- New chiral lithium aluminum hydrides based on biphenyl-2,2′- bisfenchol (BIFOL): Structural analyses and enantioselective reductions of aryl alkyl ketones
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A series of new chiral lithium aluminum hydrides based on BIFOL (biphenyl-2,2′-bisfenchol) and various alkyl alcohols (i.e., methanol, n-butanol, tert-butanol yielding BIFAl-H's) was synthesized and characterized by single crystal X-ray analyses. These investigations point to alkoxide redistribution for BIFAl-H-(O-tBu) (biphenyl-2,2′-bisfenchol aluminum hydride) species. The new BIFAl-H reagents are suitable to reduce aryl alkyl ketones with up to 62% ee. Computational transition structure analyses help to explain the experimentally observed enantioselectivities.
- Lange,Neud?rfl,Goldfuss
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- Diisopinocampheylchloroborane, a Remarkably Efficient Chiral Reducing Agent for Aromatic Prochiral Ketones
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Diisopinocampheylchloroborane, readily prepared in high chemical and optical purities (99percent ee) from (+)-α-pinene (92percent ee) via hydroboration, followed by treatment with dry hydrogen chloride in ether, reduces ketones at convenient rates at -25
- Chandrasekharan, J.,Ramachandran, P. V.,Brown, Herbert C.
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- Enantioselective reduction of aryl ketones using LiBH4 and TarB-X: A chiral Lewis acid
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High enantioselectivities are obtained using a tartaric acid-derived boronate ester in combination with lithium borohydride for asymmetric reduction of aryl ketones. The chiral Lewis acid, TarB-X, is easily prepared in 1 h, and the resulting alcohols are
- Suri, Jeff T,Vu, Truong,Hernandez, Arturo,Congdon, Julie,Singaram, Bakthan
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- 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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- 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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- Ruthenium-catalyzed hydrogenation of aromatic ketones using chiral diamine and monodentate achiral phosphine ligands
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The Ru-catalyzed asymmetric hydrogenation of ketones with chiral diamine and monodentate achiral phosphine has been developed. A wide range of ketones were hydrogenated to afford the corresponding chiral secondary alcohols in good to excellent enantioselectivities (up to 98.1% ee). In addition, an appropriate mechanism for the asymmetric hydrogenation was proposed and verified by NMR spectroscopy.
- Wang, Mengna,Zhang, Ling,Sun, Hao,Chen, Qian,Jiang, Jian,Li, Linlin,Zhang, Lin,Li, Li,Li, Chun
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- Chiral amino-pyridine-phosphine tridentate ligand, manganese complex, and preparation method and application thereof
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The invention discloses a chiral amino-pyridine-phosphine tridentate ligand, a manganese complex, and a preparation method and application thereof. The chiral amino-pyridine-phosphine tridentate ligand is shown as a formula II, and the manganese complex of the chiral amino-pyridine-phosphine tridentate ligand can be used for efficiently catalyzing and hydrogenating ketone compounds to prepare chiral alcohol compounds in a high enantioselectivity mode. The chiral amino-pyridine-phosphine tridentate ligand and the manganese complex are simple in synthesis process, good in stability, high in catalytic activity and mild in reaction conditions.
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Paragraph 0597-0600; 0602
(2020/07/13)
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- Manganese-Catalyzed Enantioselective Hydrogenation of Simple Ketones Using an Imidazole-Based Chiral PNN Tridentate Ligand
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A series of Mn(I) catalysts containing imidazole-based chiral PNN tridentate ligands with controllable 'side arm' groups have been established, enabling the inexpensive base-promoted asymmetric hydrogenation of simple ketones with outstanding activities (up to 8200 TON) and good enantioselectivities (up to 88.5percent ee). This protocol features wide substrate scope and functional group tolerance, thereby providing easy access to a key intermediate of crizotinib.
- Chen, Jiachen,Hou, Huacui,Ling, Fei,Nian, Sanfei,Wu, Feifei,Xu, Min,Yi, Xiao,Zhong, Weihui
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supporting information
p. 285 - 289
(2020/02/18)
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- P-chirogenic Trost ligands mediated asymmetric hydrogenation of simple ketones
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Herein, we report a highly active catalyst system consisting of (Rc,Rc,Rp,Rp)-P-chirogenic Trost ligand and [Ru(C6H6)Cl2]2 for asymmetric hydrogenation of simple ketones, affording the corresponding optically active alcohols in moderate enantioselectivity. A synergetic effect between P- and C-chirogenic centers of the P-chirogenic Trost ligands was observed in this asymmetric hydrogenation process.
