- From Esters to Ketones via a Photoredox-Assisted Reductive Acyl Cross-Coupling Strategy
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A method was developed for ketone synthesis via a photoredox-assisted reductive acyl cross-coupling (PARAC) using a nickel/photoredox dual-catalyzed cross-electrophile coupling of two different carboxylic acid esters. A variety of aryl, 1°, 2°, 3°-alkyl 2-pyridyl esters can act as acyl electrophiles while N-(acyloxy)phthalimides (NHPI esters) act as 1°, 2°, 3°-radical precursors. Our PARAC strategy provides an alternative and reliable way to synthesize various sterically congested 3°-3°, 3°-2°, and aryl-3° ketones under mild and highly unified conditions, which have been otherwise difficult to access. The combined experimental and computational studies identified a Ni0/NiI/NiIII pathway for ketone formation.
- Chen, Yukun,Li, Weirong,Luo, Yixin,Qi, Xiaotian,Xi, Xiaoxiang,Xu, Minghao,Yuan, Weiming,Zhao, Hongping,Zheng, Songlin
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- Bola-type PAH-based fluorophores/chemosensors: Synthesis via an unusual clemmensen reduction and photophysical studies
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Bola-type organic scaffolds are of key importance for application in a wide variety of fields. In this manuscript we wish to report our results on construction of polycyclic aromatic hydrocarbon (PAH, PAH = 9-antracenyl, 1-pyrenyl)-based bola-type fluorophores/chemosensors via an unusual Clemmensen reduction of the corresponding penta-1,4-dien-3-ones. In aqueous solutions the thus obtained bola-type molecules demonstrate intensive excimer emission at 500 nm, as well as well-pronounced “turn-off” fluorescence response towards common nitro-explosive components, such as 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), as well as, hard-to-detect pentaerythritol tetranitrate (PETN).
- Charushin, V. N.,Chupakhin, O. N.,Gorbunov, E. B.,Grzhegorzhevskii, K. V.,Kovalev, I. S.,Minin, A. S.,Sadieva, L. K.,Taniya, O. S.,Tsurkan, M. V.,Volkova, N. N.,Zyryanov, G. V.
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- Deep eutectic solvents as H2-sources for Ru(II)-catalyzed transfer hydrogenation of carbonyl compounds under mild conditions
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The employment of easily affordable ruthenium(II)-complexes as pre-catalysts in the transfer hydrogenation of carbonyl compounds in deep eutectic media is described for the first time. The eutectic mixture tetrabutylammonium bromide/formic acid = 1/1 (TBABr/HCOOH = 1/1) acts both as reaction medium and hydrogen source. The addition of a base is required for the process to occur. An extensive optimization of the reaction conditions has been carried out, in terms of catalyst loading, type of complexes, H2-donors, reaction temperature and time. The combination of the dimeric complex [RuCl(p-cymene)-μ-Cl]2 (0.01–0.05 eq.) and the ligand dppf (1,1′-ferrocenediyl-bis(diphenylphosphine)ferrocene) in 1/1 molar ratio has proven to be a suitable catalytic system for the reduction of several and diverse aldehydes and ketones to their corresponding alcohols under mild conditions (40–60 °C) in air, showing from moderate to excellent tolerability towards different functional groups (halogen, cyano, nitro, phenol). The reduction of imine compounds to their corresponding amine derivatives was also studied. In addition, the comparison between the results obtained in TBABr/HCOOH and in organic solvents suggests a non-innocent effect of the DES medium during the process.
- Cavallo, Marzia,Arnodo, Davide,Mannu, Alberto,Blangetti, Marco,Prandi, Cristina,Baratta, Walter,Baldino, Salvatore
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supporting information
(2021/02/22)
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- Surface Sulfate Ion on CdS Catalyst Enhances Syngas Generation from Biopolyols
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Photocatalytic biomass conversion represents an ideal way of generating syngas because of the sustainable use of biomass carbon and solar energy. However, the lack of efficient electron-proton transfer limits its efficiency. We here report an unprecedente
- Wang, Feng,Wang, Min,Zhang, Zhe,Zhou, Hongru
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p. 6533 - 6541
(2021/05/29)
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- Neutral-eosin Y-catalyzed regioselective hydroacylation of aryl alkenes under visible-light irradiation
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Styrene derivatives were hydroacylated with exclusive anti-Markovnikov selectivity by using neutral eosin Y as a direct hydrogen-atom-transfer (HAT) catalyst under visible-light irradiation. Aldehydes and styrenes with various substituents were tolerated (>20 examples), giving the corresponding products in moderate to high yields. The key acyl radical intermediate was generated from a direct HAT process induced by photoexcited eosin Y. Subsequent addition to styrenes and a reverse HAT process generated the ketone products.
