- A Cobalt(II) Complex Bearing the Amine(imine)diphosphine PN(H)NP Ligand for Asymmetric Transfer Hydrogenation of Ketones
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Novel chiral cobalt complex a containing amine(imine)diphosphine PN(H)NP ligand and complex b containing bis(amine)diphosphine PN(H)N(H)P ligand were synthesized. The structures of two complexes were characterized by X-ray crystallography and high resolution mass spectrometry. The catalytic performances of cobalt complexes a and b for asymmetric transfer hydrogenation (ATH) of ketones under mild conditions were evaluated using 2-propanolisopropanol as solvent and hydrogen source after being activated by 8 equivalents of base. Complex a showed a good reactivity for reduction of ketones, with a turnover number (TON) of up to 555, and a maximum enantiomeric excess (ee) value of up to 91 %. Complex b exhibited inertness for hydrogenation of ketones. Electronic structure studies on a and b were conducted to account for the function of ligands on the catalytic performances.
- Huo, Shangfei,Chen, Hong,Zuo, Weiwei
-
supporting information
p. 37 - 42
(2020/10/21)
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- Manganese catalyzed asymmetric transfer hydrogenation of ketones
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The asymmetric transfer hydrogenation (ATH) of a wide range of ketones catalyzed by manganese complex as well as chiral PxNy-type ligand under mild conditions was investigated. Using 2-propanol as hydrogen source, various ketones could be enantioselectively hydrogenated by combining cheap, readily available [MnBr(CO)5] with chiral, 22-membered macrocyclic ligand (R,R,R',R')-CyP2N4 (L5) with 2 mol% of catalyst loading, affording highly valuable chiral alcohols with up to 95% ee.
- Zhang, Guang-Ya,Ruan, Sun-Hong,Li, Yan-Yun,Gao, Jing-Xing
-
supporting information
p. 1415 - 1418
(2020/11/20)
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- Amino Acid-Functionalized Metal-Organic Frameworks for Asymmetric Base–Metal Catalysis
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We report a strategy to develop heterogeneous single-site enantioselective catalysts based on naturally occurring amino acids and earth-abundant metals for eco-friendly asymmetric catalysis. The grafting of amino acids within the pores of a metal-organic framework (MOF), followed by post-synthetic metalation with iron precursor, affords highly active and enantioselective (>99 % ee for 10 examples) catalysts for hydrosilylation and hydroboration of carbonyl compounds. Impressively, the MOF-Fe catalyst displayed high turnover numbers of up to 10 000 and was recycled and reused more than 15 times without diminishing the enantioselectivity. MOF-Fe displayed much higher activity and enantioselectivity than its homogeneous control catalyst, likely due to the formation of robust single-site catalyst in the MOF through site-isolation.
- Newar, Rajashree,Akhtar, Naved,Antil, Neha,Kumar, Ajay,Shukla, Sakshi,Begum, Wahida,Manna, Kuntal
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p. 10964 - 10970
(2021/03/29)
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- Chiral Iron(II)-Catalysts within Valinol-Grafted Metal-Organic Frameworks for Enantioselective Reduction of Ketones
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The development of highly efficient and enantioselective heterogeneous catalysts based on earth-abundant elements and inexpensive chiral ligands is essential for environment-friendly and economical production of optically active compounds. We report a strategy of synthesizing chiral amino alcohol-functionalized metal-organic frameworks (MOFs) to afford highly enantioselective single-site base-metal catalysts for asymmetric organic transformations. The chiral MOFs (vol-UiO) were prepared by grafting of chiral amino alcohol such as l-valinol within the pores of aldehyde-functionalized UiO-MOFs via formation of imine linkages. The metalation of vol-UiO with FeCl2 in THF gives amino alcohol coordinated octahedral FeII species of vol-FeCl(THF)3 within the MOFs as determined by X-ray absorption spectroscopy. Upon activation with LiCH2SiMe3, vol-UiO-Fe catalyzed hydrosilylation and hydroboration of a range of aliphatic and aromatic carbonyls to afford the corresponding chiral alcohols with enantiomeric excesses up to 99%. Vol-UiO-Fe catalysts have high turnover numbers of up to 15 ?000 and could be reused at least 10 times without any loss of activity and enantioselectivity. The spectroscopic, kinetic, and computational studies suggest iron-hydride as the catalytic species, which undergoes enantioselective 1,2-insertion of carbonyl to give an iron-alkoxide intermediate. The subsequent σ-bond metathesis between Fe-O bond and Si-H bond of silane produces chiral silyl ether. This work highlights the importance of MOFs as the tunable molecular material for designing chiral solid catalysts based on inexpensive natural feedstocks such as chiral amino acids and base-metals for asymmetric organic transformations.
