- RETRACTED ARTICLE: The Manganese(I)-Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege
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The bis(carbonyl) manganese(I) complex [Mn(CO)2(1)]Br (2) with a chiral (NH)2P2 macrocyclic ligand (1) catalyzes the asymmetric transfer hydrogenation of polar double bonds with 2-propanol as the hydrogen source. Ketones (43 substrates) are reduced to alcohols in high yields (up to >99 %) and with excellent enantioselectivities (90–99 % ee). A stereochemical model based on attractive CH–π interactions is proposed.
- Passera, Alessandro,Mezzetti, Antonio
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supporting information
p. 187 - 191
(2019/12/11)
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- A simple and efficient asymmetric hydrogenation of heteroaromatic ketones with iridium catalyst composed of chiral diamines and achiral phosphines
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An efficient iridium catalyst composed of a simple and commercially available o-methoxytriphenylphosphine and 9-Amino (9-deoxy) epi-cinchonine was applied to the asymmetric hydrogenation of heteroaromatic ketones. A range of simple heteroaromatic ketones could be hydrogenated with good to excellent enantioselectivities and high activities. In particular, thiophene ketones and furyl ketones furnished 98.6% ee with up to 2.18 × 104(1/h) TOF. This catalytic system can be of practical value.
- Li, Chun,Lu, Xunhua,Wang, Mengna,Zhang, Ling,Jiang, Jian,Yan, Shunfa,Yang, Yuanyong,Zhao, Yonglong,Zhang, Lin
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- Phosphine-NHC Manganese Hydrogenation Catalyst Exhibiting a Non-Classical Metal-Ligand Cooperative H2 Activation Mode
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Deprotonation of the MnI NHC-phosphine complex fac-[MnBr(CO)3(κ2P,C-Ph2PCH2NHC)] (2) under a H2 atmosphere readily gives the hydride fac-[MnH(CO)3(κ2P,C-Ph2PCH2NHC)] (3) via the intermediacy of the highly reactive 18-e NHC-phosphinomethanide complex fac-[Mn(CO)3(κ3P,C,C-Ph2PCHNHC)] (6 a). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16-e mangana-substituted phosphonium ylide complex fac-[Mn(CO)3(κ2P,C-Ph2P=CHNHC)] (6 b) as key intermediate able to activate H2 via a non-classical mode of metal-ligand cooperation implying a formal λ5-P–λ3-P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre-catalysts for ketone hydrogenation in the MnI series reported to date (TON up to 6200).
- Buhaibeh, Ruqaya,Filippov, Oleg A.,Bruneau-Voisine, Antoine,Willot, Jérémy,Duhayon, Carine,Valyaev, Dmitry A.,Lugan, No?l,Canac, Yves,Sortais, Jean-Baptiste
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supporting information
p. 6727 - 6731
(2019/04/17)
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- A monolith immobilised iridium Cp catalyst for hydrogen transfer reactions under flow conditions
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An immobilised iridium hydrogen transfer catalyst has been developed for use in flow based processing by incorporation of a ligand into a porous polymeric monolithic flow reactor. The monolithic construct has been used for several redox reductions demonstrating excellent recyclability, good turnover numbers and high chemical stability giving negligible metal leaching over extended periods of use.
- Rojo, Maria Victoria,Guetzoyan, Lucie,Baxendale, Ian. R.
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p. 1768 - 1777
(2015/02/19)
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- Heterogeneous asymmetric hydrogenation of heteroaromatic methyl ketones catalyzed by cinchona-modified iridium catalysts
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A heterogeneous iridium catalyst was synthesized with silica particles as support for the hydrogenation of heteroaromatic methyl ketones. The catalyst and support were characterized by solid-state NMR, HTEM, SEM, XPS, and BET. A series of heteroaromatic methyl ketones were investigated at room temperature. The catalytic system was effective and more than 99% conversion and up to 83.6% enantioselectivity were obtained in the hydrogenation of heteroaromatic methyl ketones.
