- Chiral ferrocene-indole diphosphine ligand as well as preparation method and application thereof
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The invention relates to a chiral ferrocene-indole diphosphine ligand as well as a preparation method and application thereof. The specific preparation method comprises the following steps: dissolving an indole compound and a chiral ferrocene phosphine ac
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Paragraph 0067-0068
(2021/05/22)
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- Chiral ferrocene phosphine-indole aminophosphine ligand as well as preparation method and application thereof
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The invention discloses a chiral ferrocene phosphine-indole aminophosphine ligand as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving a chiral ferrocene phosphine-indole intermediate in
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Paragraph 0046-0047
(2021/05/22)
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- OPTICALLY ACTIVE BISPHOSPHINO METHANE AND PRODUCTION METHOD THEREFOR, AND TRANSITION METAL COMPLEX AND ASYMMETRIC CATALYST
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PROBLEM TO BE SOLVED: To provide a novel optically active bisphosphine methane that is useful as a ligand for an asymmetric catalyst, has excellent oxidation resistance in the air, and is easy to handle, and to provide a transition metal complex using, as
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Paragraph 0071-0073
(2021/02/10)
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- 2,3-BISPHOSPHINOPYRAZINE DERIVATIVE, METHOD FOR PRODUCING SAME, TRANSITION METAL COMPLEX, ASYMMETRIC CATALYST, AND METHOD FOR PRODUCING ORGANIC BORON COMPOUND
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Provided is a 2,3-bisphosphinopyrazine derivative represented by the following general formula (1), wherein R1, R2, R3, and R4 represent an optionally substituted straight-chain or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted cycloalkyl group, an optionally substituted adamantyl group, or an optionally substituted phenyl group, R5 represents an optionally substituted alkyl group having 1 to 10 carbon atoms or an optionally substituted phenyl group, each R5 may be the same group or a different group, R6 represents a monovalent substituent, n denotes an integer of 0 to
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Paragraph 0262-0264
(2021/02/19)
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- P-Stereogenic N-Phosphine-Phosphite Ligands for the Rh-Catalyzed Hydrogenation of Olefins
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We have identified a successful family of simple P-stereogenic N-phosphine-phosphite ligands for the Rh-catalyzed asymmetric hydrogenation of olefins. These catalysts show excellent enantiocontrol for α-dehydroamino acid derivatives and α-enamides (ee's u
- Biosca, Maria,De La Cruz-Sánchez, Pol,Diéguez, Montserrat,Pàmies, Oscar
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p. 4730 - 4739
(2020/05/08)
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- Phosphite-thioether/selenoether Ligands from Carbohydrates: An Easily Accessible Ligand Library for the Asymmetric Hydrogenation of Functionalized and Unfunctionalized Olefins
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A large family of phosphite-thioether/selenoether ligands has been easily prepared from accessible L-(+)-tartaric acid and D-(+)-mannitol and applied in the M-catalyzed (M=Ir, Rh) asymmetric hydrogenation of a broad number of substrates (46 in total). Its highly modular architecture has been crucial to maximize the catalytic performance. Improving most of the reported approaches, this ligand family presents a broad substrate scope. By selecting the ligand parameters high enantioselectivities (ee's up to 99 %) have therefore been achieved in a broad range of both, functionalized and unfunctionalized substrates. Interestingly, both enantiomers of the hydrogenation products can be usually achieved by changing the ligand parameters.
- Margalef, Jèssica,Borràs, Carlota,Alegre, Sabina,Alberico, Elisabetta,Pàmies, Oscar,Diéguez, Montserrat
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p. 2142 - 2168
(2019/04/13)
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- A Bulky Three-Hindered Quadrant Bisphosphine Ligand: Synthesis and Application in Rhodium-Catalyzed Asymmetric Hydrogenation of Functionalized Alkenes
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A bulky three-hindered quadrant bisphosphine ligand, di-1-adamantylphosphino(tert-butylmethylphosphino)methane, named BulkyP*, has been synthesized via a convergent short pathway with chromatography-free procedures. The ligand is a crystalline solid and can be readily handled in air. Its rhodium(I) complex exhibits very high enantioselectivities and catalytic activities in the asymmetric hydrogenation of functionalized alkenes.