- Du, Peng,Liu, Yan-Lan,Lu, Xiao-Bing
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supporting information
(2020/09/22)
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- An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
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The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
- Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
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p. 8042 - 8048
(2020/09/21)
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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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- Enantioselective Hydrogenation of Ketones using Different Metal Complexes with a Chiral PNP Pincer Ligand
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The synthesis of different metal pincer complexes coordinating to the chiral PNP ligand bis(2-((2R,5R)-2,5-dimethyl-phospholanoethyl))amine is described in detail. The characterized complexes with Mn, Fe, Re and Ru as metal centers showed good activities regarding the reduction of several prochiral ketones. Comparing these catalysts, the non-noble metal complexes produced best selectivities not only for aromatic substrates, but also for different kinds of aliphatic ones leading to enantioselectivities up to 99% ee. Theoretical investigations elucidated the mechanism and rationalized the selectivity. (Figure presented.).
- Garbe, Marcel,Wei, Zhihong,Tannert, Bianca,Spannenberg, Anke,Jiao, Haijun,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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supporting information
p. 1913 - 1920
(2019/03/13)
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- Lutidine-Based Chiral Pincer Manganese Catalysts for Enantioselective Hydrogenation of Ketones
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A series of MnI complexes containing lutidine-based chiral pincer ligands with modular and tunable structures has been developed. The complex shows unprecedentedly high activities (up to 9800 TON; TON=turnover number), broad substrate scope (81 examples), good functional-group tolerance, and excellent enantioselectivities (85–98 % ee) in the hydrogenation of various ketones. These aspects are rare in earth-abundant metal catalyzed hydrogenations. The utility of the protocol have been demonstrated in the asymmetric synthesis of a variety of key intermediates for chiral drugs. Preliminary mechanistic investigations indicate that an outer-sphere mode of substrate–catalyst interactions probably dominates the catalysis.
- Zhang, Linli,Tang, Yitian,Han, Zhaobin,Ding, Kuiling
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supporting information
p. 4973 - 4977
(2019/03/17)
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- Highly Focused Library-Based Engineering of Candida antarctica Lipase B with (S)-Selectivity Towards sec-Alcohols
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Candida antarctica lipase B (CALB) is one of the most extensively used biocatalysts in both academia and industry and exhibits remarkable (R)-enantioselectivity for various chiral sec-alcohols. Considering the significance of tailor-made stereoselectivity in organic synthesis, a discovery of enantiocomplementary lipase mutants with high (R)- and (S)-selectivity is valuable and highly desired. Herein, we report a highly efficient directed evolution strategy, using only 4 representative amino acids, namely, alanine (A), leucine (L), lysine (K), tryptophan (W) at each mutated site to create an extremely small library of CALB variants requiring notably less screening. The obtained best mutant with three mutations W104V/A281L/A282K displayed highly reversed (S)-selectivity towards a series of sec-alcohol with E values up to 115 (conv. 50%, ee 94%). Compared with the previously reported (S)-selective CALB variant, W104A, a single mutation provided less selectivity, while the synergistic effects of three mutations in the best variant endow better (S)-selectivity and a broader substrate scope than the W104A variant. Structural analysis and molecular dynamics simulation unveiled the source of reversed enantioselectivity. (Figure presented.).
- Cen, Yixin,Li, Danyang,Xu, Jian,Wu, Qiongsi,Wu, Qi,Lin, Xianfu
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p. 126 - 134
(2018/12/05)
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- One-pot synthesis of chiral alcohols from alkynes by CF3SO3H/ruthenium tandem catalysis
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A practical one-pot synthesis of chiral alcohols from readily available alkynes via tandem catalysis by the combination of CF3SO3H and a fluorinated chiral diamine Ru(ii) complex in aqueous CF3CH2OH is described. Very interestingly, the combination of fluorinated catalysts and solvent exhibits a positive fluorine effect on the reactivity and enantioselectivity. A range of chiral alcohols with wide functional group tolerance was obtained in high yield and excellent stereoselectivity under simple and mild conditions.
- Liu, Huan,Liu, Sensheng,Zhou, Haifeng,Liu, Qixing,Wang, Chunqin
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p. 14829 - 14832
(2018/04/30)
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- Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
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A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, (S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, (R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.
- Ling, Fei,Nian, Sanfei,Chen, Jiachen,Luo, Wenjun,Wang, Ze,Lv, Yaping,Zhong, Weihui
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p. 10749 - 10761
(2018/09/06)
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- Ir-catalyzed asymmetric hydrogenation of simple ketones with chiral ferrocenyl P,N,N-ligands
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The Ir-catalyzed asymmetric hydrogenation of simple aromatic ketones with chiral ferrocenyl P,N,N-ligands has been developed. Under the optimized conditions, a wide range of ketones were hydrogenated to afford the corresponding chiral alcohols in good to excellent enantioselectivities (up to 98% ee).
