- Enantioselective reduction of prochiral ketones by chromium(II) complexes with amino acid ligands as the source of chirality
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Prochiral ketones were reduced to enantiomerically enriched secondary alcohols by Cr(II)[L-amino acid] complexes in good yields and moderate enantioselectivity.
- Patonay,Hajdu,Jeko,Levai,Micskei,Zucchi
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Read Online
- Copper-Catalyzed Asymmetric Hydroboration of 2 H-Chromenes Using a Chiral Diphosphine Ligand
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A highly regioselective asymmetric hydroboration of 2H-chromenes catalyzed by the complex of CuCl and diphosphine ligand (S,R)-DuanPhos has been realized under mild conditions to produce 3-boryl chromans, achieving good yields and excellent enantioselectivities up to 96% ee. This work provides an efficient approach to the synthesis of chiral 3-boryl chromans and derivatives.
- Li, Xiufen,Wang, Chaoqiong,Song, Jianqiao,Yang, Zhihong,Zi, Guofu,Hou, Guohua
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- Half-sandwich Ru (II) complexes containing (N, O) Schiff base ligands: Catalysts for base-free transfer hydrogenation of ketones
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Two new half-sandwich Ru (II)(p-cymene) complexes (1 and 2) containing dopamine-based (N, O) Schiff base ligands (L1H and L2H) were synthesized and characterized by FT-IR, UV–Visible and 1H & 13C NMR spectral techniques, and elemental analyses. The spectroscopic and analytical data revealed monobasic bidentate coordination of the ligands with Ru ion. The molecular structures of L1H, L2H and 2 were further confirmed by single crystal X-ray diffraction study. Complexes 1 and 2?have been employed as catalysts in the transfer hydrogenation of ketones using 2-propanol as a hydrogen source at 85?°C under base-free condition. Good to the excellent yield of secondary alcohols, gram scale synthesis, and high TON and TOF made this catalytic system interesting.
- Satheesh,Sathish Kumar, Pushpanathan N.,Kumara, P. Raghavendra,Karvembu, Ramasamy,Hosamani, Amar,Nethaji
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- Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
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A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
- Oestreich, Martin,Seliger, Jan
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supporting information
p. 247 - 251
(2020/10/29)
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- Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
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Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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p. 7652 - 7666
(2021/12/13)
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- Diboron-Mediated Rhodium-Catalysed Transfer Hydrogenation of Alkenes and Carbonyls
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A diboron-mediated rhodium-catalysed transfer hydrogenation system using water as the hydrogen donor is developed. In addition to a series of alkenes with good functional group tolerance, this rhodium-based catalytic system also effectively reduces aldehydes and ketones. A plausible mechanism involving the RhI-catalysed hydrogen generation and Rh0-catalysed hydrogenation is proposed for the reaction.
- Lin, Xiao,Wang, Yuhan,Hu, Yan,Zhu, Wanjiang,Dou, Xiaowei
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supporting information
p. 1046 - 1049
(2020/02/25)
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- Enantioselective Synthesis of 4-Cyanotetrahydroquinolines via Ni-Catalyzed Hydrocyanation of 1,2-Dihydroquinolines
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A Ni-catalyzed asymmetric hydrocyanation that enables the formation of 4-cyanotetrahydroquinolines in good yields with excellent enantioselectivities is presented herein. A variety of functional groups are well-tolerated, and a gram-scale reaction supports the synthetic potential of the transformation. Additionally, several crucial intermediates for pharmaceutically active agents, including a PGD2 receptor antagonist, are now accessible through asymmetric synthesis using this new protocol.
- Fang, Xianjie,Gao, Jihui,Jiao, Mingdong
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supporting information
(2020/11/18)
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- Palladium Complexes Bearing Chiral bis(NHC) Chelating Ligands on a Spiro Scaffold: Synthesis, Characterization, and Their Application in the Oxidative Kinetic Resolution of Secondary Alcohols
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A series of chiral bis-N-heterocyclic carbene ligands H2[(S)-1a-d]X2 (X = Br, I) on a spiro scaffold and their palladium complexes (S)-2a-d and (S)-3a,b were prepared and applied in the enantioselective oxidative kinetic resolution of secondary alcohols. The corresponding alcohols can be obtained in high yields with moderate to excellent ee values.
