- Efficient and Spatially Controlled Functionalization of SBA-15 and Initial Results in Asymmetric Rh-Catalyzed 1,2-Additions under Confinement
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Selectively functionalized mesoporous silica may considerably advance heterogeneous catalysis through the controlled immobilization of highly selective complex catalysts inside the mesopores. However, spatially controlled functionalization and the precise analytical verification are still a challenge. In this publication, we report a method, which ensures a selective functionalization of the mesopore surface with a clickable linker and thus makes it possible to study confinement effects during catalyzed reactions. First, we passivate the silanol groups on the particle surface and in the pore entrances of the mesoporous silica material SBA-15 with 1,1,1-trimethyl-N-(trimethylsilyl)silanamine. Then we remove the template by solvent extraction and functionalize the pore walls with 3-azidopropyltriethoxysilane before we click the catalyst. In initial experiments of asymmetric Rh-catalyzed 1,2-addition, we investigate the performance of a catalyst clicked selectively in the mesopores and compare it to the dissolved catalyst as well as to the catalyst immobilized exclusively on the external surface of SBA-15.
- Beurer, Ann-Katrin,Kirchhof, Manuel,Bruckner, Johanna R.,Frey, Wolfgang,Baro, Angelika,Dyballa, Michael,Giesselmann, Frank,Laschat, Sabine,Traa, Yvonne
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- Synthesis and Optical Resolution of 3,3,3′,3′-Tetramethyl-1,1′-spirobiindane-7,7′-diol
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A novel chiral C 2-symmetric spiro diol, 3,3,3′,3′-tetramethyl-1,1′-spirobiindane-7,7′-diol (TMSIOL), was conveniently prepared via practical seven-step route from Bisphenol A in 45.1% overall yield. l-Menthyl chloroformate is used as optical r
- Zhou, Qiaoxia,Pan, Rihuang,Shan, Huanyu,Lin, Xufeng
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- Interplay of Polarity and Confinement in Asymmetric Catalysis with Chiral Rh Diene Complexes in Microemulsions
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Microemulsions provide a unique opportunity to tailor the polarity and liquid confinement in asymmetric catalysis via nanoscale polar and nonpolar domains separated by a surfactant film. For chiral diene Rh complexes, the influence of counterion and surfa
- Abitaev, Karina,Abouhaileh, Abdulwahab,Frey, Wolfgang,Gugeler, Katrin,K?stner, Johannes,Kirchhof, Manuel,Laschat, Sabine,Sottmann, Thomas,Zens, Anna
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supporting information
p. 16853 - 16870
(2021/11/30)
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- Experimental and Theoretical Study on the Role of Monomeric vs Dimeric Rhodium Oxazolidinone Norbornadiene Complexes in Catalytic Asymmetric 1,2- And 1,4-Additions
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The influence of nuclearity and charge of chiral Rh diene complexes on the activity and enantioselectivity in catalytic asymmetric 1,2-additions of organoboron reagents to N-tosylimines and 1,4-additions to enones was investigated. For this purpose, catio
- Abitaev, Karina,Alvarez-Barcia, Sonia,Baro, Angelika,Bauer, Alina,Bauer, Matthias,Estes, Deven P.,Fischer, Felix Richard,Frey, Wolfgang,Gugeler, Katrin,K?stner, Johannes,Kirchhof, Manuel,Laschat, Sabine,Nowakowski, Michal,Plietker, Bernd,Qawasmi, Yaseen,Ringenberg, Mark R.,Schnierle, Marc,Sottmann, Thomas
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supporting information
p. 3131 - 3145
(2020/10/02)
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- Asymmetric Catalysis in Liquid Confinement: Probing the Performance of Novel Chiral Rhodium–Diene Complexes in Microemulsions and Conventional Solvents
