- A uniform bimetallic rhodium/iron nanoparticle catalyst for the hydrogenation of olefins and nitroarenes
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Mix and more than match: Relative to the catalytic activity of pure Rh nanoparticles in a dendrimer cage, Rh/Fe bimetallic nanoparticles in dendrimers have improved catalytic activity towards the hydrogenation of olefins, and unlike Wilkinson catalyst could catalyze nitroarene hydrogenation (see scheme, G4=4th generation dendrimer).
- Nakamula, Ikuse,Yamanoi, Yoshinori,Imaoka, Takane,Yamamoto, Kimihisa,Nishihara, Hiroshi
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- Microwave assisted hydrogenation of olefins by Pd NPs@polystyrene resin using a gas addition kit: A robust and sustainable protocol
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Polystyrene (PS) resin bead supported palladium nanoparticles (Pd NPs@PS resin) were prepared and their catalytic activity for the hydrogenation of olefins was investigated under microwave heating. The hydrogenation of styrene was effectively carried out in EtOH/H2O, in the presence of 0.00035 mmol of the catalyst to afford the corresponding ethylbenzene in high yield within 20 min under microwave heating. The catalyst efficiency measured in terms of turn over number (TON) and turn over frequency (TOF) was found to be 2829 and 8573 (h-1), respectively. The encapsulated palladium nanoparticles were easily recovered by a simple filtration method and reused several times without significant loss in their catalytic activity. Further, the method showed a wide substrate scope under mild reaction conditions, making it a green versatile and highly sustainable protocol.
- Sharma, Anuj S.,Kaur, Harjinder
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Read Online
- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
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Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
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supporting information
p. 9029 - 9039
(2021/06/28)
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- Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
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The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
- Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
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supporting information
p. 2157 - 2161
(2021/05/21)
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- Copper(II)-Doped ZIF-8 as a Reusable and Size Selective Heterogeneous Catalyst for the Hydrogenation of Alkenes using Hydrazine Hydrate
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In recent years, synthesis of mixed-metal organic frameworks has received considerable attention due to their superior performance than with mono-metallic metal organic frameworks (MOFs). In the present manuscript, Cu2+ ions are doped within the framework of ZIF-8 (ZIF: Zeolitic Imidazolate Frameworks) to obtain Cu@ZIF-8 and is characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV-Visible diffuse reflectance spectra (DRS), scanning electron microscope (SEM) and transmission electron microcope (TEM) studies. The reaction conditions are optimized with styrene as a model substrate using Cu@ZIF-8 as a solid catalyst. Heterogeneity of the reaction is confirmed by leaching test and the solid is reusable for three recycles with no diminishing activity. Further, the structural integrity of Cu@ZIF-8 is also retained after hydrogenation of styrene as evidenced by powder X-ray diffraction. The size selective catalysis of Cu@ZIF-8 is demonstrated by comparing the activity of Cu2+ ions adsorbed over ZIF-8 solid (Cu/ZIF-8) in the hydrogenation of 1-hexene, 1-octene, cyclohexene, cyclooctene and t-stilbene. The catalytic results indicate that Cu/ZIF-8 shows superior activity than Cu@ZIF-8 for all these olefins due to the lack of diffusion to access the active sites (Cu2+). In contrast, Cu@ZIF-8 exhibits higher activity for those olefins with lower molecular dimensions (1-hexene, 1-octene) than the pores of ZIF-8 indicating the facile diffusion of these substrates inside the pores ZIF-8 while poor activity is observed with t-stilbene due to its larger molecular dimension than the pore apertures of ZIF-8. These catalytic data clearly establish the size selective hydrogenation of Cu@ZIF-8 due to the effective confinement provided by ZIF-8 framework and the presence of the active sites within the framework. Furthermore, this is the first report showing the size selective hydrogenation of olefins promoted by Cu@ZIF-8 (mixed-metal MOFs) compared to other noble metal nanoparticles (NPs) embedded over MOFs as catalysts.
- Nagarjun, Nagarathinam,Arthy, Kannan,Dhakshinamoorthy, Amarajothi
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p. 2108 - 2119
(2021/06/01)
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- Reductive Deamination with Hydrosilanes Catalyzed by B(C6F5)3
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The strong boron Lewis acid tris(pentafluorophenyl)borane B(C6F5)3 is known to catalyze the dehydrogenative coupling of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C?N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition-metal-free reductive deamination of a broad range of amines as well as heterocumulenes such as an isocyanate and an isothiocyanate.
- Fang, Huaquan,Oestreich, Martin
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supporting information
p. 11394 - 11398
(2020/05/25)
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- Palladium Nanocatalysts Encapsulated on Porous Silica @ Magnetic Carbon-Coated Cobalt Nanoparticles for Sustainable Hydrogenation of Nitroarenes, Alkenes and Alkynes.
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Palladium nanoparticles were impregnated on porous silica shell carbon-coated cobalt nanoparticles, resulting in a magnetically retrievable material that was evaluated in the catalytic hydrogenation of nitroarenes, alkenes and alkynes. The prepared material was characterized by HR-XRD, HR-TEM, elemental mapping EDX, ICP-OES and XPS analyses, revealing highly dispersed palladium nanoparticles within the porous platform that could account for the high activity observed. Mild reaction conditions, easy retrievability of the catalyst with the aid of an external magnet, recycling in four runs with a total leaching of 19 ppm (1.2 % of the initially employed Pd amount), and high stability makes this material attractive for sustainable and environmentally benign applications.