- Qin, Chao,Hou, Chuan-Jin,Liu, Hongzhu,Liu, Yan-Jun,Huang, De-Zhi,Hu, Xiang-Ping
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supporting information
p. 719 - 722
(2018/01/17)
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- Enantioselective catalytic hydrosilylation of propiophenone with a simple combination of a cationic iridium complex and a chiral azolium salt
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This study aims to propose a simple procedure for the development of enantioselective hydrosilylation of a ketone using catalytic amounts of [Ir(cod)2]BF4 and chiral azolium salt. Previously, catalytic asymmetric hydrosilylation reac
- Teramoto, Hiro,Sakaguchi, Satoshi
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- Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation
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A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities.
- Liu, Sensheng,Liu, Huan,Zhou, Haifeng,Liu, Qixing,Lv, Jinliang
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supporting information
p. 1110 - 1113
(2018/02/23)
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- Manganese(I)-Catalyzed Enantioselective Hydrogenation of Ketones Using a Defined Chiral PNP Pincer Ligand
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A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30–40 °C, 4 h, 30 bar H2). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.
- Garbe, Marcel,Junge, Kathrin,Walker, Svenja,Wei, Zhihong,Jiao, Haijun,Spannenberg, Anke,Bachmann, Stephan,Scalone, Michelangelo,Beller, Matthias
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supporting information
p. 11237 - 11241
(2017/09/02)
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- A Chiral Metal-Organic Material that Enables Enantiomeric Identification and Purification
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We show that CMOM-3S, a previously unreported porous crystalline metal-organic material that exhibits intrinsic homochirality, serves as a general-purpose chiral crystalline sponge (CCS) and a chiral stationary phase (CSP) for gas chromatography (GC). The properties of CMOM-3S are enabled by nano-sized channels connected to adaptable molecular recognition sites that mimic enzyme-binding sites. Further, CMOM-3S is composed of inexpensive components, facile to prepare, and requires only trace amounts of analyte. When coupled with the thermal and hydrolytic stability of CMOM-3S, these features mean that a coated fused silica capillary column in which CMOM-3S serves as a CSP is both more versatile and more robust than three benchmark commercial columns. That the enantiomer with the longer GC retention time is consistently captured in CCS experiments enables CMOM-3S to serve as a powerful tool to enable both chiral purification and enantiomer identification.
- Zhang, Shi-Yuan,Yang, Cheng-Xiong,Shi, Wei,Yan, Xiu-Ping,Cheng, Peng,Wojtas, Lukasz,Zaworotko, Michael J.
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supporting information
p. 281 - 289
(2017/09/05)
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- Ni-Catalyzed Enantioselective Conjunctive Coupling with C(sp3) Electrophiles: A Radical-Ionic Mechanistic Dichotomy
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The catalytic enantioselective conjunctive coupling of C(sp3) electrophiles can be accomplished with Ni catalysis. The enantioselectivity of the reaction is dependent on reaction mechanism with many substrates able to engage in an asymmetric process with Pybox-Ni complexes, whereas other substrates provide racemic product mixtures. The link between substrate structure and selectivity is addressed.
- Lovinger, Gabriel J.,Morken, James P.
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supporting information
p. 17293 - 17296
(2017/12/15)
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- Chiral N-heterocyclic carbene iridium catalyst for the enantioselective hydrosilane reduction of ketones
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Enantioselective reduction of ketones with (EtO)2MeSiH catalyzed by an in-situ generated N-heterocyclic carbene (NHC) Ir complex at room temperature has been developed. A series of benzimidazolium salts were synthesized and screened in the asymmetric hydrosilylation reaction. As a result, propiophenone was efficiently reduced by the combined catalytic system of [IrCl(cod)]2 and NHC-Ag complex derived from N-(1-naphthalenylmethyl)-substituted benzimidazolium salt L12, affording the corresponding alcohol in 92% yield and with 92% ee. Moreover, the evaluation of an Ir catalyst precursor showed that cationic [Ir(cod)2]BF4 complex could be used. Furthermore, the introduction of a chiral hydroxyamide side arm into the benzimidazolium salt was critical for the successful design of the NHC ligand.