- Liu, Haiwang,Xue, Fei,Wang, Mu,Tang, Xinxin,Wu, Jie
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supporting information
p. 406 - 410
(2020/12/30)
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- Chemoselective and metal-free reduction of α,β-unsaturated ketones by: In situ produced benzeneselenol from O -(tert -butyl) Se-phenyl selenocarbonate
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The carbon-carbon double bond of arylidene acetones and chalcones can be selectively reduced with benzeneselenol generated in situ by reacting O-(tert-butyl) Se-phenyl selenocarbonate with hydrochloric acid in ethanol. This mild, metal-free and experimentally simple reduction procedure displays considerable functional-group compatibility, products are obtained in good to excellent yields, and the use of toxic Se/CO mixture and NaSeH, or the smelly and air-sensitive benzeneselenol, is avoided. This journal is
- Ballarotto, Marco,Siciliano, Carlo,Temperini, Andrea
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p. 33706 - 33717
(2020/10/22)
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- Highly productive α-alkylation of ketones with alcohols mediated by an Ir-oxalamidato/solid base catalyst system
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An Ir-oxalamidato complex in combination with a solid base (e.g., magnesium aluminometasilicate/Ca(OH)2) significantly improved the catalyst productivity in α-alkylation of methyl ketones with primary alcohols. Optimization through systematic variation of the oxalamidato ligand led to a practical turnover number (TON) of 10 000.40 000.
- Maeda, Hironori,Nara, Hideki,Shimizu, Hideo
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supporting information
p. 2772 - 2779
(2020/12/29)
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- Controlling the selectivity and efficiency of the hydrogen borrowing reaction by switching between rhodium and iridium catalysts
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The catalytic alkylation of ketones with alcohols via the hydrogen borrowing methodology (HB) has the potential to be a highly efficient approach for forming new carbon-carbon bonds. However, this transformation can result in more than one product being formed. The work reported here utilises bidentate triazole-carbene ligated iridium and rhodium complexes as catalysts for the selective formation of alkylated ketone or alcohol products. Switching from an iridium centre to a rhodium centre in the complex resulted in significant changes in product selectivity. Other factors-base, base loading, solvent and reaction temperature-were also investigated to tune the selectivity further. The optimised conditions were used to demonstrate the scope of the reaction across 17 ketones and 14 alcohols containing a variety of functional groups. A series of mechanistic investigations were performed to probe the reasons behind the product selectivity, including kinetic and deuterium studies.
- Wang, Danfeng,McBurney, Roy T.,Pernik, Indrek,Messerle, Barbara A.
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supporting information
p. 13989 - 13999
(2019/10/01)
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- Palladium on carbon-catalyzed Α-alkylation of ketones with alcohols as electrophiles: Scope and mechanism
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The α-alkylation of ketones with alcohols represents a green strategy for the formation of crucial carbon–carbon bonds since it only produces water as byproduct. In terms of reaction mechanism, the evidence for homogeneous catalysis supports a catalytic hydrogen-borrowing pathway; however, the reaction mechanism has not been investigated for heterogeneous Pd/C catalysts. Here, we report an improved method for α-alkylation of ketones with alcohols using commercially available Pd/C, ubiquitous in organic synthesis labs, as catalyst. The reaction conditions are mild compared to state-of-the-art for both homo- and heterogeneous catalysts, and the developed conditions produces quantitative yields for most ketones and alcohols. A hot filtration experiment and recycling of the catalyst supports the heterogeneous nature of catalysis. Importantly, the reaction mechanism is studied for the first time by a combination of stoichiometric experiments and kinetic analyses by in-situ IR (React-IR).
- Bennedsen, Niklas R.,Mortensen, Rasmus L.,Kramer, S?ren,Kegn?s, S?ren
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p. 153 - 160
(2019/02/14)
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- Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
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We developed an operationally simple method for the direct use of biomass-derived chemical entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple variations in the reaction conditions. This work is based on an unprecedented catalytic system and represents a straightforward application of biomass as a reducing reagent in chemical reactions.
- Antonchick, Andrey P.,Manna, Srimanta
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p. 3094 - 3098
(2018/09/14)
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- Chemoselective transfer hydrogenation of Α,Β-unsaturated carbonyls catalyzed by a reusable supported Pd nanoparticles on biomass-derived carbon
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We herein report highly chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds to saturated carbonyls with formic acid as a hydrogen donor over a stable and recyclable heterogeneous Pd nanoparticles (NPs) on N,O-dual doped hierarchical porous biomass-derived carbon. The synergistic effect between Pd NPs and incorporated heteroatoms on carbon plays a critical role on promoting the reaction efficiency. A series of α,β-aromatic and aliphatic unsaturated carbonyl compounds was selectively reduced to their corresponding saturated carbonyls in up to 97% isolated yields with good tolerance of various functional groups. In addition, the catalyst can be successively reused for at least 6 times without significant loss in reaction efficiency.
- Song, Tao,Duan, Yanan,Yang, Yong
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- Chemoselective Hydrogenation of α,β-Unsaturated Carbonyls Catalyzed by Biomass-Derived Cobalt Nanoparticles in Water
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Herein, we report highly chemoselective hydrogenation of α,β-unsaturated carbonyls to saturated carbonyls catalyzed by cobalt nanoparticles supported on the biomass-derived carbon from bamboo shoots with molecular hydrogen in water, which is the first prototype using a heterogeneous non-noble metal catalyst for such organic transformation as far as we know. The optimal cobalt nanocatalyst, CoOx@NC-800, manifested remarkable activity and selectivity for hydrogenation of C=C in α,β-unsaturated carbonyls under mild conditions. A broad set of α,β-aromatic and aliphatic unsaturated carbonyls were selectively reduced to their corresponding saturated carbonyls in up to 99 % yields with good tolerance of various functional groups. Meanwhile, a new straightforward one-pot cascade synthesis of saturated carbonyls was realized with high activity and selectivity via the cross-aldol condensation of ketones with aldehydes followed by selective hydrogenation. More importantly, this one-pot strategy is applicable for the expedient synthesis of Loureirin A, a versatile bioactive and medicinal molecule, from readily available starting materials, further highlighting the practical utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without significant loss in both activity and selectivity.