- Sawatsugawa, Yuuki,Tamura, Ken,Sano, Natsuhiro,Imamoto, Tsuneo
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supporting information
p. 8874 - 8878
(2019/11/03)
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- Nickel-catalyzed enantioselective hydrogenation of β-(acylamino)acrylates: Synthesis of chiral β-amino acid derivatives
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The nickel-catalyzed asymmetric hydrogenation of β-(acylamino)acrylates has been developed, affording chiral β-amino acid derivatives with excellent yields (95-99% yield) and enantioselectivities (97-99% ee). With the Ni-Binapine system, high enantioselectivities (98-99% ee) have also been obtained in the hydrogenation of Z/E isomeric mixtures of β-alkyl and β-aryl β-(acylamino)acrylates. The synthesis of chiral β-amino acid derivatives on a gram scale has also been achieved with 0.2 mol % catalyst loading.
- Li, Xiuxiu,You, Cai,Li, Shuailong,Lv, Hui,Zhang, Xumu
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supporting information
p. 5130 - 5133
(2017/11/06)
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- Studies on N-activation for the lipase-catalyzed enantioselective preparation of β-amino esters from 4-phenylazetidin-2-one
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The effect of N-substitution was examined for the enantio-selective lipase-catalyzed ring-opening reaction of racemic 4-phenylazetidin-2-one with methanol in dry organic solvents. Marked differences in the reactivity of various N-protected 4-phenylazetidin-2-ones were observed. Preparativescale reactions with Candida antarctica lipase B (Novozym 435 preparation) yielded N-acylated methyl (R)-3-amino-3- phenylpropanoates with enantiomeric excess (ee) values >99% in up to a 49% isolated yield, whereas Thermomyces lanuginosus lipase (Lipozyme TM IM) gave enantiomerically enriched methyl (S)-3-acetamido-3-phenylpropanoate. Candida antarctica lipase A catalyzed the cleavage of the N-chloroacetyl protective group, whereas all of the other examined lipases underwent the ring-opening reaction.
- Sundell, Riku,Kanerva, Liisa T.
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p. 1500 - 1506
(2015/03/04)
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- Mechanism of asymmetric hydrogenation of β-dehydroamino acids catalyzed by rhodium complexes: Large-scale experimental and computational study
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The mechanism of asymmetric hydrogenation of five representative β-dehydroamino acids catalyzed by rhodium complexes of (R)-(tert- butylmethylphosphino)(di-tert-butylphosphino)methane (trichickenfootphos, TCFP) and (R,R)-1,2-bis(tert-butylmethylphosphino)
- Gridnev, Ilya D.,Liu, Yuanyuan,Imamoto, Tsuneo
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p. 203 - 219
(2014/01/23)
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- Enantiopure narrow bite-angle P-OP ligands: Synthesis and catalytic performance in asymmetric hydroformylations and hydrogenations
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Herein is reported the preparation of a set of narrow bite-angle P-OP ligands the backbone of which contains a stereogenic carbon atom. The synthesis was based on a Corey-Bakshi-Shibata (CBS)-catalyzed asymmetric reduction of phosphomides. The structure of the resulting 1,1-P-OP ligands, which was selectively tuned through adequate combination of the configuration of the stereogenic carbon atom, its substituent, and the phosphite fragment, proved crucial for providing a rigid environment around the metal center, as evidenced by X-ray crystallography. These new ligands enabled very good catalytic properties in the Rh-mediated enantioselective hydrogenation and hydroformylation of challenging and model substrates (up to 99 % ee). Whereas for asymmetric hydrogenation the optimal P-OP ligand depended on the substrate, for hydroformylation, a single ligand was the highest-performing one for almost all studied substrates: it contains an R-configured stereogenic carbon atom between the two phosphorus ligating groups, and an S-configured 3,3′-diphenyl-substituted biaryl unit. Ligand design: Narrow-bite-angle P-OP ligands incorporating a stereogenic carbon atom in their backbone have been synthesized by Corey-Bakshi-Shibata (CBS)-catalyzed asymmetric reduction of the corresponding intermediates followed by O-phosphorylation. Rhodium complexes of these ligands provided very good catalytic performance in hydroformylations and hydrogenations (see scheme).