- Akhtar, Naved,Antil, Neha,Begum, Wahida,Chauhan, Manav,Kumar, Ajay,Manna, Kuntal,Newar, Rajashree
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p. 10450 - 10459
(2021/08/31)
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- Tridentate nitrogen phosphine ligand containing arylamine NH as well as preparation method and application thereof
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The invention discloses a tridentate nitrogen phosphine ligand containing arylamine NH as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. The tridentate nitrogen phosphine ligand disclosed by the invention is the first case of tridentate nitrogen phosphine ligand containing not only a quinoline amine structure but also chiral ferrocene at present, a noble metal complex of the type of ligand shows good selectivity and extremely high catalytic activity in an asymmetric hydrogenation reaction, meanwhile, a cheap metal complex of the ligand can also show good selectivity and catalytic activity in the asymmetric hydrogenation reaction, and is very easy to modify in the aspects of electronic effect and space structure, so that the ligand has huge potential application value. A catalyst formed by the ligand and a transition metal complex can be used for catalyzing various reactions, can be used for synthesizing various drugs, and has important industrial application value.
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Paragraph 0095-0102; 0105-0109
(2021/06/26)
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- Method for synthesizing chiral secondary alcohol compound
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The invention discloses a method for synthesizing a chiral secondary alcohol compound. The method comprises the following step of: reacting a ketone compound in an aprotic organic solvent at room temperature and inert gas atmosphere under the action of a chiral cobalt catalyst and an activating agent by taking a combination of bis(pinacolato)diboron and alcohol or water as a reducing agent to obtain the chiral secondary alcohol compound. According to the method disclosed by the invention, a combination of pinacol diborate and alcohol or water which are cheap, stable and easy to obtain is taken as a reducing agent, and a ketone compound is efficiently reduced to synthesize a corresponding chiral secondary alcohol compound in an aprotic organic solvent under the action of a chiral cobalt catalyst; in a chiral cobalt catalyst adopted by the method, when a chiral ligand is PAOR, an activating agent is NaBHEt3 or NaOtBu and an adopted raw material is aromatic ketone, the yield is 80% or above, and the optical purity is 90% or above; and when the adopted raw material is alkane ketone, the yield can reach 70% or above, and the optical purity can reach 80% or above.
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-
Paragraph 0038-0043; 0094-0098
(2021/05/29)
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- Binaphthyl-prolinol chiral ligands: Design and their application in enantioselective arylation of aromatic aldehydes
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Binaphthyl-prolinol ligands were designed and applied in enantioselective arylation of aromatic aldehydes and sequential arylation-lactonization of methyl 2-formylbenzoate. Under optimized conditions, the reactions provided the desired diarylmethanols and 3-aryl phthalides in up to 96% yields with up to 99% ee and up to 89% yields with up to 99% ee, respectively. In particular, essentially optically pure 3-aryl phthalides (over 99% ee) were obtained in large quantities through recrystallization. This journal is
- Yao, Chao,Chen, Yaoqi,Sun, Ruize,Wang, Chao,Huang, Yue,Li, Lin,Li, Yue-Ming
-
supporting information
p. 3644 - 3655
(2021/05/04)
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- Highly Enantioselective Cobalt-Catalyzed Hydroboration of Diaryl Ketones
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A highly enantioselective cobalt-catalyzed hydroboration of diaryl ketones with pinacolborane was developed using chiral imidazole iminopyridine as a ligand to access chiral benzhydrols in good to excellent yields and ee. This protocol could be carried out in a gram scale under mild reaction conditions with good functional group tolerance. Chiral biologically active 3-substituted phthalide and (S)-neobenodine could be easily constructed through asymmetric hydroboration as a key step.
- Liu, Wenbo,Guo, Jun,Xing, Shipei,Lu, Zhan
-
supporting information
p. 2532 - 2536
(2020/04/02)
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- Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth Metal Complexes Containing Trost Ligands
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Four chiral dinuclear rare-earth metal complexes [REL1]2 (RE = Y(1), Eu(2), Nd(3), La (4)) stabilized by Trost proligand H3L1 (H3L1 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) were first prepared, and all were characterized by X-ray diffraction. Complex 4 was employed as the catalyst for enantioselective hydroboration reaction of substituted ketones, and the corresponding secondary alcohols with excellent yields and high ee values were obtained using reductant HBpin. The same result was also achieved using the combination of lanthanium amides La[N(SiMe3)2]3 with Trost proligand H3L1 in a 1:1 molar ratio. The experimental findings and DFT calculation revealed the possible mechanism of the enantioselective hydroboration reaction and defined the origin of the enantioselectivity in the current system.
