- High-efficiency and minimum-waste continuous kinetic resolution of racemic alcohols by using lipase in supercritical carbon dioxide
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A novel continuous-flow scCO2 process for kinetic resolution of racemic alcohols can be performed with an immobilized lipase to lead to a quantitative mixture of the corresponding optically active acetates with up to 99% ee and unreacted alcohols with up to 99% ee, in which the productivity of the optically active compounds was improved by over 400 times compared to the corresponding batch reaction using scCO2.
- Matsuda, Tomoko,Watanabe, Kazunori,Harada, Tadao,Nakamura, Kaoru,Arita, Yoshitaka,Misumi, Yukibiro,Ichikawa, Shinichiro,Ikariya, Takao
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Read Online
- SELECTIVE REMOVAL OF TETRAHYDROPYRANYL ETHERS IN THE PRESENCE OF TERT-BUTYLDIMETHYLSILYL ETHERS WITH MAGNESIUM BROMIDE IN ETHER
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It has been found that tetrahydropyranyl ethers are cleanly and selectively deprotected in the presence of tert-butyldimethylsilyl ethers with magnesium bromide in ether.
- Kim, Sunggak,Park, Jung Ho
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Read Online
- Stereoselective opening of acetals derived from dimethyl tartrate
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Acetals of dimethyl tartrate can be used to prepare optically active secondary alcohols from the corresponding aldehydes. The key step involves treatment of the acetals with dialkylboron bromides and higher order cuprates. The process involves an unusual
- Guindon,Simoneaua,Yoakima,Gorysa,Lemieuxa,Ogilvie
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Read Online
- Highly chemo-, diastereo-, and enantioselective reduction of 1,2-dialkyl-3-aryl-1,3-diketones for preparation of aldol-type compounds
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Equation presented Highly chemo-, diastereo-, and enantioselective borohydride reduction of 2-substituted-1,3-diketones was achieved in the presence of the optically active β-ketoiminato cobalt complex catalysts to afford the optically active 2-substituted-3-hydroxyketones. The present catalytic and enantioselective reduction could provide an alternative potential for preparation of optically active anti-aldol-type compounds.
- Ohtsuka, Yuhki,Koyasu, Kiichirou,Miyazaki, Daichi,Ikeno, Taketo,Yamada, Tohru
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Read Online
- 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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- Hydrogenation of Carbonyl Derivatives Catalysed by Manganese Complexes Bearing Bidentate Pyridinyl-Phosphine Ligands
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Manganese(I) catalysts incorporating readily available bidentate 2-aminopyridinyl-phosphine ligands achieve a high efficiency in the hydrogenation of carbonyl compounds, significantly better than parent ones based on more elaborated and expensive tridentate 2,6-(diaminopyridinyl)-diphosphine ligands. The reaction proceeds with low catalyst loading (0.5 mol%) under mild conditions (50 °C) with yields up to 96%. (Figure presented.).
- Wei, Duo,Bruneau-Voisine, Antoine,Chauvin, Téo,Dorcet, Vincent,Roisnel, Thierry,Valyaev, Dmitry A.,Lugan, No?l,Sortais, Jean-Baptiste
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supporting information
p. 676 - 681
(2017/12/26)
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- Rhenium and manganese complexes bearing amino-bis(phosphinite) ligands: Synthesis, characterization, and catalytic activity in hydrogenation of ketones
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A series of rhenium and manganese complexes supported by easily accessible and easily tunable amino-bisphosphinite ligands was prepared and characterized by NMR and IR spectroscopy, HR mass spectrometry, elemental analysis, and X-ray diffraction studies. These complexes have been tested in the hydrogenation of ketones. Notably, one of the rhenium complexes, bearing an NH moiety, proved significantly more active than the rest of the series. The reaction proceeds well at 120 °C, under 50 bar of H2, in the presence of 0.5 mol % of catalyst and 1 mol % of tBuOK. Interestingly, activation of the precatalyst could be followed stepwise by NMR and a rhenium hydride was characterized by X-ray diffraction studies.