- Fernández-Pérez, Héctor,Benet-Buchholz, Jordi,Vidal-Ferran, Anton
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p. 15375 - 15384
(2016/02/18)
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- Carica papaya lipase catalysed resolution of β-amino esters for the highly enantioselective synthesis of (S)-dapoxetine
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An efficient synthesis of the (S)-3-amino-3-phenylpropanoic acid enantiomer has been achieved by Carica papaya lipase (CPL) catalysed enantioselective alcoholysis of the corresponding racemic N-protected 2,2,2-trifluoroethyl esters in an organic solvent. A high enantioselectivity (E > 200) was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. Based on the resolution of a series of amino acids, it was found that the structure of the substrate has a profound effect on the CPL-catalysed resolution. The enantioselectivity and reaction rate were significantly enhanced by switching the conventional methyl ester to an activated trifluoroethyl ester. When considering steric effects, the substituted phenyl and amino groups should not both be large for the CPL-catalysed resolution. The mechanism of the CPL-catalysed enantioselective alcoholoysis of the amino acids is discussed to delineate the substrate requirements for CPL-catalysed resolution. Finally, the reaction was scaled up, and the products were separated and obtained in good yields (≥ 80 %). The (S)-3-amino-3- phenylpropanoic acid obtained was used as a key chiral intermediate in the synthesis of (S)-dapoxetine with very high enantiomeric excess (> 99 %). A carica papaya lipase catalysed resolution of N-protected β-phenylalanine esters has been developed. High enantioselectivity was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. After 50 % conversion, the products were separated and used as key chiral intermediates for the synthesis of (S)-dapoxetine with > 99 % ee. Copyright
- You, Pengyong,Qiu, Jian,Su, Erzheng,Wei, Dongzhi
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p. 557 - 565
(2013/03/13)
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- Enantioselective hydrogenation of β-dehydroamino acids on a cinchonidine-modified palladium catalyst
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Enantioselective hydrogenation of (Z)-β-dehydroamino acids on a cinchonidine-modified Pd/Al2O3 catalyst was explored. Comparative studies by using (Z)-β-dehydroamino acids and esters identified that the carboxylic group in dehydroamino acids was essentially important to get enantioselectivities (33% for aryl substituted and 46% for alkyl substituted β-dehydroamino acids). This result extended the range of enantioselective hydrogenation of α,β-unsaturated carboxylic acids on chirally modified Pd catalysts and offered a new approach to synthesize optically active β-amino acids.
- Chen, Chunhui,Zhan, Ensheng,Li, Yong,Shen, Wenjie
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p. 117 - 121
(2013/09/23)
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- METHOD FOR PRODUCING OPTICALLY ACTIVE 1,2-BIS(DIALKYLPHOSPHINO)BENZENE DERIVATIVE
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An industrially advantageous method for producing an optically active 1,2-bis(dialkylphosphino)benzene derivative of the present invention is provided. The method is characterized in that a phosphine-borane compound represented by the following general formula (1) is subjected to a deboronation reaction, followed by lithiation, then the reaction product is subjected to reaction with an alkyldihalogenophosphine represented by RaPX′2, and thereafter the reaction product is subjected to reaction with a Grignard reagent represented by RbMgX″ to produce an optically active 1,2-bis(dialkylphosphino)benzene derivative (A). R1 and R2 respectively represent an alkyl group having 1 to 8 carbon atoms, and the number of carbon atoms is different between R1 and R2. Ra is either R1 or R2 and Rb is the other of R1 and R2. X, X′, and X″ each represent a halogen atom.