- Lu, Chengrong,Sun, Yuli,Xue, Mingqiang,Zhao, Bei
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p. 10504 - 10513
(2020/09/23)
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- Asymmetric hydrogenation method of di (hetero) aryl ketone compound
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The invention belongs to the technical field of chemical synthesis preparation, relates to asymmetric catalysis of compounds, and particularly relates to an asymmetric hydrogenation method of a di (hetero) aryl ketone compound. The asymmetric hydrogenatio
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-
Paragraph 0042-0044; 0047-0051; 0053-0057; 0104-0105
(2020/12/08)
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- Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
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Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
- Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
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p. 8796 - 8801
(2020/11/13)
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- Enantioselective Si-H Insertion Reactions of Diarylcarbenes for the Synthesis of Silicon-Stereogenic Silanes
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We report the first example of enantioselective, intermolecular diarylcarbene insertion into Si-H bonds for the synthesis of silicon-stereogenic silanes. Dirhodium(II) carboxylates catalyze an Si-H insertion using carbenes derived from diazo compounds where selective formation of an enantioenriched silicon center is achieved using prochiral silanes. Fourteen prochiral silanes were evaluated with symmetrical and prochiral diazo reactants to produce a total of 25 novel silanes. Adding an ortho substituent on one phenyl ring of a prochiral diazo enhances enantioselectivity up to 95:5 er with yields up to 98percent. Using in situ IR spectroscopy, the impact of the off-cycle azine formation is supported based on the structural dependence for relative rates of diazo decomposition. A catalytic cycle is proposed with Si-H insertion as the rate-determining step, supported by kinetic isotope experiments. Transformations of an enantioenriched silane derived from this method, including selective synthesis of a novel sila-indane, are demonstrated.
- Jagannathan, Jake R.,Fettinger, James C.,Shaw, Jared T.,Franz, Annaliese K.
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supporting information
p. 11674 - 11679
(2020/07/27)
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- Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates
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A palladium-catalyzed intramolecular Mizoroki-Heck-type reaction of diarylmethyl tert-butyl carbonates has been developed. The reaction proceeds under external base-free, neutral conditions to form the corresponding methyleneindanes in good yields only with liberation of CO2 and tBuOH. The resulting exo-methylene moiety is reactive and thus a good synthetic handle for further manipulations. Additionally, the asymmetric synthesis is also possible through a Pd/chiral Mandyphos ligand-mediated kinetic resolution. To the best of our knowledge, this is the first successful example of catalytic enantioselective Mizoroki-Heck-type reaction of secondary benzyl electrophiles. (Figure presented.).
- Matsude, Akihiro,Hirano, Koji,Miura, Masahiro
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supporting information
p. 518 - 522
(2019/12/24)
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- Isosterically designed chiral catalysts: Rationale, optimization and their application in enantioselective nucleophilic addition to aldehydes
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Proline-based N,N′-dioxide ligands were designed on the basis of isosteric approach, and were successfully applied in enantioselective nucleophilic addition to aldehydes. In the presence of 10 mol% of chiral ligand 1b, enantioselective addition of diethylzinc to aldehydes provided the corresponding secondary alcohols in up to 90% isolated yield and up to 99% ee. Similarly, using 3e as chiral ligand, enantioselective arylation and alkynylation of aldehydes also proceeded readily, leading to the desired chiral alcohols in up to 92% isolated yield at 99% ee and 80% isolated yields and up to 84% ee, respectively. The current work would shed light on expanding the structure diversity in the design of chiral ligands and chiral catalysts.
- Gao, En,Li, Qiao,Duan, Lili,Li, Lin,Li, Yue-Ming
-
supporting information
(2020/10/20)
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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; 0606
(2020/07/13)
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- A Direct Br?nsted Acid-Catalyzed Azidation of Benzhydrols and Carbohydrates
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Benzhydryl alcohols were converted into their corresponding diarylazidomethane analogues using azidotrimethylsilane (TMSN3) in the presence of a catalytic amount of a Br?nsted acid HBF4·OEt2. The azidation reactions proceeded in high yields and demonstrated excellent functional group tolerance to electron-donating and electron-withdrawing substituents. In addition, a range of unprotected functional groups including amine, amide, aldehyde and alcohol were well-tolerated. Furthermore, this methodology was successfully applied to carbohydrates for the preparation of the corresponding azide derivatives.
- Regier, Jeffery,Maillet, Robert,Bolshan, Yuri
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p. 2390 - 2396
(2019/04/14)
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- Highly Enantioselective Synthesis of Chiral Benzhydrols via Manganese Catalyzed Asymmetric Hydrogenation of Unsymmetrical Benzophenones 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 asymmetrical hydrogenation of unsymmetrical benzophenones with outstanding activity (up to 13 000 TON) and excellent enantioselectivity (up to >99% ee). This protocol uses K2CO3 as an industrially desirable base and features a wide substrate scope and functional group tolerance. Moreover, the imine group in the catalyst is crucial for accessing high activities and good enantioselectivities.