- Li, Haoran,Wei, Duo,Bruneau-Voisine, Antoine,Ducamp, Maxime,Henrion, Micka?l,Roisnel, Thierry,Dorcet, Vincent,Darcel, Christophe,Carpentier, Jean-Fran?ois,Soulé, Jean-Fran?ois,Sortais, Jean-Baptiste
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supporting information
p. 1271 - 1279
(2018/04/30)
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- Enzymatic chemical transformations of aldehydes, ketones, esters and alcohols using plant fragments as the only biocatalyst: Ximenia americana grains
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The present study demonstrated the ability of Ximenia american as a biocatalyst in reduction, hydrolysis and esterification reactions. The reduction reactions of aldehydes and ketones, ester hydrolysis and esterification of alcohols were carried out with interesting results. Reduction of ketones afforded yields of 6–60% with ee in the range of 35–>99% and that of aldehydes in yields of 51–99%. On the other hand, ester hydrolysis afforded yields of 58–98% with ee in the range 34–87%, while esterification of alcohols in 18–99% yields. Experimental conditions for all reactions have been defined using standard substrates as indicated in results and discussion. Some of the products are the potential building blocks for the synthesis of molecules which are of pharmaceutical and agrochemical importance.
- da Silva, Romézio Alves Carvalho,de Mesquita, Bruna Marques,de Farias, Iolanda Frota,do Nascimento, Patrícia Georgiana Garcia,de Lemos, Telma Leda Gomes,Queiroz Monte, Francisco José
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p. 187 - 194
(2018/01/05)
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- Hydrogenation of Carbonyl Derivatives with a Well-Defined Rhenium Precatalyst
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The first efficient and general rhenium-catalyzed hydrogenation of carbonyl derivatives was developed. The key to the success of the reaction was the use of a well-defined rhenium complex bearing a tridentate diphosphinoamino ligand as the catalyst (0.5 mol %) at 70 °C in the presence of H2 (30 bar). The mechanism of the reaction was investigated by DFT(PBE0-D3) calculations.
- Wei, Duo,Roisnel, Thierry,Darcel, Christophe,Clot, Eric,Sortais, Jean-Baptiste
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- Transfer Hydrogenation of Carbonyl Derivatives Catalyzed by an Inexpensive Phosphine-Free Manganese Precatalyst
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A very simple and inexpensive catalytic system based on abundant manganese as transition metal and on an inexpensive phosphine-free bidendate ligand, 2-(aminomethyl)pyridine, has been developed for the reduction of a large variety of carbonyl derivatives with 2-propanol as hydrogen donor. Remarkably, the reaction proceeds at room temperature with low catalyst loading (down to 0.1 mol %) and exhibits a good tolerance toward functional groups. High TON (2000) and TOF (3600 h-1) were obtained.
- Bruneau-Voisine, Antoine,Wang, Ding,Dorcet, Vincent,Roisnel, Thierry,Darcel, Christophe,Sortais, Jean-Baptiste
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supporting information
p. 3656 - 3659
(2017/07/15)
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- Hydrogenation of ketones with a manganese PN3P pincer pre-catalyst
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A catalytic hydrogenation of carbonyl derivatives with a manganese pre-catalyst has been developed. The key feature is the use of an air stable cationic manganese pre-catalyst bearing a tridendate ligand with a 2,6-(diaminopyridinyl)diphosphine scaffold. Under 50?bar of H2, at 130?°C, various ketones were reduced to the corresponding alcohols with moderate to good yield.
- Bruneau-Voisine, Antoine,Wang, Ding,Roisnel, Thierry,Darcel, Christophe,Sortais, Jean-Baptiste
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- Selective synthesis of primary amines by reductive amination of ketones with ammonia over supported Pt catalysts
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Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the C£O stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
- Nakamura, Yoichi,Kon, Kenichi,Touchy, Abeda Sultana,Shimizu, Ken-Ichi,Ueda, Wataru
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p. 921 - 924
(2015/03/18)
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- Identification of an ε-keto ester reductase for the efficient synthesis of an (R)-α-lipoic acid precursor
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Abstract A novel reductase (CpAR2) with unusually high activity toward an ε-keto ester, ethyl 8-chloro-6-oxooctanoate, was isolated from Candida parapsilosis. The asymmetric reduction of ethyl 8-chloro-6-oxooctanoate using Escherichia coli cells coexpressing CpAR2 and glucose dehydrogenase genes gave ethyl (R)-8-chloro-6-hydroxyoctanoate, a key precursor for the synthesis of (R)-α-lipoic acid, in high space-time yield (530 gL-1d-1) and with excellent enantiomeric excess (>99%). This bioprocess was shown to be viable on a 10-L scale. This method provides a greener and more cost-effective method for the industrial production of (R)-α-lipoic acid.