- Manabe, Yoshiki,Shinohara, Kanako,Nakamura, Hanako,Teramoto, Hiro,Sakaguchi, Satoshi
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p. 138 - 145
(2016/06/15)
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- Phosphine-free chiral iridium catalysts for asymmetric catalytic hydrogenation of simple ketones
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Novel pyridylalkylamine and aminopyridinato ligand stabilized iridium complexes with no P ligand are introduced. These complexes have been investigated as catalysts for asymmetric hydrogenation of simple ketones, resulting in an active catalyst for bulky alkyl aryl ketones that is α-methylpropiophenone. The ligands were synthesized from inexpensive starting materials and their modular design allows for the introduction of a broad variety of substitution patterns. Additionally, better activity and selectivity was observed at 20 °C and 20 bar H2 pressure with a catalyst loading as low as 0.05 mol% iridium. These phosphorus free catalysts have always been a central issue in both academic and industrial research.
- Kumar, Prashant,Irrgang, Torsten,Kostakis, George E.,Kempe, Rhett
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p. 39335 - 39342
(2016/05/24)
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- Stereoselective reduction of aromatic ketones by a new ketoreductase from Pichia glucozyma
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A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.
- Contente, Martina Letizia,Serra, Immacolata,Brambilla, Marta,Eberini, Ivano,Gianazza, Elisabetta,De Vitis, Valerio,Molinari, Francesco,Zambelli, Paolo,Romano, Diego
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p. 193 - 201
(2016/01/09)
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- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
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The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
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p. 21293 - 21301
(2016/03/08)
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- Expanding substrate scope of lipase-catalyzed transesterification by the utilization of liquid carbon dioxide
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Secondary alcohols having bulky substituents on both sides of the chiral center are often poor substrates for most lipases. Here we reported that substrate scopes of two of the most used lipases, Candida antarctica lipase B and Burkholderia cepacia lipase, were found to be expanded toward more bulky secondary alcohols such as 1-phenyl-1-dodecanol and 2-methyl-1-phenyl-1-propanol by simply using them in liquid carbon dioxide as a solvent. The effects of solvents, reaction pressure, and pre-treatment of the enzyme with liquid CO2on this acceleration phenomenon were also studied.
- Hoang, Hai Nam,Matsuda, Tomoko
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p. 7229 - 7234
(2016/10/26)
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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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- Performance of Recombinant-Whole-Cell-Catalyzed Reductions in Deep-Eutectic-Solvent-Aqueous-Media Mixtures
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Deep-eutectic solvents (DES) are cost-effective, nonhazardous solvents that may be used in biocatalysis as nonconventional media that enable biotransformations with industrially sound high substrate loadings. Based on promising prognoses, this paper explo
- Müller, Christoph R.,Lavandera, Iván,Gotor-Fernández, Vicente,Domínguezdemaría, Pablo
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p. 2654 - 2659
(2015/09/15)
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- Iron achieves noble metal reactivity and selectivity: Highly reactive and enantioselective iron complexes as catalysts in the hydrosilylation of ketones
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Chiral iron alkyl and iron alkoxide complexes bearing boxmi pincers as stereodirecting ligands have been employed as catalysts for enantioselective hydrosilylation reactions with unprecedented activity and selectivity (TOF = 240 h-1 at -40 °C, ee up to 99% for alkyl aryl ketones), which match the performance of previously established noble-metal-based catalysts. This shows the potential of earth-abundant metals such as iron for replacing platinum-metals without any drawbacks for the reaction design.
- Bleith, Tim,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 2456 - 2459
(2015/03/04)
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- Chiral bicyclic NHC/Ir complexes for catalytic asymmetric transfer hydrogenation of ketones
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A diverse series of chiral bicyclic NHC/Ir complexes were prepared via a previously developed divergent synthesis of chiral imidazolium salts. Among the complexes, 8dz was found to be an excellent catalyst precursor for the Ir-catalyzed asymmetric transfer hydrogenation of ketones. The reaction of ketones with 8dz proceeded smoothly to give corresponding alcohols with high enantioselectivities (up to 98%) and productivities (TON up to 4500).
- Yoshida, Kazuhiro,Kamimura, Takumi,Kuwabara, Hiroshi,Yanagisawa, Akira
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supporting information
p. 15442 - 15445
(2015/10/20)
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- Biotransformation of aromatic ketones and ketoesters with the non-conventional yeast Pichia glucozyma
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The non-conventional yeast Pichia glucozyma CBS 5766 has been used for the biotransformation of different aromatic ketones and ketoesters. The growth and biotransformation conditions were optimised for the reduction of acetophenone and under optimised conditions, propiophenone, butyrophenone and valerophenone were reduced to the corresponding (S)-alcohols with high yields and enantioselectivity. Ketoreductase(s) of Pichia glucozyma showed high catalytic activities also towards aromatic β- and γ-ketoesters, being often competitive with esterase(s). These concurrent activities allowed for the preparation of hydroxyesters, hydroxyacids and lactones often in a very selective manner.