- Purohit, Gunjan,Rawat, Diwan S.,Reiser, Oliver
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p. 569 - 575
(2019/11/19)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0149-0152
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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p. 3082 - 3087
(2020/10/02)
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- Novel CoNi-metal-organic framework crystal-derived CoNi?C: Synthesis and effective cascade catalysis
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Evaluating the catalytic influence of metal sites on derivates obtained from the calcination of metal-organic frameworks (MOFs) is very important for the rational construction of novel MOFs. Based on this catalytic functional guidance, two new Co-MOF and CoNi-MOF crystals were designed and synthesized, and further pyrolyzed to obtain corresponding porous carbon-based catalysts. Interestingly, the derivates exhibited better catalytic performance toward the tandem reaction of dehydrogenation of NH3BH3 and subsequent hydrogenation reduction of nitro/olefin compounds than those of the CoNi-ZIF (a star MOF)-derived CoNi?carbon and most metal catalysts. Significantly, the CoNi?C maintained excellent activity, even after 30 cycles, demonstrating its great longevity and durability, which are especially important for the practical application of metal catalysts in industrial catalysis.
- Chen, Yu-Zhen,Li, Chenchen,Sun, Jia-Lu,Wang, Guo-Ming,Wang, Lin,Zhang, Jian-Wei
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supporting information
p. 10567 - 10573
(2020/09/18)
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- Pd-Nanoparticles immobilized organo-functionalized SBA-15: An efficient heterogeneous catalyst for selective hydrogenation of C–C double bonds of α,β-unsaturated carbonyl compounds
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A novel PdNPs/SBA-NH2-LA catalyst has been prepared by a post-synthetic grafting approach via successive anchoring of propylamine (SBA-NH2) and lipoic acid (SBA-NH2-LA) functional groups followed by palladium nanoparticles immobilization. The Physico-chemical properties of the catalyst were extensively investigated by XRD, N2 adsorption-desorption, XPS, FT-IR, and TEM analysis. The PdNPs/SBA-NH2-LA catalyst is found to be highly selective for the hydrogenation of C–C double bonds of α, β-unsaturated carbonyl compounds. Excellent conversion (95–99 %) and selectivity (>99 %) with high turn over frequency (330?1065 h?1) achieved at room temperature under atmospheric hydrogen pressure within 30?90 min of reaction time. This kind of high activity is expected from its structural and textural integrity of the catalyst.
- Burri, David Raju,Narani, Anand,Natte, Kishore,Reddy Kannapu, Hari Prasad
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- Transition metal complexes of a bis(carbene) ligand featuring 1,2,4-triazolin-5-ylidene donors: structural diversity and catalytic applications
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Dialkylation of the 1,3-bis(1,2,4-triazol-1-yl)benzene with ethyl bromide results in the formation of [L-H2]Br2which, upon salt metathesis with NH4PF6, readily yields the bis(triazolium) salt [L-H2](PF6)2with non-coordinating counterions. [L-H2](PF6)2and Ag2O react in a 1?:?1 ratio to yield a binuclear AgI-tetracarbene complex of the composition [(L)2Ag2](PF6)2which undergoes a facile transmetalation reaction with [Cu(SMe2)Br] to deliver the corresponding CuI-NHC complex [(L)2Cu2](PF6)2. In contrast, the [L-H2]Br2reacts with [Ir(Cp*)Cl2]2to generate a doubly C-H activated IrIII-NHC complex5. Similarly, the triazolinylidene donor supported diorthometalated RuII-complex6is also obtained. Complexes5and6represent the first examples of a stable diorthometalated binuclear IrIII/RuII-complex supported by 1,2,4-triazolin-5-ylidene donors. The synthesized IrIII-NHC complex5is found to be more effective than its RuII-analogue (6) for the reduction of a range of alkenes/alkynesviathe transfer hydrogenation strategy. Conversely, RuII-complex6is identified as an efficient catalyst (0.01 mol% loading) for the β-alkylation of a wide range of secondary alcohols using primary alcohols as alkylating partnersviaa borrowing hydrogen strategy.
- Donthireddy, S. N. R.,Illam, Praseetha Mathoor,Rit, Arnab,Singh, Vivek Kumar
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p. 11958 - 11970
(2020/09/21)
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- +: A Masked Potent Boron Lewis Acid
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The chemistry of the boron cation has been revitalized in the past decade due to its newfound application in stoichiometric and catalytic organic reactions. To extend the frontier of boron cation catalysis, we came to discover that a mesityl-substituted η5-Cp*-coordinated boron cation could serve as a powerful Lewis acid for organic catalytic transformations. The boron cation [Cp*B-Mes][B(C6F5)4] ([1][B(C6F5)4]) stabilized in a boronium-like electronic structure binds to Et3PO readily and displays an acceptor number exceeding that of B(C6F5)3 on the Gutmann-Beckett acidity scale. The steric and electronic stabilization exerted by the electron-donating Cp? renders the highly Lewis acidic boron cation an easy-to-handle catalyst for hydrodeoxygenation of aryl ketones at ambient temperature. The exceptional catalytic performance of [1]+ implies that the incorporation of a coordinatively flexible substituent at boron is critical in bringing catalytic activity and stability to boron cation catalysts.
