- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
-
Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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p. 8738 - 8741
(2021/09/08)
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- Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
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A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
- Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
-
supporting information
p. 18591 - 18598
(2021/06/28)
-
- Catalytic Access to Functionalized Allylic gem-Difluorides via Fluorinative Meyer–Schuster-Like Rearrangement
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An unprecedented approach for efficient synthesis of functionalized allylic gem-difluorides via catalytic fluorinative Meyer–Schuster-like rearrangement is disclosed. This transformation proceeded with readily accessible propargylic fluorides, and low-cost B–F reagents and electrophilic reagents by sulfide catalysis. A series of iodinated, brominated, and trifluoromethylthiolated allylic gem-difluorides that were difficult to access by other methods were facilely produced with a wide range of functional groups. Importantly, the obtained iodinated products could be incorporated into different drugs and natural products, and could be expediently converted into many other valuable gem-difluoroalkyl molecules as well. Mechanistic studies revealed that this reaction went through a regioselective fluorination of alkynes followed by a formal 1,3-fluorine migration under the assistance of the B–F reagents to give the desired products.
- An, Rui,Li, Huimin,Liao, Lihao,Wu, Jin-Ji,Xu, Yang,Zhao, Xiaodan
-
supporting information
p. 11010 - 11019
(2020/05/18)
-
- Efficient preparation and application of monodisperse palladium loaded graphene oxide as a reusable and effective heterogeneous catalyst for suzuki cross-coupling reaction
-
A homogeneously dispersed graphene oxide supported palladium nanomaterial (Pd?GO) has been successfully synthesized and used as a catalyst in cross-coupling reactions at room temperature. Various analytical techniques such as X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) were used to characterize the monodisperse Pd?GO. Monodisperse Pd?GO nanomaterials were used for the cross-coupling reactions which brought together organic molecules with functional significance. This catalyst showed superior catalytic activity and stability for these coupling reactions. High product yields, short reaction times and mild reaction conditions, obtained by the using of developed catalysts. Importantly, the catalyst can be used at least five experiments successfully without losing its efficiency.
- Diler, Fatma,Burhan, Hakan,Genc, Hayriye,Kuyuldar, Esra,Zengin, Mustafa,Cellat, Kemal,Sen, Fatih
-
-
- Fine-Bubble-Slug-Flow Hydrogenation of Multiple Bonds and Phenols
-
We describe a promising method for the continuous hydrogenation of alkenes or alkynes by using a newly developed fine-bubble generator. The fine-bubble-containing slug-flow system was up to 1.4 times more efficient than a conventional slug-flow method. When applied in the hydrogenation of phenols to the corresponding cyclohexanones, the fine bubble-slug-flow method suppressed over-reduction. As this method does not require the use of excess gas, it is expected to be widely applicable in improving the efficiency of gas-mediated flow reactions.
- Iio, Takuya,Nagai, Kohei,Kozuka, Tomoki,Sammi, Akhtar Mst,Sato, Kohei,Narumi, Tetsuo,Mase, Nobuyuki
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supporting information
p. 1919 - 1924
(2020/11/09)
-
- Discovery of Lipophilic Bisphosphonates That Target Bacterial Cell Wall and Quinone Biosynthesis
-
We report that alkyl-substituted bisphosphonates have activity against Bacillus anthracis Sterne (0.40 μg/mL), Mycobacterium smegmatis (1.4 μg/mL), Bacillus subtilis (1.0 μg/mL), and Staphylococcus aureus (13 μg/mL). In many cases, there is no effect of serum binding, as well as low activity against a human embryonic kidney cell line. Targeting of isoprenoid biosynthesis is involved with 74 having IC50 values of ~100 nM against heptaprenyl diphosphate synthase and 200 nM against farnesyl diphosphate synthase. B. subtilis growth inhibition was rescued by addition of farnesyl diphosphate, menaquinone-4 (MK-4), or undecaprenyl phosphate (UP), and the combination of MK-4 and UP resulted in a 25× increase in ED50, indicating targeting of both quinone and cell wall biosynthesis. Clostridioides difficile was inhibited by 74, and since this organism does not synthesize quinones, cell wall biosynthesis is the likely target. We also solved three X-ray structures of inhibitors bound to octaprenyl diphosphate and/or undecaprenyl diphosphate synthases.
- Malwal, Satish R.,Chen, Lu,Hicks, Hunter,Qu, Fiona,Liu, Weidong,Shillo, Alli,Law, Wen Xuan,Zhang, Jianan,Chandnani, Neal,Han, Xu,Zheng, Yingying,Chen, Chun-Chi,Guo, Rey-Ting,Abdelkhalek, Ahmed,Seleem, Mohamed N.,Oldfield, Eric
-
supporting information
p. 2564 - 2581
(2019/03/07)
-
- Hydrogenation of hydrophobic substrates catalyzed by gold nanoparticles embedded in Tetronic/cyclodextrin-based hydrogels
-
Hydrogenation of alkenes, alkynes and aldehydes was investigated under biphasic conditions using Au nanoparticles (AuNP) embedded into combinations of α-cyclodextrin (α-CD) and a poloxamine (Tetronic90R4). Thermo-responsive AuNP-containing α-CD/Tetronic90R4 hydrogels are formed under well-defined conditions of concentration. The AuNP displayed an average size of ca. 7 nm and a narrow distribution, as determined by TEM. The AuNP/α-CD/Tetronic90R4 system proved to be stable over time. Upon heating above the gel-to-sol transition temperature, the studied catalytic system allowed hydrogenation of a wide range of substrates such as alkenes, alkynes and aldehydes under biphasic conditions. Upon repeated heating/cooling cycles, the Au NP/α-CD/Tetronic90R4 catalytic system could be recycled several times without a significant decline in catalytic activity.