- Song, Tao,Ma, Zhiming,Yang, Yong
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p. 1313 - 1319
(2019/01/25)
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- Activation of anti-oxidant Nrf2 signaling by enone analogues of curcumin
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Inflammation and oxidative stress are common in many chronic diseases. Targeting signaling pathways that contribute to these conditions may have therapeutic potential. The transcription factor Nrf2 is a major regulator of phase II detoxification and anti-oxidant genes as well as anti-inflammatory and neuroprotective genes. Nrf2 is widespread in the CNS and is recognized as an important regulator of brain inflammation. The natural product curcumin exhibits numerous biological activities including ability to induce the expression of Nrf2-dependent phase II and anti-oxidant enzymes. Curcumin has been examined in a number of clinical studies with limited success, mainly owing to limited bioavailability and rapid metabolism. Enone analogues of curcumin were examined with an Nrf2 reporter assay to identify Nrf2 activators. Analogues were separated into groups with a 7-carbon dienone spacer, as found in curcumin; a 5-carbon enone spacer with and without a ring; and a 3-carbon enone spacer. Activators of Nrf2 were found in all three groups, many of which were more active than curcumin. Dose-response studies demonstrated that a range of substituents on the aromatic rings of these enones influenced not only the sensitivity to activation, reflected in EC50 values, but also the extent of activation, which suggests that multiple mechanisms are involved in the activation of Nrf2 by these analogues.
- Deck, Lorraine M.,Hunsaker, Lucy A.,Vander Jagt, Thomas A.,Whalen, Lisa J.,Royer, Robert E.,Vander Jagt, David L.
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supporting information
p. 854 - 865
(2017/12/13)
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- Hydrogenation of Ketones and Esters Catalyzed by Pd/C?SiO2
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Hydrogenation of unsaturated ketones and esters with molecular hydrogen on the 5%Pd/C?SiO2 heterogeneous catalyst has been studied. The reaction direction and yield are determined by the starting compounds structure. Hydrogenation of unsaturated ketones containing phenyl group at the double carbon–carbon atom is accompanied by the reduction of the ketone group into the alcohol one. Hydrogenation of unsaturated esters is accompanied by transesterification.
- Akchurin,Baibulatov,Dokichev
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p. 195 - 198
(2018/03/26)
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- Antimicrobial Activity of Monoketone Curcuminoids Against Cariogenic Bacteria
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We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A (10) displayed promising activity against Streptococcus mutans (MIC?=?50?μg/ml) and Streptococcus mitis (MIC?=?50?μg/ml) as well as moderate activity against S.?sanguinis (MIC?=?100?μg/ml), Lactobacillus casei (MIC?=?100?μg/ml), and Streptococcus salivarius (MIC?=?200?μg/ml). Results indicated higher activity of compound 10 than that of its bis-β-diketone analog. Additionally, compounds 3a (1,5-bis(4-methylphenyl)pentan-3-one) and 7b (1,5-bis(4-bromophenyl)pentan-3-ol) were moderately active against S.?mitis (MIC?=?100?μg/ml) and S.?salivarus (MIC?=?200?μg/ml).
- Vieira, Tatiana M.,dos Santos, Isabella A.,Silva, Thayná S.,Martins, Carlos H. G.,Crotti, Ant?nio E. M.
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- Chelation-Assisted C-H and C-C Bond Activation of Allylic Alcohols by a Rh(I) Catalyst under Microwave Irradiation
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Chelation-assisted Rh(I)-catalyzed ketone synthesis from allylic alcohols and alkenes through C-H and C-C bond activations under microwave irradiation was developed. Aldimine is formed via olefin isomerization of allyl alcohol under Rh(I) catalysis and condensation with 2-amino-3-picoline, followed by continuous C-H and C-C bond activations to produce a dialkyl ketone. The addition of piperidine accelerates the reaction rate by promoting aldimine formation under microwave conditions.