- Ling, Fei,Hou, Huacui,Chen, Jiachen,Nian, Sanfei,Yi, Xiao,Wang, Ze,Song, DIngguo,Zhong, Weihui
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supporting information
p. 3937 - 3941
(2019/06/08)
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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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- Substituent Position-Controlled Stereoselectivity in Enzymatic Reduction of Diaryl- and Aryl(heteroaryl)methanones
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We report here the discovery of a novel ketoreductase (KRED), named KmCR2, with a broad substrate spectrum on bioreduction of sterically bulky diaryl- and aryl(heteroaryl)methanones. The position of the substituent on aromatic rings (meta versus para or ortho) was revealed to control the stereospecificity of KmCR2. The stereoselective preparation of both enantiomers of diaryl- or aryl(heteroaryl)methanols using strategically engineered substrates with a traceless directing group (bromo group) showcased the potential application of this substrate-controlled bioreduction reaction. The combined use of substrate engineering and protein engineering, was demonstrated to be a useful strategy in efficiently improving stereoselectivity or switching stereopreference of enzymatic processes. (Figure presented.).
- Li, Zhining,Wang, Zexu,Wang, Yuhan,Wu, Xiaofan,Lu, Hong,Huang, Zedu,Chen, Fener
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supporting information
p. 1859 - 1865
(2019/03/07)
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- Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo- and Enantio-Selective Aryl Transfer Reagents
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An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.
- Chaumont-Olive, Pauline,Rouen, Mathieu,Barozzino-Consiglio, Gabriella,Ben Abdeladhim, Amel,Maddaluno, Jacques,Harrison-Marchand, Anne
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supporting information
p. 3193 - 3197
(2019/01/25)
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- Asymmetric Catalysis Using Aromatic Aldehydes as Chiral α-Alkoxyalkyl Anions
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We have developed a new umpolung strategy for catalytically forming a chiral α-alkoxyalkyl anion from an aromatic aldehyde for use in asymmetric synthesis. The reaction between aromatic aldehydes and aryl or allyl electrophiles with a silylboronate utilizing a chiral copper-N-heterocyclic carbene catalyst and a palladium-bisphosphine catalyst in a synergistic manner occurred with high enantioselectivities to deliver the three-component coupling products, chiral silyl-protected secondary alcohol derivatives. Our method features the catalytic generation of enantioenriched chiral α-alkoxyalkylcopper(I) intermediates from aldehydes and their subsequent palladium-catalyzed stereospecific cross-coupling.
- Yabushita, Kenya,Yuasa, Akihiro,Nagao, Kazunori,Ohmiya, Hirohisa
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supporting information
p. 113 - 117
(2019/01/08)
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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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- Enantioselective Reduction of Ketones Catalyzed by Rare-Earth Metals Complexed with Phenoxy Modified Chiral Prolinols
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Enantioselective reduction of ketones and α,β-unsaturated ketones by pinacolborane (HBpin) has been well-established by using chiral rare-earth metal catalysts with phenoxy modified prolinols. A number of highly optically active alcohols were obtained from reduction of simple ketones catalyzed by ytterbium complex 1 [L4Yb(L4H)] (H2L4 = (S)-2- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol). Moreover, α,β-unsaturated ketones were selectively reduced to a wide range of chiral allylic alcohols with excellent yields, high enantioselectivity, and complete chemoselectivity, catalyzed by a single component chiral ytterbium complex 2 [L1Yb(L1H)] (H2L1 = (S)-2,4-di-tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol).
- Song, Peng,Lu, Chengrong,Fei, Zenghui,Zhao, Bei,Yao, Yingming
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p. 6093 - 6100
(2018/05/23)
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- A Ferrocene-Based NH-Free Phosphine-Oxazoline Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
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A new type of ferrocene-based phosphine-oxazoline ligand has been prepared over a few simple steps. An iridium complex of this ligand is air stable and exhibits excellent performance for the asymmetric hydrogenation of simple ketones (up to 98% yield, up to 99% ee, and 20?000 S/C). Exo-α,β-unsaturated cyclic ketones could be regiospecifically hydrogenated to give chiral allylic alcohols with good results. This study indicates that P,N-ligands can also efficiently promote Ir-catalyzed asymmetric hydrogenation without NH-hydrogen-bonding assistance.