- Zhang, Dao,Yu, Jueqin
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p. 605 - 613
(2020/02/13)
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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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- Ruthenium(II)-Chitosan, an Enantioselective Catalyst for the Transfer Hydrogenation of N-Heterocyclic Ketones
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The present study aimed at extending the applicability of a recently developed stereoselective catalytic system to the preparation of optically enriched N-heterocyclic alcohols. Chiral ruthenium catalyst formed in situ using the chitosan biopolymer as ligand, which provided good results in the transfer hydrogenation of heterobicyclic compounds, such as 4-chromanone and 4-thiochromanone, was used in reactions of various N-containing prochiral ketones. High enantioselectivities were reached in transfer hydrogenations of bicyclic compounds bearing nitrogen either in aromatic or cycloaliphatic moieties, provided that the amino group was protected or shielded by a nearby substituent. Results were rationalized by interactions of the nitrogen with the metal and/or ligand. N-containing bicyclic compounds having heteroatoms in both rings were also prepared and tested. The detrimental effect of the pyridyl moiety was compensated by the beneficial influence of the heteroatom in the cycloaliphatic ring, as indicated by high rates and good enantioselectivities obtained in reactions of these compounds. Preparation of several N-heterocyclic alcohols, in good yields and high optical purities was achieved using Ru(II)-chitosan complex.
- Kolcsár, Vanessza Judit,Fül?p, Ferenc,Sz?ll?si, Gy?rgy
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p. 2725 - 2731
(2019/05/24)
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- Oxygen mediated highly efficient cobalt(ii) porphyrin-catalyzed reduction of functional chromones: experimental and computational studies
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The highly efficient oxygen mediated reduction of functional chromones with sodium borohydride (NaBH4) catalyzed by cobalt(ii) porphyrins afforded biologically active chroman-4-ols as the reduction products in 80-98% yields. Oxygen assists in the formation of hydridocobalt(iii) porphyrin as a key intermediate, which releases hydride rapidly to reduce the chromones. Additionally, the correlation between quantum calculation results of the catalysts' conversions, yields, times and logarithms of the rate constants for the oxygen assisted reduction reaction was studied. The mechanism of the reaction was also justified by establishing a quantitative relationship between the rate constant, the α-HOMO orbital of the catalytic complex and the stabilization energy of the complex with oxygen.
- Poonam,Kumari, Pratibha,Grishina, Maria,Potemkin, Vladimir,Verma, Abhishek,Rathi, Brijesh
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p. 5228 - 5238
(2019/03/29)
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- TRI-SUBSTITUTED ARYL AND HETEROARYL DERIVATIVES AS MODULATORS OF PI3-KINASE AND AUTOPHAGY PATHWAYS
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The present disclosure relates to tri-substituted aryl and heteroaryl derivatives, pharmaceutical compositions containing them, and methods of using them, including methods for modulating autophagy or preventing, reversing, slowing or inhibiting the PI3K-AKT-MTOR pathway, and methods of treating diseases that are associated with autophagy or the PI3K-AKT-MTOR pathway.
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Paragraph 0358
(2019/11/04)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- Diastereoselective Synthesis of Cyclic sp 3 -Enriched cis -β-Alkoxysulfonyl Chlorides
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A three-step synthesis of β-alkoxy-substituted alicyclic sulfonyl chlorides from cyclic alkenes and alcohols is reported. The scope of the method was studied for a range of the substrates with various steric and electronic properties. The title compounds were obtained on a hundred-gram scale in up to 52% overall yield scale as single cis -diastereomers.
- Sokolov, Andriy,Golovach, Sergey,Kozlinsky, Ihor,Dolia, Krystyna,Tolmachev, Andrey A.,Kuchkovska, Yuliya,Grygorenko, Oleksandr O.
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supporting information
p. 848 - 858
(2019/02/10)
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- Oxidative β-Halogenation of Alcohols: A Concise and Diastereoselective Approach to Halohydrins
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β-Halohydrins bearing transformable halo- and hydroxyl groups, are easily converted into various valuable blocks in organic and pharmaceutical synthesis. A diastereoselective β-halogenation of benzylic alcohols was achieved under simple and low-cost conditions, which provided a direct synthesis of β-halohydrins. The simple reaction conditions, easily available reagents, high diastereoselectivities, and additional oxidant-free make this reaction very attractive and practical.