- Lee, Chang-Hee,Jun, Chul-Ho
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p. 736 - 741
(2017/11/27)
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- Acceptorless Dehydrogenation of N-Heterocycles and Secondary Alcohols by Ru(II)-NNC Complexes Bearing a Pyrazoyl-indolyl-pyridine Ligand
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Ruthenium(II) hydride complexes bearing a pyrazolyl-(2-indol-1-yl)-pyridine ligand were synthesized and structurally characterized by NMR analysis and X-ray single crystal crystallographic determinations. These complexes efficiently catalyzed acceptorless dehydrogenation of N-heterocycles and secondary alcohols, respectively, exhibiting highly catalytic activity with a broad substrate scope. The present work has established a strategy to construct highly active transition metal complex catalysts and provides an atom-economical and environmentally benign protocol for the synthesis of aromatic N-heterocyclic compounds and ketones.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 584 - 591
(2018/03/08)
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- Isolation and Characterization of Regioisomers of Pyrazole-Based Palladacycles and Their Use in α-Alkylation of Ketones Using Alcohols
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Regioisomers of 3,5-diphenyl-1-(4-(trifluoromethyl)phenyl)-1H-pyrazole-based palladacycles (1 and 2) were synthesized by the aromatic C-H bond activation of N/3-aryl ring. The application of these regioisomers as catalysts to enable the formation of α-alkylated ketones or quinolines with alcohols using a hydrogen borrowing process is evaluated. Experimental results reveal that palladacycle 2 is superior over palladacycle 1 to catalyze the reaction under similar reaction conditions. The reaction mechanisms for the palladacycles 1 and 2 catalyzed α-alkylation of acetophenone were studied using density functional theoretical (DFT) methods. The DFT studies indicate that palladacycle 2 has an energy barrier lower than that of palladacycle 1 for the alkylation reaction, consistent with the better catalytic activity of palladacycle 2 seen in the experiments. The palladacycle-phosphine system was found to tolerate a wide range of functional groups and serves as an efficient protocol for the synthesis of α-alkylated products under solvent-free conditions. In addition, the synthetic protocol was successfully applied to prepare donepezil, a drug for Alzheimer's disease, from simple starting materials.
- Mamidala, Ramesh,Samser, Shaikh,Sharma, Nishant,Lourderaj, Upakarasamy,Venkatasubbaiah, Krishnan
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supporting information
p. 3343 - 3351
(2017/09/18)
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- Ruthenium phosphine-pyridone catalyzed cross-coupling of alcohols to form α-alkylated ketones
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An efficient and green route to access diverse functionalized ketones via dehydrogenative-dehydrative cross-coupling of primary and secondary alcohols is demonstrated. Selective and tunable formation of ketones or alcohols is catalyzed by a recently developed proton responsive ruthenium phosphine-pyridone complex. Light alcohols such as ethanol could be used as alkylating agents in this methodology. Moreover, selective tandem double alkylation of isopropanol is achieved by sequential addition of different alcohols.
- Sahoo, Apurba R.,Lalitha, Gummidi,Murugesh,Bruneau, Christian,Sharma, Gangavaram V.M.,Suresh, Surisetti,Achard, Mathieu
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p. 10727 - 10731
(2018/05/31)
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- Dimeric Ruthenium(II)-NNN Complex Catalysts Bearing a Pyrazolyl-Pyridylamino-Pyridine Ligand for Transfer Hydrogenation of Ketones and Acceptorless Dehydrogenation of Alcohols
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Dimeric pincer-type ruthenium(II)-NNN complexes bearing an unsymmetrical pyrazolyl-pyridylamino-pyridine ligand were prepared and characterized by NMR, elemental analysis, and X-ray single crystal structural determination. These complexes exhibited very high catalytic activity for both transfer hydrogenation of ketones and acceptorless dehydrogenation of secondary alcohols, achieving TOF values up to 1.9 × 106 h-1 in the transfer hydrogenation of ketones. The high catalytic activity of the Ru(II) complex catalysts is attributed to the presence of the unprotected NH functionality in the ligand and hemilabile unsymmetrical coordination environment around the central metal atoms in the complex.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 3638 - 3644
(2017/10/03)
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- Manganese-Catalyzed Hydrogen-Autotransfer C?C Bond Formation: α-Alkylation of Ketones with Primary Alcohols
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A novel catalytic hydrogen-autotransfer protocol for the atom-efficient α-alkylation of ketones with readily available alcohols is presented. The use of manganese complexes bearing non-innocent PNP pincer ligands enabled the functionalization of a broad range of valuable ketones, including 2-oxindole, estrone 3-methyl ether, and testosterone. Mechanistic investigations suggest the participation of an intramolecular amidate-assisted alcohol-dehydrogenation process.
- Pe?a-López, Miguel,Piehl, Patrick,Elangovan, Saravanakumar,Neumann, Helfried,Beller, Matthias
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supporting information
p. 14967 - 14971
(2016/11/25)
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- Nickel-Catalyzed Hydroacylation of Styrenes with Simple Aldehydes: Reaction Development and Mechanistic Insights
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The first nickel-catalyzed intermolecular hydroacylation reaction of alkenes with simple aldehydes has been developed. This reaction offers a new approach to the selective preparation of branched ketones in high yields (up to 99%) and branched selectivities (up to 99:1). Experimental data provide evidence for reversible formation of acyl-nickel-alkyl intermediate, and DFT calculations show that the aldehyde C-H bond transfer to a coordinated alkene without oxidative addition is involved. The origin of the reactivity and regioselectivity of this reaction was also investigated computationally, which are consistent with experimental observations.