- Tseng, Hsi-Ching,Shen, Chao-Tang,Matsumoto, Kentaro,Shih, Ding-Nan,Liu, Yi-Hung,Peng, Shie-Ming,Yamaguchi, Shigehiro,Lin, Ya-Fan,Chiu, Ching-Wen
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supporting information
p. 4516 - 4521
(2019/11/14)
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- Sustainable visible light assisted in situ hydrogenation via a magnesium-water system catalyzed by a Pd-g-C3N4 photocatalyst
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A non-hazardous and relatively mild protocol was formulated for an effectual hydrogen generation process via a "magnesium-activated water" system with a Pd-g-C3N4 photocatalyst under visible light at room temperature. Water functions photochemically as a hydrogen donor without any external source with the Pd-g-C3N4 photocatalyst. The synthesized Pd-g-C3N4 photocatalyst is highly efficient under visible light for the selective reduction of a wide range of unsaturated derivatives and nitro compounds to afford excellent yields (>99%). The photocatalyst Pd-g-C3N4 could be easily recovered and reused for several runs without any deactivation during the photochemical hydrogen transfer reaction process.
- Sharma, Priti,Sasson, Yoel
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supporting information
p. 261 - 268
(2019/01/28)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Room Temperature Iron-Catalyzed Transfer Hydrogenation and Regioselective Deuteration of Carbon-Carbon Double Bonds
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An iron catalyst has been developed for the transfer hydrogenation of carbon-carbon multiple bonds. Using a well-defined β-diketiminate iron(II) precatalyst, a sacrificial amine and a borane, even simple, unactivated alkenes such as 1-hexene undergo hydrogenation within 1 h at room temperature. Tuning the reagent stoichiometry allows for semi- and complete hydrogenation of terminal alkynes. It is also possible to hydrogenate aminoalkenes and aminoalkynes without poisoning the catalyst through competitive amine ligation. Furthermore, by exploiting the separate protic and hydridic nature of the reagents, it is possible to regioselectively prepare monoisotopically labeled products. DFT calculations define a mechanism for the transfer hydrogenation of propene with nBuNH2 and HBpin that involves the initial formation of an iron(II)-hydride active species, 1,2-insertion of propene, and rate-limiting protonolysis of the resultant alkyl by the amine N-H bond. This mechanism is fully consistent with the selective deuteration studies, although the calculations also highlight alkene hydroboration and amine-borane dehydrocoupling as competitive processes. This was resolved by reassessing the nature of the active transfer hydrogenation agent: experimentally, a gel is observed in catalysis, and calculations suggest this can be formulated as an oligomeric species comprising H-bonded amine-borane adducts. Gel formation serves to reduce the effective concentrations of free HBpin and nBuNH2 and so disfavors both hydroboration and dehydrocoupling while allowing alkene migratory insertion (and hence transfer hydrogenation) to dominate.
- Espinal-Viguri, Maialen,Neale, Samuel E.,Coles, Nathan T.,MacGregor, Stuart A.,Webster, Ruth L.
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supporting information
p. 572 - 582
(2019/01/08)
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- Tris(pyrazolyl)borate Cobalt-Catalyzed Hydrogenation of C=O, C=C, and C=N Bonds: An Assistant Role of a Lewis Base
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The combination of tris(pyrazolyl)borate cobalt complexes and Lewis base is developed as an efficient catalyst precursor in the homogeneous hydrogenation. A broad substrate scope including carbonyls, alkenes, enamines, and imines is reduced with 60 atm of H2 at 60 °C. Mechanistic studies support the hydrogenation operates through a frustrated Lewis pair (FLP)-like reduction process. These results highlight the development of novel non-noble metal catalytic processes, when combined with the diverse small molecule activation chemistry associated with FLPs.
- Lin, Yang,Zhu, De-Ping,Du, Yi-Ran,Zhang, Rui,Zhang, Suo-Jiang,Xu, Bao-Hua
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supporting information
p. 2693 - 2698
(2019/04/25)
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- Homogeneous Palladium-Catalyzed Transfer Hydrogenolysis of Benzylic Alcohols Using Formic Acid as Reductant
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We report the first homogeneous palladium-based transfer hydrogenolysis of benzylic alcohols using an in situ formed palladium-phosphine complex and formic acid as reducing agent. The reaction requires a catalyst loading as low as only 1 mol % of palladium and just a slight excess of reductant to obtain the deoxygenated alkylarenes in good to excellent yields. Besides demonstrating the broad applicability for primary, secondary and tertiary benzylic alcohols, a reaction intermediate could be identified. Additionally, it could be shown that partial oxidation of the applied phosphine ligand was beneficial for the course of the reaction, presumably by stabilizing the active catalyst. Reaction profiles and catalyst poisoning experiments were used to characterize the catalyst, the results of which indicate a homogeneous metal complex as the active species.