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Paragraph 0074; 0075; 0076; 0077; 0078
(2013/07/19)
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- Rigid P-chiral phosphine ligands with tert -butylmethylphosphino groups for rhodium-catalyzed asymmetric hydrogenation of functionalized alkenes
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Both enantiomers of 2,3-bis(tert-butylmethylphosphino)quinoxaline (QuinoxP*), 1,2-bis(tert-butylmethylphosphino)benzene (BenzP*), and 1,2-bis(tert-butylmethylphosphino)-4,5-(methylenedioxy)benzene (DioxyBenzP*) were prepared in short steps from enantiopure (S)- and (R)-tert-butylmethylphosphine-boranes as the key intermediates. All of these ligands were crystalline solids and were not readily oxidized on exposure to air. Their rhodium complexes exhibited excellent enantioselectivities and high catalytic activities in the asymmetric hydrogenation of functionalized alkenes, such as dehydroamino acid derivatives and enamides. The practical utility of these catalysts was demonstrated by the efficient preparation of several chiral pharmaceutical ingredients having an amino acid or a secondary amine component. A rhodium complex of the structurally simple ligand BenzP* was used for the mechanistic study of asymmetric hydrogenation. Low-temperature NMR studies together with DFT calculations using methyl α-acetamidocinnamate as the standard model substrate revealed new aspects of the reaction pathways and the enantioselection mechanism.
- Imamoto, Tsuneo,Tamura, Ken,Zhang, Zhenfeng,Horiuchi, Yumi,Sugiya, Masashi,Yoshida, Kazuhiro,Yanagisawa, Akira,Gridnev, Ilya D.
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supporting information; experimental part
p. 1754 - 1769
(2012/03/11)
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- Three-hindered quadrant phosphine ligands with an aromatic ring backbone for the rhodium-catalyzed asymmetric hydrogenation of functionalized alkenes
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The three-hindered quadrant phosphine ligands (R)-1-tert- butylmethylphosphino-2-(di-tert-butylphosphino)benzene ((R)-3H-BenzP*) and (R)-2-tert-butylmethylphosphino-3-(di-tert-butylphosphino)quinoxaline ((R)-3H-QuinoxP*) exhibited good to excellent enantioselectivities in the rhodium-catalyzed asymmetric hydrogenation of selected dehydroamino acid derivatives, enamides, and ethenephosphonates.
- Zhang, Zhenfeng,Tamura, Ken,Mayama, Daisuke,Sugiya, Masashi,Imamoto, Tsuneo
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experimental part
p. 4184 - 4188
(2012/06/18)
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- Development of a commercial process for (S)-β-phenylalanine (1)
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The development of a commercial manufacturing route for (S)-β-phenylalanine 8, a key pharmaceutical building block, is described. The different approaches which were investigated, based on catalytic asymmetric hydrogenation of enamide intermediates and on biocatalysis using acylase and lipase hydrolyses, are compared. The lipase resolution route was chosen for scale-up, and the final two-step process, based on readily available raw materials, is shown to be robust at full manufacturing scale
- Grayson, J. Ian,Roos, Juergen,Osswald, Steffen
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scheme or table
p. 1201 - 1206
(2011/12/16)
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- Highly efficient iridium-catalyzed asymmetric hydrogenation of unprotected β-enamine esters
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A highly efficient and enantioselective hydrogenation of unprotected β-enamine esters catalyzed by Ir-(S,S)-f-Binaphane complex has been developed. This methodology provides straightforward access to free β-amino acids in high yields with excellent enantioselectivities up to 97% ee and high reactivities (TON > 5000).