- Ai, Lingsheng,Wang, Weijin,Wei, Jialiang,Li, Qing,Song, Song,Jiao, Ning
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supporting information
p. 437 - 441
(2019/02/26)
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- Preparation method of chroman-6-sulfonyl chloride
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The invention relates to a preparation method of chroman-6-sulfony chloride, which mainly solves the technical problem that a compound is lack of an industrialized synthetic method. The preparation method comprises three steps: step 1, dissolving chroman-4-ketone in methanol, adding sodium borohydride at a low temperature, and reacting to obtain chroman-4-ol; step 2, dissolving the chroman-4-ol indichloromethane, and successfully adding triethyl silicane and trifluoroacetic acid at the low temperature to react and to generate chroman; and step III, mixing the chroman and chloroform, adding chlorosulfonic acid at the low temperature to facilitate the reaction, and generating the chroman-6-sulfonyl chloride.
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Paragraph 0007
(2018/04/03)
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- Chemoselective transfer hydrogenation of nitroarenes, ketones and aldehydes using acylthiourea based Ru(II)(p-cymene) complexes as precatalysts
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A new series of Ru(II)(η6-p-cymene) complexes (1–5) was synthesized from pyridine based acylthiourea ligands (L1-L5) and [Ru(η6-p-cymene)Cl2]2. All the ligands and complexes were well characterized by UV-Visible, FT-IR, mass and 1H & 13C NMR spectroscopic techniques. The molecular structures of the ligands (L1, L2, L4 and L5) and complex 1 were confirmed using single crystal X-ray diffraction study. The Ru(II)(η6-p-cymene) complexes (1–5) were proved to be efficient precatalysts for the transfer hydrogenation of carbonyl compounds and nitroarenes in the presence of 2-propanol as a hydrogen donor and KOH as a base. The catalytic transfer hydrogenation reactions were chemoselective towards the nitro group in presence of carbonyl group, which is a rare scenario in homogeneous catalysis. The catalyst was compatible with broad range of substrates which include furfural, quinone and many heterocycles. The catalytic reactions exhibited very high conversions (upto 100%) and excellent yields (upto 99%). Turn Over Number (TON) was found upto 990.
- Sathishkumar, Pushpanathan N.,Raveendran, Neethi,Bhuvanesh, Nattamai S.P.,Karvembu, Ramasamy
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- Catalytic carbonyl hydrosilylations: Via a titanocene borohydride-PMHS reagent system
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Reduction of a wide range of aldehydes and ketones with catalytic amounts of titanocene borohydride in concert with a stoichiometric poly(methylhydrosiloxane) (PMHS) reductant is reported. Preliminary mechanistic studies demonstrate that the reaction is mediated by a reactive titanocene(iii) complex, whose oxidation state remains constant throughout the reaction.
- Fianu, Godfred D.,Schipper, Kyle C.,Flowers, Robert A.
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p. 3469 - 3473
(2017/08/21)
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- An efficient FeCl3-mediated approach for reduction of ketones through N-heterocyclic carbene boranes
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An efficient FeCl3-mediated approach for reduction of ketones by NHC-BH3 has been developed. A series of ketones were smoothly converted to the corresponding alcohols in good to excellent yields through NHC-BH3 reductive process.
- Wang, Ming-Hui,Chen, Ling-Yan
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supporting information
p. 732 - 735
(2017/03/31)
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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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- 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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- Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes
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Hydrogenations constitute fundamental processes in organic chemistry and allow for atom-efficient and clean functional group transformations. In fact, the selective reduction of nitriles, ketones, and aldehydes with molecular hydrogen permits access to a green synthesis of valuable amines and alcohols. Despite more than a century of developments in homogeneous and heterogeneous catalysis, efforts toward the creation of new useful and broadly applicable catalyst systems are ongoing. Recently, Earth-abundant metals have attracted significant interest in this area. In the present study, we describe for the first time specific molecular-defined manganese complexes that allow for the hydrogenation of various polar functional groups. Under optimal conditions, we achieve good functional group tolerance, and industrially important substrates, e.g., for the flavor and fragrance industry, are selectively reduced.
- Elangovan, Saravanakumar,Topf, Christoph,Fischer, Steffen,Jiao, Haijun,Spannenberg, Anke,Baumann, Wolfgang,Ludwig, Ralf,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8809 - 8814
(2016/07/29)
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- γ-Sultam-cored N,N-ligands in the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of aryl ketones
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The synthesis of new enantiopure syn- and anti-3-(α-aminobenzyl)-benzo-γ-sultam ligands 6 and their application in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation (ATH) of ketones using formic acid/triethylamine is described. In particular, benzo-fused cyclic ketones afforded excellent enantioselectivities in reasonable time employing a low loading of the syn ligand-containing catalyst. A never-before-seen dynamic kinetic resolution (DKR) during reduction of a γ-keto carboxylic ester (S7) derivative of 1-indanone is realized leading as well to excellent induction.