- Zhang, Yu-Jun,Zhang, Wen-Xia,Zheng, Gao-Wei,Xu, Jian-He
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supporting information
p. 1697 - 1702
(2015/06/02)
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- Hydrosilylation of aldehydes and ketones catalyzed by half-sandwich manganese(I) N-heterocyclic carbene complexes
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Easily available manganese(I) N-heterocyclic carbene (NHC) complexes, Cp(CO)2Mn(NHC), obtained in one step from industrially produced cymantrene, were evaluated as pre-catalysts in the hydrosilylation of carbonyl compounds under UV irradiation. Complexes with NHC ligands incorporating at least one mesityl group led to the most active and selective catalytic systems. A variety of aldehydes (13 examples) and ketones (11 examples) were efficiently reduced under mild conditions [Cp(CO)2Mn(IMes) (1 mol%), Ph 2SiH2 (1.5 equiv.), hν (350 nm), toluene, 25 °C, 1-24 h] with good functional group tolerance.
- Zheng, Jianxia,Elangovan, Saravanakumar,Valyaev, Dmitry A.,Brousses, Remy,Cesar, Vincent,Sortais, Jean-Baptiste,Darcel, Christophe,Lugan, Noel,Lavigne, Guy
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supporting information
p. 1093 - 1097
(2014/04/03)
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- A convenient nickel-catalysed hydrosilylation of carbonyl derivatives
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Hydrosilylation of aldehydes and ketones catalysed by nickel acetate and tricyclohexylphosphine as the catalytic system was demonstrated using polymethylhydrosiloxane as a cheap reducing reagent. The Royal Society of Chemistry 2013.
- Zheng, Jianxia,Darcel, Christophe,Sortais, Jean-Baptiste
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- Hydrosilylation of aldehydes and ketones catalyzed by an n-heterocyclic carbene-nickel hydride complex under mild onditions
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Half-sandwich N-heterocyclic carbene (NHC)-nickel complexes of the general formula [NiACHTUNGTRENUNG(NHC)ClCp?] (Cp?= Cp, Cp*) efficiently catalyze the hydrosilylation of aldehydes and ketones at room temperature in the presence of a catalytic amount of sodium triethylborohydride and thus join the fairly exclusive club of well-defined nickel(II) catalyst precursors for the hydrosilylation of carbonyl functionalities. Of notable interest is the isolation of an intermediate nickel hydride complex that proved to be the real catalyst precursor.
- Bheeter, Linus P.,Henrion, Mickael,Brelot, Lydia,Darcel, Christophe,Chetcuti, Michael J.,Sortais, Jean-Baptiste,Ritleng, Vincent
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supporting information
p. 2619 - 2624
(2013/01/15)
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- Iron piano-stool phosphine complexes for catalytic hydrosilylation reaction
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A family of six cyclopentadienyl-iron carbonyl complexes bearing phosphine ligands (PPh3, PMe2Ph and PCy3) with iodide or PF6 as a counter-anion were prepared and used as catalysts for the hydrosilylation of carbonyl derivatives. Aldehydes were reduced at 30 °C, using PMHS as the silane, whereas ketones were reduced at 70 °C using PhSiH3.
- Zheng, Jianxia,Misal Castro, Luis C.,Roisnel, Thierry,Darcel, Christophe,Sortais, Jean-Baptiste
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experimental part
p. 301 - 307
(2012/03/13)
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- Stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-ol and its propionate, the sex pheromones of pine sawflies
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The stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-ol (diprionol) and its propionate, the sex pheromones of pine sawflies (Neodiprion sp. and other), in high enantiomeric purity was achieved from (1R,3S)-2,2-dichloro-3-methylcyclopropane
- Kovalenko, Vitaly,Matiushenkov, Evgenii
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p. 1393 - 1399,7
(2020/09/16)
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- Chiral surfactant-type catalyst for asymmetric reduction of aliphatic ketones in water
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A novel chiral surfactant-type catalyst is developed. Micelles formed in water by association of the catalysts themselves, and this was confirmed by TEM analyses. Asymmetric transfer hydrogenation of aliphatic ketones catalyzed by the chiral metallomicellar catalyst gave good to excellent conversions and remarkable stereoselectivities (up to 95% ee). Synergistic effects between the metal-catalyzed center and the hydrophobic microenvironment of the core in the metallomicelle led to high enantioselectivities.
