- Stereoselective cyclizations mediated by functionalized organomagnesium reagents and catalyzed by cobalt or copper salts
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The iodine-magnesium exchange reaction with i-PrMgCl allows a mild preparation of functionalized arylmagnesium compounds bearing a leaving group in the molecule. With the appropriate transition-metal catalyst (a copper or cobalt salt), cyclization reactions occur leading to five- or six-membered ring systems in good yields.
- Kneisel, Florian F.,Monguchi, Yasunari,Knapp, Kolja M.,Zipse, Hendrik,Knochel, Paul
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Read Online
- A Novel Cyclodehydration Reaction of Hydroxy-phenols using Imidate Esters as Leaving Groups
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A mild, efficient and stereospecific intramolecular method for converting hydroxy-phenols into benzodioxans, dihydrobenzopyrans and dihydrobenzofurans via imidate esters, and suitable for large scale operation is described.
- Procopiou, Panayiotis A.,Brodie, Alastair C.,Deal, Martyn J.,Hayman, David F.
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Read Online
- A novel catalyst Pd@ompg-C3N4 for highly chemoselective hydrogenation of quinoline under mild conditions
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Polymeric mesoporous carbon graphitic nitrides (mpg-C3N 4) and ordered mesoporous graphitic carbon nitrides (ompg-C 3N4) with different surface area and morphology were used to prepare palladium catalysts (Pd@C3N4) by an easy ultrasonic-assisted method. These catalysts demonstrated excellent activity and selectivity for hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline under mild temperature (30-50 °C) and H2 pressure (1 bar). Pd@ompg-C3N4(r = 2.5) showed the best catalytic performance and both the activity and selectivity could be maintained for at least six reaction runs. The introduction of ordered cylindrical mesoporous structure and high concentration of surface Pd0 (about 70%) contribute to the high reaction activity and selectivity over Pd@ompg-C 3N4 catalysts.
- Gong, Yutong,Zhang, Pengfei,Xu, Xuan,Li, Yi,Li, Haoran,Wang, Yong
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Read Online
- Organometallic Synthesis of Bimetallic Cobalt-Rhodium Nanoparticles in Supported Ionic Liquid Phases (CoxRh100?x@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates
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The synthesis, characterization, and catalytic properties of bimetallic cobalt-rhodium nanoparticles of defined Co:Rh ratios immobilized in an imidazolium-based supported ionic liquid phase (CoxRh100?x@SILP) are described. Following an organometallic approach, precise control of the Co:Rh ratios is accomplished. Electron microscopy and X-ray absorption spectroscopy confirm the formation of small, well-dispersed, and homogeneously alloyed zero-valent bimetallic nanoparticles in all investigated materials. Benzylideneacetone and various bicyclic heteroaromatics are used as chemical probes to investigate the hydrogenation performances of the CoxRh100?x@SILP materials. The Co:Rh ratio of the nanoparticles is found to have a critical influence on observed activity and selectivity, with clear synergistic effects arising from the combination of the noble metal and its 3d congener. In particular, the ability of CoxRh100?x@SILP catalysts to hydrogenate 6-membered aromatic rings is found to experience a remarkable sharp switch in a narrow composition range between Co25Rh75 (full ring hydrogenation) and Co30Rh70 (no ring hydrogenation).
- Rengshausen, Simon,Van Stappen, Casey,Levin, Natalia,Tricard, Simon,Luska, Kylie L.,DeBeer, Serena,Chaudret, Bruno,Bordet, Alexis,Leitner, Walter
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- Heterogeneous Hydrogenation of Quinoline Derivatives Effected by a Granular Cobalt Catalyst
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We communicate a convenient method for the pressure hydrogenation of quinolines in aqueous solution by using a particulate cobalt-based catalyst that is prepared in situ from simple Co(OAc)2 4H2O through reduction with abundant zinc powder. This catalytic protocol permits a brisk and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines thereby relying solely on easy-to-handle reagents that are all readily obtained from commercial sources. Both the reaction setup assembly and the autoclave charging procedure are conducted on the bench outside an inert-gas-operated containment system, thus rendering the overall synthesis time-saving and operationally very simple.