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The role of liquid confinement on the asymmetric Rh catalysis was studied using the 1,2-addition of phenylboroxine (2) to N-tosylimine 1 in the presence of [RhCl(C2H4)2]2 and chiral diene ligands as benchmark reaction. To get access to Rh complexes of different polarity, enantiomerically pure C2-symmetric p-substituted 3,6-diphenylbicyclo[3.3.0]octadienes 4 and diastereomerically enriched unsymmetric norbornadienes 5 and 6 carrying either the Evans or the SuperQuat auxiliary were synthesized. A microemulsion containing the equal amounts of H2O/KOH and toluene/reactants was formulated using the hydrophilic sugar surfactant n-octyl β-d-glucopyranoside (C8G1) to mediate the miscibility between the nonpolar reactants and KOH, needed to activate the Rh–diene complex. Prominent features of this organized reaction medium are its temperature insensitivity as well as the presence of water and toluene-rich compartments with a domain size of 55 ? confirmed by small-angle X-ray scattering (SAXS). Although bicyclooctadiene ligands 4 a,b,e performed equally well under homogeneous and microemulsion conditions, ligands 4 c,d gave a different chemoselectivity. For norbornadienes 5, 6, however, microemulsions markedly improved conversion and enantioselectivity as well as reaction rate, as was confirmed by kinetic studies using ligand 5 b.
- Deimling, Max,Kirchhof, Manuel,Schwager, Barbara,Qawasmi, Yaseen,Savin, Alex,Mühlh?user, Tina,Frey, Wolfgang,Claasen, Birgit,Baro, Angelika,Sottmann, Thomas,Laschat, Sabine
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supporting information
p. 9464 - 9476
(2019/07/04)
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- Chiral benzene backbone-based sulfoxide-olefin ligands for highly enantioselective Rh-catalyzed addition of arylboronic acids to: N-tosylarylimines
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An efficient Rh-catalyzed addition of arylboronic acids to N-tosylarylimines has been developed with chiral benzene backbone-based sulfoxide-olefin ligands, where 2-methoxy-1-naphthyl sulfinyl functionalized olefin ligands have shown to be more effective.
- Xue, Feng,Liu, Qibin,Zhu, Yong,Qing, Yunfei,Wan, Boshun
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p. 25377 - 25381
(2019/08/28)
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- Heterogeneous Chiral Diene-Rh Complexes for Asymmetric Arylation of α,β-Unsaturated Carbonyl Compounds, Nitroalkenes, and Imines
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A chiral diene ligand with tertiary alkyl amine-derived secondary amide moiety was immobilized on cross-linked polystyrene (PS) by radical polymerization, which was combined with Rh to form heterogeneous chiral Rh complexes (PS-diene Rh?Cl). PS-diene Rh?Cl catalyzed asymmetric arylation reactions of α,β-unsaturated carbonyl compounds (ketones, esters, and amides), nitroalkenes, and imines afforded the desired products in high yields with excellent enantioselectivities. PS-diene Rh?Cl is stable in air, can be stored for several months, and can be reused more than 10 times without any reduction of either yield or enantioselectivity. We also developed a method of activation of PS-diene Rh?Cl to generate more active species. (Figure presented.).
- Kuremoto, Tatsuya,Yasukawa, Tomohiro,Kobayashi, Shū
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supporting information
p. 3698 - 3703
(2019/07/12)
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- Rhodium-Catalyzed Asymmetric Addition of Organoboronic Acids to Aldimines Using Chiral Spiro Monophosphite-Olefin Ligands: Method Development and Mechanistic Studies
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The synthesis of a novel type of chiral spiro monophosphite-olefin (SMPO) ligands based on a hexamethyl-1,1′-spirobiindane scaffold was accomplished starting from Bisphenol C. The optimal ligand could serve as an elegant chiral bidentate ligand in the Rh-catalyzed asymmetric 1,2-addition of organoboronic acids to various acyclic/cyclic aldimines, leading to chiral amines with high yields and excellent enantioselectivities. Detailed stereochemical models for enantioselective induction were elucidated through DFT calculations and postulated the origins of the higher enantioselectivity of phosphite-olefin ligands.