- Ciszek, Benjamin,Fleischer, Ivana
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p. 12259 - 12263
(2018/08/28)
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- Disilaruthena- and Ferracyclic Complexes Containing Isocyanide Ligands as Effective Catalysts for Hydrogenation of Unfunctionalized Sterically Hindered Alkenes
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Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3′ and 4′, were synthesized and characterized by spectroscopy and crystallography. Both 3′ and 4′ showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1′ and 2′, the isocyanide complexes 3′ and 4′ were more robust under the hydrogenation conditions, and were still active even at higher temperatures (～80 °C) under high hydrogen pressure (～20 atm). The iron complex 3′ exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4′ catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4′ for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfaltz, which are catalysts with the highest activity in the literature. DFT calculations suggested two plausible catalytic cycles, both of which involved activation of H2 assisted by the metal-silicon bond through σ-bond metathesis of late transition metals (oxidative hydrogen migration). The linear structure of M C≡N - C (ipso carbon of the mesityl group) played an essential role in the efficient hydrogenation of sterically hindered tetrasubstituted alkenes.
- Sunada, Yusuke,Ogushi, Hajime,Yamamoto, Taiji,Uto, Shoko,Sawano, Mina,Tahara, Atsushi,Tanaka, Hiromasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Nagashima, Hideo
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supporting information
p. 4119 - 4134
(2018/03/29)
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- Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
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The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
- Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
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supporting information
p. 4417 - 4429
(2018/04/05)
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- Highly active Ru-g-C3N4 photocatalyst for visible light assisted selective hydrogen transfer reaction using hydrazine at room temperature
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The present study describes the highly efficient heterogeneous photoactive catalyst Ru-g-C3N4 screened for selective transfer hydrogenation of nitroarenes and olefins. Photoactive catalyst Ru-g-C3N4 exhibits excellent reactivity in visible light under very mild reaction conditions via using hydrazine hydrate as a source of hydrogen with high turnover number. The easily separable heterogeneous photoactive Ru-g-C3N4 catalyst is straightforward to handle in visible light (LED lamp), non-toxic, environmentally friendly and at the same time eliminates the use of high pressure hydrogenation reactors without the need for external sources of energy.
- Sharma, Priti,Sasson, Yoel
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- Methyl Hydrazinocarboxylate as a Practical Alternative to Hydrazine in the Wolff-Kishner Reaction
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Herein we describe a facile protocol for the reduction of aromatic ketones and aldehydes to the corresponding methylene unit. The procedure involves isolation of a carbomethoxyhydrazone intermediate that is easily decomposed to the reduced product without the requirement for large quantities of pernicious hydrazine.
- Cranwell, Philippa B.,Russell, Andrew T.,Smith, Christopher D.
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p. 131 - 135
(2015/12/26)
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- Domino Methylenation/Hydrogenation of Aldehydes and Ketones by Combining Matsubara's Reagent and Wilkinson's Catalyst
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The methylenation/hydrogenation cascade reaction of aldehydes or ketones through a domino process involving two ensuing steps in a single pot is realized. The compatibility of Matsubara's reagent and Wilkinson's complex give a combination that allows, under dihydrogen, the transformation of a carbonyl function into a methyl group. This new method is suitable to introduce an ethyl motif from aromatic and aliphatic aldehydes with total chemoselectivity and total retention of α-stereochemical purity. The developed procedure is also extended to the introduction of methyl groups from ketones.
- Maazaoui, Radhouan,Pin-Nó, María,Gervais, Kevin,Abderrahim, Raoudha,Ferreira, Franck,Perez-Luna, Alejandro,Chemla, Fabrice,Jackowski, Olivier
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supporting information
p. 5732 - 5737
(2016/12/14)
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- Dual oxidation/bromination of alkylbenzenes
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In the presence of sodium bromide and Oxone, a range of alkylbenzene derivatives are brominated and/or oxidized with up to four C-H bonds being functionalized.
- Aborways, Marwa M.,Moran, Wesley J.
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p. 983 - 985
(2016/02/16)
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- Application of Pd Nanoparticles Supported on Mesoporous Hollow Silica Nanospheres for the Efficient and Selective Semihydrogenation of Alkynes
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Herein, the preparation of a heterogeneous catalyst consisting of 1-2 nm sized Pd nanoparticles supported on amino-functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono- And disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over-reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.
- Verho, Oscar,Zheng, Haoquan,Gustafson, Karl P. J.,Nagendiran, Anuja,Zou, Xiaodong,B?ckvall, Jan-E.
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p. 773 - 778
(2016/03/05)
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- Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor
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There are few examples of catalytic transfer hydrogenations of simple alkenes and alkynes that use water as a stoichiometric H or D atom donor. We have found that diboron reagents efficiently mediate the transfer of H or D atoms from water directly onto unsaturated C-C bonds using a palladium catalyst. This reaction is conducted on a broad variety of alkenes and alkynes at ambient temperature, and boric acid is the sole byproduct. Mechanistic experiments suggest that this reaction is made possible by a hydrogen atom transfer from water that generates a Pd-hydride intermediate. Importantly, complete deuterium incorporation from stoichiometric D2O has also been achieved.
- Cummings, Steven P.,Le, Thanh-Ngoc,Fernandez, Gilberto E.,Quiambao, Lorenzo G.,Stokes, Benjamin J.