- Timelthaler, Daniel,Topf, Christoph
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- Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
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The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
- Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
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p. 2909 - 2915
(2021/03/14)
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- Preparation of NiCu Alloy Catalyst for the Hydrodeoxygenation of Benzofuran
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A series of bimetallic NixCu(10-x)/SiO2 (where x is the mass fraction of Ni and the total metal loading was fixed at 10 wt%.) catalysts with different Ni/Cu mass ratio are prepared and characterized by X-Ray diffraction (XRD), N2 adsorption-desorption, inductively coupled plasma mass spectrometry (ICP-MS), H2 temperature-programmed reduction (H2-TPR) and transmission electron microscope (TEM). The benzofuran (BF) hydrodeoxygenation (HDO) performance of as-prepared catalysts are evaluated in a fixed flow reactor. The results showed that the incorporation of Cu to Ni/SiO2 catalyst can increase surface area of catalyst and improve the reducibility of nickel oxide species, which contributed to higher catalytic activity and total deoxygenated compounds yield. Moreover, the strong synergistic effect between Ni and Cu led to the formation of NiCu alloy at the Ni mass fraction of 5 wt% and thus induced smaller crystallite size and exposure of more active particles, which inevitably contributed to the improved HDO performance for Ni5Cu5/SiO2 catalyst. At 300 °C, 3.0 MPa, MHSV=3.0 h?1 and H2/oil = 500(v/v), the total yield of deoxygenated products over Ni5Cu5/SiO2 catalyst reached 86.0%, which is increased by 10.8% and 77.4% as compared to those of monometallic Ni/SiO2 (75.2%) and Cu/SiO2 catalysts (8.8%), respectively. Finally, a possible reaction network for HDO of BF on Ni5Cu5/SiO2 catalyst was proposed. Graphic Abstract: [Figure not available: see fulltext.]
- Zhu, Tianhan,Song, Hua,Li, Feng,Chen, Yanguang
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p. 1670 - 1682
(2020/10/21)
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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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- Preparation method of 2,3-dihydrobenzofuran
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The invention discloses a preparation method of 2,3-dihydrobenzofuran. The preparation method comprises the following steps: with phenol and 2-bromoacetaldehyde diethyl acetal as initial raw materials, carrying out condensing to obtain 2-phenoxyacetaldehyde diethyl acetal; carrying out cyclizing to obtain benzofuran; and finally, conducting hydrogenating to obtain 2,3-dihydrobenzofuran. The methodprovided by the invention can be used for preparing 2,3-dihydrobenzofuran, and has the advantages of easily available raw materials, mild reaction conditions, easy operation, good product quality, high yield, low cost, small environmental pollution and relatively high economic benefits.
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Paragraph 0027-0028
(2020/07/02)
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- Selective Hydrogenation of Benzofurans Using Ruthenium Nanoparticles in Lewis Acid-Modified Ruthenium-Supported Ionic Liquid Phases
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Ruthenium nanoparticles immobilized on a Lewis-acid-functionalized supported ionic liquid phase (Ru?SILP-LA) act as effective catalysts for the selective hydrogenation of benzofuran derivatives to dihydrobenzofurans. The individual components (nanoparticles, chlorozincate-based Lewis-acid, ionic liquid, support) of the catalytic system are assembled using a molecular approach to bring metal and acid sites in close contact on the support material, allowing the hydrogenation of O-containing heteroaromatic rings while keeping the aromaticity of C6-rings intact. The chlorozincate species were identified to be predominantly [ZnCl4]2- anions using X-ray photoelectron spectroscopy and are in close interaction with the metal nanoparticles. The Ru?SILP-[ZnCl4]2- catalyst exhibited high activity, selectivity, and stability for the catalytic hydrogenation of a variety of substituted benzofurans, providing easy access to biologically relevant dihydrobenzofuran motifs under continuous flow conditions.
- Bordet, Alexis,El Sayed, Sami,Hetaba, Walid,Leitner, Walter,Luska, Kylie L.,Weidenthaler, Claudia
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p. 2124 - 2130
(2020/02/11)
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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; 0213-0216
(2020/05/14)
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- Synthesis of Ni2P/Al2O3 utilizing triphenylphosphine (TPP) as the phosphorus source for hydrodeoxygenation of benzofuran
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A novel route to synthesize highly active Ni2P/Al2O3 (TPP) utilizing triphenylphosphine (TPP) as the phosphorus source at a low temperature of 573 K is described. The as-prepared catalysts were characterized by X-ray diffraction (XRD), CO uptake, Brunner-Emmett-Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the Ni2P/Al2O3 (TPP) catalyst and the role of the TPP phosphorus source were studied using hydrodeoxygenation (HDO) of benzofuran (BF) as a probe reaction. The results show that the use of TPP as the phosphorus source could suppress the strong interaction between phosphate and Al2O3, thereby the formation of AlPO4 was avoided. As compared to the Ni2P/Al2O3 prepared by using (NH4)2HPO4 as the phosphorus source, Ni2P/Al2O3 (TPP) possessed significantly higher surface area and smaller Ni2P particle size. The HDO activity and yield of O-free products over the Ni2P/Al2O3 (TPP) catalyst were increased by 17.2% and 36.0%, respectively, when compared with those found for Ni2P/Al2O3 prepared using (NH4)2HPO4. The use of TPP as the phosphorus source could effectively promote the dehydration of 2-ethylphenol (2-EtPh) to form ethylbenzene (EB), and the demethylation of ethylcyclohexane (ECH) to methylcyclohexane (MCH).
- Jiang, Bolong,Jiang, Nan,Han, Chunbao
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p. 7577 - 7582
(2020/06/19)
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- Light-Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII-Aryl Complex
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A highly effective C?O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C?O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle.