- Wang, Yanzhao,Yang, Guoqiang,Xie, Fang,Zhang, Wanbin
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supporting information
p. 6135 - 6139
(2018/09/27)
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- Chiral Lithium Amido Zincates for Enantioselective 1,2-Additions: Auto-assembling Reagents Involving a Fully Recyclable Ligand
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A methodology consisting in carrying out enantioselective nucleophilic 1,2-additions (ee values up to 97 %) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto-assemble when mixing, in a 1:1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully recoverable thanks to a simple acid–base wash, allowing being recycled and re-use without loss of stereochemical information.
- Rouen, Mathieu,Chaumont, Pauline,Barozzino-Consiglio, Gabriella,Maddaluno, Jacques,Harrison-Marchand, Anne
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p. 9238 - 9242
(2018/06/04)
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- 1-Hydrosilatrane: A Locomotive for Efficient Ketone Reductions
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An efficient method for the reduction of ketones with 1-hydrosilatrane is described. In the presence of a Lewis base activator, the resulting secondary alcohols are rapidly formed in good to excellent yields (20 examples, 71–99 % yields). The relative bulkiness of 1-hydrosilatrane also enables the diastereoselective reduction of (–)-menthone to (+)-neomenthol, and the use of a chiral alkoxide activator can lead to the enantioselective reduction of prochiral ketones.
- Varjosaari, Sami E.,Skrypai, Vladislav,Suating, Paolo,Hurley, Joseph J. M.,Gilbert, Thomas M.,Adler, Marc J.
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supporting information
p. 229 - 232
(2017/01/24)
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- COMPOSITIONS AND METHODS FOR REDUCTION OF KETONES, ALDEHYDES AND IMINIUMS, AND PRODUCTS PRODUCED THEREBY
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A method of producing an alcohol, comprises reducing an aldehyde or a ketone with a hydridosilatrane. The reducing is carried out with an activator.
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Paragraph 0093-0094
(2018/01/20)
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- Asymmetric Transfer Hydrogenation of (Hetero)arylketones with Tethered Rh(III)-N-(p-Tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine Complexes: Scope and Limitations
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A series of new tethered Rh(III)/Cp? complexes containing the N-(p-tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine ligand have been prepared, characterized, and evaluated in the asymmetric transfer hydrogenation (ATH) of a wide range of (hetero)aryl ketones. The reaction was performed under mild conditions with the formic acid/triethylamine (5:2) system as the hydrogen source and provided enantiomerically enriched alcohols with good yields and high to excellent enantioselectivities. Although the nature of the substituents on the phenyl tethering ring did not alter the stereochemical outcome of the reaction, complexes bearing electron-donating groups exhibited a higher catalytic activity than those having electron-withdrawing groups. A scale-up of the ATH of 4-chromanone to the gram scale quantitatively delivered the reduced product with excellent enantioselectivity, demonstrating the potential usefulness of these new complexes.
- Zheng, Long-Sheng,Llopis, Quentin,Echeverria, Pierre-Georges,Férard, Charlène,Guillamot, Gérard,Phansavath, Phannarath,Ratovelomanana-Vidal, Virginie
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p. 5607 - 5615
(2017/06/07)
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- The inexpensive additive N-methylmorpholine effectively decreases the equivalents of nucleophiles in the catalytic highly enantioselective arylation of aryl aldehydes
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Highly enantioselective arylation of aryl aldehydes catalyzed by (S)-H8-BINOL-Ti(Oi-Pr)2 complex in the presence of N-methylmorpholine (NMM) as an effective and inexpensive additive is described for the first time. We found high enan
- Wang, Pei,Liu, Yue,Zhang, Ya-Lun,Da, Chao-Shan
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supporting information
p. 443 - 450
(2017/07/25)
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- Highly enantioselective asymmetric reactions involving zinc ions promoted by chiral aziridine alcohols
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Enantiomerically pure, chiral secondary and tertiary aziridine alcohols (including the aziridine analogue of ProPhenol—AziPhenol) have proven to be highly effective catalysts for enantioselective asymmetric reactions in the presence of zinc ions, including arylation of aromatic aldehydes, epoxidation of chalcone and addition of diethylzinc to aldehydes, leading to the desired chiral products in high chemical yields (up to 90%) and with ee's up to 90%. A higher catalytic activity of Prophenol-type bis(aziridine alcohol) in the aforementioned asymmetric transformations has been demonstrated.
- Jarzyński, Szymon,Utecht, Greta,Le?niak, Stanis?aw,Rachwalski, Micha?
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p. 1774 - 1779
(2017/11/16)
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- Chiral thiophosphoramide catalyzed asymmetric aryl transfer reactions for the synthesis of functional diarylmethanols
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In this investigation, chiral thiophosphoramide 3d was easily prepared from chiral (1R,2R)-1,2-diphenylethylenediamine and then applied as an efficient chiral ligand in the catalytic asymmetric arylation reactions of various aromatic aldehydes. The corresponding diarylmethanol products were produced with good to excellent yields (up to 98%) and enantioselectivities (up to 94%). The recovery of chiral ligand 3d could be as high as 96%.