- Li, Jiahong,Tang, Yuanfu,Wang, Qiwei,Li, Xuefeng,Cun, Linfeng,Zhang, Xiaomei,Zhu, Jin,Li, Liangchun,Deng, Jingen
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supporting information
p. 18522 - 18525
(2013/01/15)
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Paragraph 0074
(2011/05/14)
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- Regioselective ω-hydroxylation of medium-chain n-alkanes and primary alcohols by CYP153 enzymes from Mycobacterium marinum and Polaromonas sp. strain JS666
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The oxofunctionalization of saturated hydrocarbons is an important goal in basic and applied chemistry. Biocatalysts like cytochrome P450 enzymes can introduce oxygen into a wide variety of molecules in a very selective manner, which can be used for the synthesis of fine and bulk chemicals. Cytochrome P450 enzymes from the CYP153A subfamily have been described as alkane hydroxylases with high terminal regioselectivity. Here we report the product yields resulting from C5-C12 alkane and alcohol oxidation catalyzed by CYP153A enzymes from Mycobacterium marinum (CYP153A16) and Polaromonas sp. (CYP153A P. sp.). For all reactions, byproduct formation is described in detail. Following cloning and expression in Escherichia coli, the activity of the purified monooxygenases was reconstituted with putidaredoxin (CamA) and putidaredoxin reductase (CamB). Although both enzyme systems yielded primary alcohols and α,ω-alkanediols, each one displayed a different oxidation pattern towards alkanes. For CYP153A P. sp. a predominant ω-hydroxylation activity was observed, while CYP153A16 possessed the ability to catalyze both ω-hydroxylation and α,ω- dihydroxylation reactions.
- Scheps, Daniel,Honda Malca, Sumire,Hoffmann, Helen,Nestl, Bettina M.,Hauer, Bernhard
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scheme or table
p. 6727 - 6733
(2011/11/30)
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- Reduction processes biocatalyzed by Vigna unguiculata
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Whole cells from the Brazilian beans feijao de corda (Vigna unguiculata) have been employed as biocatalysts in different bioreduction processes. Good to excellent selectivities can be obtained in the reduction of aromatic and aliphatic ketones, as well as β-ketoesters, depending on the conversions and the chemoselectivity on the substrate structure. This biocatalyst was also able to reduce the nitro moiety of different aromatic nitro compounds, showing as well enoate reductase activity, and chemoselectively catalyzing the double bond reduction of 4-phenyl-3-buten-2-one with moderate conversion.
- Bizerra, Ayla M.C.,Gonzalo, Gonzalo de,Lavandera, Ivan,Gotor-Fernandez, Vicente,de Mattos, Marcos Carlos,de Oliveira, Maria da Conceicao F.,Lemos, Telma L.G.,Gotor, Vicente
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experimental part
p. 566 - 570
(2010/08/06)
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Page/Page column 8
(2010/03/31)
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- Lentinus strigellus: a new versatile stereoselective biocatalyst for the bioreduction of prochiral ketones
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Growing cells of the basiodiomycete Lentinus strigellus in potato-dextrose broth have been used for the first time as a biocatalyst in the stereoselective reduction of aromatic and aliphatic ketones. Most of the aromatic ketones were converted into the corresponding optically active alcohols in up to >99% enantiomeric excess under very mild reaction conditions. Among the aliphatic ketones tested, 2-octanone was enzymatically reduced by this microorganism to enantiopure (S)-2-octanol with almost complete conversion.
- Barros-Filho, Bartholomeu A.,de Oliveira, Maria da Conceicao F.,Lemos, Telma L.G.,de Mattos, Marcos C.,Gonzalo, Gonzalo de,Gotor-Fernandez, Vicente,Gotor, Vicente
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experimental part
p. 1057 - 1061
(2009/10/02)
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- Mechanistic investigation of the Candida albicans CCT 0776 stereoinversion system and application to obtain enantiopure secondary alcohols
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Phenylethanol deracemization with Candida albicans CCT 0776 whole cells yields the (R)-enantiomer in over 99% enantiomeric excess and 98% yield. The deracemization process involves, in the first step, a fast, highly (S)-selective oxidation (NADP and O2 dependent) and, in the second step, a slower partially (S)-selective reduction (NADH dependent) of the intermediate ketone. The process was extended to other 2-alkanols, 1,2-diols and 1,3-diols and, with the exception of 1,3-diol (unreactive), the enantiomeric excess and yield of the deracemization were about 99% and 62-98%, respectively.