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supporting information
p. 6107 - 6110
(2016/06/09)
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- Iron-catalyzed olefin hydrogenation at 1 bar H2 with a FeCl3-LiAlH4 catalyst
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The scope and mechanism of a practical protocol for the iron-catalyzed hydrogenation of alkenes and alkynes at 1 bar H2 pressure were studied. The catalyst is formed from cheap chemicals (5 mol% FeCl3-LiAlH4, THF). A homogeneous mechanism operates at early stages of the reaction while active nanoparticles form upon ageing of the catalyst solution. This journal is
- Gieshoff, Tim N.,Villa, Matteo,Welther, Alice,Plois, Markus,Chakraborty, Uttam,Wolf, Robert,Jacobi Von Wangelin, Axel
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supporting information
p. 1408 - 1413
(2015/03/18)
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- Enhanced Reactivity of Aerobic Diimide Olefin Hydrogenation with Arylboronic Compounds: An Efficient One-Pot Reduction/Oxidation Protocol
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A catalyst-free and efficient method for simultaneous olefin hydrogenation and oxidation of arylboronate esters to phenols with hydrazine hydrate and molecular oxygen is presented. The process is based on the utilization of a readily available Lewis acidic arylboron compound, which evades common problems associated with the catalyst-free aerobic hydrogenation of olefins with diimide. Using an operationally simple procedure, the protocol smoothly delivers phenol derivatives and various alkanes in excellent yields with remarkable functional group compatibility. The method allows the reaction to be scaled up to 1 g of the starting materials.
- Santra, Surojit,Guin, Joyram
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supporting information
p. 7253 - 7257
(2015/11/25)
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- General transfer hydrogenation by activating ammonia-borane over cobalt nanoparticles
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Cobalt nanoparticles containing both Co2+ and Co0 species supported on carbon nitride can function as heterogeneous nanocatalysts for a general transfer hydrogenation reaction in aqueous ammonia-borane solution at room temperature. The conversions of nitroarenes, olefins, imines, aldehydes, ketones and cyanobenzene are high with superior selectivity under mild conditions. This noble-metal-free catalyst is also cheap and reusable.
- Zhao, Tian-Jian,Zhang, Ya-Nan,Wang, Kai-Xue,Su, Juan,Wei, Xiao,Li, Xin-Hao
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p. 102736 - 102740
(2015/12/11)
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- An unprecedented anionic Ln-MOF with a cage-within-cage motif: Spontaneous reduction and immobilization of ion-exchanged Pd(II) to Pd-NPs in the framework
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An unprecedented microporous anionic Ln-MOF, [Me2NH2]24[Tb12(TATB)16(HCOO)12]·12DMF·48H2O (1) (H3TATB = 4,4′,4′′-s-triazine-2,4,6-tribenzoic acid), which is a rare cage-within-cage structure through interpenetration rather than covalent bonding, has been synthesized. Compound 1 contains a 3D net which is constructed using a large and a small Ln-carboxylate cage alternately arranged by sharing faces with each other. Interpenetration of two identical 3D nets occurs in such a way that each small cage of one net is encapsulated within the large cage of the other and vice versa, generating an overall 3D double-walled cage framework. Such interpenetration creates a unique structure of double-shelled hollow space to accommodate Pd nanoparticles (Pd-NPs), which could effectively prevent Pd-NPs from aggregation and leaching. Moreover, the ion-exchanged Pd(ii) embedded in the framework can be readily reduced at room temperature with no requirement of any chemical or thermal treatments, affording Pd-NPs with uniform size and even distribution. As a result, the as-prepared Pd-NPs@1 exhibits excellent activity and cycling stability for the hydrogenation of styrene and its derivatives.
- Han, Yun-Hu,Tian, Chong-Bin,Lin, Ping,Du, Shao-Wu
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p. 24525 - 24531
(2015/12/09)
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- On the ionizing properties of supercritical carbon dioxide: Uncatalyzed electrophilic bromination of aromatics
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Supercritical carbon dioxide (scCO2), a solvent with a zero dipole moment, low dielectric constant, and no hydrogen bonding behavior, is a suitable medium to perform the uncatalyzed electrophilic bromination of weakly activated aromatics with no interference of radical pathways. The ability of scCO2 to promote these reactions matches those of strongly ionizing solvents such as aqueous acetic and trifluoroacetic acids. Conversely, carbon tetrachloride, with similar polarity parameters to scCO2, leads exclusively to side chain functionalization. The strong quadrupole moment, and the acidic, but non basic, Lewis character of carbon dioxide, are proposed as key factors for the singular performance of scCO2 in reactions involving highly polar and ionic intermediates.
- Delgado-Abad, Thais,Martnez-Ferrer, Jaime,Reig-Lpez, Javier,Mello, Rossella,Acerete, Rafael,Asensio, Gregorio,Gonzlez-Nez, Mara Elena
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p. 51016 - 51021
(2015/01/16)
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- Preparation of a ternary Pd-Rh-P amorphous alloy and its catalytic performance in selective hydrogenation of alkynes
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Palladium-rhodium-phosphorus amorphous alloy nanoparticles (～5.2 nm) were prepared via a facile one-pot synthesis method, exhibiting excellent catalytic behaviour in selective hydrogenation of alkynes under mild conditions. The Royal Society of Chemistry 2014.