- Chevry,Menuel,Léger,No?l,Monflier,Hapiot
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p. 9865 - 9872
(2019/07/04)
-
- Method for preparing dihydrocitronellal
-
The invention provides a method for preparing dihydrocitronellal. The method comprises the following steps of: taking raw material citral as a hydrogen acceptor, taking an alcohol compound as a hydrogen donor, and carrying out intermolecular hydrogen transfer reaction under the action of a catalyst system to obtain the dihydrocitronellal; the citral acid value is required to be less than 0.1 mg KOH/g; the catalyst system comprises heterogeneous nickel catalyst components including nickel, a carrier and bimetallic alkoxide. The method has the advantages of normal reaction pressure, low reactiontemperature, easy control, cheap and easily available catalyst, high product selectivity and raw material conversion rate, high byproduct selectivity, easy separation of the dihydrocitronellal by rectification, simple and feasible method, and suitability for industrial production.
- -
-
Paragraph 0053-0112
(2019/12/08)
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- An Atom-Economic and Stereospecific Access to Trisubstituted Olefins through Enyne Cross Metathesis Followed by 1,4-Hydrogenation
-
The combination of intermolecular enyne cross metathesis and subsequent 1,4-hydrogenation opens a stereocontrolled and atom-economic access to trisubstituted olefins. By investigating different combinations of functionalized alkyne and alkene substrates, we found that the outcome (yield, E / Z ratio) of the Grubbs II-catalyzed enyne cross-metathesis step depends on the substrate's structure, the amount of the alkene (used in excess), and the (optional) presence of ethylene. In any case, the 1,4-hydrogenation, catalyzed by 1,2-dimethoxybenzene-Cr(CO) 3, proceeds stereospecifically to yield exclusively the E -products from both the E- and Z- 1,3-diene intermediates obtained by metathesis. A rather broad scope and functional group compatibility of the method is demonstrated by means of 15 examples.
- Ratsch, Friederike,Schmalz, Hans-Günther
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supporting information
p. 785 - 792
(2018/01/27)
-
- On the Use of Polyelectrolytes and Polymediators in Organic Electrosynthesis
-
Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators results in an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators with the TEMPO-mediated transformation of alcohols into carbonyl compounds as a test reaction. Catalyst benchmarking based on cyclic voltammetry studies indicated that the redox-active polymer can compete with molecularly defined TEMPO species. Alcohol oxidation was also highly efficient on a preparative scale, and our polymer-based approach allowed for the separation of both mediator and supporting electrolyte in a single membrane filtration step. Moreover, we have shown that both components can be reused multiple times.
- Schille, Benjamin,Giltzau, Niels Ole,Francke, Robert
-
supporting information
p. 422 - 426
(2018/02/21)
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- Effect of citral and citral related compounds on viability of pancreatic and human B-lymphoma cell lines
-
Citral, 3,7-dimethyl-2,6-octadienal, is a key component of the essential oils extracted from several lemon-scented herbal plants. It has been demonstrated to be an effective antifungal agent and in recent years, to have antiproliferative effect in certain tumor cell lines: thus citral could be a potential anticancer drug. In this study, we investigated the effect of citral on the proliferation of pancreatic cell tumor lines (MIA PaCa-2 cells) and human B-lymphoma (DeFew cells). To analyze which part of the molecule is pivotal for the activity, we also studied the effect of several citral related compounds, in particular focusing on some chemical aspects of the terpenic scaffold. The in vitro studies revealed the significant cytotoxic activity of some of the tested compounds.
- Di Mola, Antonia,Massa, Antonio,De Feo, Vincenzo,Basile, Anna,Pascale, Maria,Aquino, Rita Patrizia,De Caprariis, Paolo
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p. 631 - 639
(2017/02/15)
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- Synergistic Effect of Tungsten Nitride and Palladium for the Selective Hydrogenation of Cinnamaldehyde at the C=C bond
-
Herein, a series of catalysts made of Pd-WN on various supports was synthesized by modifying supports with small-size WN NPs firstly and loading Pd subsequently. Their catalytic performances were evaluated for selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HALD). Interestingly, it was found the synergistic effect between Pd and WN can improve conversion and selectivity of CAL to HALD. Among these catalysts, Pd-WN/SBA-15 shows best performance with highest conversion (99 %) and selectivity to HALD (97 %), which is superior to commercial 5 % Pd/C catalyst. The hydrogenation kinetics of Pd-WN/SBA-15 has been adequately represented by a standard pseudo-first-order approximation, and it discloses that the existence of WN can effectively decrease the activation energy (23.2 kJ mol-1). The synergistic effect of Pd and WN results in enriching the electron density of Pd, increasing the ratio of surface Pd0 and decreasing the size of Pd on the Pd-WN/SBA-15 catalyst.
- Wang, Dong,Zhu, Yujun,Tian, Chungui,Wang, Lei,Zhou, Wei,Dong, Yongli,Yan, Haijing,Fu, Honggang
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p. 1718 - 1726
(2016/05/19)
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- Method of producing hydrogen of the reaction product and substrate
-
PROBLEM TO BE SOLVED: To provide a new production method requiring no reactor having high stirring power for high-temperature and high-pressure conditions in a gas-liquid catalytic reaction of a liquid phase of a substrate with hydrogen in the presence of a solid catalyst. SOLUTION: Micro or nano bubbles are introduced into a liquid phase consisting of a solvent and a substrate so that a reaction product is produced by gas-liquid contact of the substrate with hydrogen in the presence of the solid catalyst. The substrate is one of organic compounds having an unsaturated carbon bond and secondary and tertiary alcohols. COPYRIGHT: (C)2013,JPOandINPIT
- -
-
Paragraph 0045; 0046
(2017/03/24)
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- The effect of catalyst preparation conditions on the synthesis of menthol from citronellal on Ru/H-BEA
-
Heterogeneous Ru/H-BEA catalysts are suitable catalysts for the one-pot transformation of citronellal to menthols, which requires a combined cyclization-hydrogenation step. Here, we report the role of different preparation conditions-namely the choice of the Ru-precursor (Ru(NO)(NO3)3), Ru(acac)3, RuCl3 and Ru3(CO)12) as well as the reduction temperature (523-923 K) of the catalyst. Using Ru(NO)(NO3)3 as precursor the highest activity was obtained, while the product distribution was not strongly affected by the choice of the precursor. On the contrary the reduction temperature leads to very different product distributions: Increasing it from 623 K to 923 K for a 1%Ru/H-BEA-25 catalyst the competitive hydrogenation of citronellal was diminished, which leads to an increased selectivity to menthols from 77% to 87% and additional the activity increases with a factor of 3.4. This behaviour might be due to a dealumination of the zeolite during reduction at higher temperatures. Moreover, in combination with appropriate reaction conditions a yield to menthols of 92% can be reached.