- Mantovani, Simone M.,Angolini, Celio F.F.,Marsaioli, Anita J.
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experimental part
p. 2635 - 2638
(2010/03/30)
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- Enantioselective addition of dimethylzinc to aldehydes catalyzed by N-substituted mandelamide-Ti(IV) complexes
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Amides derived from (S)-(+)-mandelic acid in the presence of titanium isopropoxide catalyze the enantioselective addition of dimethylzinc to aromatic aldehydes with good yields and ee up to 90%.
- Blay, Gonzalo,Fernandez, Isabel,Hernandez-Olmos, Victor,Marco-Aleixandre, Alicia,Pedro, Jose R.
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p. 1953 - 1958
(2007/10/03)
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- PHEROMONES AND METHOD OF PREVENTING INFESTATION OF CONTARINIA NASTURTII
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The present invention relates to a pheromone mixture comprising 2,9-diacetoxyundecane, 2,10-diacetoxyundecane and 2-acetoxyundecane, as a racemate or, biologically active stereoisomers thereof, as well as a method for monitoring and/or mating disruption of swede midge, Contarinia nasturtii, in Brassica vegetables, in particular Brussels sprouts, cauliflower and broccoli.
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Page/Page column 9
(2008/06/13)
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- Nitrous oxide oxidation catalyzed by ruthenium porphyrin complex
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Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200°C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.
- Tanaka, Hirotaka,Hashimoto, Kentaro,Suzuki, Kyosuke,Kitaichi, Yasunori,Sato, Mitsuo,Ikeno, Taketo,Yamada, Tohru
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p. 1905 - 1914
(2007/10/03)
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- Kinetic resolution of propargylic and allylic alcohols by Candida antarctica lipase (Novozyme 435)
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A number of chiral propargylic and allylic alcohols were resolved by lipase-catalyzed kinetic resolution (Novozyme 435). In some cases the enantiomeric excess was high (up to >99%).
- Raminelli, Cristiano,Comasseto, Joao V.,Andrade, Leandro H.,Porto, Andre L.M.
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p. 3117 - 31722
(2007/10/03)
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- Opening of tartrate acetals using dialkylboron bromide: Evidence for stereoselectivity downstream from ring fission
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Johnson-type acetals derived from dimethyl tartrate give, after opening with Me2BBr and cuprate displacement, secondary alcohols with high diastereoselectivity (>30:1). The mechanism proposed for the induction of diastereoselectivity is downstream from the ring fission. It implies a direct participation of the Lewis acid as a source of nucleophile and the stereospecific transformation of the resulting bromo acetal through an invertive and temperature-dependent process. The acetals are prepared by reaction of the desired aldehyde with dimethyl tartrate. Removal of the auxiliary is accomplished through Sml2 reduction or by an addition - elimination protocol using methoxide.
- Guindon, Yvan,Ogilvie, William W.,Bordeleau, Josee,Cui, Wei Li,Durkin, Kathy,Gorys, Vida,Juteau, Helene,Lemieux, Rene,Liotta, Dennis,Simoneau, Bruno,Yoakim, Christiane
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p. 428 - 436
(2007/10/03)
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- Towards a Large-Scale Asymmetric Reduction Process with Isolated Enzymes: Expression of an (S)-Alcohol Dehydrogenase in E. coli and Studies on the Synthetic Potential of this Biocatalyst
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An NAD-dependent and widely applicable (S)-alcohol dehydrogenase is isolated and described as a novel enzyme. It is expressed in an E. coli strain with a high production potential. The application of this enzyme in asymmetric biocatalytic reduction is presented as well. This enzyme shows a broad substrate range comprising aliphatic and aromatic ketones as well as β-keto esters. The synthetic application of this new (S)-alcohol dehydrogenase led to optically active alcohols in high conversion rates accompanied by enantioselectivities of up to > 99% ee. Compared to the wild-type enzyme significant advantages are observed besides the improved availability, such as a high enantioselectivity independent of the reaction time. Furthermore, the alcohol dehydrogenase was cloned and successfully overexpressed in E. coli resulting in a biocatalyst with a potential to be available on technical scale in the future. The development of a large-scale available and widely applicable (S)-alcohol dehydrogenase is one prerequisite to use isolated enzymes for asymmetric reduction processes as a valuable tool.