- Wang, Yabai,Zong, Hua,Huang, Huayin,Song, Ling
-
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- Fine tuning of molecular and supramolecular properties of simple trianglimines-the role of the functional group
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Chiral, triangular poly-azamacrocycles (trianglimines) readily available from enantiomerically pure trans-1,2-diaminocyclohexane and various aromatic dialdehydes, differ in their nature and substitution pattern. The highly symmetrical macrocycle having two electron-donating groups attached to the aryl moieties is formed under thermodynamic control that fulfilled the so called entropy of symmetry rule. Conversely, from the 2-nitroterephthaldehyde a kinetic product of trivial C1 symmetry is solely obtained, whereas from 2-methoxyterepthaldehyde a mixture of C3- and C1-symmetrical macrocycles are formed. The factors that contribute to the mechanism of the macrocycle formation were determined on the basis of an experimental/theoretical approach. The non-symmetrical structure of the macrocycle resulted from a symmetrical intermediate that appeared during cyclocondensation. The chiroptical properties of the trianglimines were studied by means of experimental ECD and VCD methods supported by quantum-chemical calculations. The nitro-substituted trianglimine appeared to be a simple, low molecular weight supergelator forming in polar media of stable chiral organogels. The structure of the gel is affected by the nature and chirality of the dopant. The hexaimine macrocycles after reduction of the CN imine bonds formed trianglamines-useful chiral ligands in stereoselective synthesis. The Zn-trianglamine complexes were employed as catalysts for asymmetric hydrosilylation of prochiral ketones, providing products of enantiomeric excess up to 98%. This remains the best result obtained for Zn-diamine catalysed asymmetric hydrosilylation of ketones so far.
- Gajewy,Szymkowiak,Kwit
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p. 53358 - 53369
(2016/06/14)
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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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- Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts
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A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η6-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee.
- Touge, Taichiro,Nara, Hideki,Fujiwhara, Mitsuhiko,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 10084 - 10087
(2016/09/03)
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- Zinc-Catalyzed Enantioselective Hydrosilylation of Ketones and Imines under Solvent-Free Conditions
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The zinc acetate promoted asymmetric hydrosilylation of various ketones and imines under solvent-free conditions was examined by using an unprecedented low catalyst loading. Exposure of ketones to 0.05 mol % Zn-based chiral diamine complex in the presence of triethoxysilane afforded enantioenriched alcohols in excellent yields (up to 98 %) and enantioselectivities (up to 97 % ee). This methodology also allowed for the chemoselective 1,2-reduction of α,β-unsaturated ketones and imines.
- Szewczyk, Marcin,Bez?ada, Agata,Mlynarski, Jacek
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p. 3575 - 3579
(2016/12/14)
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- Enantioselective addition of organozinc reagents to carbonyl compounds catalyzed by a camphor derived chiral γ-amino thiol ligand
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In this article, the design and synthesis of the chiral camphor derived γ-amino thiol ligand 17 and its application in catalytic enantioselective carbon-carbon forming reactions through the addition of organozinc reagents to carbonyl compounds is described. The catalytic activity and enantioselectivity of ligand 17 is demonstrated in the enantioselective addition of various organozinc reagents to aldehydes and ketoesters, offering the corresponding alcohols in high yields and enantioselectivities. The role of the mercapto group in the highly enantioselective 1,2-addition reaction of organozincs to aldehyde is also discussed.
- Wu, Hsyueh-Liang,Wu, Ping-Yu,Cheng, Ying-Ni,Uang, Biing-Jiun
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p. 2656 - 2665
(2016/05/10)
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- Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones
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A bis-cyclometalated iridium(iii) complex with metal-centered chirality catalyzes the enantioselective transfer hydrogenation of ketones with high enantioselectivities at low catalyst loadings down to 0.002 mol%. Importantly, the rate of catalysis and enantioselectivity are markedly improved in the presence of a pyrazole co-ligand. The reaction is proposed to proceed via an iridium-hydride intermediate exploiting metal-ligand cooperativity (bifunctional catalysis).
- Tian, Cheng,Gong, Lei,Meggers, Eric
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supporting information
p. 4207 - 4210
(2016/03/19)
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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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- Iron-catalyzed asymmetric hydrosilylation of ketones
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A series of iron complexes of chiral iminopyridine-oxazoline (IPO) ligands have been synthesized. The most sterically hindered iron catalyst exhibits excellent activity (up to 99% yield) and high enantioselectivity (up to 93% ee) in asymmetric hydrosilylation of aryl ketones. This journal is
- Zuo, Ziqing,Zhang, Lei,Leng, Xuebing,Huang, Zheng
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supporting information
p. 5073 - 5076
(2015/03/30)
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- Cobalt-catalyzed asymmetric hydroboration of aryl ketones with pinacolborane
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The highly enantioselective cobalt-catalyzed hydroboration reaction of aryl ketones with HBpin was developed using iminopyridine oxazoline ligands. Halides, amines, ethers, sulfides, esters and amides are well tolerated under the mild reaction conditions, demonstrating its synthetic advantage. Substituted diaryl ketones could also be hydroborated with high enantioselectivity.
