- Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes
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The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B2pin2) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me4NF to activate B2pin2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.
- Tran, Hai N.,Stanley, Levi M.
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supporting information
p. 395 - 399
(2021/12/27)
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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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- C1-Symmetric PNP Ligands for Manganese-Catalyzed Enantioselective Hydrogenation of Ketones: Reaction Scope and Enantioinduction Model
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A family of ferrocene-based chiral PNP ligands is reported. These tridentate ligands were successfully applied in Mn-catalyzed asymmetric hydrogenation of ketones, giving high enantioselectivities (92%~99% ee for aryl alkyl ketones) as well as high efficiencies (TON up to 2000). In addition, dialkyl ketones could also be hydrogenated smoothly. Manganese intermediates that might be involved in the catalytic cycle were analyzed. DFT calculation was carried out to help understand the chiral induction model. The Mn/PNP catalyst could discriminate two groups with different steric properties by deformation of the phosphine moiety in the flexible 5-membered ring.
- Zeng, Liyao,Yang, Huaxin,Zhao, Menglong,Wen, Jialin,Tucker, James H. R.,Zhang, Xumu
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p. 13794 - 13799
(2020/11/30)
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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 terpene auxiliaries III: Spiroborate esters from (1R,2S,3R,5R)-3-amino-apopinan-2-ol as highly effective catalysts for asymmetric reduction of ketones with borane
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New spiroborate esters, derived from terpene amino alcohols, (S)-prolinol, and 2-aminoethanol, were employed as catalysts in the borane reduction of acetophenone and other aryl alkyl and halogenated ketones. The corresponding alcohols were obtained in high yields and with enantioselectivities up to 98% ee. The influence of the amino alcohol and the diol moieties of spiroborate on the reaction selectivity was examined. The catalyst load, the nature of the solvent, the borane source, and the reaction conditions were also investigated.
- ?wiklińska, Marta,Krzemiński, Marek P.,Tafelska-Kaczmarek, Agnieszka
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p. 1453 - 1458
(2015/12/09)
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- Iron catalyzed asymmetric hydrogenation of ketones
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Chiral molecules, such as alcohols, are vital for the manufacturing of fine chemicals, pharmaceuticals, agrochemicals, fragrances, and novel materials. These molecules need to be produced in high yield and high optical purity and preferentially catalytically. Among all the asymmetric catalytic reactions, asymmetric hydrogenation with H2 (AH) is the most widely used in the industry. With few exceptions, these AH processes use catalysts based on the three critical metals, rhodium, ruthenium, and iridium. Herein we describe a simple, industrially viable iron catalyst that allows for the AH of ketones, a process currently dominated by ruthenium and rhodium catalysts. By combining a chiral, 22-membered macrocyclic ligand with the cheap, readily available Fe 3(CO)12, a wide variety of ketones have been hydrogenated under 50 bar H2 at 45-65 C, affording highly valuable chiral alcohols with enantioselectivities approaching or surpassing those obtained with the noble metal catalysts. In contrast to AH by most noble metal catalysts, the iron-catalyzed hydrogenation appears to be heterogeneous.
- Li, Yanyun,Yu, Shenluan,Wu, Xiaofeng,Xiao, Jianliang,Shen, Weiyi,Dong, Zhenrong,Gao, Jingxing
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supporting information
p. 4031 - 4039
(2014/04/03)
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- 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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- Iron- and cobalt-catalyzed asymmetric hydrosilylation of ketones and enones with bis(oxazolinylphenyl)amine ligands
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Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetric hydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones.
- Inagaki, Tomohiko,Phong, Le Thanh,Furuta, Akihiro,Ito, Jun-Ichi,Nishiyama, Hisao
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supporting information; experimental part
p. 3090 - 3096
(2010/08/05)
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- Nonpeptide urotensin-II receptor antagonists: A new ligand class based on piperazino-phthalimide and piperazino-isoindolinone subunits
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We have discovered two related chemical series of nonpeptide urotensin-II (U-II) receptor antagonists based on piperazino-phthalimide (5 and 6) and piperazino-isoindolinone (7) scaffolds. These structure types are distinctive from those of U-II receptor antagonist series reported in the literature. Antagonist 7a exhibited single-digit nanomolar potency in rat and human cell-based functional assays, as well as strong binding to the human U-II receptor. In advanced pharmacological testing, 7a blocked the effects of U-II in vitro in a rat aortic ring assay and in vivo in a rat ear-flushmodel. Adiscussion of U-II receptor antagonist pharmacophores is presented, and a specifically defined model is suggested from tricycle 13, which has a high degree of conformational constraint.