- Shan, Huanyu,Zhou, Qiaoxia,Yu, Jinglu,Zhang, Shuoqing,Hong, Xin,Lin, Xufeng
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p. 11873 - 11885
(2018/09/18)
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- Electronic and Steric Tuning of an Atropisomeric Disulfoxide Ligand Motif and Its Use in the Rh(I)-Catalyzed Addition Reactions of Boronic Acids to a Wide Range of Acceptors
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A novel chiral disulfoxide ligand pair bearing fluorine atoms at the 6 and 6′ position of its atropisomeric backbone, (M,S,S)- and (P,S,S)-p-Tol-6F-BIPHESO, was synthesized. Complexation to a rhodium(I) precursor gave rise to μ-Cl- and μ-OH-bridged rhodiu
- Zhao, Guang-Zhen,Foster, Daven,Sipos, Gellért,Gao, Pengchao,Skelton, Brian W.,Sobolev, Alexandre N.,Dorta, Reto
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p. 9741 - 9755
(2018/09/06)
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- Highly Enantioselective Ferrocenyl Palladacycle-Acetate Catalysed Arylation of Aldimines and Ketimines with Arylboroxines
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Benzylic N-substituted stereocenters constitute a frequent structural motif in drugs. Their highly enantioselective generation is hence of technical importance. An attractive strategy is the arylation of imines with organoboron reagents. Chiral Rh complexes have reached a high level of productivity for this reaction type. In this article we describe that an electron rich PdIIcatalyst also performs well in the arylation of aldimines, comparable to the best Rh catalysts. The ferrocenyl palladacycle-acetate catalyst allows for a broad substrate scope and very high enantioselectivities. Commonly observed side reactions like aryl–aryl homocouplings and imine hydrolysis could be blocked. Mechanistic studies implicate that a) the acetate ligand is crucial for transmetallation, b) the active catalyst is most likely a palladacycle-OAc monomer, c) the rate limiting step is probably the product release. By added KOAc the arylation could also be applied to ketimines.
- Schrapel, Carmen,Frey, Wolfgang,Garnier, Delphine,Peters, René
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p. 2448 - 2460
(2017/02/23)
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- Planar-chiral phosphine-olefin ligands exploiting a (Cyclopentadienyl)manganese(I) scaffold to achieve high robustness and high enantioselectivity
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A series of 2-methyl-1,3-propenylene-bridged (η5-diarylphosphinocyclopentadienyl)(phosphine)manganese(I) di-carbonyl complexes 2 have been developed as a new class of phosphine-olefin ligands based on a planar-chiral transition-metal scaffold,
- Kamikawa, Ken,Tsen, Ya-Yi,Jian, Jia-Hong,Takahashi, Tamotsu,Ogasawara, Masamichi
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supporting information
p. 1545 - 1553
(2017/02/10)
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- Role of Regioisomeric Bicyclo[3.3.0]octa-2,5-diene Ligands in Rh Catalysis: Synthesis, Structural Analysis, Theoretical Study, and Application in Asymmetric 1,2- and 1,4-Additions
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In order to study the impact of regioisomeric diene ligands on the formation and catalytic activity of Rh complexes, a series of C2- and CS-symmetric 2,5-disubstituted bicyclo[3.3.0]octa-2,5-dienes C2-L and CS-L, respectively, were synthesized from Weiss diketone by simultaneous deprotonation/electrophilic trapping of both oxo functions, and the catalytic behavior was studied in the presence of [RhCl(C2H4)2]2. Complexes [RhCl(C2-L)]2 bearing C2-symmetric ligands catalyzed effectively the asymmetric arylation of N-tosylaldimines to (S)-diarylamines with yields and ee values up to 99%. In Hayashi-Miyaura reactions, however, the complexes showed poor catalytic activity. When complexes [RhCl(CS-L)]2 with CS-symmetric ligand or mixtures of [RhCl(C2-L)]2 and [RhCl(CS-L)]2 were employed in 1,2-additions, racemic addition products were observed, suggesting a C=C isomerization of the diene ligands. X-ray crystal structure analysis of both Rh complexes formed from the [RhCl(C2H4)2]2 precursor and ligands C2-L and CS-L revealed that only the C2-symmetric ligand C2-L coordinated to the Rh, whereas CS-L underwent a Rh-catalyzed C=C isomerization to rac-C2-L, which then gave the racemic [RhCl(rac-C2-L)]2 complex. DFT calculations of the relative stabilities of the Rh complexes and the proposed intermediates provided a mechanistic rationale via Rh-mediated hydride transfer.