- Pl??er, Jutta,Dedeaga, Fatma,Lucas, Martin,Claus, Peter
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p. 100 - 108
(2016/03/05)
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- Highly efficient and chemoselective hydrogenation of α,β-unsaturated carbonyls over Pd/N-doped hierarchically porous carbon
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Palladium nanoparticles supported on N-doped hierarchically porous carbon, Pd/CNx, has been developed as a highly efficient, reusable and environmentally benign heterogeneous catalyst for the selective hydrogenation of various α,β-unsaturated carbonyls to their corresponding saturated carbonyls under mild conditions (303 K, 1 bar H2). Complete conversion of a series of α,β-unsaturated carbonyls was achieved with excellent selectivity (>99%) within 4 h. Moreover, the catalyst can be easily recovered by centrifugation and withstands recycling up to 8 times without apparent loss of activity and selectivity. The considerable catalytic performance is attributed to the hierarchically porous network and incorporation of nitrogen atoms. This catalytic system opens up an efficient, selective, recyclable and sustainable method for selective hydrogenation.
- Wei, Zhongzhe,Gong, Yutong,Xiong, Tianyi,Zhang, Pengfei,Li, Haoran,Wang, Yong
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p. 397 - 404
(2015/02/02)
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- Room-temperature hydrogenation of citral catalyzed by palladium-silver nanocrystals supported on SnO2
-
We have developed two strategies to optimize Pd catalysts. On one hand, Ag was introduced into Pd and then they were applied to the selective hydrogenation of citral under mild conditions. The addition of metallic Ag could tune the selectivity of Pd and made it suitable for the selective hydrogenation of the conjugated double bond. The selectivity of citronellal increased from 0 (for Pd/C and Pd0.7Ag0.3/C) to 96% (for Pd0.4Ag0.6/C) as the Ag content increased. On the other hand, the addition of SnO2 made the Pd catalysts more inclined to activate the C=O bond and gave better performance for the hydrogenation of the conjugated double bond compared with the corresponding Pd-Ag catalysts. The selectivity of citronellal increased from 0 (for Pd0.7Ag0.3/C) to 76% (for Pd0.7Ag0.3-SnO2/C was used) after the addition of SnO2. On the basis of these results, we developed a catalyst (Pd0.6Ag0.4-SnO2/C) with the best catalytic performance for the selective hydrogenation of citral (the conversion of citral reached 99%, and the selectivity was up to 96%). We have developed two strategies to optimize Pd catalysts for the selective hydrogenation of citral and exploited a catalyst (Pd0.6Ag0.4-SnO2/C) with the best catalytic performance (the conversion of citral reached 99%, and the selectivity was up to 96%).
- Wang, Shuo,Shen, Rongan,Chen, Zheng,Wang, Jiaxi,Wang, Dingsheng,Li, Yadong
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p. 2120 - 2124
(2015/05/05)
-
- Investigation of the Aggregation Properties of a Chiral Porphyrin Bearing Citronellal Meso Substituent Groups
-
A new porphyrin bearing four R or S hydrogenated citronellal units directly bound to the meso positions of the porphyrin ring was synthesized and fully characterized through MALDI-TOF, NMR, UV/Vis absorption, and fluorescence emission spectroscopies. Both enantiomers exhibit a monomeric nature in a series of organic solvents. Acting on the polarity of the solvent, i.e., increasing the amount of water in mixture with acetone, aggregation occurs, as revealed by UV/Vis absorption, fluorescence emission, and resonance light scattering. The occurrence of both H- and J-type aggregates was suggested by fluorescence lifetime measurements. In contrast to the monomeric species, these aggregates exhibit CD spectra reflecting the chirality of the building blocks. AFM microscopy shows that micrometer ribbon-like structures form by the casting solution of these porphyrins in acetone/water onto a glass surface. Chirality 27:900-906, 2015.
- Castriciano, Maria Angela,Zagami, Roberto,Trapani, Mariachiara,Romeo, Andrea,Patanè, Salvatore,Monsù Scolaro, Luigi
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p. 900 - 906
(2015/11/16)
-
- Immobilization of palladium catalyst on magnetically separable polyurea nanosupport
-
This work describes a method for preparing magnetic polyurea nanoparticles (PU NPs) and their utilization as a catalyst support. The method is based on entrapment of hydrophilic magnetic nanoparticles within the polyurea matrix. The synthetic process of these magnetic polyurea nanoparticles is based on oil-in-oil nanoemulsification of an organic polar phase comprised of N,N-dimethylacetamide (DMAc), 2,6-diaminopyridine and ionic liquid modified magnetite nanoparticles (MNPs-IL), in heptane containing a suitable surfactant. This was followed by interfacial polycondensation reaction between an isocyanate monomer, polymethylenepolyphenyl isocyanate (PAPI 27), and the amine monomer producing magnetically separable polyurea nanoparticles. Subsequently, these particles were employed as a catalyst nanosupport. Two catalytic systems based on the encapsulation of Pd(OAc)2 within magnetic PU NPs or their adsorption on the surface of these particles were produced and subjected to hydrogenation reactions and selective hydrogenations of α,β-unsaturated compounds. Pd(OAc)2 adsorbed on the surface of the magnetic PU NPs demonstrated high catalytic activity and selectivity, which was superior to the conventional catalyst Pd/C or palladium nanoparticles supported directly on the surface of magnetite nanoparticles. The catalyst was easily recovered from the reaction mixture by applying an external magnetic field and recycled over five times without observing any significant loss in its catalytic efficiency. This journal is
- Natour, Suzana,Abu-Reziq, Raed
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p. 48299 - 48309
(2014/12/10)
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- (6R,10R)-6,10,14-TRIMETYLPENTADECAN-2-ONE PREPARED FROM 3,7-DIMETYLOCT-2-ENAL OR 3,7-DIMETYLOCTA-2,6-DIENAL
-
The present invention relates to a process of manufacturing (6R,10R)-6,10,14-trimetylpentadecan-2-one in a multistep synthesis from 3,7-dimetyloct-2-enal or 3,7-dimetylocta-2,6-dienal. The process is very advantageous in that it forms the desired chiral product from a mixture of stereoisomers of the starting product in an efficient way.