- Contente, Martina Letizia,Molinari, Francesco,Zambelli, Paolo,De Vitis, Valerio,Gandolfi, Raffaella,Pinto, Andrea,Romano, Diego
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supporting information
p. 7051 - 7053
(2015/02/02)
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- Enantioselective Hydrosilylation of Ketones Catalyzed by a Readily Accessible N-Heterocyclic Carbene-Ir Complex at Room Temperature
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A series of functionalized azolium compounds were synthesized from chiral α-amino acid derivatives such as β-amino alcohols. of hydroxy-amide-functionalized azolium salts thus obtained with Ag2O afforded N-heterocyclic carbene-Ag (NHC-Ag) complexes. Subsequent treatment of the resulting silver compound with [IrCl(cod)]2 yielded monodentate IrCl(cod)(NHC), which was stable in air. The NHC-Ir complex facilitated efficient asymmetric hydrosilylation of ketones using (EtO)2MeSiH under ambient conditions. A chiral ligand containing an isobutyl stereodirecting group was found to be the best ligand for the functionalized NHC-Ir complexes that were examined. A linear relationship was found between the catalyst ee and the product ee. The hydroxy functional group on the NHC ligand side-arm not only induced stereocontrol but also enhanced the reaction rate.
- Shinohara, Kanako,Kawabata, Shun,Nakamura, Hanako,Manabe, Yoshiki,Sakaguchi, Satoshi
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p. 5532 - 5539
(2014/10/16)
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- Tandem α-Alkylation/Asymmetric Transfer Hydrogenation of Acetophenones with Primary Alcohols
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Tandem α-alkylation/asymmetric transfer hydrogenation of acetophenones with primary alcohols, mediated by a single ruthenium catalyst, is described. Under optimized reaction conditions and with use of [Ru(p-cymene)Cl2]2 in combination with an amino acid hydroxyamide ligand, the chiral secondary alcohol products were isolated in moderate yields and in moderate to good enantiomeric excess (up to 89 % ee). One catalyst - one pot - two reactions. Acetophenones are initially alkylated with primary alcohols by the borrowing hydrogen methodology. The alkylation products are directly converted to enantiomerically enriched secondary alcohols.
- Kovalenko, Oleksandr O.,Lundberg, Helena,Hübner, Dennis,Adolfsson, Hans
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supporting information
p. 6639 - 6642
(2016/02/19)
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- Asymmetric transfer hydrogenation of ketones catalyzed by nickel complex with new PNO-type ligands
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The new polydentate mixed-N, P, O chiral ligands have been synthesized by the condensation of bis(o-formylphenyl)-phenylphosphane and R-phenylglycinol in CHCl3, and fully characterized by IR, NMR and EIMS spectra. These ligands were employed with a simple Ni complex Ni(PPhs) 2Cl2 in situ as catalytic systems for asymmetric transfer hydrogenation of ketones, and the corresponding optical alcohols were obtained with up to 84% ee under mild conditions.
- Dong, Zhen Rong,Li, Yan Yun,Yu, Shen Luan,Sun, Guo Song,Gao, Jing Xing
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scheme or table
p. 533 - 536
(2012/06/16)
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- Synthesis of novel chiral tetraaza ligands and their application in enantioselective transfer hydrogenation of ketones
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Novel chiral tetraaza ligands (R)-N, N′-bis[2-(piperidin-1-yl) benzylidene]propane-1, 2-diamine 6 and (S)-N-[2-(piperidin-1-yl)benzylidene]-3- {[2-(piperidin-1-yl)benzylidene]amino}-alanine sodium salt 7 have been synthesized and fully characterized by NM
- Yu, Shen Luan,Li, Yan Yun,Dong, Zhen Rong,Gao, Jing Xing
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scheme or table
p. 395 - 398
(2012/06/18)
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- A new chiral sulfinyl-NH-pyridine ligand for Ir-catalyzed asymmetric transfer hydrogenation reaction
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A new flexible C1-symmetric tridentate ligand (S)-N-(2-(tert-butylsulfinyl)benzyl)-1-(pyridin-2-yl)methanamine sulfoxide (L1) was successfully prepared and utilized as a chiral ligand for Ir(I)-catalyzed ATH (asymmetric transfer hydrogenation) reactions. Without any cooperation of other chiral center, encouraging ee and conversion values have been achieved, which provide us a better understanding on these types of ligands and a new strategy to develop new high-efficiency chiral catalysts for asymmetric reaction.