- Lawson, Edward C.,Luci, Diane K.,Ghosh, Shyamali,Kinney, William A.,Reynolds, Charles H.,Qi, Jenson,Smith, Charles E.,Wang, Yuanping,Minor, Lisa K.,Haertlein, Barbara J.,Parry, Tom J.,Damiano, Bruce P.,Maryanoff, Bruce E.
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experimental part
p. 7432 - 7445
(2010/06/19)
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- A flexible route to chiral 2-endo-substituted 9-oxabispidines and their application in the enantioselective oxidation of secondary alcohols
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A new and flexible route to enantiomerically pure bi-and tricyclic 9-oxabispidines has been developed with use of (1R,5S)-7-methyl-2-oxo-9-oxa-3,7- diazabicyclo[33.1]nonane-3-carboxylic acid tert-butyl ester as the common late-stage intermediate. The 9-oxabispidines synthesized were evaluated as the chiral ligands in the Pd(II)-catalyzed oxidative kinetic resolution of secondary alcohols giving good to excellent selectivity factors of up to 19.
- Breuning, Matthias,Steiner, Melanie,Mehler, Christian,Paasche, Alexander,Hein, David
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supporting information; experimental part
p. 1407 - 1410
(2009/07/11)
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- A class of readily available optically pure 7,7′-disubstituted BINAPs for asymmetric catalysis
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A class of optically pure 7,7′-disubstituted BINAPs have been prepared starting with a catalytic asymmetric oxidative coupling reaction. A general, concise, and straightforward synthetic procedure has been established, and is suitable for all optically pure 7,7′-disubstituted BINAPs 1a-h, regardless of the substituents' structure in the 7,7′-positions. The catalytic potential of this class of ligands has been investigated in the highly enantioselective Rh-catalyzed 1,4-addition of aryl boronic acids to enones (up to 99.8% ee), and Ru-catalyzed asymmetric hydrogenation of simple aromatic ketones (up to S/C=100,000, up to 98% ee) and β-ketoesters (up to S/C=10,000, up to 99.8% ee), respectively.
- Yuan, Wei-Cheng,Cun, Lin-Feng,Mi, Ai-Qiao,Jiang, Yao-Zhong,Gong, Liu-Zhu
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experimental part
p. 4130 - 4141
(2009/09/30)
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- UROTENSIN II RECEPTOR ANTAGONISTS
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The invention is directed to Urotensin II antagonists. More specifically, the present invention relates to certain novel compounds, methods for preparing compounds, compositions, intermediates and derivatives thereof and methods for treating Urotensin-II mediated disorders. Pharmaceutical and veterinary compositions and methods of treating cardiovascular disorders and various other disease states or conditions using compounds of the invention are also described.
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Page/Page column 201-202
(2010/11/28)
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- New paracyclophane phosphine for highly enantioselective ruthenium-catalyzed hydrogenation of prochiral ketones
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The synthesis of a new paracyclophane phosphine is described. This ligand was highly efficient in the ruthenium-catalyzed asymmetric hydrogenation of various aromatic and heteroaromatic ketones. Georg Thieme Verlag Stuttgart.
- Cheemala, Murthy N.,Gayral, Maud,Brown, John M.,Rossen, Kai,Knochel, Paul
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p. 3877 - 3885
(2008/09/18)
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- Rhodium-catalyzed asymmetric transfer hydrogenation of aryl alkyl ketones employing ligands derived from amino acids
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The combination of (pentamethylcyclopentadienyl)rhodium dichloride dimer [{RhCl2Cp*}2] and pseudodipeptide ligands, formed from N-Boc protected amino acids and amino alcohols, resulted in efficient and selective catalysts for the asymmetric transfer hydrogenation of ketones in 2-propanol. A number of different secondary alcohols was obtained in high yields and in excellent enantioselectivity using these in situ formed catalysts. Deuterium-labeling experiments showed that the hydride transfer reaction occurs via the monohydridic route.