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-
Page/Page column 47
(2014/07/08)
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- Cu-Catalyzed cascades to carbocycles: Union of diaryliodonium salts with alkenes or alkynes exploiting remote carbocations
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Copper-catalyzed cascade reactions between alkenes or alkynes and diaryliodonium salts form carbocyclic products in a single step. Arylation of the unsaturated functional group is proposed to form a carbocation intermediate that facilitates hydride shift pathways to translocate the positive charge to a remote position and enables ring formation via a Friedel-Crafts-type reaction.
- Zhang, Fengzhi,Das, Shoubhik,Walkinshaw, Andrew J.,Casitas, Alicia,Taylor, Michael,Suero, Marcos G.,Gaunt, Matthew J.
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supporting information
p. 8851 - 8854
(2014/07/08)
-
- Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols
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Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.
- Larionov, Evgeny,Lin, Luqing,Gune, Laure,Mazet, Clment
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supporting information
p. 16882 - 16894
(2015/01/09)
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- PROCESS OF ASYMMETRIC HYDROGENATION OF KETALS AND ACETALS
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The present invention relates to a process of the asymmetric hydrogenation of a ketal of an unsaturated ketone or an acetal of an unsaturated aldehyde by molecular hydrogen in the presence of at least one chiral iridium complex. This process yields chiral compounds in a very efficient way and is very advantageous in that the amount of iridium complex can be remarkably reduced.
- -
-
Page/Page column 61-62
(2014/07/08)
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- Biocatalytic asymmetric alkene reduction: Crystal structure and characterization of a double bond reductase from Nicotiana tabacum
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The application of biocatalysis for the asymmetric reduction of activated C=C is a powerful tool for the manufacture of high-value chemical commodities. The biocatalytic potential of "-ene" reductases from the Old Yellow Enzyme (OYE) family of oxidoreductases is well-known; however, the specificity of these enzymes toward mainly small molecule substrates has highlighted the need to discover "-ene" reductases from different enzymatic classes to broaden industrial applicability. Here, we describe the characterization of a flavin-free double bond reductase from Nicotiana tabacum (NtDBR), which belongs to the leukotriene B4 dehydrogenase (LTD) subfamily of the zinc-independent, medium chain dehydrogenase/reductase superfamily of enzymes. Using steady-state kinetics and biotransformation reactions, we have demonstrated the regio- and stereospecificity of NtDBR against a variety of α,β-unsaturated activated alkenes. In addition to catalyzing the reduction of typical LTD substrates and several classical OYE-like substrates, NtDBR also exhibited complementary activity by reducing non-OYE substrates (i.e., reducing the exocyclic C=C double bond of (R)-pulegone) and in some cases showing an opposite stereopreference in comparison with the OYE family member pentaerythritol tetranitrate (PETN) reductase. This serves to augment classical OYE "-ene" reductase activity and, coupled with its aerobic stability, emphasizes the potential industrial value of NtDBR. Furthermore, we also report the X-ray crystal structures of the holo-, binary NADP(H)-bound, and ternary [NADP+ and 4-hydroxy-3-methoxycinnamaldehyde (9a)-bound] NtDBR complexes. These will underpin structure-driven site-saturated mutagenesis studies aimed at enhancing the reactivity, stereochemistry, and specificity of this enzyme.
- Mansell, David J.,Toogood, Helen S.,Waller, John,Hughes, John M.X.,Levy, Colin W.,Gardiner, John M.,Scrutton, Nigel S.
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p. 370 - 379
(2013/08/25)
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- Metal-free, hydroacylation of CC and NN bonds via aerobic C-H activation of aldehydes, and reaction of the products thereof
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In this report, a thorough evaluation of the use of aerobically initiated, metal-free hydroacylation of various CC and NN acceptor molecules with a wide range of aldehydes is presented. The aerobic-activation conditions that have been developed are in sharp contrast to previous conditions for hydroacylation, which tend to use transition metals, peroxides that require thermal or photochemical degradation, or N-heterocyclic carbenes. The mildness of the conditions enables a number of reactions involving sensitive reaction partners and, perhaps most significantly, allows for α-functionalised chiral aldehydes to undergo radical-based hydroacylation with complete retention of optical purity. We also demonstrate how the resulting hydroacylation products can be transformed into other useful intermediates, such as γ-keto- sulfonamides, sultams, sultones, cyclic N-sulfonyl imines and amides.
- Chudasama, Vijay,Akhbar, Ahmed R.,Bahou, Karim A.,Fitzmaurice, Richard J.,Caddick, Stephen
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supporting information
p. 7301 - 7317
(2013/10/22)
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- Pd nanoparticles immobilized on graphite oxide modified with a base: Highly efficient catalysts for selective hydrogenation of citral
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In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenation of citral. These catalysts were characterized by various techniques including IR, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the Pd particles with size less than 5 nm were uniformly distributed throughout the support, and they were in the electron-deficient state due to the strong interactions with the modified support. The resultant Pd-TMG/GO catalyst displayed high efficiency for the selective hydrogenation of citral with a turnover frequency of 7100 h-1 as well as superior selectivity to citronellal of 89.6%. Moreover, the catalyst can be reused for five times without obvious activity loss, which may result from its stable structure.
- Zhao, Yanfei,Zhang, Hongye,Huang, Changliang,Chen, Sha,Yu, Bo,Xu, Jilei,Liu, Zhimin
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p. 203 - 209
(2013/07/26)
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- Micro and nanobubble based strategy for gas-liquid-solid multiphase reactions: Palladium-catalysed hydrogenation of carbon-carbon unsaturated bonds
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An autoclave-free, gas-liquid-solid multiphase hydrogenation of carbon-carbon unsaturated bonds using hydrogen micro and nanobubbles (MNBs) is developed. The process allows the liquid phase of the reaction mixture to maintain a high concentration of hydrogen gas. Georg Thieme Verlag Stuttgart New York.