- Hummel, Werner,Abokitse, Kofi,Drauz, Karlheinz,Rollmann, Claudia,Gr?ger, Harald
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p. 153 - 159
(2007/10/03)
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- Catalytic Meerwein-Ponndorf-Verley (MPV) and Oppenauer (OPP) reactions: Remarkable acceleration of the hydride transfer by powerful bidentate aluminum alkoxides
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A highly efficient catalytic procedure for Meerwein-Ponndorf-Verley (MPV) reduction has been devised by employing (2,7-dimethyl-1,8-biphenylenedioxy)bis(dialkoxyaluminum) (3) as a catalyst. For example, reduction of 4-phenylcyclohexanone in CH2Cl2 with i-PrOH (1 equiv) as a hydride source in the presence of a catalytic amount of the in situ generated 3a (1 mol%) smoothly proceeded at room temperature within 1 hour to furnish 4-phenylcyclohexanol in 82% isolated yield. In sharp contrast, the conventional MPV reduction with stoichiometric Al(i-PrO)3 resulted in the recovery of the starting ketone under similar conditions. Our approach also enabled the reverse reaction of MPV reduction, i.e., Oppenauer (OPP) oxidation in a truly catalytic manner. Furthermore, these findings prompted us to develop a simultaneous intramolecular reduction/oxidation of hydroxy carbonyl substrates via the MPV reaction process in the presence of bidentate aluminum catalyst 1, where highly chemoselective hydride transfer from a secondary alcohol moiety to the remote carbonyl group took place. Finally, we demonstrate that the modern MPV system is applicable to high-speed, catalytic Tishchenko reactions. For instance, the dimerization product of cyclohexanecarbaldehyde was obtained in almost quantitative yield using only 0.2 mol% of catalyst 3a. Based on this result, highly stereoselective intramolecular Tishchenko reduction of a β-hydroxy ketone was also accomplished successfully.
- Ooi, Takashi,Miura, Tomoya,Itagaki, Yoshifumi,Ichikawa, Hayato,Maruoka, Keiji
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p. 279 - 291
(2007/10/03)
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- Highly chemoselective catalytic hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols using phosphine-stabilized copper(I) hydride complexes
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A base metal hydrogenation catalyst composed of the phenyldimethylphosphine-stabilized copper(I) hydride complex provides for the highly chemoselective hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols, including the regioselective 1,2-reduction of α,β- unsaturated ketones and aldehydes to allylic alcohols. The active catalyst can be derived in situ by phosphine exchange using commercial [(Ph3P)CuH]6 or from the reaction of copper(l) chloride, sodium tert-butoxide, and dimethylphenylphosphine under hydrogen. The catalyst derived from 1,1,1- tris(diphenylphosphinomethyl)ethane is mechanistically interesting but less synthetically useful. (C) 2000 Elsevier Science Ltd.
- Chen, Jian-Xin,Daeuble, John F.,Brestensky, Donna M.,Stryker, Jeffrey M.
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p. 2153 - 2166
(2007/10/03)
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- Two Classes of Enzymes of Opposite Stereochemistry in an Organism: One for Fluorinated and Another for Nonfluorinated Substrates
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Reduction of methyl ketones by dried cells of Geotrichum candidum (APG4) afforded (S)-alcohols in excellent enantiomeric excess (ee), whereas the reduction of trifluoromethyl ketones gave the corresponding alcohols of the opposite configuration also in excellent ee. The replacement of the methyl moiety with a trifluoromethyl group alters both the bulkiness and the electronic properties, the effect of which on the stereoselectivity was examined. No inversion in stereochemistry was observed in the reduction of hindered ketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another with the opposite stereoselectivity catalyzed the reduction of trifluoromethyl ketones. Furthermore, both APG4 and the isolated enzyme were applied to the reduction of fluorinated ketones on a preparative scale, which resulted in the synthesis of chiral fluorinated alcohols with excellent ee.
- Matsuda, Tomoko,Harada, Tadao,Nakajima, Nobuyoshi,Itoh, Toshiyuki,Nakamura, Kaoru
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p. 157 - 163
(2007/10/03)
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- Highly selective cleavage of prenyl ethers by means of a TiCl4-n-Bu4NI mixed reagent
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Treatment of the prenyl ether of ethyl salicylate with a TiCl4-n-Bu4NI mixed reagent resulted in cleavage of the C-O bond to provide ethyl salicylate in quantitative yield. On the other hand, no cleavage reaction was observed when ethyl p-prenyloxybenzoate was used as a substrate. In this system, the cleavage reaction of ethers proved to be accelerated by the chelating effect of a neighboring group in the substrate.