- Rast, Slavko,Modec, Barbara,Stephan, Michel,Mohar, Barbara
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p. 2112 - 2120
(2016/02/18)
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- Selective acetylation of primary alcohols by ethyl acetate
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A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
- Singha, Raju,Ray, Jayanta K.
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supporting information
p. 5395 - 5398
(2016/11/11)
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- Polystyrene-supported triphenylsilyl chloride for the silylation-based kinetic resolution of secondary alcohols
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A silyl chloride derivatized styrene polymer was employed in the silylation-based kinetic resolution of secondary alcohols for chromatography-free separation of alcohol enantiomers. Synthetically useful selectivity factors were obtained; furthermore, the polymer was recycled for use in a subsequent kinetic resolution, and it maintained its selectivity and integrity. Probability of precipitation: A silyl chloride polymer is employed in a kinetic resolution for the chromatography-free separation of enantiomers. After one enantiomer is covalently bonded to the polymer, it is precipitated from the solution for easy recovery. The polymer can also be recycled in subsequent kinetic resolutions without loss in selectivity.
- Akhani, Ravish K.,Clark, Robert W.,Yuan, Liang,Wang, Li,Tang, Chuanbing,Wiskur, Sheryl L.
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p. 1527 - 1530
(2015/05/27)
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- Ansa-Ruthenium(II) Complexes of R2NSO2DPEN-(CH2)n(η6-Aryl) Conjugate Ligands for Asymmetric Transfer Hydrogenation of Aryl Ketones
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New 3rd generation designer ansa-ruthenium(II) complexes featuring N,C-alkylene-tethered N,N-dialkylsulfamoyl-DPEN/η6-arene ligands, exhibited good catalytic performance in the asymmetric transfer hydrogenation (ATH) of various classes of (het)aryl ketones in formic acid/triethylamine mixture. In particular, benzo-fused cyclic ketones furnished 98 to >99.9% ee using a low catalyst loading.
- Ki?ic, Andrea,Stephan, Michel,Mohar, Barbara
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p. 2540 - 2546
(2015/08/18)
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- Alternative Hydrogen Source for Asymmetric Transfer Hydrogenation in the Reduction of Ketones
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cis-1,4-Butenediol is shown to be a highly active hydrogen source for asymmetric transfer hydrogenation in the reduction of ketones. With the use of a ruthenium catalyst, cis-1,4-butenediol is isomerised and subsequently oxidised to a lactone as an irreversible step, which provides the driving force for the asymmetric reduction of ketones.
- Wakeham, Russell J.,Morris, James A.,Williams, Jonathan M. J.
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p. 4039 - 4041
(2015/12/26)
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- Asymmetric reduction of ketones by biocatalysis using clementine mandarin (Citrus reticulata) fruit grown in annaba or by ruthenium catalysis for access to both enantiomers
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Biocatalytic reduction of prochiral ketones using freshly ripened clementine mandarin (Citrus reticulata) in aqueous medium is reported. High enantioselectivities were observed, especially for the bioreduction of indanone 3, tetralone 4, and thiochromanone 5 with respectively 95%, 99%, and 86% enantiomeric excess (ee). Enantioselective bio- and metalcatalyzed reactions were compared. Chiral ruthenium catalysts afforded good asymmetric inductions (>75% ee) in most cases, enantiomeric excesses depending on the nature of substrate and ligand. N-aminoindanol prolinamide L3 was revealed as the best ligand for most ketones. Interestingly, for several substrates both enantiomers could be obtained using either Citrus reticulata or ruthenium complex.
- Bennamane, Manhel,Zeror, Saoussen,Aribi-Zouioueche, Louisa
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p. 205 - 210
(2015/03/18)
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- A General, Practical Triethylborane-Catalyzed Reduction of Carbonyl Functions to Alcohols
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A combination of the abundant and low-cost triethylborane and sodium alkoxide generates a highly efficient catalyst for reduction of esters, as well as ketones and aldehydes, to alcohols using an inexpensive hydrosilane under mild conditions. The catalyst system exhibits excellent chemoselectivity and a high level of functional group tolerance. Mechanistic studies revealed a resting state of sodium triethylalkoxylborate that is the product of the reaction of BEt3 with sodium alkoxide. This borate species reacts with hydrosilane to form NaBEt3H, which rapidly reduces esters.