- Ren, Mengrui,Li, Changming,Chen, Jiale,Wei, Min,Shi, Shuxian
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p. 1920 - 1924
(2014/06/24)
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- Palladium nanoparticles in situ generated in metal-organic films for catalytic applications
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Palladium nanoparticles were first in situ generated in metal-organic films for catalytic applications. Layer-by-layer assembly of metal-organic films consisting of rigid-rod chromophores connected by terminal pyridine moieties to palladium centers on solid substrates was presented. Bipyridyl and polypyridyl ligands were used as building blocks to explore the influence of different ligand structures on catalytic properties. Metal-organic films were characterized by UV-Vis spectra, atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results show that the deposition mechanism of metal-organic films is perfect layer-by-layer self-assembling with complete surface coverage and regular growth. Moreover, the catalytic activity toward the hydrogenation of olefin was investigated. Based on XPS and TEM, the catalytic activity toward the hydrogenation of olefin was ascribed to the in situ formation of Pd nanoparticles from Pd ions in metal-organic films. This film material is an active catalyst for the hydrogenation of olefin under mild conditions. Furthermore, catalytic results indicated that monodentate bipyridyl ligands exhibited superior catalytic activity than tridentate polypyridyl ligands. Catalytic activity is related to the loading amount of catalysts and permeability. More importantly, this study points toward the potential application of metal-organic films as heterogeneous catalysts with easy separation and good recyclability. This journal is the Partner Organisations 2014.
- Gao, Shuiying,Cao, Minna,Li, Weijin,Cao, Rong
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p. 12185 - 12193
(2014/08/05)
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- Photodriven Transfer Hydrogenation of Olefins
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An improved practical method for the photodriven diimide reduction of olefins was investigated. This catalyst-free procedure proceeds at ambient temperature, utilizes air as oxidant and a lower hydrazine loading, and produces inert nitrogen gas as the sole byproduct. Several functional groups were tolerated, and in some cases, the reaction was chemoselective. Challenging substrates such as cinnamate ester derivatives and trans-stilbene were reduced in excellent yields. The small amount of UVA rays emitted from a household compact fluorescent light bulb was proposed to enable the cis/trans isomerization of the diimide and to promote the loss of hydrogen from the diimide.
- Leow, Dasheng,Chen, Ying-Ho,Hung, Tzu-Hang,Su, Ying,Lin, Yi-Zhen
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supporting information
p. 7347 - 7352
(2016/02/18)
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- Catalyst enhancement and recyclability by immobilization of metal complexes onto graphene surface by noncovalent interactions
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The immobilization of a homogeneous catalyst onto a solid surface is one of the major challenges in catalysis, because it may facilitate the separation of the catalyst and the reaction products and may also give rise to the reutilization of the catalyst in multiple subsequent cycles. Noncovalent interactions between the catalyst and the support are arising as interesting alternatives to the more widely used covalent interactions, because they avoid the functionalization of both the catalyst and the surface, which may in turn lead to the modification of the inherent properties of the catalyst. However, some other problems may arise, such as leaching. In this work, we have obtained two complexes containing an N-heterocyclic carbene ligand with a pyrene tag, which we immobilized onto the surface of reduced graphene oxide (rGO), by π-stacking. The catalytic properties of the parent molecular complexes and hybrid materials have been studied in the palladium-catalyzed hydrogenation of alkenes and the ruthenium-catalyzed alcohol oxidation. The results show that the catalytic properties are improved in the hybrid materials, compared to the catalytic outcomes provided by the homogeneous analogues. Although the palladium-catalyzed reactions may be due to the formation of Pd nanoparticles, the ruthenium-catalyzed ones are facilitated by the supported molecular catalyst. The catalyst stability was analyzed by means of recyclability studies, hot filtration test, and large-scale experiments. Both hybrid materials have been reused up to 10 times without any decrease in activity, affording quantitative yield of products. The hot filtration experiment reveals that the catalysis is heterogeneous in nature without any detectable leaching or boomerang effect. The work constitutes a clear improvement over other known immobilization methodologies and offers a practical methodology which may inspire future developments of efficient heterogenized catalysts.
- Sabater, Sara,Mata, Jose A.,Peris, Eduardo
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p. 2038 - 2047
(2014/06/24)
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- A sustainable process for catalytic oxidative bromination with molecular oxygen
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Workin′ in a bromine: A palladium-polyoxometalate amphiphilic hybrid material serves as catalyst for oxidative brominations. The emulsion-based process avoids the use of toxic and corrosive bromination agents such as Br 2 or HBr, and uses molecular oxygen as oxidant. The only side product is water, which is also the reaction medium. The catalyst offers good recoverability and recyclability. Copyright
- Huang, Zhijun,Li, Fengbo,Chen, Bingfeng,Lu, Tao,Yuan, Yin,Yuan, Guoqing
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p. 1337 - 1340
(2013/09/12)
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- Metal and H2O2 free aerobic oxidative aromatic halogenation with [RNH3+] [NO3-]/HX and [BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl) as multifunctional ionic liquids
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Novel multifunctional ionic liquids (ILs) are generated by addition of HBr or HCl to alkylammonium nitrates ([RNH3+] [NO 3-]) and to 3-methyl-1-(butyl-4-sulfonyl)imidazolium nitrate ([BMIM(SO3H)][NO3]). The resulting [RNH 3+] [NO3-]/HX and mono (3-methyl-1-(butyl-4-sulfonyl)imidazolium) monohalogenide mononitrate ([BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl)) systems act as solvent and promoter for aerobic oxidative halogenation of arenes under mild conditions in high yields that can be repeated over several cycles.