- Tang, Lei,Wang, Qiwei,Wang, Juanjuan,Lin, Zechao,Wang, Xiaobei,Cun, Linfeng,Yuan, Weicheng,Zhu, Jin,Liao, Jian,Deng, Jingen
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scheme or table
p. 3839 - 3842
(2012/08/14)
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- Homogeneous enantioselective catalysis in a continuous-flow microreactor: Highly enantioselective borohydride reduction of Ketones catalyzed by optically active cobalt complexes
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Highly enantioselective homogeneous catalysis under continuous-flow conditions was established for the cobalt-catalyzed borohydride reduction of tetralone derivatives. A microreactor allowed higher reaction temperature with the residence time of 12 min than the corresponding batch system to maintain enantioselectivity as well as reactivity. The present system was directly applied to gram-scale synthesis to afford the reduced product with 92% ee.
- Hayashi, Takuo,Kikuchi, Satoshi,Asano, Yukako,Endo, Yoshishige,Yamada, Tohru
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experimental part
p. 1235 - 1240
(2012/09/21)
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- Stereoselective benzylic hydroxylation of alkylbenzenes and epoxidation of styrene derivatives catalyzed by the peroxygenase of Agrocybe aegerita
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Here we report on the stereoselective benzylic hydroxylation and C1-C2 epoxidation of alkylbenzenes and styrene derivatives, respectively, by a heme-thiolate peroxygenase (EC 1.11.2.1) from the fungus Agrocybe aegerita. Benzylic hydroxylation led exclusively to the (R)-1-phenylalkanols. For (R)-1-phenylethanol, (R)-1-phenylpropanol and (R)-1-tetralol, the ee reached >99%. For longer chain lengths, the enantiomeric excesses (ee) and total turnover numbers (TTN) decreased while the number of by-products, e.g. 1-phenylketones, increased. Epoxidation of straight chain and cyclic styrene derivatives gave a heterogeneous picture and resulted in moderate to excellent ee values and TTN: e.g., in the case of (1R,2S)-cis-β-methylstyrene oxide formation, an ee >99% and a TTN of 110000 was achieved. Hydroxylation and epoxidation were true peroxygenations, which was demonstrated by the incorporation of 18O from H218O2 into the products. The use of fed-batch devices and varying feeding strategies for the substrate and co-substrate turned out to be a suitable approach to optimize peroxygenase catalysis.
- Kluge, Martin,Ullrich, Rene,Scheibner, Katrin,Hofrichter, Martin
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supporting information; experimental part
p. 440 - 446
(2012/04/10)
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- Optical resolution of aromatic alcohols using silica nanoparticles grafted with helicene
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Optically active silica nanoparticles, with a 70-nm diameter, grafted with (P)-1,12-dimethyl-8-methoxycarbonylbenzo[c]phenanthrene-5-carboxyamide were synthesized, and their use in the kinetic resolution of aromatic alcohols was examined. Up to 61% ee for (S)-2,2-dimethyl-1-phenyl-1-propanol was obtained by a preferential precipitation of aggregates formed with (P)-nanoparticles.
- Ichinose, Wataru,Miyagawa, Masamichi,An, Zengjian,Yamaguchi, Masahiko
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supporting information; experimental part
p. 3123 - 3125
(2012/07/28)
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- Redesign of enzyme for improving catalytic activity and enantioselectivity toward poor substrates: Manipulation of the transition state
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Secondary alcohols having bulky substituents on both sides of the hydroxy group are inherently poor substrates for most lipases. In view of this weakness, we redesigned a Burkholderia cepacia lipase to create a variant with improved enzymatic characteristics. The I287F/I290A double mutant showed a high conversion and a high E value (>200) for a poor substrate for which the wild-type enzyme showed a low conversion and a low E value (5). This enhancement of catalytic activity and enantioselectivity of the variant resulted from the cooperative action of two mutations: Phe287 contributed to both enhancement of the (R)-enantiomer reactivity and suppression of the (S)-enantiomer reactivity, while Ala290 created a space to facilitate the acylation of the (R)-enantiomer. The kinetic constants indicated that the mutations effectively altered the transition state. Substrate mapping analysis strongly suggested that the CH/π interaction partly enhanced the (R)-enantiomer reactivity, the estimated energy of the CH/π interaction being -0.4 kcal mol-1. The substrate scope of the I287F/I290A double mutant was broad. This biocatalyst was useful for the dynamic kinetic resolution of a variety of bulky secondary alcohols for which the wild-type enzyme shows little or no activity. The Royal Society of Chemistry 2012.