- Mase, Nobuyuki,Isomura, Shogo,Toda, Mitsuo,Watanabe, Naoharu
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supporting information
p. 2225 - 2228
(2013/11/06)
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- Reduction of citral in water under typical transfer hydrogenation conditions-Reaction mechanisms with evolution of and hydrogenation by molecular hydrogen
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The reduction of an α,β-unsaturated aldehyde, citral, was investigated over a 10 wt% Pd catalyst under transfer hydrogenation (TH) conditions in a closed system with microwave assistance. Surprisingly, it was found that hydrogen was produced quite fast under the microwave irradiation during the reaction, and the reduction of citral was proved to go mainly through consecutive pathways of hydrogen production - hydrogenation rather than those commonly considered for TH reactions. Similar reaction pathways were also observed with a homogeneous catalyst of [RuCl2(C6H 6)]2 and other typical hydrogen donors like formate salts and isopropanol, which are usually used in the typical transfer hydrogenations.
- Liu, Ruixia,Wang, Yu,Cheng, Haiyang,Yu, Yancun,Zhao, Fengyu,Arai, Masahiko
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p. 315 - 320
(2013/02/23)
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- Alkaline modifiers as performance boosters in citral hydrogenation over supported ionic liquid catalysts (SILCAs)
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Supported ionic liquid catalysts (SILCAs) consist of nano-scale catalytic species immobilized in an ionic liquid layer which, in turn, is immobilized on a solid support. In this work, novel SILCAs containing various inorganic alkaline modifiers (e.g. potassium hydroxide) were prepared and applied in citral hydrogenation reactions. The supported ionic liquid catalyst systems demonstrated enhanced reaction rates and improved selectivities toward citronellal in citral hydrogenation. With the addition of an alkaline modifier into ionic liquid layer, the catalyst selectivity increased from 16% to 74%. In fact, a highly selective reaction route toward citronellal was accomplished.
- Salminen, Eero,Virtanen, Pasi,Kordás, Krisztián,Mikkola, Jyri-Pekka
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p. 126 - 131
(2013/01/15)
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- Application of a cross-linked Pd-chitosan catalyst in liquid-phase- hydrogenation using molecular hydrogen
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Chitosan was cross-linked with hexamethylendiisocyanate and loaded with Pd which was subsequently reduced with NaBH4. The prepared catalyst was characterized by FT-IR and elemental analysis. The metal content was determined by ICP-MS measurements. Several substrates (cyclohex-2-enone, benzalacetophenone, 1,2-diphenylacetylene, and N-benzylidenaniline) were hydrogenated successfully in ethanol at mild conditions (50 °C, p(H 2) ~6 bar) utilizing a microwave reactor. Reaction parameters like temperature, hydrogen pressure, and the solvent were varied. It was shown that the reduction of the catalyst is crucial for catalytic activity. The catalyst was reused ten times for the hydrogenation of cyclohex-2-enone, without showing a dramatic loss in immobilized metal content. Also the polymeric support material did not show any decomposition.
- Schü?ler, Stefan,Blaubach, Nico,Stolle, Achim,Cravotto, Giancarlo,Ondruschka, Bernd
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p. 231 - 238
(2013/02/23)
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- Synthesis of poly(naphthalenecarboxamide)s with low polydispersity by chain-growth condensation polymerization
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Condensation polymerization of 6-(N-substituted-amino)-2-naphthoic acid esters (1) was investigated as an extension of chain-growth condensation polymerization (CGCP). Methyl 6-(3,7-dimethyloctylamino)-2-naphthoate (1b) was polymerized at -10 °C in the presence of phenyl 4-methylbenzoate (2) as an initiator and lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS) as a base. When the feed ratio [1a]0/[2]0 was 10 or 20, poly(naphthalenecarboxamide) with defined molecular weight and low polydispersity was obtained, together with a small amount of cyclic trimer. However, polymer was precipitated during polymerization under similar conditions in [1a]0/[2]0 = 34. To increase the solubility of the polymer, monomers 1c and 1d with a tri(ethylene glycol) (TEG) monomethyl ether side chain instead of the 3,7-dimethyloctyl side chain were synthesized. Polymerization of the methyl ester monomer 1c did not proceed well, affording only oligomer and unreacted 1c, whereas polymerization of the phenyl ester monomer 1d afforded well-defined poly(naphthalenecarboxamide) together with small amounts of cyclic oligomers in [1d]0/[2]0 = 10 and 29. The polymerization at high feed ratio ([1d]0/[2]0 = 32.6) was accompanied with self-condensation to give polyamide with a lower molecular weight than the calculated value. Such undesirable self-condensation would result from insufficient deactivation of the electrophilic ester moiety by the electron-donating resonance effect of the amide anion.
- Mikami, Koichiro,Daikuhara, Hiroaki,Kasama, Jyunya,Yokoyama, Akihiro,Yokozawa, Tsutomu
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experimental part
p. 3020 - 3029
(2012/05/05)
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- Palladium-supported ionic liquid catalyst (Pd-SH-SILC) immobilized on mercaptopropyl silica gel as a chemoselective, reusable and heterogeneous catalyst for catalytic hydrogenation
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Palladium acetate was immobilized as Pd-SH-SILC (Pd-supported ionic liquid catalyst) in the pores of amorphous mercaptopropyl silica gel with the aid of an ionic liquid [bmim]BF4. The heterogeneous Pd-SH-SILC was effective for catalytic hydrogenation of a variety of olefins at atmospheric pressure and room temperature. It withstood recycling up to 10 times by decantation.