- Tsuritani, Takayuki,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 8121 - 8124
(2007/10/03)
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- Highly efficient, catalytic Meerwein-Ponndorf-Verley reduction with a novel bidentate aluminum catalyst
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Double electrophilic activation of carbonyl groups allows a modern variant of the Meerwein-Ponndorf-Verley reduction to be carried out under mild conditions with bidentate catalyst 1 (see reaction). Various carbonyl substrates can be reduced efficiently at room temperature in CH2Cl2 with 2-propanol or sec-phenthyl alcohol in the presence of a catalytic amount of 1. This system is also applicable to the Oppenauer oxidation of secondary alcohols to the corresponding ketones.
- Ooi, Takashi,Miura, Tomoya,Maruoka, Keiji
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p. 2347 - 2349
(2007/10/03)
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- Asymmetric reduction of ketones by the acetone powder of Geotrichum candidum
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Aromatic ketones, β-keto esters, and simple aliphatic ketones were reduced with excellent selectivity to the corresponding (S)-alcohols by using the acetone powder of Geotrichum candidum. This method is superior in reactivity and stereoselectivity to reduction by the whole-cell. The experimental conditions for the reduction system such as ratio of the biocatalyst to the substrate, kinds of coenzymes, alcohol for coenzyme regeneration, and buffer, pH, and reaction temperature were investigated, and stability and preservability of the biocatalyst were also examined. This method is very convenient for the synthesis of optically pure alcohols on a gram scale.
- Nakamura,Matsuda
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p. 8957 - 8964
(2007/10/03)
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- Rate acceleration in nucleophilic alkylation of carbonyl compounds with a new template containing two metallic centers
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Two aluminum centers aligned in the same direction capture carbonyl groups in such a way that efficient alkyl transfer becomes possible from aluminum to the carbon atom. This occurs via a favorable cyclic six-membered transition state (a). Carbonyl compounds can now be alkylated with otherwise less reactive alkylmetal species.
- Ooi, Takashi,Takahashi, Makoto,Maruoka, Keiji
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p. 835 - 837
(2007/10/03)
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- Different stereochemistry for the reduction of trifluoromethyl ketones and methyl ketones catalyzed by alcohol dehydrogenase from Geotrichum
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Reduction of trifluoromethyl ketones by a crude alcohol dehydrogenase from Geotrichum affords (S)-trifluoromethyl carbinols in excellent ee, whereas the reduction of methyl ketones gives the corresponding alcohols of the opposite configuration in excellent ee.
- Nakamura, Kaoru,Matsuda, Tomoko,Itoh, Toshiyuki,Ohno, Atsuyoshi
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p. 5727 - 5730
(2007/10/03)
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- Stereoselectivity in the enzymic oxidation of racemic alkyl methylcarbinols - A new approach to the L-enantiomers
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The R-enantiomers of racemic alkyl methylcarbinols are oxidized specifically by fatty alcohol oxidase (FAOD) from alkane-utilizing yeasts so that the S-enantiomers can be gained in pure state. Fatty alcohol oxidase converts stereospecifically L(-)-enantiomers of alkyl methyl carbinols.
- Mueller,Guentherberg,Drechsler,Mauersberger,Kortus,Oehme
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p. 2009 - 2012
(2007/10/02)
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- Selective reduction of less reactive carbonyl groups in the presence of diborane and sodium bisulfite on silica gel
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The less reactive carbonyl group of a mixture of reducible groups of carbonyl compounds was preferentially reduced with diborane on silica gel by first forming the adduct of the more reactive carbonyl group with sodium bisulfite.For example, 4-acetylbenzaldehyde could be converted to 4-(1-hydroxylethyl)benzaldehyde in 93percent selectivity; in a mixture of 4-phenyl-acetophenone and 4-phenylbenzaldehyde, biphenylethanol was preferentially formed in 95percent yield with 16percent yield of 4-phenylbenzyl alcohol.Silica gel and sodium bisulfite were essential for this selective reaction.Aliphatic and aromatic aldehydes and unhindered cyclohexanones could be selectively protected by this method.