- Wettergren, Jenny,Zaitsev, Alexey B.,Adolfsson, Hans
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p. 2556 - 2562
(2008/09/19)
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- Enantioswitchable catalysts for the asymmetric transfer hydrogenation of aryl alkyl ketones
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(Chemical Equation Presented) A subtle change in the ligand structure, replacing the carbonyl oxygen with sulfur in simple α-amino acid amides, resulted in a dramatic activity and selectivity improvement in the rhodium- or ruthenium-catalyzed reduction of ketones under hydrogen transfer conditions. In addition, in most cases, a switch of the product's absolute configuration was observed on going from amides to the corresponding thioamides. Under optimized conditions, we obtained the secondary alcohol products in high yield and enantioselectivity (up to 97% ee) using only 0.25 mol % catalyst loading.
- Zaitsev, Alexey B.,Adolfsson, Hans
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p. 5129 - 5132
(2007/10/03)
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- A simple protocol for the one pot synthesis of chiral secondary benzylic alcohols by catalytic enantioselective reduction of aromatic ketones
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A simple and efficient protocol for the one-pot catalytic enantioselective reduction of prochiral aromatic ketones mediated by in situ prepared catalysis derived from (S)-(-)-diphenyl-pyrrolidin-2-yl-methanol, is reported.
- Ponzo, Viviana L.,Kaufman, Teodoro S.
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p. 1128 - 1130
(2007/10/03)
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- Resolution of methylarylmethanols via oxidation with Nocardia corallina
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Ten different racemates of methylarylmethanols were subjected to whole cells of Nocardia corallina B-276 to give, via enantioselective oxidations, the corresponding ketone and the enantiomerically enriched secondary alcohol in moderate yields and excellent e.e.s. The configuration of the resulting alcohol is (R). This procedure permits a very good separation of the racemates of meta- and para-monosubstituted methylarylmethanols.
- Perez, Herminia I.,Luna, Hector,Manjarrez, Norberto,Solis, Aida
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p. 1709 - 1712
(2007/10/03)
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- Practical and efficient procedure for the in situ preparation of B-alkoxyoxazaborolidines. Enantioselective reduction of prochiral ketones
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A new method for the in situ elaboration of B-alkoxyoxazaborolidines is presented. Their use in the enantioselective reduction of prochiral aromatic ketones provides excellent chemical and optical yields of chiral alcohols.
- Ponzo, Viviana L.,Kaufman, Teodoro S.
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p. 495 - 496
(2007/10/03)
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- New planar chiral P,N-ligands containing tricarbonyl(arene)chromium for enantioselective asymmetric hydroboration of styrenes
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Optically active (1,2-disubstituted arene) chromium tricarbonyl complexes 2A-2D with a pyridyl and a phosphorus group in the two ortho benzylic positions have been stereoselectively synthesized from a commercially available (+)-(4,6-O-benzylidene)methyl-α-D-glucopyranoside. These chromium complexes have been used as chiral ligands in the preparation of rhodium catalysts for the hydroboration of styrene derivatives. High enantioselectivities were observed in the hydroboration of vinylarenes.
- Son, Seung Uk,Jang, Hye-Young,Han, Jin Wook,Lee, In Su,Chung, Young Keun
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p. 347 - 354
(2007/10/03)
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- A convenient and economical method for the preparation of DIP-chloride(TM) and its application in the asymmetric reduction of aralkyl ketones
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A convenient and economical in situ preparation of DIP-chloride(TM) from NaBH4, BCl3 and α-pinene is described. Its application in the asymmetric reduction of representative aralkyl ketones is presented.
- Zhao, Mangzhu,King, Anthony O.,Larsen, Robert D.,Verhoeven, Thomas R.,Reider, Paul J.
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p. 2641 - 2644
(2007/10/03)
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- The first chiral version of Jackson N-benzyl-N-tosylaminoacetal cyclization. A new enantioselective total synthesis of 1-S-(-)-salsolidine
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The first chiral version of Jackson N-benzyl-N-tosylaminoacetal cyclization, enabling a new and efficient enantioselective total synthesis of 1-S-(-)-salsolidine, is reported. Chirality was introduced by oxazaborolidine-catalyzed reduction of an aralkyl ketone, coupled with a Mitsunobu-type amination of the resulting benzylic alcohol, resulting in complete configurational inversion of the latter.
- Ponzo, Viviana L.,Kaufman, Teodoro S.
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p. 9105 - 9108
(2007/10/02)
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