- Mühlh?user, Tina,Savin, Alex,Frey, Wolfgang,Baro, Angelika,Schneider, Andreas J.,D?teberg, Heinz-Günter,Bauer, Florian,K?hn, Andreas,Laschat, Sabine
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p. 13468 - 13480
(2017/12/26)
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- Asymmetric Arylation of Imines Catalyzed by Heterogeneous Chiral Rhodium Nanoparticles
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Asymmetric arylation of aldimines catalyzed by heterogeneous chiral rhodium nanoparticles has been developed. The reaction proceeded in aqueous media without significant decomposition of the imines by hydrolysis to afford chiral (diarylmethyl)amines in high yields with outstanding enantioselectivities. This catalyst system exhibited the highest turnover number (700) in heterogeneous catalysts reported to date for these reactions. The reusability of the catalyst was also demonstrated.
- Yasukawa, Tomohiro,Kuremoto, Tatsuya,Miyamura, Hiroyuki,Kobayashi, Sh?
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p. 2716 - 2718
(2016/06/15)
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- A Chiral Disulfoxide Ligand for the Efficient Rhodium-Catalyzed 1,2-Addition of Arylboroxines to N-Tosylarylimines
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Enantiomerically pure diarylmethylamines are important building blocks in active pharmaceutical ingredients. Herein, we report a rhodium precatalyst with a chiral disulfoxide ligand that effects the 1,2-addition of arylboroxines to aromatic imines to give high yields and high enantioselectivities of these products. The present paper describes a system that is very simple, where the ease of synthesis of the chiral ligand is combined with low catalyst loadings and reaction conditions that do not need any additives or external base.
- Zhao, Guang-Zhen,Sipos, Gellért,Salvador, Alvaro,Ou, Arnold,Gao, Pengchao,Skelton, Brian W.,Dorta, Reto
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supporting information
p. 1759 - 1766
(2016/06/09)
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- Chiral Bicyclic Bridgehead Phosphoramidite (Briphos) Ligands for Asymmetric Rhodium-Catalyzed 1,2- and 1,4-Addition
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A complementary solution for Rh-catalyzed enantioselective 1,2- and 1,4-arylation with two structurally related chiral ligands is reported. A chiral bicyclic bridgehead phosphoramidite (briphos) ligand derived from 1-aminoindane was efficient for the 1,2-arylation of N-sulfonyl imines, while that derived from 1,2,3,4-tetrahydro-1-naphthylamine was efficient for 1,4-arylation of α,β-unsaturated cyclic ketones. For α,β-unsaturated N-tosyl ketimines, the briphos derived from 1-aminoindane was found to selectively provide γ, γ-diaryl N-tosyl enamines with high yields and stereoselectivities.
