ketones, a process currently dominated by ruthenium and rhodium catalysts. By combining a chiral, 22-membered macrocyclic ligand with the cheap, readily available Fe 3(CO)12, a wide variety of ketones have been hydrogenated under 50 bar H2 at 45-65 C, affording highly valuable chiral alcohols with enantioselectivities approaching or surpassing those obtained with the noble metal catalysts. In contrast to AH by most noble metal catalysts, the iron-catalyzed hydrogenation appears to be heterogeneous.
- Li, Yanyun,Yu, Shenluan,Wu, Xiaofeng,Xiao, Jianliang,Shen, Weiyi,Dong, Zhenrong,Gao, Jingxing
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supporting information
p. 4031 - 4039
(2014/04/03)
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- Highly enantioselective transfer hydrogenation of ketones with chiral (NH)2P2 Macrocyclic Iron(II) complexes
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Bis(isonitrile) iron(II) complexes bearing a C2-symmetric diamino (NH)2P2 macrocyclic ligand efficiently catalyze the hydrogenation of polar bonds of a broad scope of substrates (ketones, enones, and imines) in high yield (up to 99.5 %), excellent enantioselectivity (up to 99 % ee), and with low catalyst loading (generally 0.1 mol %). The catalyst can be easily tuned by modifying the substituents of the isonitrile ligand. Paying the iron price: Bis(isonitrile) iron(II) complexes with a C2-symmetric diamino (NH)2P2 macrocyclic ligand efficiently catalyze the hydrogenation of polar bonds of a broad scope of substrates (ketones, enones, imines) in high yield (up to 99.5 %), excellent enantioselectivity (up to 99 % ee), and with low catalyst loading (generally 0.1 mol %).
- Bigler, Raphael,Huber, Raffael,Mezzetti, Antonio
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supporting information
p. 5171 - 5174
(2015/04/27)
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- Kluyveromyces marxianus CBS 6556 growing cells as a new biocatalyst in the asymmetric reduction of substituted acetophenones
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The use of microorganism growing cells is a well recognized methodology in biocatalyzed organic reactions. A non-conventional thermotolerant Kluyveromyces marxianus yeast strain was used for the bio-reduction of different arylketones. Differently substituted ketones were converted into the corresponding (S)-alcohols with up to 96% enantiomeric excess under very mild reaction conditions. Kluyveromyces marxianus represents a promising biocatalyst for the production of optically active 1-arylethanols.
- Vitale, Paola,D'Introno, Cinzia,Perna, Filippo Maria,Perrone, Maria Grazia,Scilimati, Antonio
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p. 389 - 394
(2013/06/26)
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- Novel chiral C2-symmetric multidentate aminophosphine ligands for use in catalytic asymmetric reduction of ketones
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A series of novel chiral C2-symmetric multidentate aminophosphine ligands have been successfully synthesized by Schiff-base condensation of bis(o-formylphenyl)phenylphosphane and easily available monoprotected (1R,2R)-diaminocyclohexane. The ca
- Xu, Ya-Qing,Yu, Shen-Luan,Li, Yan-Yun,Dong, Zhen-Rong,Gao, Jing-Xing
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p. 527 - 530
(2013/07/27)
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- Copper-catalyzed asymmetric hydrogenation of aryl and heteroaryl ketones
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High throughput screening enabled the development of a Cu-based catalyst system for the asymmetric hydrogenation of prochiral aryl and heteroaryl ketones that operates at H2 pressures as low as 5 bar. A ligand combination of (R,S)-N-Me-3,5-xylyl-BoPhoz and tris(3,5-xylyl)phosphine provided benzylic alcohols in good yields and enantioselectivities. The electronic and steric characteristics of the ancillary triarylphosphine were important in determining both reactivity and selectivity.
- Krabbe, Scott W.,Hatcher, Mark A.,Bowman, Roy K.,Mitchell, Mark B.,McClure, Michael S.,Johnson, Jeffrey S.
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supporting information
p. 4560 - 4563
(2013/09/24)
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- Asymmetric hydrogenation of aromatic ketones using an iridium(I) catalyst containing ferrocene-based P-N-N tridentate ligands
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Six ferrocene-based P-N-N tridentate ligands have been synthesized and applied in the Ir-catalyzed asymmetric hydrogenation of aromatic ketones. A wide range of ketones are hydrogenated enantioselectively to afford the corresponding optically active alcohols in the enantioselectivities of up to 86.6% ee. The substituent groups on the P-phenyl and pyridine rings play an important role with regard to the enantioselectivity.
- Nie, Huifang,Zhou, Gang,Wang, Quanjun,Chen, Weiping,Zhang, Shengyong
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p. 1567 - 1571
(2014/01/06)
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- Second-generation amino acid furanoside based ligands from D-glucose for the asymmetric transfer hydrogenation of ketones
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A novel series of modular amino acid thioamide ligands functionalized with carbohydrates were introduced and employed in the rhodium-catalyzed asymmetric transfer hydrogenation (ATH) of aryl alkyl ketones, including the less-studied heteroaromatic ketones. The ligands are based on amino acid hydroxyamides (pseudodipeptides), which are the most successful ligands previously used in asymmetric hydrogen transfer reactions. High enantioselectivities [up to 99 % enantiomeric excess (ee)] were achieved in the ATH of a wide range of aryl alkyl ketones by using catalysts generated in situ from [RhCl2Cp] 2 (Cp=C5Me5) and thioamide ligands comprising a 3-benzyl glucofuranoside backbone and a bulky isopropyl group in the α-amino acid moiety. Interestingly, both enantiomers of the alcohol products can readily be obtained with high enantioselectivity by simply changing the absolute configuration of the α-amino acid. The good performance can be extended to a very challenging class of industrially interesting heteroaromatic ketones (up to 99 % ee). The next generation: High enantioselectivities are achieved in the asymmetric transfer hydrogenation of a wide range of aryl alkyl ketones by using catalysts generated in situ from [RhCl2Cp]2 (Cp=C5Me5) and thioamide ligands prepared from commercial α-amino acids and D-glucose. The good performance extends to a very challenging class of industrially interesting heteroaromatic ketones. Boc=tert-butoxycarbonyl, Bz=benzoyl. Copyright
- Coll, Mercedes,Pamies, Oscar,Adolfsson, Hans,Dieguez, Montserrat
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p. 3821 - 3828
(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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- Nickel(II)-dipyridylphosphine-catalyzed enantioselective hydrosilylation of ketones in air
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Out of thin air: Catalytic amounts of nickel(II) salt and non-racemic dipyridylphosphine ligand, as well as the stoichiometric hydride source PhSiH3, formed an effective catalyst system for the Ni II-catalyzed asymmetric hydrosilylat
- Wu, Fei-Fei,Zhou, Ji-Ning,Fang, Qiang,Hu, Yi-Hu,Li, Shijun,Zhang, Xi-Chang,Wu, Jing,Chan, Albert S. C.
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supporting information
p. 2527 - 2530,4
(2020/09/02)
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- Ruthenium(II) pyrazolyl-pyridyl-oxazolinyl complex catalysts for the asymmetric transfer hydrogenation of ketones
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Lowering the ketone: RuII complexes containing a chiral pyridyl-based 1H-pyrazolyl-oxazolinyl NNN ligand were synthesized and structurally characterized by X-ray crystallographic studies. These complex catalysts efficiently catalyzed the asymmetric transfer hydrogenation of ketones, reaching up to 99a % ee for the desired products (see scheme). Copyright
- Ye, Wenjing,Zhao, Miao,Yu, Zhengkun
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supporting information; experimental part
p. 10843 - 10846
(2012/09/10)
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