- Chihara, Teiji,Wakabayasi, Tamie,Taya, Kazuo,Ogawa, Haruo
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p. 720 - 724
(2007/10/02)
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- The Constituents of the Bark of Litsea elliptica (Lauraceae)
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Extraction of the fresh bark of Litsea elliptica Bl., yielded (+)-reticuline (4) and a steam-volatile oil containing undec-10-en-2-one (1) and tridec-12-en-2-one (2).
- Arbain, Dayar,Dasman,,Ibrahim, Satria,Sargent, Melvyn V.
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p. 1949 - 1952
(2007/10/02)
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- A Novel Method for the Preparation of Ethers from Carbonyl Compounds with Benzenetellurol Catalyzed by ZnI2
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Benzenetellurol is shown to behave as an effective reagent for the reductive conversion of carbonyl compounds into unsymmetrical ethers under the catalytic influence of ZnI2.
- Nagakawa, Keiichi,Osuka, Masahiro,Sasaki, Kazuaki,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 1331 - 1334
(2007/10/02)
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- Perfluorocarbon polymer oxidation catalyst and preparation of carbonyl compound
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This invention deals with the use of a perfluorocarbon polymer oxidation catalyst consisting of a perfluorocarbon main chain and a side chain constructed from structural units of chromium (III) difluoromethylene sulfonate or cerium (IV) difluoromethylene sulfonate in a method of preparing a carbonyl compound through an oxidation of an alcohol.
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- A Phenyl-lithium Activated Fe4S4 Cluster as a Hydride Transfer Agent in the Hydrogenation of Carbonyl Compounds
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A phenyl-lithium activated Fe4S4 cluster acts as a hydride transfer agent in the hydrogenation of carbonyl compounds with hydrogen gas to give alcohols and exhibits substrate selectivity in the hydrogenation.
- Inoue, Hiroo,Nagao, Yoshiharu,Haruki, Eiichi
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p. 501 - 502
(2007/10/02)
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- Aminoborohydrides as Reducing Agents. 1. Sodium (Dimethylamino)- and (tert-Butylamino)borohydrides as Selective Reducing Agents
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Replacement of a hydride in borohydride by an electron-donating alkylamino group greatly enhances the reducing ability of the resulting reagents.Thus, sodium (dimethylamino)- and (tert-butylamino)borohydrides (1, NaDMAB, and 2, NaTBAB, respectively) not only reduce aldehydes and ketones to alcohols but also are effective for the conversion of esters to alcohols and primary amides to amines in good to excellent yields.Tertiary amides are reduced to alcohols (i.e., N,N-dimethylamides) or amines (i.e.N,N-diisopropylamides) depending on the steric bulk of the alkyl substituents on nitrogen.However, secondary amides are not reduced by the reagents allowing selective conversion of primary and tertiary amides in the presence of secondary amides.Nitriles are attacked by the reagents but do not afford synthetically useful amounts of amine products.Aryl halides are slowly converted to arenes, but alkyl halides and epoxides undergo unusual reactions with the amino portion of the reagents.
- Hutchins, Robert O.,Learn, Keith,El-Telbany, Farag,Stercho, Yuriy P.
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p. 2438 - 2443
(2007/10/02)
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- SELECTIVE PROTECTION OF CARBONYL COMPOUNDS BY GIRARD'S REAGENT USING SILICA GEL AS A SOLID SUPPORT
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The Girard's reagent, which gives water-soluble derivatives of carbonyl compounds, was used together with silica gel as a protective reagent of them in a non-aqueous solvent system.Less hindered or more reactive carbonyl compounds were selectively protected by this method in competitive reductions.
- Chihara, Teiji,Waniguchi, Erika,Wakabayashi, Tamie,Taya, Kazuo
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p. 1647 - 1648
(2007/10/02)
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- Active Metals from Potassium-Graphite. Air-Oxidized Nickel-Graphite as a New Selective Hydrogenation Catalyst
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Air exposure of Ni-Gr1 affords a modified, less active hydrogenation catalyst (air-oxidized nickel-graphite, Ni-Gr2), owing to a partial oxidation of the metal, which is able to reduce carbon-carbon, carbon-oxygen, and carbon-nitrogen multiple bonds under 30 atm of hydrogen in the temperature range 30-130 deg C.A remarkable bond selectivity in the hydrogenation of polyfunctional molecules such as unsaturated carbonyl compounds and β-diketones is observed.
- Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
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p. 5344 - 5348
(2007/10/02)
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