- Li, Chun,Zhang, Lin,Zheng, Congye,Zheng, Xueli,Fu, Haiyan,Chen, Hua,Li, Ruixiang
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p. 821 - 824
(2014/06/23)
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- Effect of the pyrrole polymerization mechanism on the antioxidative activity of nonenzymatic browning reactions
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The present investigation was undertaken to study how the antioxidative activity (AA) of nonenzymatic browning reactions is changing at the same time that the browning (by the pyrrole polymerization mechanism) is being produced. The antioxidative activiti
- Hidalgo, Francisco J.,Nogales, Fatima,Zamora, Rosario
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p. 5703 - 5708
(2007/10/03)
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- General asymmetric hydrogenation of hetero-aromatic ketones
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(matrix presented) Het = hetero-aromatic ring (R,R)-Ru cat = trans-RuCl2[(R)-xylbinap][(R)-daipen] trans-RuCl2[(R)-xylbinap][(R)-daipen] or the S,S complex acts as an efficient catalyst for asymmetric hydrogenation of hetero-aromatic ketones. The hydrogenation proceeds with a substrate-to-catalyst molar ratio of 1000-40000 to give chiral alcohols in high ee and high yield. The enantioselectivity appears to be little affected by the properties of the hetero-aromatic ring. This method allows for asymmetric synthesis of duloxetine, an inhibitor of serotonin and norepinephrine uptake carriers.
- Ohkuma, Takeshi,Koizumi, Masatoshi,Yoshida, Makoto,Noyori, Ryoji
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p. 1749 - 1751
(2007/10/03)
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- Contribution of pyrrole formation and polymerization to the nonenzymatic browning produced by amino-carbonyl reactions
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Recent studies have hypothesized that pyrrole formation and polymerization may be contribute to the nonenzymatic browning produced in both oxidized lipid/protein reactions and the Maillard reaction. To develop a methodology that would allow investigation of the contribution of this browning mechanism, the kinetics of formation of color, fluorescence, and pyrrolization in 4,5(E)-epoxy-2(E)-heptenal/lysine and linolenic acid/lysine model systems were studied. In both cases similar kinetics for the three measurements were observed at the two temperatures assayed (37 and 60 °C), and there was a high correlation among color, fluorescence, and pyrrolization measurements obtained as a function of incubation time. Because the color and fluorescence production in the 4,5(E)-epoxy-2(E)-heptenal/lysine system is a consequence of pyrrole formation and polymerization, the high correlations observed with the unsaturated fatty acid also suggest a contribution of the pyrrole formation and polymerization to the development of color and fluorescence observed in the fatty acid/lysine system. Although the contribution of other mechanisms cannot be discarded, all of these results suggest that when the pyrrole formation and polymerization mechanism contributes to the nonenzymatic browning of foods, a high correlation among color, fluorescence, and pyrrolization measurements should be expected.
- Zamora,Alaiz,Hidalgo
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p. 3152 - 3158
(2007/10/03)
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- 3-arylcarbonyl-1-(C-attached-N-heteryl)-1H-indoles
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2-R2 -R4 -substituted-3-R3 -CO-1-[(C-attached-N-herteryl)-(Alk)n ]-1H-indoles useful as analgesic, anti-rheumatic, anti-inflammatory or anti-glaucoma agents.
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- Diels-Alder Reactions of Vinyl Derivatives of Five-Membered Monoheterocyclic Compounds
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Vinylpyrroles having electron-withdrawing substituents react with dienophiles to give ? adducts while the furan and thiophene analogues do not.The difference in reactivity among the monoheterocycles can be explained in terms of the greater electron-releasing ability of the nitrogen atom in the pyrrole.The s-cis conformation of the (1H-pyrrol-2-yl)maleate derivatives appears to be an important factor in their undergoing the cycloaddition reaction.
- Noland, Wayland E.,Lee, Chang Kiu,Bae, Sun Kun,Chung, Bong Yul,Hahn, Chi Sun,Kim, Keun Jae
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p. 2488 - 2491
(2007/10/02)
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