- Peng, Dongjie,Zhang, Mintao,Huang, Zheng
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supporting information
p. 14737 - 14741
(2015/10/19)
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- RUTHENIUM-DIAMINE COMPLEX AND METHOD FOR PRODUCING OPTICALLY ACTIVE COMPOUND
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Provided is a ruthenium complex that is represented by general formula (1*) and is useful as an asymmetric reduction catalyst. (In the formula, * is an asymmetric carbon atom; R1 is an arenesulfonyl group, and the like; R2 and R3 are a phenyl group, and the like; R10 through R14 are selected from a hydrogen atom, C1-10 alkyl group, and the like, but R10 through R14 are not simultaneously hydrogen atoms; X is a halogen atom and the like; j and k are each either 0 or 1; and j+k is 0 or 2.)
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Paragraph 0144; 0145
(2014/03/24)
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- Enzymatic resolution of chroman-4-ol and its core analogues with Burkholderia cepacia lipase
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A convenient protocol for lipase resolution of chroman-4-ol and its analogues (six- and seven-membered rings with O, S, SO2) has been elaborated. The structure of substrates has minor influence on the efficiency of resolution.
- Kucher, Olexandr V.,Kolodyazhnaya, Anastasiya O.,Smolii, Oleg B.,Boiko, Alexandr I.,Kubyshkin, Vladimir S.,Mykhailiuk, Pavel K.,Tolmachev, Andrey A.
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p. 563 - 567
(2014/05/06)
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- Asymmetric reduction of ketones by biocatalysis using medlar (Mespilus germanica L) fruit grown in Algeria
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The biocatalytic reduction of ketones was performed using medlar fruit (Mespilus germanica L), which is grown in large amounts in Algeria. Experiments were performed using aqueous medium with fresh medlar. Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were reduced with enantiomeric excess (ee) of up to 98%. High enantioselectivities have been observed especially for the bioreduction of tetralone 4 and thiochromanone 5 with ee of 89% and 98%, respectively. Bioreduction using different parts of medlar indicate that chromanone 6 was reduced with good asymmetric inductions 77% ee 85% whichever part of fruit was employed (whole, flesh, or juice) and medlar juice exhibited the best activity.
- Bennamane, Manhel,Zeror, Saousen,Aribi-Zouioueche, Louisa
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p. 327 - 332
(2015/02/19)
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- Synthesis, enantiomeric separation and docking studies of spiropiperidine analogues as ligands of the nociceptin/orphanin FQ receptor
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A series of triazospirodecanone derivatives were synthesized as potential NOP ligands. 8-(Chroman-4-yl)-1-phenyl-1,3,8-triazaspiro[4.5]decan-4-one (4) and its 5-fluoro analogue (18) proved to be active as agonists with EC50 values in the submicromolar range. Single enantiomers of compound 4 were separated and tested as NOP agonists; the eutomer R-(+)-4 showed a pEC 50 of 7.34. Finally docking studies were performed on the NOP receptor to identify the most significant stereospecific interactions.
- Battisti, Umberto M.,Corrado, Sandra,Sorbi, Claudia,Cornia, Andrea,Tait, Annalisa,Malfacini, Davide,Cerlesi, Maria Camilla,Calò, Girolamo,Brasili, Livio
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p. 973 - 983
(2014/07/08)
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- Linear free-energy relationship and rate study on a silylation-based kinetic resolution: Mechanistic insights
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The substituent effect of different p-substituted triphenylsilyl chlorides on silylation-based kinetic resolutions was explored. Electron-donating groups slow down the reaction rate and improve the selectivity, while electron-withdrawing groups increase the reaction rate and decrease the selectivity. Linear free-energy relationships were found correlating both selectivity factors and initial rates to the σpara Hammett parameters. A weak correlation of selectivity factors to Charton values was also observed when just alkyl substituents were employed but was nonexistent when substituents with more electronic effects were incorporated. The rate data suggest that a significant redistribution of charge occurs in the transition state, with an overall decrease in positive charge. The linear free-energy relationship derived from selectivity factors is best understood by the Hammond postulate. Early and late transition states describe the amount of substrate participation in the transition state and therefore the difference in energy between the diastereomeric transition states of the two enantiomers. This work highlights our efforts toward understanding the mechanism and origin of selectivity in our silylation-based kinetic resolution.
- Akhani, Ravish K.,Moore, Maggie I.,Pribyl, Julia G.,Wiskur, Sheryl L.
