- Bimetallic Oriented (Au/Cu2O) vs. Monometallic 1.1.1 Au (0) or 2.0.0 Cu2O Graphene-Supported Nanoplatelets as Very Efficient Catalysts for Michael and Henry Additions
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Michael and Henry addition reactions have been investigated using mono (Au and Cu2O) and bimetallic nanoplatelets (Au/Cu2O) grafted onto few-layers graphene (fl-G) films as heterogeneous catalysts by comparison with homogeneous NaOH and K2CO3 ones. In the presence of the heterogeneous catalysts, these reactions occurred in the absence of any extrinsic (NaOH and K2CO3) base with turnover numbers (TONs) at least four orders of magnitude higher. While the homogeneous catalysts provided TONs close to the unity for Au/Cu2O/fl-G this was of the order of 107. These reactions also occurred with a very good selectivity to the targeted products. These performances are in line with the basicity of these catalysts demonstrated from CO2 chemisorption measurements. The effect of the nanosize and the interaction of the nanoparticles with the graphene are also important to achieve this high activity.
- Simion, Andrada,Candu, Natalia,Coman, Simona M.,Primo, Ana,Esteve-Adell, Ivan,Michelet, Véronique,Parvulescu, Vasile I.,Garcia, Hermenegildo
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Read Online
- Michael addition catalyzed by difluorotris(pentafluoroethyl)phosphorane
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Difluorotris(pentafluoroethyl)phosphorane, (C2F5)3PF2, was found to be an active catalyst for the Michael addition reaction of 1,3-β-diketones or β-ketoesters (Michael donors) and linear or cyclic unsaturated ketones (Michael acceptors). The reaction proceeds under mild conditions with low catalyst loading and results in the formation of the Michael addition products in moderate to high yields. The developed protocol does not require the use of a base for the in situ generation of a carbanion (Michael donor).
- Bittner, Bozena,Koppe, Karsten,Frank, Walter,Ignat'Ev, Nikolai
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supporting information
p. 22 - 27
(2015/12/30)
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- Polymer-incarcerated gold-palladium nanoclusters with boron on carbon: A mild and efficient catalyst for the sequential aerobic oxidation-Michael addition of 1,3-dicarbonyl compounds to allylic alcohols
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We have developed a polymer-incarcerated bimetallic Au-Pd nanocluster and boron as a catalyst for the sequential oxidation-addition reaction of 1,3-dicarbonyl compounds with allylic alcohols. The desired tandem reaction products were obtained in good to excellent yields under mild conditions with broad substrate scope. In the course of our studies, we discovered that the excess reducing agent, sodium borohydride, reacts with the polymer backbone to generate an immobilized tetravalent boron catalyst for the Michael reaction. In addition, we found bimetallic Au-Pd nanoclusters to be particularly effective for the aerobic oxidation of allylic alcohols under base- and water-free conditions. The ability to conduct the reaction under relatively neutral and anhydrous conditions proved to be key in maintaining good catalyst activity during recovery and reuse of the catalyst. Structural characterization (STEM, EDS, SEM, and N2 absorption/desorption isotherm) of the newly prepared PI/CB-Au/Pd/B was performed and compared to PI/CB-Au/Pd. We found that while boron was important for the Michael addition reaction, it was found to alter the structural profile of the polymer-carbon black composite material to negatively affect the allylic oxidation reaction.
- Yoo, Woo-Jin,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information; experimental part
p. 3095 - 3103
(2011/04/25)
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- Lewis acid catalyzed conjugate addition and the formation of heterocycles using Michael acceptors under solvent-free conditions
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Conjugate addition and conjugate-addition-initiated ring closure (CAIRC) reactions of β-dicarbonyl compounds with Michael acceptors have been studied using several Lewis acid catalysts under solvent-free conditions. Excellent chemoselectivity was obtained when various Michael acceptors were treated with several β-dicarbonyl compounds. On the other hand, 2-bromo-2-cyclopentenone and 3-bromo-3-vinyl methyl ketone furnished 2,3-dihydrofurans instead of the 1,4-adducts when treated with the same reagents. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mekonnen, Alemayehu,Carlson, Rolf
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p. 2005 - 2013
(2007/10/03)
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- Synthesis of new chiral 6-carbonyl 2,3,8,8a-tetrahydro-7H-oxazolo[3,2-a] pyridines
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The preparation of new chiral 6-carbonyl 2,3,8,8a-tetrahydro-7H-oxazolo[3, 2-a]pyridines by an efficient two-step procedure is described.
- Noel, Romain,Vanucci-Bacque, Corinne,Fargeau-Bellassoued, Marie-Claude,Lhommet, Gerard
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p. 9044 - 9047
(2007/10/03)
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