- Xiao, Li-Jun,Fu, Xiao-Ning,Zhou, Min-Jie,Xie, Jian-Hua,Wang, Li-Xin,Xu, Xiu-Fang,Zhou, Qi-Lin
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supporting information
p. 2957 - 2960
(2016/03/19)
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- Chemoselective biohydrogenation of α,β- and α,β,γ,δ-unsaturated ketones by the marine-derived fungus Penicillium citrinum CBMAI 1186 in a biphasic system
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To broaden the range of applicability of a reduction reaction mediated by the marine fungal strain Penicillium citrinum CBMAI 1186 to organic chemical processes, the ability of whole mycelia to grow in biphasic mixtures with organic solvents was tested with acetone, ethyl acetate, n-butanol, dichloromethane, n-hexane and toluene. n-Hexane was the least toxic solvent according to the amount of mycelial mass grown in an artificial sea water medium mixed with each solvent. Therefore, whole hyphae of P. citrinum CBMAI 1186 were used as biocatalysts in the chemoselective biotransformation of the carbon-carbon double bond in α,β-, di-α,β-, and mono-α,β,γ,δ-unsaturated ketones (3a, 3c-f) in a biphasic system of phosphate buffer and n-hexane (9:1). Only the di-α,β,γ,δ-unsaturated ketone (3b) was not biocatalyzed under these conditions. In general, there were good conversions of saturated ketones by the enoate reductase enzymes of P. citrinum CBMAI 1186.
- Ferreira, Irlon M.,Meira, Eloá B.,Rosset, Isac G.,Porto, André L.M.
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- Palladium nanoparticles supported on fibrous-structured silica nanospheres (KCC-1): An efficient and selective catalyst for the transfer hydrogenation of alkenes
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An efficient palladium catalyst supported on fibrous silica nanospheres (KCC-1) has been developed for the hydrogenation of alkenes and α,β-unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high-resolution TEM, chemisorption) with analogous mesoporous (MCM-41, SBA-15) silica-supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC-1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC-1-supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.
- Qureshi, Ziyauddin S.,Sarawade, Pradip B.,Albert, Matthias,D'Elia, Valerio,Hedhili, Mohamed N.,K?hler, Klaus,Basset, Jean-Marie
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p. 635 - 642
(2015/03/05)
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- Oxidation and β-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands
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The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for C-C bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and β-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3)(cod)(MeIm(2- methoxybenzyl))][BF4] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0) of 1283 h-1, and also in the β-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new C-C bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde.
- Jiménez, M. Victoria,Fernández-Tornos, Javier,Modrego, F. Javier,Pérez-Torrente, Jesús J.,Oro, Luis A.
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supporting information
p. 17877 - 17889
(2015/12/08)
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- Tandem hydrogenation and condensation of fluorinated α,β-unsaturated ketones with primary amines, catalyzed by nickel
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A simple homogeneous catalytic system based on nickel phosphine complexes has been developed for the transfer hydrogenation and condensation of α,β-unsaturated ketones to yield saturated ones and saturated imines using primary amines as hydrogen donors. Thus, a wide range of fluorinated 1,5-diaryl-1,4-pentadiene-3-ones were allowed to react with substituted benzylamines in the presence of [(dippe)Ni(μ-H)]2 (dippe = 1,2-bis-(diisopropylphosphino)-ethane) using ethanol as a solvent at 180 °C to give the corresponding saturated carbonyl compounds; here hydrogenation of the CC bond was preferred over the CO bond. Under the same reaction conditions but using an excess of benzylamine, a tandem process is then favoured, starting also with the reduction of the CC bond followed by a nucleophilic addition of the primary amine to yield valuable saturated imines with good to excellent yields (62%-91%).
- Castellanos-Blanco, Nahury,Flores-Alamo, Marcos,García, Juventino J.
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p. 15653 - 15663
(2015/09/07)
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- A novel transition metal-free conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source
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A novel and efficient method has been developed for the chemoselective conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source to the corresponding saturated ketones in moderate to good yields. The present protocol does not require the use of transition metal, and is efficient being applicable to a wide range of substrates (25 examples).
- Zhou, Xiaomeng,Li, Xiaokang,Zhang, Wei,Chen, Junmin
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p. 5137 - 5140
(2015/02/19)
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- Continuous flow synthesis of ketones from carbon dioxide and organolithium or grignard reagents
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We describe an efficient continuous flow synthesis of ketones from CO 2 and organolithium or Grignard reagents that exhibits significant advantages over conventional batch conditions in suppressing undesired symmetric ketone and tertiary alcohol byproducts. We observed an unprecedented solvent-dependence of the organolithium reactivity, the key factor in governing selectivity during the flow process. A facile, telescoped three-step-one-flow process for the preparation of ketones in a modular fashion through the in-line generation of organometallic reagents is also established.
- Wu, Jie,Yang, Xiaoqing,He, Zhi,Mao, Xianwen,Hatton, T. Alan,Jamison, Timothy F.