- Guo, Jun,Chen, Jianhui,Lu, Zhan
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supporting information
p. 5725 - 5727
(2015/03/30)
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- 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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- Nickel(0)-Catalyzed Enantio- and Diastereoselective Synthesis of Benzoxasiloles: Ligand-Controlled Switching from Inter- to Intramolecular Aryl-Transfer Process
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A highly enantioselective synthesis of 3-aryl-, vinyl-, and alkynyl-2,1-benzoxasiloles (up to 99.9% ee and 99% yield) was achieved via the sequential activation of an aldehyde and a silane by nickel(0). This strategy was applied to a simultaneous generation of carbon- and silicon-stereogenic centers with excellent selectivity (dr = 99:1) via diastereotopic aryl transfer. Initial mechanistic studies revealed the complete switching of an aryl-transfer process from an intermolecular (racemic synthesis in the presence of IPr) to an intramolecular (enantioselective synthesis using chiral NHC, L5) fashion. A plausible rationale for the switching of the aryl-transfer process is given by a preliminary DFT calculation, which suggests that the coordination of 1 to the nickel(0)/L5 fragment in an 2-arene:2-aldehyde fashion would be a key to the intramolecular process, while the formation of the corresponding intermediate is not possible in the presence of IPr. Owing to the chemically labile nature of its C-Si and O-Si bonds, enantioenriched benzoxasiloles are utilized for the synthesis of chiral building blocks and antihistaminic and anticholinergic drug molecules such as (R)-orphenadrine and (S)-neobenodine with no erosion of the enantiomeric excess.
- Kumar, Ravindra,Hoshimoto, Yoichi,Yabuki, Hayato,Ohashi, Masato,Ogoshi, Sensuke
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p. 11838 - 11845
(2015/09/28)
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- Zn(salen)-catalyzed enantioselective phenyl transfer to aldehydes and ketones with organozinc reagent
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Abstract A chiral zinc complex of salen was found to be an efficient catalyst for the phenyl transfer of organozinc reagent to aromatic aldehydes and ketones. High enantioselectivities were obtained in reactions of both aromatic aldehydes and ketones (up to 97% and 92% ee, respectively).
- Shimizu, Keisuke,Uetsu, Hidenori,Gotanda, Takashi,Ito, Katsuji
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p. 1238 - 1242
(2015/03/31)
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- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
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Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
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p. 9368 - 9373
(2015/02/19)
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- Diastereomeric aziridine carbinol catalyzed enantioselective arylation reaction: Toward the asymmetric synthesis of both enantiomers of chiral 3-aryl phthalide
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The diastereomeric aziridine carbinols are applied, respectively, as efficient chiral ligand in the catalysis of asymmetric arylation and sequential arylation-lactonization cascade. The two diastereomers, which are facilely synthesized from the same chiral source, function as pseudo enantiomers in arylation of aromatic aldehydes providing the different enantiomers of the diarylmethanols with almost the same excellent enantioselectivities. The arylation method is also carried out in tandem with lactonization process to afford a concise synthetic approach to both enantiomers of optically active 3-aryl phthalide.
- Song, Xixi,Hua, Yuan-Zhao,Shi, Jing-Guo,Sun, Ping-Ping,Wang, Min-Can,Chang, Junbiao
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p. 6087 - 6093
(2014/07/21)
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- Tropos amino alcohol mediated enantioselective aryl transfer reactions to aromatic aldehydes
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The preparation of new chiral amino alcohols that possess a flexible biphenylazepine moiety and can work as tropos catalysts, is presented. In these compounds, the sign of the induced axial chirality depends on the nature of stereogenic centers near the flexible fragment and can determine the stereochemical outcome in asymmetric reactions mediated by them. The efficiency of these new ligands has been explored in the asymmetric addition of arylzinc species prepared in situ to aromatic aldehydes. Among them, amino alcohol (1R,2S)-4 gave the best results and afforded optically active diarymethanols, which are precursors of well-known chiral drugs, in high yields and with enantioselectivity up to 96 %.