- Hagiwara, Hisahiro,Nakamura, Tomomi,Hoshi, Takashi,Suzuki, Toshio
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scheme or table
p. 1133 - 1137
(2011/06/26)
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- Continuous selective hydrogenation of citral in a trickle-bed reactor using ionic liquid modified catalysts
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The influence of the ionic liquid [BMIM][N(CN)2] on the palladium catalyzed hydrogenation of citral in a trickle-bed reactor has been investigated. Applying the SCILL concept (solid catalyst with ionic liquid layer), it was possible to attain citronellal selectivities close to 100% at the cost of catalyst activity. However, the yield of this intermediate was approximately four times higher compared to the neat palladium catalyst. The latter and its SCILL counterpart both seem to have long-term stability, which is relevant for any future industrial application. This is the first time that SCILL systems have been compared directly to their IL-free equivalents in continuous mode.
- W?rz, Nicolai,Arras, Jürgen,Claus, Peter
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experimental part
p. 319 - 324
(2011/10/05)
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- Shape controlled synthesis of palladium nanocrystals by combination of oleylamine and alkylammonium alkylcarbamate and their catalytic activity
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The shape of Pd nanocrystals (NCs) can be controlled by combination of oleylamine (OAm) and alkylammonium alkylcarbamate (AAAC), and Pd spheres, tetrahedra and multipods have been synthesized. The multipods and tetrahedra are much more active than the sph
- Hu, Baoji,Ding, Kunlun,Wu, Tianbin,Zhou, Xiaosi,Fan, Honglei,Jiang, Tao,Wang, Qian,Han, Buxing
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supporting information; experimental part
p. 8552 - 8554
(2011/01/03)
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- Physically and chemically mixed TiO2-supported Pd and Au catalysts: unexpected synergistic effects on selective hydrogenation of citral in supercritical CO2
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The selective hydrogenation of citral was studied with various TiO2-supported monometallic and bimetallic Pd and Au catalysts and their physical mixtures in supercritical CO2 (scCO2). Significant synergistic effects appeared when active Pd species was chemically or physically mixed with less active Au species. The total rate of conversion was greatly enhanced and the selectivity to citronellal (CAL) was improved. The physical properties of those catalysts were characterized by TEM, HRTEM-EDS, XPS, and UV/Vis and their features of H2 desorption were examined by TPD. The physical and chemical characterization results were used to discuss the reasons for the unexpected synergistic effects observed. The same selective hydrogenation was also conducted in a conventional non-polar organic solvent of n-hexane to examine the roles of scCO2. The use of scCO2 was effective for accelerating the hydrogenation of citral and improving the selectivity to CAL.
- Liu, Ruixia,Yu, Yancun,Yoshida, Kazuki,Li, Guiming,Jiang, Haoxi,Zhang, Minhua,Zhao, Fengyu,Fujita, Shin-ichiro,Arai, Masahiko
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scheme or table
p. 191 - 200
(2010/09/17)
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- Colloidal noble-metal and bimetallic alloy nanocrystals: A general synthetic method and their catalytic hydrogenation properties
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A general single-step strategy has been developed for the direct thermal decomposition of noble-metal salts in octadecylamine to synthesize octahedron- and rod-shaped noblemetal aggregates and monodisperse noble-metal or bimetallic alloy nanocrystals without introducing any additive into the system. It has presented a facile and economic way to fabricate these nanocrystals, especially alloy nanocrystals, which does not require a post-synthesis solid-state annealing process. The morphology of the nanocrystals can be easily controlled by tuning the synthetic temperature. Their ability to catalyze heterogeneous Suzuki coupling reactions has been investigated and showed satisfactory catalytic activity. The catalytic performanee of the monometallic and bimetallic alloy nanocrystals were also evaluated in the selective hydrogenation of citral in a conventional organic solvent (toluene) and a green solvent (supercritical carbon dioxide, scCO2). Interestingly, the catalysts performed differently to each other when they were in ScCO2 owing to the different morphology, which should be readily optimized for further use.
- Song, Shuyan,Liu, Ruixia,Zhang, Yu,Feng, Jing,Liu, Dapeng,Xing, Yan,Zhao, Fengyu,Zhang, Hongjie
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scheme or table
p. 6251 - 6256
(2010/07/13)
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- A Convenient access to (All-rac)-α-tocopherol acetate from linalool and dihydromyrcene
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Refluxing trimethylhydroquinone 2 in 10:1 dodecane/CH2Cl 2 with linalool 3b (two-fold excess) and camphorsulfonic acid, then treating the crude condensation product (consisting of a mixture of the chromanols 1b and 1c, alongside the tricyclic compounds 9 and 10) sequentially with Ac2O and m-CPBA afforded, after removal by column chromatography of the 9/10 acetates, a mixture of the regioisomeric epoxides 1jOAc and 1kOAc (ratio 9:1, total 60%). Treatment of this mixture with Al(O-i-Pr)3 followed by CuI-catalysed Wurtz coupling of the acetates of the resulting allylic alcohols with citronellylmagnesium chloride 12a, and finally hydrogenation then provided the title acetate (overall 46% from 2).
- Gembus, Vincent,Sala-Jung, Nathalie,Uguen, Daniel
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experimental part
p. 829 - 842
(2009/12/25)
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- Regioselective catalytic hydrogenation of citral with ionic liquids as reaction modifiers
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Silica and polyaniline supported palladium catalysts prepared by different techniques (incipient-wetness impregnation, deposition precipitation) using Pd(OAc)2 or H2PdCl4 as precursors were studied in the liquid-phase hydrogenation of citral under addition of several ionic liquids ([BMIM][NTf2], [BMIM][PF6], [BMPL][NTf 2], [BMIM][DCA], [BMPL][DCA], [B3MPYR][DCA]) either as catalyst coating or as additive. By an incipient-wetness technique, the catalysts were coated with a mixture of IL in acetone. The catalysts were characterized by nitrogen physisorption, whereby a decrease of surface area and pore volume was detected by the IL coated catalysts. Furthermore, ICP-OES, TEM and IR spectroscopy were performed to analyze metal content, particle size and coverage of the catalyst with ionic liquid. Citral hydrogenation was performed at 323 K and under 2.0 MPa H2 in an autoclave with off-line GC analysis of the product mixtures. Beside stirrer speed, catalyst mass and citral concentration, the type and quantity of ionic liquid were also varied to elucidate their influence on activity and selectivity of the Pd/SiO2 catalysed citral hydrogenation. The results show that treatment of the catalyst with ionic liquids - independent of catalyst coating or additive - leads to a selectivity enhancement of the desired product, citronellal. With [PF6] - or [NTf2]- as the IL anion, maximum selectivities were (60 ± 2)% at 70% conversion. In particular, dicyanamide (DCA) containing ionic liquids allow, under optimised conditions, the quantitative one-pot synthesis of citronellal, at least if the Pd/SiO 2 catalyst was coated with 29 wt% [B3MPYR][DCA]. By using polyaniline supported Pd catalysts and [BMIM][DCA] as additive, the consecutive hydrogenation towards dihydrocitronellal was less pronounced and the influence of metal precursor, support material and preparation technique of the catalyst could be excluded. Hydrogenation of pure citral on [BMIM][DCA] coated palladium catalysts offers a solvent-free, green route to citronellal in reasonable selectivities (S = 86%).