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p. 2384 - 2396
(2014/04/17)
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- Preparative access to medicinal chemistry related chiral alcohols using carbonyl reductase technology
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Libraries of highly enantioenriched secondary alcohols in both enantiomeric forms were synthesised by enzymatic reduction of their parent ketones using selectAZyme carbonyl reductase (CRED) technology. Commercially available CREDs were able to reduce a range of substrate classes efficiently and with very high enantioselectivity. Matching substrate classes to small subsets of CREDs enabled the fast development of preparative bioreductions and the rapid generation of 100-1500 mg samples of chiral alcohols in typically >95% ee and the majority in ≥99.0% ee. The conditions for small scale synthesis were then scaled up to 0.5 kg to deliver one of the chiral alcohols, (S)-1-(4-bromophenyl)-2-chloroethanol, in 99.8% ee and 91% isolated yield.
- Rowan, Andrew S.,Moody, Thomas S.,Howard, Roger M.,Underwood, Toby J.,Miskelly, Iain R.,He, Yanan,Wang, Bo
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p. 1369 - 1381
(2013/12/04)
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- Enantioselective reduction of 4-chromanone and its derivatives by selected filamentous fungi
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Biotransformation of 4-chromanone and its derivatives in the cultures of three biocatalysts: Didymosphaeria igniaria, Coryneum betulinum and Chaetomium sp. is presented. The biocatalysts were chosen due to their capability of enantiospecific reduction of low-molecular-weight ketones (acetophenone and its derivatives and α- and β-tetralone). The substrates were reduced to the respective S-alcohols with high enantiomeric excesses, according to the Prelog's rule. In the culture of Chaetomium sp. after longer biotransformation time an inversion of configuration of the formed alcohols was also observed. The highest yield of transformation was observed for 6-methyl-4-chromanone. In all the tested cultures, the higher was the molecular weight of a chromanone, the lower conversion percent was observed.
- Janeczko, Tomasz,Dmochowska-Gladysz, Jadwiga,Szumny, Antoni,Kostrzewa-Suslow, Edyta
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p. 278 - 282
(2013/10/22)
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- Use of tridentate TsDPEN/pyridine ligands in ruthenium-catalysed asymmetric reduction of ketones
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A series of enantiomerically pure tridentate ligands based on the 1,2-diphenylethane-1,2-diamine structure, containing additional pyridine groups, was prepared and tested in asymmetric transfer hydrogenation of ketones using Ru3(CO)12 as a metal source. Alcohols were formed in up to 93% ee in the best cases, and good results were obtained with ortho-haloarylketones.
- Darwish, Moftah O.,Wallace, Alistair,Clarkson, Guy J.,Wills, Martin
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supporting information
p. 4250 - 4253
(2013/07/26)
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- RUTHENIUM-DIAMINE COMPLEXES AND METHOD FOR PRODUCING OPTICALLY ACTIVE COMPOUNDS
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Provided is a catalyst for asymmetric reduction, which can be produced by a convenient and safe production method, has a strong catalytic activity, and has excellent stereoselectivity. The present invention relates to a ruthenium complex represented by the following formula (1): wherein R1 represents an alkyl group or the like; Y represents a hydrogen atom; X represents a halogen atom or the like; j and k each represent 0 or 1; R2 and R3 each represent an alkyl group or the like; R11 to R19 each represent a hydrogen atom, an alkyl group or the like; Z represents oxygen or sulfur; n1 represents 1 or 2; and n2 represents an integer from 1 to 3, a method for producing the ruthenium complex, a catalyst for asymmetric reduction formed from the ruthenium complex, and methods for selectively producing an optically active alcohol and an optically active amine using the catalyst for asymmetric reduction.
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Page/Page column 23; 25
(2012/03/26)
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- Rh(II)-Cp-TsDPEN catalyzed aqueous asymmetric transfer hydrogenation of chromenones into saturated alcohol: C=C and C=O reduction in one step
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As an efficient catalyst for asymmetric transfer hydrogenation reaction (ATH reaction) of α,β-unsaturated ketones, Rh-Cp-TsDPEN (Cp = 1,2,3,4,5-pentamethylcyclopenta-1,3-diene, TsDPEN = N-(p-toluenesulfonyl)-1,2- diphenyl- ethylenediamine) shows high chemoselectivity on C=O and C=C reduction. In our method, both C=O and C=C bonds in a variety of chromenone derivatives were reduced efficiently in aqueous media, resulting in at least 98% ee and up to 99% yields in a convenient way without further purification. The product was a useful intermediate for deriving chiral chroman-4-amine, which was reported as an effective agent against hypotension and inflammatory pain by inhibiting human bradykinin B1 receptor.