- Hou, Guohua,Zhang, Xumu,Li, Wei,Ma, Miaofeng,Zhang, Xiaowei
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supporting information; experimental part
p. 12844 - 12846
(2010/11/05)
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- Readily available chiral phosphine-aminophosphine ligands derived from 1-phenylethylamine for Rh-catalyzed enantioselective hydrogenations
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A series of new chiral phosphine-aminophosphine ligands have been prepared via a two- or three-step transformation from commercially available and inexpensive (S)-1-phenylethylamine, and successfully used in the rhodium-catalyzed asymmetric hydrogenation
- Zhou, Xiao-Mao,Huang, Jia-Di,Luo, Li-Bin,Zhang, Cheng-Lu,Zheng, Zhuo,Hu, Xiang-Ping
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experimental part
p. 420 - 424
(2010/07/02)
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- Enantiopure 1,2-Bis(tert-butylmethylphosphino)benzene as a highly efficient ligand in rhodium-catalyzed asymmetric hydrogenation
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Figure Presented. An electron-rich P-stereogenic bisphosphine ligand named "BenzP" was conveniently prepared from o-dibromobenzene and enantiopure tert-butylmethylphosphine-borane. Its rhodium complex exhibited excellent enantioselectivities of up to 99.9% and high catalytic activity of up to 10000 h-1 TOF in asymmetric hydrogenations of various functionalized alkenes.
- Tamura, Ken,Sugiya, Masashi,Yoshida, Kazuhiro,Yanagisawa, Akira,Imamoto, Tsuneo
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supporting information; experimental part
p. 4400 - 4403
(2010/12/25)
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- Highly enantioselective synthesis of β-amino acid derivatives by the lewis base catalyzed hydrosilylation of β-enamino esters
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A study was conducted to demonstrate highly enantioselective synthesis of β-amino acid derivatives by the Lewis base catalyzed hydrosilylation of βenamino esters. It was found that these catalyst and its analogue displayed excellent activities and enantioselectivities in promoting hydrosilylation of N-aryl β-enamino esters. N-picolinoylpyrrolidine derivatives and N-picolioylephedrine were also evaluated in hydrosilylation of (Z)-methyl 3-phenyl-3-(phenylamino)acrylate. The generality of the Lewis base organocatalyzed hydrosilylation of various β-enamino esters were examined under the optimized conditions. It was observed that the catalytic system exhibited a high sensitivity to the N-substituents, while all the N-aryl β-enamino esters underwent the hydrosilylation smoothly to give corresponding β-amino esters.
- Zheng, Hong-Jie,Chen, Wen-Bing,Wu, Zhi-Jun,Deng, Jin-Gen,Lin, Wen-Qing,Yuan, Wei-Cheng,Zhang, Xiao-Mei
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p. 9864 - 9867
(2009/10/02)
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- Iridium-catalyzed hydrogenation of β-dehydroamino acid derivatives using monodentate phosphoramidites
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The iridium-catalyzed asymmetric hydrogenation of 13 different β-dehydroamino acid derivatives to give optically active β-amino acid esters has been examined. Readily accessible monodentate octahydrobinaphthol- based phosphoramidites were used as chiral ligands. Good to excellent enantioselectivities and yields were obtained for the E isomers, whereas poorer catalyst performance was found for the Z isomers. Importantly, to obtain high enantioselectivity, substitution at the 3,3′-positions of the ligands was necessary. Enantioselectivities of up to 94% ee were achieved under optimized conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Enthaler, Stephan,Erre, Giulia,Junge, Kathrin,Schroeder, Kristin,Addis, Daniele,Michalik, Dirk,Hapke, Marko,Redkin, Dmitry,Beller, Matthias
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scheme or table
p. 3352 - 3362
(2009/04/07)
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- Lipases in β-dipeptide synthesis in organic solvents
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A number of β-dipeptides were prepared by two-step lipase-catalyzed reactions where N-acetylated β-amino esters were first activated as 2,2,2-trifluoroethyl esters with Candida antarctica lipase B (CAL-B). The activated esters were then used to acylate a
- Li, Xiang-Guo,Kanerva, Liisa T.