- Arras, Juergen,Steffan, Martin,Shayeghi, Yalda,Ruppert, Dominik,Claus, Peter
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experimental part
p. 716 - 723
(2010/04/23)
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- Selective hydrogenation of citral catalyzed with palladium nanoparticles in CO2-in-water emulsion
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CO2-in-Water (C/W) emulsion was formed by using a nonionic surfactant of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (P123), and palladium nanoparticles were synthesized in situ in the present work. The catalytic performa
- Liu, Ruixia,Wu, Chaoyong,Wang, Qiang,Ming, Jun,Hao, Yufen,Yu, Yancun,Zhao, Fengyu
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experimental part
p. 979 - 985
(2010/04/23)
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- Zr-zeolite beta: A new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-menthol
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The transformation of citral to menthols involves hydrogenation steps as well as cyclisation of the intermediate, citronellal. The ability of Zrzeolite beta to catalyse the cyclisation with high diastereoselectivity to (±)-isopulegol is the critical step
- Nie, Yuntong,Jaenicke, Stephan,Chuah, Gaik-Khuan
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experimental part
p. 1991 - 1999
(2009/09/06)
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- Isolation and absolute configuration determination of aliphatic sulfates as the Daphnia kairomones inducing morphological defense of a phytoplankton - Part 2
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4,8-Dimethylnonyl sulfate (1) and 3-methyl-4E-decenyl sulfate (2) were isolated from Daphnia pulex as the Daphnia kairomones that induced morphological defense of a freshwater phytoplankton Scenedesmus gutwinskii var. heterospina (NIES-802). The absolute configuration at C4 of 1 was determined by Ohrui's method applied to alcohol 3. The absolute stereochemistry at C3 of 2 was determined by 1H-NMR analysis of the (R)-1NMA ester of alcohol 11.
- Yasumoto, Ko,Nishigami, Akinori,Aoi, Hiroaki,Tsuchihashi, Chise,Kasai, Fumie,Kusumi, Takenori,Ooi, Takashi
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p. 129 - 132
(2008/09/21)
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- The promoting effect of a dicyanamide based ionic liquid in the selective hydrogenation of citral
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Conventional supported heterogeneous palladium catalysts in combination with a dicyanamide based ionic liquid are highly active with excellent selectivity in enabling the one-pot synthesis of citronellal through citral hydrogenation. The Royal Society of Chemistry.
- Arras, Juergen,Steffan, Martin,Shayeghi, Yalda,Claus, Peter
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scheme or table
p. 4058 - 4060
(2009/03/11)
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- Design of catalyst systems for the one-pot synthesis of menthols from citral
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Stable, active, and highly selective bifunctional Ni/Al-MCM-41 catalysts were developed for the one-pot synthesis of menthols from citral. The liquid-phase hydrogenation of citral to citronellal was studied on silica-supported noble (Pt, Pd, Ir) and nonnoble (Ni, Co, Cu) metals. It was found that citronellal is selectively formed at the beginning of the reaction only on Pd and Ni catalysts. The consecutive ene-cyclization of citronellal to isopulegols was investigated on solid acids containing exclusively Lewis (ZnO/SiO2) or strong Broensted (CsHPA) acid sites, and also on catalysts containing both Lewis and Broensted acid sites of either strong (zeolites, SiO2-Al2O3) or moderate (Al-MCM-41) strength. The isopulegol formation rate was higher on samples exhibiting dual Lewis/Broensted acidity, such as SiO2-Al2O3, Al-MCM-41, and zeolite HBEA. Based on these previous results, bifunctional catalysts containing Pd or Ni supported on SiO2-Al2O3, Al-MCM-41, or zeolite HBEA were prepared and tested for citral conversion to menthols. The catalyst stability and the effect of hydrogen pressure and metal loading on menthol productivity were also investigated. The best catalyst was Ni(8%)/Al-MCM-41, which yielded more than 90% menthols at 2026.0 kPa and showed no significant deactivation after two consecutive catalytic tests.
- Trasarti,Marchi,Apesteguia
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p. 155 - 165
(2008/02/03)
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- Nature of catalyst deactivation during citral hydrogenation: A catalytic and ATR-IR study
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Deactivation of a 5 wt% Pd/Al2O3 catalyst during hydrogenation of citral (1) to citronellal (2), 3,7-dimethyl-2-octenal (3), and dihydrocitronellal (4) has been studied in a continuous-flow fixed-bed reactor. The reactions were carried out at 40 °C and 190 bar in hexane, supercritical CO2, or ethane as solvents. ATR-IR spectroscopic analysis of the solid/liquid interphase under reaction conditions at low pressure revealed that 1 and 3 decarbonylate on the Pd surface resulting in strongly adsorbed CO and CxHy-type hydrocarbon fragments. The absence of decarbonylation products from 2 and 4 and the excellent chemoselectivity for the hydrogenation of the C=C bonds are interpreted by adsorption of the molecules in a tilted position on Pd, π-bonded via one C=C bond (2) or di-π-bonded via the C=C-C=O fragment (1 and 3). A practically important observation is that a short reoxidation by air of the used Pd/Al2O3 under very mild conditions (40 °C, 6 bar) can circumvent further deactivation, but the original activity cannot be regained. All these observations indicate that the irreversible deactivation of Pd/Al2O3 cannot be traced to CO poisoning. We propose that site blocking caused by heavier oligomeric surface products is the major reason for the observed catalyst deactivation. Elsevier Inc. All rights reserved.