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supporting information
p. 8416 - 8420
(2014/08/18)
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- Polymer-stabilized palladium nanoparticles for the chemoselective transfer hydrogenation of α,β-unsaturated carbonyls: Single-step bottom-Up approach
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Polypyrrole stabilised palladium nanoparticles show good catalytic efficiency for the chemoselective transfer hydrogenation of α,β- unsaturated carbonyl compounds. The catalyst is very specific and selectively hydrogenates the olefins or acetylenes only,
- Mahato, Sanjit K.,Ul Islam, Rafique,Acharya, Chiranjit,Witcomb, Michael J.,Mallick, Kaushik
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p. 1419 - 1426
(2014/05/20)
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- Anti-neoplastic activity of 1,3-diaza-2-functionalized-adamantan-6-one compounds against melanoma cells
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Four series of 1,3-diaza-2-functionalized-adamantan-6-one derivatives, bearing at the 2 position SO, SO2, POCl and PO2H functional groups, were synthesized via a key quadruple Mannich reaction, followed by transformation of an aminal functionality into th
- Sharabi-Ronen, Yifat,Levinger, Shlomo,Lellouche, Miri Ben-Dahan,Albeck, Amnon
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- Palladium nanoparticles supported on magnesium hydroxide fluorides: A selective catalyst for olefin hydrogenation
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A one-pot synthesis of palladium nanoparticles supported on magnesium hydroxide fluoride has been performed with the fluorolytic sol-gel method. The prepared catalysts were characterized by using various physicochemical techniques. The sol-gel method led to high surface area (> 135 m2g-1), mesoporous catalysts (pore volume=0.19-0.23 cm3g-1, pore diameter= 3-5 nm) with uniformly dispersed palladium nanoparticles approximately 2 nm in diameter on the surface. The catalysts synthesized by using different concentrations of aqueous hydrofluoric acid exhibited changing surface and acidic properties. Very high dispersion of palladium on magnesium fluoride (47%) was obtained with 1 wt% palladium loading. The catalysts were used for hydrogenation of various olefins in the presence of other organic functionalities at room temperature and atmospheric hydrogen pressure. Various substituted olefins were hydrogenated with almost 100% conversion and selectivity. The catalysts were recycled efficiently over five cycles without appreciable loss in catalytic activity. There was no palladium leaching under the reaction conditions, which was confirmed by inductively coupled plasma atomic emission spectroscopy analysis. Activation of olefin on the catalyst surface could not be observed by in situ FTIR studies, indicating facile activation of hydrogen on the palladium supported on magnesium hydroxide fluoride.
- Acham, Vaibhav R.,Biradar, Ankush V.,Dongare, Mohan K.,Kemnitz, Erhard,Umbarkar, Shubhangi B.
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p. 3182 - 3191
(2015/02/05)
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- Chemoselective transfer hydrogenation of α,β-unsaturated carbonyls using palladium immobilized ionic liquid catalyst
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This work reports a simple and highly efficient protocol for chemoselective transfer hydrogenation of α,β-unsaturated carbonyls using immobilized palladium metal-containing ionic liquid as a versatile heterogeneous catalyst with an excellent conversion and chemoselectivity (up to 100 %). The influence of various reaction parameters such as the effect of hydrogen donor, solvent, temperature, and time were studied. The catalyst was recycled for four consecutive cycles without significant loss in the catalytic activity. The developed protocol is more advantageous due to the use of HCOONH4 as a hydrogen source, mild reaction conditions, and simple workup procedure and applicable for a wide range of substrates.
- Patil, Nilesh M.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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p. 1803 - 1809
(2015/02/19)
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- α-alkylation of ketones by trialkylamines under heterogeneous Pd/C catalysis
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Ketones are regioselectively α-alkylated with trialkylamines in toluene at 120 °C in the presence of Pd/C.
- Yoon, Il Chul,Kim, Tae Gyun,Cho, Chan Sik
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p. 1890 - 1892
(2014/05/06)
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- Modulating the rotation of a molecular rotor through hydrogen-bonding interactions between the rotator and stator
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Two molecular rotors were synthesized (see picture). An investigation of the rotator rotation based on the imaginary parts of the complex dielectric constant (ε′′) for each molecular rotor at various frequencies and temperatures revealed that the rotation
- Zhang, Qian-Chong,Wu, Fang-Ting,Hao, Hui-Min,Xu, Hang,Zhao, Hai-Xia,Long, La-Sheng,Huang, Rong-Bin,Zheng, Lan-Sun
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p. 12602 - 12605
(2013/12/04)
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- Synthesis and Antimalarial Activity of Dihydroperoxides and Tetraoxanes Conjugated with Bis(benzyl)acetone Derivatives
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Dihydroperoxides and tetraoxanes derived from symmetrically substituted bis(arylmethyl)acetones were synthesized in modest to good yields using several methods. Three of these compounds exhibit an important in vitro antimalarial activity (1.0μm≤IC50≤5.0μm) against blood forms of the human malaria parasite Plasmodium falciparum.
- Franco, Lucas Lopardi,de Almeida, Mauro Vieira,e Silva, Luiz Francisco Rocha,Vieira, Pedro Paulo Ribeiro,Pohlit, Adrian Martin,Valle, Marcelo Siqueira
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experimental part
p. 790 - 797
(2012/06/18)
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- Triphenylphosphine-cyclometallated iridium(III) pyrimidine complexes: Synthesis, crystal structures and application in α-alkylation of ketones with alcohols
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Two triphenylphosphine (PPh3)-cyclometallated iridium(III) pyrimidine complexes Ir(NDMP)2PPh3Cl 1 and Ir(NDMP)(PPh3)2Cl2 2 (NDMP = 2-(2-naphthyl)-4,6- dimethyl-pyrimidine) were synthesized and characterized by NMR, IR, ESI-MS, and elemental analysis. Additionally, their detailed structures have been determined by X-ray single-crystal diffraction. The complex 1 was a PPh3-biscyclometalated Ir(III) complex, while 2 was a PPh 3-monocyclometalated Ir(III) complex. These complexes were found to be efficient catalysts for α-alkylation of ketones with alcohols.