- Prebil, Rok,Laali, Kenneth K.,Stavber, Stojan
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supporting information
p. 2108 - 2111
(2013/06/05)
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- Metal-ligand core-shell nanocomposite catalysts for the selective semihydrogenation of alkynes
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Catalysts with a sheltered upbringing: Novel core-shell nanocomposite catalysts consisting of active metal nanoparticles encapsulated by macroligands have been prepared. They have Pd nanoparticles (PdNPs) as an active core and shell ligands having sulfoxide moieties coordinated to the PdNPs. The shell protects the catalyst from coordination by alkenes and allows the lead-free selective semihydrogenation of a wide range of alkynes without any additives (see scheme). Copyright
- Mitsudome, Takato,Takahashi, Yusuke,Ichikawa, Satoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1481 - 1485
(2013/04/10)
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- Rhodium-cobalt bimetallic nanoparticles: A catalyst for selective hydrogenation of unsaturated carbon-carbon bonds with hydrous hydrazine
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Our studies on the effect of metal compositions on the catalytic activity of the rhodium-based bimetallic nanocatalysts revealed that the nanoparticles with a 4:1 ratio of rhodium to cobalt, were more active than the rhodium monometallic nanoparticles in the selective hydrogenation of unsaturated carbon-carbon bonds with hydrous hydrazine as a hydrogen source. The nanocatalysts effected this hydrogenation process in good-to-excellent yields with high functional group tolerance, and could be reused 10 times without the loss of catalytic activity. The catalyst characterization by X-ray photoelectron spectroscopy, transmission electron microscopy and line-scanning analysis suggested that the coexistence of metallic rhodium and cobalt plays an important role in the enhancement of catalytic activity. Copyright
- Lin, Jin,Chen, Jing,Su, Weiping
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- Easily-controlled chemoselective hydrogenation by using palladium on boron nitride
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The hydrogenation catalyzed heterogeneously by palladium on boron nitride (Pd/BN) in methanol realized the chemoselective hydrogenation of only azides, alkenes, and alkynes in the presence of other reducible functionalities such as benzyl ethers, aryl halides, aryl ketones, and nitro groups. Furthermore, the totally chemoselective semihydrogenation of alkynes could also be achieved without the reduction of other coexisting reducible functionalities, which include azides and alkenes, by using Pd/BN in pyridine as a solvent. Be unique, be selective: The chemoselective hydrogenation of azides, alkenes, and alkynes was achieved without the reduction of other reducible functionalities by the use of a heterogeneous palladium on boron nitride (Pd/BN) catalyst. Furthermore, Pd/BN was applicable to the unique and chemoselective semihydrogenation of alkynes without the reduction of azido functionalities in the presence of pyridine or diethylenetriamine.
- Yabe, Yuki,Sawama, Yoshinari,Yamada, Tsuyoshi,Nagata, Saori,Monguchi, Yasunari,Sajiki, Hironao
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p. 2360 - 2366
(2013/08/23)
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- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
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Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
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p. 1673 - 1679
(2013/02/22)
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- Assembly and post-modification of a metal-organic nanotube for highly efficient catalysis
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A metal-organic nanotube (MONT) was synthesized by linking up the bent organic ligands and the tetra-coordinated zinc cations under mild conditions. Structural analysis revealed that the MONT has a very large exterior wall diameter of 4.91 nm and an interior channel diameter of 3.32 nm. Interlocking of the nanotubes gives rise to a 3D chiral framework containing 1D helical cylindered channels with diameter of 2.0 nm. The MONT has very interesting property by synergizing the functionality of nanotubes, metal-organic frameworks (MOFs), and N-heterocyclic carbenes (NHCs). The dye adsorption experiments demonstrate that the channels of the MONTs are accessible to large reagents typically used for catalysis. The postmodification of the MONT can be easily operated by unmarking the imidazolium moieties in the channel walls, which was conducted as a highly active heterogeneous catalyst for Suzuki-Miyaura and Heck coupling reactions, hydrogenation of olefins and nitrobenzene, while the constituent elements are less efficient for these reactions under the same conditions.