- Burgener, Marco,Wirz, Ronny,Mallat, Tamas,Baiker, Alfons
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p. 152 - 161
(2007/10/03)
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- Steric and magnetic asymmetry distinguished by encapsulation
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Guests in an achiral cavity experience asymmetric magnetic environments induced by chiral centers outside the cavity. Copyright
- Amaya, Toru,Rebek Jr., Julius
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p. 6216 - 6217
(2007/10/03)
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- Precursors for fragrant ketones and fragrant aldehydes
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The present invention refers to fragrance precursors of formula I for a fragrant ketone of formula II and one or more fragrant aldehydes or ketones of formula III and IV, These fragrance precursors are useful in perfumery, especially in the fine and functional perfumery.
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- Efficient isomerization of allylic alcohols to saturated carbonyl compounds by activated rhodium and ruthenium complexes
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A range of readily available rhodium complexes of the general structures Rh(PPh3)3+ PF6- and RhX(PPh3)3 (X = H, Me, Ph) have been prepared and used in situ for the isomerization of allylic alcohols to their corresponding saturated carbonyl compounds. The isomerization of octen-3-ol, selected as a model, yielded octan-3-one in good yield. This reaction has been extended to the corresponding ruthenium complexes of the general structures [RuCl(PPh3)3]+ PF6-, RuXCl(PPh3)3 and RuX2(PPh3)3 (X = H, Me, Ph). It is noteworthy that many of these complexes have not been employed previously for this isomerization. The scope and efficiency of the process has been demonstrated by four representative complexes [RhH(PPh3)3, RuH2(PPh3)3, RuPh2(PPh3)3, RuCl(PPh3)3+ PF6-] with a wide variety of allylic alcohols. The reaction of primary allylic alcohols in the presence of RuCl(PPh3)3+ PF6- in methanol yields aldehydes protected as their methyl acetals. Deuterium labelling experiments are in agreement with a 1,3-hydride shift mechanism.
- Uma, Ramalinga,Davies, Maxwell K.,Crevisy, Christophe,Gree, Rene
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p. 3141 - 3146
(2007/10/03)
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- Universal approach to the synthesis of juvenoid hydroprene and methoprene from 4-methyltetrahydropyran
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A universal approach to the synthesis of juvenoid hydroprene and methoprene was developed on the basis of monoalkylation of acetoacetate by 1-acetoxy-5-bromo-3-methylpentane, the product of acidic decyclization of 4-methyltetrahydropyran.
- Ishmuratov,Yakovleva,Galyautdinova,Faifer,Kharisov,Zorin,Tolstikov
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p. 486 - 489
(2007/10/03)
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- Syntheses of the Juvenoid (S)-(+)-Hydroprene from L-(-)-Menthol
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The versatile chiral synthon methyl (R)-5,5-dimethoxy-3-methylpentanoate has been prepared for the first time via ozonolytic decyclization of (R)-4-menthenone, which is available from L-(-)-menthol. The optically pure juvenoid (S)-(+)-hydroprene can be prepared from the synthon.
- Kharisov, R. Ya.,Gazetdinov, R. R.,Ishmuratov, G. Yu.,Tolstikov, G. A.
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p. 140 - 142
(2007/10/03)
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- New approach to rapid generation and screening of diverse catalytic materials on electrode surfaces
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This paper describes a general approach to rapid generation and screening of catalytic materials on electrode surfaces. The properties of the corresponding polymers, including catalytic performance, can be modulated by varying the monomer feed ratios, monomer concentrations, and applied polymerization potential. Thus, the generation of the polymeric TEMPO (2,2,6,6-tetramethylpiperidin-1-yloxy) catalysts was performed by electrochemical copolymerization of 2,2'-bithiophene with the TEMPO catalyst precursors containing pyrrole side chains. A library of catalyst films was obtained over a wide range of bithiophene/pyrrole ratios upon repeated scanning of the applied potential from +0.5 to +1.4 V (vs Ag/AgCl). The resulting catalyst films were utilized in both chemical and electrochemical oxidation of primary alcohols to aldehydes.
- Siu,Yekta,Yudin
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p. 11787 - 11790
(2007/10/03)
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- Liquid-phase hydrogenation of citral over Pt/SiO2 catalysts - II. Hydrogenation of reaction intermediate compounds
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Liquid-phase hydrogenation of the four principal reaction intermediates during citral hydrogenation (nerol, geraniol, citronellal, and citronellol) was studied at 298 and 373 K under 20 atm H2 at concentrations of 0.5-1M in hexane. Decomposition of geraniol and nerol to form adsorbed CO on Pt as an inhibitor was proposed to be responsible for the activity minimum observed during citral hydrogenation. A decrease in the initial reaction rate as temperature increased from 298 to 373 K was exhibited during the hydrogenation of all four compounds. Furthermore, simultaneous hydrogenation of citronellal and geraniol at 298 K resulted in a continuous decrease in the rate of citronellal disappearance in contrast to the nearly constant rate of disappearance observed during hydrogenation of citronellal alone. Competitive hydrogenation of citral with either geraniol or citronellal showed that geraniol hydrogenation to citronellol was kinetically insignificant during citral hydrogenation at 373 K. The relative rates of hydrogenation of the compounds indicated that the hydrogenation rate of the C=C bond in this family of compounds was greater than that of the C=O bond, as evidenced by the ordering of the hydrogenation activity: geraniol > nerol > citronellol > E-citral > citronellal _ Z-citral. The product distributions obtained during hydrogenation of citronellal indicated that higher reaction temperatures favor activation of the C=O bond relative to the C=C bond.
- Vannice,Singh,Sysak
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p. 181 - 191
(2007/10/03)
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