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p. 5593 - 5596
(2007/10/03)
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- Are β-acylaminoacrylates hydrogenated in the same way as α-acylaminoacrylates?
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Five catalyst-substrate complexes of the type [Rh(chiral ligand)(β-dehydroamino acid derivative)]BF4 were characterized for the first time by X-ray analysis (see example). Low-temperature NMR spectroscopy proved that three of these complexes ar
- Drexler, Hans-Joachim,Baumann, Wolfgang,Schmidt, Thomas,Zhang, Songlin,Sun, Ailing,Spannenberg, Anke,Fischer, Christine,Buschmann, Helmut,Heller, Detlef
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p. 1184 - 1188
(2007/10/03)
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- Efficient asymmetric hydrogenation with rhodium complexes of C 1-symmetric 2,5-dimethylphospholane-diphenylphosphines
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The unsymmetrical, optically active ligands 1,2-C6H 4(pph2)((R,R)-2,5-dimethylphospholanyl) (1a) and the new 1,1′-Fe(C5H4)2(PPh 2)((R,R)-2,5-dimethylphospholanyl) (1b) form compl
- Basra, Sandeep,De Vries, Johannes G.,Hyett, David J.,Harrison, Gayle,Heslop, Katie M.,Orpen, A. Guy,Pringle, Paul G.,Von Der Luehe, Karl
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p. 1901 - 1905
(2007/10/03)
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- Rhodium-catalyzed asymmetric hydrogenation of functionalized olefins using monodentate spiro phosphoramidite ligands
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Novel chiral monodentate phosphorus ligands, SIPHOS, were conveniently synthesized from 1,1′-spirobiindane-7,7′-diol. The Rh complexes of SIPHOS can catalyze the hydrogenation of α-dehydroamino esters in mild conditions, providing α-amino acid derivatives
- Fu, Yu,Guo, Xun-Xiang,Zhu, Shou-Fei,Hu, Ai-Guo,Xie, Jian-Hua,Zhou, Qi-Lin
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p. 4648 - 4655
(2007/10/03)
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- Synthesis of monodentate chiral spiro phosphonites and the electronic effect of ligand in asymmetric hydrogenation
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New monodentate chiral phosphonites were synthesized from enantiomerically pure 1,1′-spirobiindane-7,7′-diol. The phosphonites 2 were efficient ligands for the Rh-catalyzed asymmetric hydrogenation of α- and β-dehydroamino acid derivatives, providing the
- Fu, Yu,Hou, Guo-Hua,Xie, Jian-Hua,Xing, Liang,Wang, Li-Xin,Zhou, Qi-Lin
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p. 8157 - 8160
(2007/10/03)
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- A bisphosphepine ligand with stereogenic phosphorus centers for the practical synthesis of β-aryl-β-amino acids by asymmetric hydrogenation
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Excellent enantioselectivities and reactivities were observed in the hydrogenation of a variety of methyl (Z)-β-aryl-β-(acetyl-amino)acrylates in the presence of a rhodium catalyst with the chiral ligand binapine (see scheme). This bisbinaphthophosphepine
- Tang, Wenjun,Wang, Weimin,Chi, Yongxiang,Zhang, Xumu
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p. 3509 - 3511
(2007/10/03)
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- Preparation and asymmetric hydrogenation of β-aryl-substituted β-acylaminoacrylates
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The Rh-catalyzed asymmetric hydrogenation of β-aryl-substituted (E)-β-acylaminoacrylates, which were isolated for the first time, with, for example [Rh{(R,R)- (Et-FerroTANE)}(nbd)]+ as catalyst (see picture) proceeds under very mild conditions
- You, Jingsong,Drexler, Hans-Joachim,Zhang, Songlin,Fischer, Christine,Heller, Detlef
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p. 913 - 916
(2007/10/03)
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- Synthesis of a new chiral bisphospholane ligand for the Rh(I)-catalyzed enantioselective hydrogenation of isomeric β-acylamido acrylates
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The highly stereoselective synthesis of a chiral silylphospholane has been described, which can be advantageously used as a building block under base-free conditions for the construction of diphosphines related to DuPHOS. The utility of silylphospholane is shown in the synthesis of a new bisphospholane ligand 1 (MalPHOS), which is characterized by a maleic anhydride backbone. The ligand forms with Rh(I) a complex with a larger bite angle P-Rh-P than the analogue Me-DuPHOS complex. Both complexes have been tested in the asymmetric hydrogenation of unsaturated α- and β-amino acid precursors of pharmaceutical relevance. In several cases, the new catalyst was superior in comparison to the Me-DuPHOS complex, in particular when (Z)-configured β-acylamido acrylates were used as substrates.