- Tang, Lei,Lin, Zechao,Wang, Qiwei,Wang, Xiaobei,Cun, Linfeng,Yuan, Weicheng,Zhu, Jin,Deng, Jingen
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scheme or table
p. 3828 - 3830
(2012/08/14)
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- The enantiospecific synthesis of chromanes and isochromanes using a variant of an intramolecular Nicholas reaction
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The enantiospecific synthesis of chromanes and isochromanes obtained from an intramolecular Nicholas cyclisation reaction is discussed. During the course of this study we observed the formation of chroman-4-ones from a CAN deprotection step of a dioxolane and this is also discussed.
- Tyrrell, Elizabeth,Mazloumi, Khatebeh,Banti, Donatella,Sajdak, Paulina,Sinclair, Alex,Le Gresley, Adam
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p. 4280 - 4282
(2012/09/22)
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- Efficient and selective hydrosilylation of carbonyl compounds catalyzed by iron acetate and N-hydroxyethylimidazolium salts
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Aromatic aldehydes, along with aryl alkyl, heteroaryl alkyl, and dialkyl ketones were efficiently reduced to their corresponding primary and secondary alcohols, respectively, in high yields, using the commercially available and inexpensive polymeric silane, polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by in situ generated iron complexes containing hydroxyethyl-functionalized NHC ligands. Turnover frequencies up to 600 h-1 were obtained.
- Buitrago, Elina,Tinnis, Fredrik,Adolfsson, Hans
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supporting information; experimental part
p. 217 - 222
(2012/03/27)
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- Silylation-based kinetic resolution of monofunctional secondary alcohols
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The nucleophilic small molecule catalyst (-)-tetramisole was found to catalyze the kinetic resolution of monofunctional secondary alcohols via enantioselective silylation. Optimization of this new methodology allows for selectivity factors up to 25 utilizing commercially available reagents and mild reaction conditions.
- Sheppard, Cody I.,Taylor, Jessica L.,Wiskur, Sheryl L.
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p. 3794 - 3797
(2011/10/02)
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- Stereoselective amination of chiral benzylic ethers using chlorosulfonyl isocyanate: Total synthesis of (+)-Sertraline
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The stereoselective amination of various chiral benzylic ethers using chlorosulfonyl isocyanate is developed, and the application of this method to the total synthesis of a potent antidepressant, (+)-sertraline, from readily available 1-naphthol is also described (Figure presented).
- Lee, Sang Hwi,Kim, In Su,Li, Qing Ri,Dong, Guang Ri,Jeong, Lak Shin,Jung, Young Hoon
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experimental part
p. 10011 - 10019
(2012/02/05)
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- Homogeneous hydrogenation of electron-deficient alkenes by iridium complexes
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The catalytic homogeneous hydrogenation of electron-deficient alkenes (nucleophilic hydrogenation) was achieved in the presence of iridium complexes and a base as co-catalyst. Contrary to hydrogenation of electron-rich alkenes, which is inactivated by bases, the hydrogenation of the electron-deficient alkenes turned out to be base activated. Here, we present a more thorough study on the capacities but also limitations of this new reaction mechanism using screenings of the reaction conditions as well as different Ir complexes and substrates. The formation of a catalytically active Ir complex is proposed. The active complex usually attacks a soft electron-deficient atom, if more than one possibility exists (as shown by density functional theory computations). Additionally, first examples of enantiomeric enrichments in the presence of chiral Ir complexes are presented. The high catalyst load needed and the moderate yields show that the active complex is very unstable under conditions of nucleophilic hydrogenation and is quickly deactivated, which has to be addressed in further studies. Copyright
- Semeniuchenko, Volodymyr,Exner, Thomas E.,Khilya, Volodymyr,Groth, Ulrich
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experimental part
p. 804 - 809
(2012/03/26)
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- Bu4N[Fe(CO)3(NO)]-catalyzed hydrosilylation of aldehydes and ketones
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The nucleophilic Fe complex Bu4N[Fe(CO)3(NO)] (TBAFe) has been used as a highly active catalyst for the mild hydrosilylation of a variety of functionalized aldehydes and ketones using inexpensive PMHS as stoichiometric reductant. The corresponding alcohols were obtained in good-to-excellent yields at low catalyst loadings of only 1 mol-% and reaction temperatures of 30-50 °C.