- Lee, Ansoo,Kim, Hyunwoo
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supporting information
p. 3520 - 3527
(2016/05/24)
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- Enantioselective palladium-catalyzed arylation of N-tosylarylimines with arylboronic acids using a chiral 2,2′-bipyridine ligand
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With the aid of an axially chiral 2,2′-bipyridine ligand, we have successfully developed a palladium-catalyzed method for the enantioselective arylation of N-tosylarylimines, furnishing the chiral diarylmethamines with high yields and enantioselectivities
- Gao, Xiang,Wu, Bo,Yan, Zhong,Zhou, Yong-Gui
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supporting information
p. 55 - 58
(2015/12/30)
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- The first chiral diene-based metal-organic frameworks for highly enantioselective carbon-carbon bond formation reactions
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We have designed the first chiral diene-based metal-organic framework (MOF), E2-MOF, and postsynthetically metalated E2-MOF with Rh(i) complexes to afford highly active and enantioselective single-site solid catalysts for C-C bond fo
- Sawano, Takahiro,Ji, Pengfei,McIsaac, Alexandra R.,Lin, Zekai,Abney, Carter W.,Lin, Wenbin
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p. 7163 - 7168
(2015/11/23)
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- Phosphine-olefin ligands based on a planar-chiral (π-Arene)chromium scaffold: Design, synthesis, and application in asymmetric catalysis
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The NMR and X-ray crystallographic studies clarified that planar-chiral alkenylene-bridged (phosphino-π-arene)(phosphine)chromium complexes 3 were capable of coordinating to a rhodium(I) cation in a bidentate fashion at the (π-arene)-bound phosphorus atom
- Ogasawara, Masamichi,Tseng, Ya-Yi,Arae, Sachie,Morita, Tomotaka,Nakaya, Takeshi,Wu, Wei-Yi,Takahashi, Tamotsu,Kamikawa, Ken
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supporting information
p. 9377 - 9384
(2014/07/21)
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- Development of new P-chiral P,π-dihydrobenzooxaphosphole hybrid ligands for asymmetric catalysis
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A new family of P-chiral P,π-hybrid ligands was prepared from the dihydrobenzooxaphosphole core. These new ligands were demonstrated to be both sterically and electronically tunable at the substituents on the phosphorus atom and the π-system of the ligand. Application of these new ligands to the catalytic asymmetric addition of boronic acids to imine electrophiles was shown to proceed with high levels of enantioinduction. (Chemical Equation Presented).
- Sieber, Joshua D.,Chennamadhavuni, Divya,Fandrick, Keith R.,Qu, Bo,Han, Zhengxu S.,Savoie, Jolaine,Ma, Shengli,Samankumara, Lalith P.,Grinberg, Nelu,Lee, Heewon,Song, Jinhua J.,Senanayake, Chris H.
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supporting information
p. 5494 - 5497
(2015/02/05)
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- Kinetic resolution of planar-chiral (η6-arene)chromium complexes by molybdenum-catalyzed asymmetric ring-closing metathesis
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Molybdenum-catalyzed asymmetric ring-closing metathesis has been used for the kinetic resolution of racemic planar-chiral (η6-arene) chromium complexes with excellent enantioselectivity. The products are excellent precursors for the synthesis of various planar-chiral (η6-arene) chromium derivatives and can also be applied as chiral ligands in rhodium-catalyzed asymmetric reactions. Copyright
- Ogasawara, Masamichi,Wu, Wei-Yi,Arae, Sachie,Watanabe, Susumu,Morita, Tomotaka,Takahashi, Tamotsu,Kamikawa, Ken
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supporting information; experimental part
p. 2951 - 2955
(2012/05/20)
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- Chiral diphosphane- and NHC-containing ruthenium catalysts for the catalytic asymmetric arylation of aldimines with organoboron reagents
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For the first time, we report the application of [RuCl2(η 6-p-cymene)]2 in the arylation of N-activated aldimines with boronic acids and its derivatives to afford chiral amines, which are important intermediates in the syntheses of key bioactive compounds. The behavior of the chiral ligands, the imine substrates, and the organoboron reagents were studied. Very good enantioselectivities were obtained. A new method is presented for the synthesis of chiral substituted amines by employing Ru catalysts along with known chiral phosphane ligands and a new NHC-type chiral ligand. Organoboron reagents were applied as the aryl transfer agents. High enantioselectivities were achieved with this new method, and some mechanistic insights are provided.