- Kong, Guo-Qiang,Ou, Sha,Zou, Chao,Wu, Chuan-De
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p. 19851 - 19857
(2013/02/22)
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- Chemoselective hydrogenation of the olefinic bonds using a palladium/magnesium-lanthanum mixed oxide catalyst
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A palladium/magnesium-lanthanum mixed oxide catalyst is found to be an efficient heterogeneous catalyst for the chemoselective hydrogenation of olefinic double bonds in the presence of various functional groups. The catalyst was recovered by centrifugation and reused for several cycles with consistent activity and selectivity. Copyright
- Kantam, Mannepalli Lakshmi,Kishore, Ramineni,Yadav, Jagjit,Sudhakar, Medak,Venugopal, Akula
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supporting information; experimental part
p. 663 - 669
(2012/04/23)
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- Magnetic nanoparticles entrapped in siliceous mesocellular foam: A new catalyst support
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γ-Fe2O3 nanoparticles were formed inside the cage-like pores of mesocellular foam (MCF). These magnetic nanoparticles showed a uniform size distribution that could be easily controlled by the MCF pore size, as well as by the hydrocarbon chain length used for MCF surface modification. Throughout the entrapment process, the pore structure and surface area of the MCF remained intact. The resulting magnetic MCF facilitated the immobilization of biocatalysts, homogeneous catalysts, and nanoclusters. Moreover, the MCF allowed for facile catalyst recovery by using a simple magnet. The supported catalysts exhibited excellent catalytic efficiencies that were comparable to their homogeneous counterparts. Copyright
- Lee, Su Seong,Riduan, Siti Nurhanna,Erathodiyil, Nandanan,Lim, Jaehong,Cheong, Jian Liang,Cha, Junhoe,Han, Yu,Ying, Jackie Y.
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experimental part
p. 7394 - 7403
(2012/07/27)
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- Chemoselective hydrogenation using molecular sieves-supported Pd catalysts: Pd/MS3A and Pd/MS5A
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Palladium catalysts embedded on molecular sieves (MS3A and MS5A) were prepared by the adsorption of Pd(OAc)2 onto molecular sieves with its in situ reduction to Pd0 by MeOH as a reducing agent and solvent. 0.5% Pd/MS3A and 0.5% Pd/MS5A catalyzed the hydrogenation of alkynes, alkenes, and azides with a variety of coexisting reducible functionalities, such as nitro group, intact. It is noteworthy that terminal alkenes of styrene derivatives possessing electron-donating functionalities on the benzene nucleus were never hydrogenated under 0.5% Pd/MS5A-catalyzed conditions, while internal alkenes of 1-propenylbenzene derivatives were readily reduced to the corresponding alkanes.
- Takahashi, Tohru,Yoshimura, Masatoshi,Suzuka, Hiroyasu,Maegawa, Tomohiro,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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experimental part
p. 8293 - 8299
(2012/09/21)
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- Selective hydrogenation of alkenes under ultramild conditions
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SiliaCat Pd0 solid catalyst heterogeneously mediates at room temperature the selective hydrogenation of a wide variety of alkenes under hydrogen balloon conditions using a modest 0.1 mol % catalyst amount. The catalyst is recyclable with negligible leaching of valued palladium, providing the chemical industry with a suitable replacement for less selective metal-based catalysts.
- Pandarus, Valerica,Gingras, Genevieve,Beland, Francois,Ciriminna, Rosaria,Pagliaro, Mario
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experimental part
p. 1230 - 1234
(2012/07/28)
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- Reduction of carbonyl to methylene: Organosilane-Ga(OTf)3 as an efficient reductant system
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Direct carbonyl reduction to methylene has been achieved by mild reductant system obtained from the combination of organosilane and gallium (III) trifluoromethanesulfonate {Ga(OTf)3}, a water tolerant, recyclable, catalyst. Among a series of organosilanes studied, dimethylchlorosilane (Me 2SiHCl, DMCS) showed the highest efficiency. Both aromatic and aliphatic ketones were effectively reduced to the corresponding methylene products with high functional groups tolerance, under very mild conditions in a relatively short period of time with good to excellent yields. Graphical Abstract: [Figure not available: see fulltext.]
- Surya Prakash,Do, Clement,Mathew, Thomas,Olah, George A.
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experimental part
p. 507 - 511
(2012/01/04)
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- InBr3-catalyzed reduction of ketones with a hydrosilane: Deoxygenation of aromatic ketones and selective synthesis of secondary alcohols and symmetrical ethers from aliphatic ketones
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An InBr3-Et3SiH reducing system was developed to selectively convert aliphatic ketones to a variety of secondary alcohols in moderate to good yields. An initial mixing of InBr3 and PhSiH 3 was followed by the addition of aliphatic ketones and a solvent to afford the symmetrical ether derivatives.
- Sakai, Norio,Nagasawa, Ken,Ikeda, Reiko,Nakaike, Yumi,Konakahara, Takeo
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experimental part
p. 3133 - 3136
(2011/06/26)
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- Highly active iridium(i) complexes for the selective hydrogenation of carbon-carbon multiple bonds
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New iridium(i) complexes, bearing a bulky NHC/phosphine ligand combination, have been established as extremely efficient hydrogenation catalysts that can be used at low catalyst loadings, and are compatible with functional groups which are often sensitive to more routinely employed hydrogenation methods.
- Bennie, Linsey S.,Fraser, Calum J.,Irvine, Stephanie,Kerr, William J.,Andersson, Shalini,Nilsson, Goeran N.
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supporting information; experimental part
p. 11653 - 11655
(2011/12/05)
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- A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system
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[ReBr2(NO)(CH3CN)(PTA)2] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h-1.
- Dong, Hailin,Berke, Heinz
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experimental part
p. 1803 - 1808
(2011/06/19)
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