- Dieskau, Andre P.,Begouin, Jeanne-Marie,Plietker, Bernd
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experimental part
p. 5291 - 5296
(2011/11/13)
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- Selective hydrosilylation of ketones catalyzed by in situ -generated iron NHC complexes
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Aryl alkyl-, heteroaryl alkyl- and dialkyl ketones were readily reduced to their corresponding secondary alcohols in high yields, using the commercially available and inexpensive polymeric silane polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by an in situ-generated iron complex, conveniently generated from iron(II) acetate and the commercially available N-heterocyclic carbene (NHC) precursor IPr·HCl.
- Buitrago, Elina,Zani, Lorenzo,Adolfsson, Hans
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experimental part
p. 748 - 752
(2012/01/05)
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- Rhodium-catalyzed synthesis of 2,3-disubstituted indoles from β,β-Disubstituted stryryl azides
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Rings la carte: Rhodium carboxylate complexes catalyze selective cascade reactions to produce a range 2,3-disubstituted indoles from β,β- disubstituted stryryl azides. The selective migration of aryl groups appears to originate from a putative phenonium ion reactive intermediate (see scheme).
- Sun, Ke,Liu, Sheng,Bec, Patryk M.,Driver, Tom G.
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supporting information; experimental part
p. 1702 - 1706
(2011/04/24)
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- Enantioselective reduction of ketones and imines catalyzed by (CN-Box)ReV-oxo complexes
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The development and application of chiral, non-racemic ReV-oxo complexes to the enantioselective reduction of prochiral ketones is described. In addition to the enantioselective reduction of prochiral ketones, we report the application of these complexes to 1) a tandem Meyer-Schuster rearrangement/reduction to access enantioenriched allylic alcohols and 2) the enantioselective reduction of imines.
- Nolin, Kristine A.,Ahn, Richard W.,Kobayashi, Yusuke,Kennedy-Smith, Joshua J.,Toste, F. Dean
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supporting information; experimental part
p. 9555 - 9562
(2010/10/03)
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- Asymmetric hydrogenation of aromatic heterocyclic ketones catalyzed by the MsDPEN-Cp*Ir(III) complex
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Asymmetric hydrogenation of aromatic heterocyclic ketones catalyzed by Cp*Ir(OTf)(Msdpen) (MsDPEN = N-(methanesulfonyl)-l,2-diphenylethylenediamine) affords the heterocyclic alcohols in 93% to >99% ee. The reaction is conducted in a methanolic solution with a substrate-to-catalyst molar ratio of 200-5000 under 15 atm of H2. The heterocyclic rings of substrates are left intact.
- Utsumi, Noriyuki,Tsutsumi, Kunihiko,Watanabe, Masahiko,Murata, Kunihiko,Arai, Noriyoshi,Kurono, Nobuhito,Ohkuma, Takeshi
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experimental part
p. 141 - 147
(2010/04/29)
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- Synthesis and reactivity of 2-aminoethanethiolato-bridged dinuclear Ru(hmb) complexes (hmb = η6-hexamethylbenzene): Mechanistic consideration on transfer hydrogenation with bifunctional [RuCl 2(hmb)]2/2-aminoethanethiol catalyst system
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A series of dinuclear Ru(hmb) complexes with a bridging 2-aminoethanethiolato ligand (S-NH) have been newly prepared by controlling the stoichiometry of starting materials. Their catalytic performance in the racemization of an optically pure secondary alcohol indicated that the relative proportion of the Ru(hmb) and the S-NH unit in these catalyst precursors in addition to the amount of base as an activating agent is crucially important to generate a catalytically active species. Moreover, chiral versions of dinuclear Ru(S-NH)(hmb) complexes displayed excellent catalytic performance in terms of reactivity and enantioselectivity for the asymmetric transfer hydrogenation of aromatic ketones using HCO2H-N(C2H5) 3. In agreement with these results, the crossover experiment using a symmetrically bridged dinuclear complex, [Ru(μ-SCH2CH 2NH2)(hmb)]2Cl2, and its Cp*Ir dinuclear congener, [Cp*Ir(μ-SCH2CH2NH 2)]2Cl2 (Cp* = η5-C 5(CH3)5), suggested that the catalytic performance in the hydrogen transfer is originated from the mononuclear amido complex Ru(SCH2CH2NH)(hmb) bearing a Ru/NH bifunctionality.
- Ito, Masato,Watanabe, Akira,Shibata, Yuji,Ikariya, Takao
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scheme or table
p. 4584 - 4592
(2011/01/07)
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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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