- Marques, Carolina S.,Burke, Anthony J.
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experimental part
p. 4232 - 4239
(2012/09/22)
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- Design and synthesis of new chiral phosphorus-olefin bidentate ligands and their use in the rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl imines
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Novel chiral phosphorus-olefin bidentate ligands have been synthesized in a few steps from a readily available enantiopure compound. These ligands have been applied to a rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl aldimines, achieving high yield and enantioselectivity.
- Shintani, Ryo,Narui, Rintaro,Tsutsumi, Yosuke,Hayashi, Sayuri,Hayashi, Tamio
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supporting information; experimental part
p. 6123 - 6125
(2011/07/30)
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- Catalytic enantioselective addition of phenylboronic acid and phenylboroxine to N-tosylimines: PdII and RhI catalysis
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This is the first account of a successful, PdII-catalysed enantioselective addition of phenylboronic acid to electron-deficient N-tosylarylimines by using chiral diphosphane ligands. A number of commercial diphosphane ligands were screened. Des
- Marques, Carolina S.,Burke, Anthony J.
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supporting information; experimental part
p. 1639 - 1643
(2010/06/16)
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- C 1-symmetric dicyclopentadienes as new chiral diene ligands for asymmetric rhodium-catalyzed arylation of N-tosylarylimines
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Monosubstituted C1-symmetric dicyclopentadienes as a new class of diene ligands have been developed for asymmetric arylation of N-tosylarylimines in excellent yields (98-99%) with high enantioselectivities (90-96%). The preparation of these diene ligands relied on an efficient lipase-catalyzed resolution as the key step.
- Shao, Cheng,Yu, Hong-Jie,Wu, Nuo-Yi,Feng, Chen-Guo,Lin, Guo-Qiang
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supporting information; experimental part
p. 3820 - 3823
(2010/10/21)
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- Electronic and steric tuning of chiral diene ligands for rhodium-catalyzed asymmetric arylation of imines
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Rhodium-catalyzed asymmetric arylation of imines using electronically and sterically-modified chiral diene ligands gave the corresponding diarylmethylamines in high yield and with high enantioselectivity using just 0.3 mol% of catalyst.
- Okamoto, Kazuhiro,Hayashi, Tamio,Rawal, Viresh H.
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supporting information; experimental part
p. 4815 - 4817
(2009/12/08)
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- Catalytic enantioselective arylation of N-tosylarylimines with arylboronic acids using C2-symmetric cationic N-heterocyclic carbene Pd 2+ diaquo complexes
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The asymmetric arylation of N-tosylimines with arylboronic acids was realized by using chiral cationic C2-symmetric N-heterocyclic carbene (NHC) Pd2+ diaquo complex 5b as the catalyst in combination with 1.0 equiv of K3PO
- Ma, Guang-Ning,Zhang, Tao,Shi, Min
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supporting information; experimental part
p. 875 - 878
(2009/07/18)
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- An N-linked bidentate phosphoramidite ligand (N-Me-BIPAM) for rhodium-catalyzed asymmetric addition of arylboronic acids to N-sulfonylarylaldimines
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A chiral N-linked C2-symmetric bidentate phosphoramidite (N-Me-BIPAM) was newly developed for the rhodium-catalyzed enantioselective addition of arylboronic acids to N-sulfonylimines. This ligand achieved high enantioselectivities in a range of
- Kurihara, Kazunori,Yamamoto, Yasunori,Miyaura, Norio
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experimental part
p. 260 - 270
(2009/09/06)
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- Design of C2-symmetric tetrahydropentalenes as new chiral diene ligands for highly enantioselective Rh-catalyzed arylation of N-tosylarylimines with arylboronic acids
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A new type of C2-symmetric chiral diene ligand bearing a simple bicyclic [3.3.0] backbone was discovered. (3aS,6aS)-3,6-diphenyl-1,3a,4,6a-tetrahydropentalene was applied successfully in the Rh-catalyzed asymmetric arylation of N-tosylarylimine
- Wang, Zhi-Qian,Feng, Chen-Guo,Xu, Ming-Hua,Lin, Guo-Qiang
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p. 5336 - 5337
(2008/02/03)
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- Enantioselective Rh-catalyzed arylation of N-tosylarylimines with arylboronic acids
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The asymmetric arylation of N-tosylarylimines with arylboronic acids was realized by using rhodium/(S)-ShiP as catalyst. The reaction proceeded in aqueous toluene to give diarylmethylamines in good yields with up to 96% ee.