- Xu, Chen,Dong, Xin-Ming,Wang, Zhi-Qiang,Hao, Xin-Qi,Li, Zhen,Duan, Lu-Meng,Ji, Bao-Ming,Song, Mao-Ping
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experimental part
p. 214 - 218
(2012/03/11)
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- Pd-aminoclay nanocomposite as an efficient recyclable catalyst for hydrogenation and suzuki cross coupling reactions
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A highly water dispersible Pd-aminoclay nanocomposite is found to be effective catalytic system for the hydrogenation of α,β-unsaturated carbonyl compounds and Suzuki coupling reactions in aqueous media. The catalytic hydrogenation of α,β-unsaturated carbonyl compounds proceeds at room temperature to afford the corresponding products in excellent yields with high chemoselectivity. The cross coupling of aryl bromides and iodides with aryl boronic acids proceeds efficiently under aqueous conditions at 90 °C to afford the corresponding biaryls in excellent yields with high selectivity. The Suzuki reaction proceeds smoothly even in the absence of external base due to the basic nature of the catalyst support. The catalyst could be easily recovered and recycled three times without a significant loss of activity in hydrogenation and Suzuki cross coupling reactions. Copyright
- Kumar, A. Sravanth,Datta,Rao, T. Srinivasa,Raghavan,Eswaramoorthy,Reddy, B.V. Subba
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experimental part
p. 2000 - 2007
(2012/07/28)
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- Palladium nanoparticles in Suzuki cross-couplings: Tapping into the potential of tris-imidazolium salts for nanoparticle stabilization
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Inspired by the proclivity of various palladium sources to form nanoparticles in imidazolium-based ionic liquids, we now report that tris-imidazolium salts bearing hexadecyl chains and a bridging mesitylene moiety are potent stabilizers of palladium nanoparticles efficiently prepared via a Chaudret-type hydrogenation of the bis(dibenzylideneacetone)palladium(0). The palladium nanoparticles have been isolated in pure form and characterized by 1H nuclear magnetic resonance, transmission electron microscopy, electron diffraction and dynamic light scattering. The new materials proved effective in Suzuki cross-coupling at a loading of 0.2% palladium. Thus, using a tris-imidazolium iodide-palladium material, a series of biaryl products has been prepared starting from aryl bromides and some activated chlorides. The possibility that this catalytic activity might be due to the formation of palladium N-heterocyclic carbenes has been addressed through solid state 13C NMR and the synthesis of an imidazolium analogue in which the acidic 2-H was replaced with a methyl group. Copyright
- Planellas, Marc,Pleixats, Roser,Shafir, Alexandr
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supporting information; experimental part
p. 651 - 662
(2012/05/04)
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- Iridium NHC based catalysts for transfer hydrogenation processes using glycerol as solvent and hydrogen donor
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A series of iridium and ruthenium N-heterocyclic carbene based catalysts of general formula [IrI2(AcO)(bis-NHC)] or [Ru(η6-arene) (NHC)CO3] have been tested in the reduction of several organic carbonyl compounds using glycerol as solvent and hydrogen donor, by the transfer hydrogenation methodology. The Ir(III) complexes with a chelating bis-NHC ligand and sulfonate groups were the most efficient, due to their solubility in the reaction media and to the strong electron-donor properties of the bis-carbene ligands. The same two catalysts were moderately active in the reduction of olefins and alkynes and, more remarkably, show excellent chemoselectivity in the reduction of the alkenic double bond of α,β-unsaturated ketones, a valuable process for which glycerol had never been used before.
- Azua, Arturo,Mata, Jose A.,Peris, Eduardo
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experimental part
p. 5532 - 5536
(2011/12/13)
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- Carbon-carbon bond formation between secondary alcohols and aldehydes under ruthenium-catalyzed redox shuttle
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Secondary alcohols are coupled with aldehydes in dioxane in the presence of a catalytic amount of a ruthenium catalyst along with KOH to give coupled ketones or coupled secondary alcohols depending on the molar ratio of secondary alcohols to aldehydes and the presence (or absence) of a sacrificial hydrogen acceptor. Copyright
- Cho, Chan Sik,Kim, Bok Tae,Yoon, Nam Sik
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experimental part
p. 695 - 698
(2012/01/05)
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- Rapid and regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester catalyzed by titanium tetrachloride
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A regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester as the reducing agent and titanium tetrachloride as a catalyst is described. The short reaction times and mild reaction conditions are the advantages of this method. Georg Thieme Verlag Stuttgart New York.