- Pisani, Laura,Bochicchio, Carmela,Superchi, Stefano,Scafato, Patrizia
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p. 5939 - 5945
(2015/03/30)
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- Synthesis of Ar-BINMOL ligands by [1,2]-wittig rearrangement to probe their catalytic activity in 1,2-addition reactions of aldehydes with Grignard reagents
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We have demonstrated a highly diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues. The present study demonstrates a unique cascade chirality transfer in a [1,2]-Wittig rearrangement that leads to chiral diols with three stereogenic centers, which include a chiral sp 3 center at the alcohol and C2-axial chirality. Screening these ligands in the arylation of aromatic aldehydes with Grignard reagents shows that the naphthyl-substituted BINMOL promotes the aryl transfer reaction in good yields (70-92 %) and moderate-to-good enantioselectivities (up to 72 % ee), and a series of control experiments substantiates that the axial chirality and the chiral sp3 center at the alcohol of the Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements. In addition, this study demonstrated the importance of the chiral sp3 center at the alcohol on Ar-BINMOL for the aryl transfer reaction. Finally, we found that the chiral Ar-BINMOL ligand 2h mediated the titanium-promoted 1,2-addition of MeMgBr to aldehydes to give the desired products in good yields with excellent enantioselectivities (up to 92 % ee). Ar-BINMOL ligands: A new diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues has been established through cascade chirality transfer of a [1,2]-Wittig rearrangement. The axial and sp3 central chirality of Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements in the 1,2-addition of aldehydes with Grignard reagents. Copyright
- Zheng, Long-Sheng,Jiang, Ke-Zhi,Deng, Yuan,Bai, Xing-Feng,Gao, Guang,Gu, Feng-Lei,Xu, Li-Wen
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p. 748 - 750
(2013/03/28)
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- Practical enantioselective arylation and heteroarylation of aldehydes with in situ prepared organotitanium reagents catalyzed by 3-aryl-H 8-BINOL-derived titanium complexes
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A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl- and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP-H 8-BINOL (3 d; DPP=3,5-diphenylphenyl) and DTBP-H8-BINOL (3 e; DTBP=3,5-di-tert-butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2-thienylmethanols can be synthesized enantioselectively by using commercially available 2-thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol % catalyst loading, demonstrating its preparative utility. Titanium does it! Titanium complexes derived from 3-aryl-H8-BINOLs exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %; see scheme). Copyright
- Uenishi, Ami,Nakagawa, Yuya,Osumi, Hironobu,Harada, Toshiro
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supporting information
p. 4896 - 4905
(2013/05/09)
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- Enhancement of enantioselectivity by alcohol additives in asymmetric hydrogenation with bis(oxazolinyl)phenyl ruthenium catalysts
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Bis(oxazolinyl)phenyl ruthenium(ii) complexes were found to catalyze asymmetric hydrogenation of ketones, in which chiral bulky alcohol additives showed significant enhancement of enantioselectivity even in protic solvents. The Royal Society of Chemistry 2012.
- Ito, Jun-Ichi,Teshima, Tomoki,Nishiyama, Hisao
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supporting information; experimental part
p. 1105 - 1107
(2012/03/08)
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- Preparation and catalytic performances of a molecularly imprinted RU-complex catalyst with an NH2 binding site on a SiO2 surface
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A catalyst surface with an active metal site, a shape-selective reaction space, and an NH2 binding site for o-fluorobenzophenone was designed and prepared by the molecular imprinting of a supported metal complex on a SiO2 surface. A ligand of a SiO2-supported Ru complex that has a similar shape to the product of o-fluorobenzophenone hydrogenation was used as a template. An NH2 binding site for o-fluorobenzophenone was spatially arranged on the wall of a molecularly imprinted cavity with a similar shape to the template. The structures of the SiO2-supported and molecularly imprinted Ru catalysts were characterized in a step-by-step manner by means of solid-state magic angle spinning (MAS) NMR, XPS, UV/Vis, N 2 adsorption, XRF, and Ru K-edge EXAFS. The molecularly imprinted Ru catalyst exhibited excellent shape selectivity for the transfer hydrogenation of benzophenone derivatives. It was found that the NH2 binding site on the wall of the molecularly imprinted cavity enhanced the adsorption of o-fluorobenzophenone, of which the reduction product was imprinted, whereas there was no positive effect in the case of o-methylbenzophenone, which cannot interact with the NH2 binding site through hydrogen bonding. Tailoring a pocket: A molecularly imprinted Ru-complex catalyst with an NH 2 binding site for o-fluorobenzophenone has been successfully designed and prepared on a SiO2 surface for shape-selective transfer hydrogenation (see scheme). Copyright
- Yang, Yong,Weng, Zhihuan,Muratsugu, Satoshi,Ishiguro, Nozomu,Ohkoshi, Shin-Ichi,Tada, Mizuki
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experimental part
p. 1142 - 1153
(2012/03/26)
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