- Duan, Hai-Feng,Jia, Yi-Xia,Wang, Li-Xin,Zhou, Qi-Lin
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p. 2567 - 2569
(2007/10/03)
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- Expanding the C2-symmetric bicyclo[2.2.1]hepta-2,5-diene ligand family: Concise synthesis and catalytic activity in rhodium-catalyzed asymmetric addition
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New C2-symmetric bicyclo[2.2.1]hepta-2,5-dienes bearing methyl and phenyl substituents at the 2 and 5 positions were prepared enantiomerically pure through a two-step sequence starting from the readily available bicyclo[2.2.1]hepta-2,5-dione. Due to the instability or volatility of these dienes, their isolation was achieved through the formation of the corresponding stable [RhCl(diene)]2 complexes. These chiral rhodium complexes displayed high activity and enantioselectivity (up to 99% ee) in the rhodium-catalyzed 1,4-addition and 1,2-addition of phenylboronic acid to cyclic enones and N-sulfonylimines, respectively.
- Berthon-Gelloz, Guillaume,Hayashi, Tamio
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p. 8957 - 8960
(2007/10/03)
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- C2-Symmetric bicyclo[3.3.1]nona-2,6-diene and bicyclo[3.3.2]deca-2,6-diene: New chiral diene ligands based on the 1,5-cyclooctadiene framework
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As a new type of C2-symmetric chiral diene ligands, which coordinate to a metal by their 1,5-cyclooctadiene framework, we prepared 2,6-disubstituted bicyclo[3.3.1]nona-2,6-diene (bnd*) and bicyclo[3.3.2]deca-2,6-diene (bdd*), and examined their catalytic activity and enantioselectivity for rhodium-catalyzed asymmetric 1,4-addition to α,β-unsaturated ketones and 1,2-addition to N-sulfonylimines. High enantioselectivity of the Ph-bnd* ligand was observed in the addition of phenylboroxine to N-tosylimine and N-4-nitrobenzenesulfonylimine of 4-chlorobenzaldehyde to give phenyl(4-chlorophenyl)methylamines in high enantiomeric excess (98-99% ee).
- Otomaru, Yusuke,Kina, Asato,Shintani, Ryo,Hayashi, Tamio
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p. 1673 - 1679
(2007/10/03)
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- C2-symmetric bicyclo[2.2.2]octadienes as chiral ligands: Their high performance in rhodium-catalyzed asymmetric arylation of N-tosylarylimines
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Asymmetric synthesis of diarylmethylamines with high enantioselectivity (95-99% ee) was realized by use of a new C2-symmetric diene ligand, (1R,4R)-2,5-diphenylbicyclo[2.2.2]octa-2,5-diene (Ph-bod*), for the rhodium-catalyzed asymmetric arylati
- Tokunaga, Norihito,Otomaru, Yusuke,Okamoto, Kazuhiro,Ueyama, Kazuhito,Shintani, Ryo,Hayashi, Tamio
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p. 13584 - 13585
(2007/10/03)
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