- Ema, Tadashi,Nakano, Yasuko,Yoshida, Daiki,Kamata, Shusuke,Sakai, Takashi
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supporting information; experimental part
p. 6299 - 6308
(2012/09/05)
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- A novel lipase enzyme panel exhibiting superior activity and selectivity over lipase B from Candida antarctica for the kinetic resolution of secondary alcohols
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A novel, commercially available lipase enzyme panel performing kinetic bioresolutions of a number of secondary alcohols is reported. The secondary alcohols that have been chosen are known from the literature to be particularly challenging substrates to resolve. Following initial screening, four co-solvents were investigated for each lead enzyme in an effort to assess their tolerance to common organic solvents. The superiority of these novel enzymes over lipase B from Candida antarctica (CALB) has been demonstrated.
- O'Neill, Maeve,Beecher, Denis,Mangan, David,Rowan, Andrew S.,Monte, Agnieszka,Sroka, Stefan,Modregger, Jan,Hundle, Bhupinder,Moody, Thomas S.
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experimental part
p. 583 - 586
(2012/08/13)
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- New chiral amino alcohol ligands derived from 1-phenylethylamine for efficient Ru-catalyzed asymmetric transfer hydrogenation
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A series of chiral amino alcohols have been prepared from cheap and readily available (S)-1-phenylethylamine through a one-step transformation. The ability of these newly developed amino alcohols as chiral ligands was evaluated in the Ru-catalyzed asymmet
- Han, Mei-Ling,Hu, Xiang-Ping,Huang, Jia-Di,Chen, Li-Gong,Zheng, Zhuo
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experimental part
p. 222 - 225
(2011/05/03)
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- Asymmetric transfer hydrogenation of acetophenone derivatives with novel chiral phosphinite based η6-p-cymene/ruthenium(II) catalysts
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Enantioselective reduction of prochiral ketones to optically active secondary alcohols is an important subject in synthetic organic chemistry because the resulting chiral alcohols are extremely useful, biologically active compounds. The new chiral ligands (2R)-2-[benzyl{(2-((diphenylphosphanyl)oxy) ethyl)}amino]butyldiphenylphosphinite, 1 and (2R)-2-[benzyl{(2- ((dicyclohexylphosphanyl)oxy)ethyl)}amino]butyldicyclohexylphosphinite, 2 and the corresponding ruthenium(II) complexes 3 and 4 have been prepared. The structures of these complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. 31P-{1H} NMR, DEPT, 1H-13C HETCOR or 1H-1H COSY correlation experiments were used to confirm the spectral assignments. These ruthenium(II)-phosphinite complexes have been used as catalysts for the asymmetric transfer hydrogenation of acetophenone derivatives. Under optimized conditions, aromatic ketones were reduced in good conversions and in moderate to good enantioselectivities (up to 85% ee).
- Aydemir, Murat,Meric, Nermin,Baysal, Akin,Turgut, Yilmaz,Kayan, Cezmi,?eker, Sevil,To?rul, Mahmut,Gümgüm, Bahattin
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supporting information; experimental part
p. 1541 - 1546
(2011/06/17)
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- Palladium-catalyzed asymmetric hydrogenation of simple ketones activated by Br?nsted acids
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Homogeneous Pd(OCOCF3)2/(R)-C4-TunePhos has been successfully applied in the asymmetric hydrogenation of simple ketones activated by catalytic amount of Br?nsted acid with up to 88% ee.
- Zhou, Xiao-Yu,Wang, Duo-Sheng,Bao, Ming,Zhou, Yong-Gui
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supporting information; experimental part
p. 2826 - 2829
(2011/06/21)
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- A novel C3-symmetric prolinol-squaramide catalyst for the asymmetric reduction of ketones by borane
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A novel C3-symmetric prolinol-squaramide has been developed for the asymmetric reduction of ketones by borane. By using only 5 mol % catalyst 1a for the reaction, high yields and excellent enantioselectivities (up to 95% yield, 93% ee) were obtained. Moreover, 1a can be easily recovered by simple precipitation and re-used for four cycles without losing the selectivity. Copyright
- Wu, Xiang-Fei,Min, Chang,Nyamzundui, Enkhtsetseg,Zhou, Hai-Bing,Dong, Chune
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experimental part
p. 1640 - 1643
(2011/12/22)
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- First example of hydrolytic kinetic resolution of acrylate of secondary alcohols by lipase Amano AK
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Lipase Amano AK is found to be extremely efficient catalyst for hydrolytic kinetic resolution of acrylates of secondary alcohols in aqueous phosphate buffer at pH 7.0. Both aliphatic and benzylic secondary alcohols show good to excellent E values.
- Bora, Pranjal P.,Bez, Ghanashyam,Anal, Jasha Momo H.