- Che, Jun,Lam, Yulin
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experimental part
p. 2415 - 2420
(2010/11/19)
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- Hydrogenation of olefins using Hantzsch ester catalyzed by palladium on carbon
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Hantzsch 1,4-dihydropyridine (HEH), a well-known model compound of coenzyme NAD(P)H was found as an efficient reducing agent in hydrogenation of unactivated olefins catalyzed by Pd/C. α,β-Unsaturated ketones also underwent hydrogenation, affording the corresponding saturated ketones selectively.
- Liu, Qiang,Li, Jing,Shen, Xiao-Xia,Xing, Rui-Guang,Yang, Jie,Liu, Zhengang,Zhou, Bo
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scheme or table
p. 1026 - 1028
(2009/05/11)
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- Synthesis of enol lactones via Cu(I)-catalyzed intramolecular O-vinylation of carboxylic acids
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With the catalysis of Cul/trans-W,W-dimethylcyclohexane-1,2-diamine, a number of carboxylic acids underwent efficient intramolecular O-vinylation with vinyl bromides leading to the synthesis of the corresponding five- and six-membered enol lactones. The same catalytic system also led to the efficient cycloisomerization of alkynoic acids.
- Sun, Changhul,Fang, Yewen,Li, Shuang,Zhang, Yue,Zhao, Qlwu,Zhu, Shana,Li, Chaozhong
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scheme or table
p. 4084 - 4087
(2009/12/06)
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- The effects of amine and acid catalysts on efficient chelation-assisted hydroacylation of alkene with aliphatic aldehyde
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Efficient intermolecular hydroacylation of 1-alkene with aliphatic aldehyde was achieved using a catalyst mixture of cyclohexylamine, p-trifluoromethylbenzoic acid, Wilkinson's complex and 2-amino-3-picoline. The formation of unwanted aldol side-product w
- Jo, Eun-Ae,Jun, Chul-Ho
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experimental part
p. 3338 - 3340
(2009/08/17)
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- Scope of the suzuki-miyaura cross-coupling reaction of potassium trifluoroboratoketohomoenolates
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Potassium trifluoroboratoketohomoenolates were prepared in good yields from either the corresponding α,β-unsaturated compounds or methyl ketones. These organoboron reagents were effectively cross-coupled with various aryl and heteroaryl chlorides.
- Molander, Gary A.,Jean-Gerard, Ludivine
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supporting information; experimental part
p. 1297 - 1303
(2009/06/28)
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- Alcohols for the α-alkylation of methyl ketones and indirect aza-wittig reaction promoted by nickel nanoparticles
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Nickel nanoparticles have been found to activate primary alcohols used for the α-alkylation of ketones or in indirect aza-Wittig reactions. These processes involve hydrogen transfer from the alcohol to the intermediate α,β-unsaturated ketone or imine, respectively. All these reactions are carried out in the absence of any ligand, hydrogen acceptor or base under mild reaction conditions. For the first time nickel is employed as a potential alternative to noble-metal-based catalysts in both reactions. A reaction mechanism is proposed on the basis of some deuteration experiments. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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experimental part
p. 4908 - 4914
(2009/05/27)
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- Regiospecific solvent-free transfer hydrogenation of α,β-unsaturated carbonyl compounds catalyzed by a cationic ruthenium(II) compound
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[(PPh3)2Ru(CH3CN)3Cl][BPh4] has been found to catalyze the selective reduction of double bonds in α,β-unsaturated ketones with high conversions when formic acid is the hydrogen donor.
- Naskar, Sipra,Bhattacharjee, Manish
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p. 465 - 467
(2008/02/03)
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- Development of a convoluted polymeric nanopalladium catalyst: α-alkylation of ketones and ring-opening alkylation of cyclic 1,3-diketones with primary alcohols
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A novel solid-phase catalyst of palladium nanoparticles, nano-Pd-V, was prepared from PdCl2 with main-chain viologen polymers via complexation and reduction. This insoluble nanocatalyst nano-Pd-V efficiently promoted α-alkylation of ketones with primary alcohols in the presence of Ba(OH)2·H2O under atmospheric conditions without organic solvents. The nano-Pd-V catalyst was reused without loss of catalytic activity. Ring-opening alkylation of cyclic 1,3-diketones with primary alcohols was also catalyzed by the nano-Pd-V catalyst.
- Yamada, Yoichi M.A.,Uozumi, Yasuhiro
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p. 8492 - 8498
(2008/02/09)
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- The α-alkylation of methyl ketones with primary alcohols promoted by nickel nanoparticles under mild and ligandless conditions
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Nickel nanoparticles have been found to promote the α-alkylation of ketones with primary alcohols in the absence of any added ligand or base, under mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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p. 1877 - 1880
(2008/02/10)
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- Dakin-West synthesis of β-aryl ketones
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Triethylamine and 1-methylimidazole were found to be selective catalysts for the Dakin-West synthesis of diaryl ketones and aryl methyl ketones, respectively. In the 1-methylimidazole-catalyzed reaction, catalysis is due to the simultaneous formation of both an effective acylating agent, 1-acyl-3-methylimidazolium, and a base, carboxylate anion. Hydrocinnamic acid, a compound previously reported to be unreactive under Dakin-West conditions, forms 4-phenyl-2-butanone when the reaction is catalyzed by 1-methylimidazole.
- Tran, Khanh-Van,Bickar, David
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p. 6640 - 6643
(2007/10/03)
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