- Holz, Jens,Monsees, Axel,Jiao, Haijun,You, Jinsong,Komarov, Igor V.,Fischer, Christine,Drauz, Karlheinz,Boerner, Armin
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p. 1701 - 1707
(2007/10/03)
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- Highly effective chiral ortho-substituted BINAPO ligands (o-BINAPO): Applications in Ru-catalyzed asymmetric hydrogenations of β-aryl-substituted β-(acylamino)acrylates and β-keto esters
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A novel family of chiral ortho-substituted BINAPO ligands (o-BINAPO) were synthesized from BINOL, and their Ru complexes were highly efficient catalysts for asymmetric hydrogenation of β-aryl-substituted β-(acylamino)acrylates and β-aryl-substituted β-keto esters. The Ru-bisphosphinite catalysts can tolerate an E/Z mixture of β-aryl-substituted β-(acylamino)acrylates. These highly enantioselective hydrogenations provide a useful way to prepare β-aryl-substituted β-amino acids and β-hydroxyl acids. Copyright
- Zhou, Yong-Gui,Tang, Wenjun,Wang, Wen-Bo,Li, Wenge,Zhang, Xumu
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p. 4952 - 4953
(2007/10/03)
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- Highly efficient synthesis of chiral β-amino acid derivatives via asymmetric hydrogenation
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(Formula Presented) The Rh-TangPhos complex is an efficient hydrogenation catalyst for making chiral β-amino acid derivatives. With the Rh-TangPhos system, high enantioselectivities (up to 99.6%) and turnover numbers have been obtained in the hydrogenatio
- Tang, Wenjun,Zhang, Xumu
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p. 4159 - 4161
(2007/10/03)
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- Aluminum-controlled reactivity and diastereoselectivity toward radical reactions of optically active aldimines with metallic samarium
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The intermolecular pinacol-type coupling reaction and allylation reaction of optically active imines bearing a β-hydroxy group were performed stereoselectively with metallic samarium after treatment of the imines with trimethylaluminum.
- Yanada,Okaniwa,Kaieda,Ibuka,Takemoto
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p. 1283 - 1286
(2007/10/03)
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- Enantioselective synthesis of β-amino acids based on BINAP-ruthenium(II) catalyzed hydrogenation
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BINAP-Ru(II) catalyzed hydrogenation of β-substituted (E)-β-(acylamino)acrylic acids allows efficient enantioselective synthesis of β-amino acids. The Z double bond isomers which possess an intramolecular hydrogen bond between amide and ester groups are more reactive but are hydrogenated with poor enantioselectivity. BINAP-Rh(I) complexes afford only moderate stereoselectivity with the opposite sense of enantioselection.
- Lubell,Kitamura,Noyori
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p. 543 - 554
(2007/10/02)
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