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p. 270 - 275
(2012/07/03)
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- Chiral iridium(I) bis(NHC) complexes as catalysts for asymmetric transfer hydrogenation
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The common use of NHC complexes in transition-metal mediated C-C coupling and metathesis reactions in recent decades has established W-heterocyclic carbenes as a new class of ligand for catalysis. The field of asymmetric catalysis with complexes bearing N
- Diez, Claus,Nagel, Ulrich
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experimental part
p. 509 - 516
(2010/10/18)
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- Selective reaction of camphor-derived exo-formyl [2.2.1]bicyclic carbinol with alkyl primary amines: Application to the preparation of new chiral catalysts for asymmetric reduction of aryl ketones
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Reaction of camphor-derived exo-formyl [2.2.1]bicyclic carbinol with various alkyl primary amines gave regio- and stereo-specific [3.2.1]bicyclic α-amino ketones. A detailed mechanism of the reaction was discussed. This reaction was further applied to the preparation of some camphor-derived oxazaborolidines, one of which proved to be an efficient chiral catalyst for the asymmetric borane reduction of prochiral aryl ketones at room temperature.
- Yang, Te-Fang,Shen, Chien-Hung,Hsu, Chi-Tung,Chen, Li-Hsun,Chuang, Chih-Hsiang
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experimental part
p. 8734 - 8738
(2011/01/04)
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- Ruthenium-catalysed hydrogenation of aromatic ketones using monodentate phosphoramidite ligands
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A ruthenium pre-catalyst containing two equivalents of the bulky monodentate phosphoramidite 3,3′-dimethyl-PipPhos and one equivalent of a chiral diamine such as 1,2-diphenylethylenediamine or 1,2-diaminocyclohexane was used for the asymmetric hydrogenation of aromatic ketones. A range of substituted and unsubstituted aryl alkyl ketones was hydrogenated using only 0.1 mol% of this catalyst with full conversions and enantioselectivities up to 97%. The phosphoramidite and diamine ligands matched when both had the same configuration, i.e., S-phosphoramidite with S,S-diamine. In that case the product was obtained with high enantioselectivity and the R-configuration. The mismatched case produced the product in lower ee. The product configuration was determined by the configuration of the diamine ligand. A mechanistic proposal was made.
- Stegink, Bart,Van Boxtel, Lonneke,Lefort, Laurent,Minnaard, Adriaan J.,Feringa, Ben L.,De Vries, Johannes G.
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supporting information; experimental part
p. 2621 - 2628
(2010/12/25)
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- Enantioselective, organocatalytic reduction of ketones using bifunctional thiourea-amine catalysts
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Prochiral ketones are reduced to enantioenriched, secondary alcohols using catecholborane and a family of air-stable, bifunctional thiourea-amine organocatalysts. Asymmetric induction is proposed to arise from the in situ complexation between the borane and chiral thiourea-amine organocatalyst resulting in a stereochemically biased boronate-amine complex. The hydride in the complex is endowed with enhanced nucleophilicity while the thiourea concomitantly embraces and activates the carbonyl.
- Li, De Run,He, Anyu,Falck
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supporting information; experimental part
p. 1756 - 1759
(2010/10/04)
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- A concise synthesis of (S)-(+)-ginnol based on catalytic enantioselective addition of commercially unavailable Di(n -alkyl)zinc to aldehydes and ketones
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Catalytic, enantioselective n-alkyl addition of commercially unavailable di(n-alkyl)zinc reagents, which were prepared by a refined version of Charettes procedure with Grignard reagents, to aldehydes and ketones was developed. To minimize the side reactions in the catalysis by chiral phosphoramide ligand (1) or 3,3-diphosphoryl-BINOL ligand (2), a preparation of di(n-alkyl)zinc reagents with a 1:2.5:1.6 molar ratio of ZnClNaOMe/RMgCl under solvent-free conditions was essential. Optically pure (S)-(+)-ginnol (17) was readily synthesized in one step for the first time by the catalytic enantioselective n-nonylation of icosanal. Georg Thieme Verlag.
- Hatano, Manabu,Mizuno, Tomokazu,Ishihara, Kazuaki
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experimental part
p. 2024 - 2028
(2010/10/04)
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- Chiral 1,1′-binaphthylazepine-derived amino alcohol catalyzed asymmetric aryl transfer reactions with boroxine as aryl source
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Using chiral 1,1′-binaphthylazepine-derived amino alcohol as catalyst, the direct addition of in situ prepared arylzinc (with triphenylboroxine as aryl source) to various aryl aldehydes can afford optically active diarylmethanols in high yields and enantioselectivities (up to 96%).
- Liu, Can,Guo, Zong-Liang,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
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experimental part
p. 159 - 164
(2010/09/04)
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