- Cao, Rui,Lai, Chu-Hui,Li, Gang,Liu, Fengyi,Lu, Huan-Huan,Wang, Chao,Xiao, Jianliang,Xue, Dong,Yang, Liu,Zhang, Wei
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supporting information
p. 12714 - 12719
(2020/06/02)
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- Method for synthesizing darifenacin intermediate 2,3-dihydrobenzofuran
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The invention discloses a method for synthesizing a darifenacin intermediate 2,3-dihydrobenzofuran. The method comprises the following steps that a reaction bottle containing an organic solvent is cooled to 5-mius 5 DEG C, then a reductant and benzofuranone are added into the reaction bottle in sequence, heating is carried out for a reaction, after the reaction is completed, a reaction solution iscooled, the cooled reaction solution is quenched, concentrated, extracted, dried and filtered, and a filtrate is concentrated to obtain 2-hydroxyphenethylethanol; the 2-hydroxyphenylethanol and an acidic catalyst are added into the organic solvent, a reaction is performed under a heating condition, after the reaction is completed, a reaction solution is cooled, water is added into the cooled reaction solution, mixing and uniform stirring are carried out, standing and separating are carried out, an organic phase is dried and filtered, and reduced pressure distillation is performed to obtain the darifenacin intermediate 2,3-dihydrobenzofuran. The method for synthesizing the darifenacin intermediate 2,3-dihydrobenzofuran has the advantages that the synthetic method is simpler, the reaction condition is mild, the yield is high, the purity is high, and the cost is low.
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Paragraph 0027; 0031; 0035; 0039; 0043
(2019/08/14)
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- Redox-Neutral Coupling between Two C(sp3)?H Bonds Enabled by 1,4-Palladium Shift for the Synthesis of Fused Heterocycles
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The intramolecular coupling of two C(sp3)?H bonds to forge a C(sp3)?C(sp3) bond is enabled by 1,4-Pd shift from a trisubstituted aryl bromide. Contrary to most C(sp3)?C(sp3) cross-dehydrogenative couplings, this reaction operates under redox-neutral conditions, with the C?Br bond acting as an internal oxidant. Furthermore, it allows the coupling between two moderately acidic primary or secondary C?H bonds, which are adjacent to an oxygen or nitrogen atom on one side, and benzylic or adjacent to a carbonyl group on the other side. A variety of valuable fused heterocycles were obtained from easily accessible ortho-bromophenol and aniline precursors. The second C?H bond cleavage was successfully replaced with carbonyl insertion to generate other types of C(sp3)-C(sp3) bonds.
- Rocaboy, Ronan,Anastasiou, Ioannis,Baudoin, Olivier
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p. 14625 - 14628
(2019/09/16)
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- Oxalic Diamides and tert-Butoxide: Two Types of Ligands Enabling Practical Access to Alkyl Aryl Ethers via Cu-Catalyzed Coupling Reaction
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A robust and practical protocol for preparing alkyl aryl ethers has been developed, which relies on using two types of ligands to promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction scope is very general for a variety of coupling partners, particularly for challenging secondary alcohols and (hetero)aryl chlorides. In case of coupling with aryl chlorides and bromides, two oxalic diamides serve as the powerful ligands. The tert-butoxide is first demonstrated as a ligand for Cu-catalyzed coupling reaction, leading to alkoxylation of aryl iodides complete at room temperature. Additionally, a number of carbohydrate derivatives are applicable for this coupling reaction, affording the corresponding carbohydrate-aryl ethers in 29-98% yields.
- Chen, Zhixiang,Jiang, Yongwen,Zhang, Li,Guo, Yinlong,Ma, Dawei
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p. 3541 - 3549
(2019/02/26)
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- Semiheterogeneous Dual Nickel/Photocatalytic (Thio)etherification Using Carbon Nitrides
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A carbon nitride material can be combined with homogeneous nickel catalysts for light-mediated cross-couplings of aryl bromides with alcohols under mild conditions. The metal-free heterogeneous semiconductor is fully recyclable and couples a broad range of electron-poor aryl bromides with primary and secondary alcohols as well as water. The application for intramolecular reactions and the synthesis of active pharmaceutical ingredients was demonstrated. The catalytic protocol is applicable for the coupling of aryl iodides with thiols as well.
- Cavedon, Cristian,Madani, Amiera,Seeberger, Peter H.,Pieber, Bartholom?us
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supporting information
p. 5331 - 5334
(2019/07/08)
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- Preparation method of 2,3-dihydrobenzofuran
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The invention discloses a preparation method of 2,3-dihydrobenzofuran. The method comprises the following steps of (1) dissolving RuCl3 into water; performing stirring and uniform mixing; adding gamma-Al2O3 particles; performing ultrasonic oscillation for 1 to 2h; performing equivalent-volume impregnation under the conditions of 30 to 40 DEG C for 36 to 48h; then, performing drying under the conditions of 110 to 120 DEG C to obtain an RuCl3-Al2O3 composite catalyst; (2) adding o-chlorophenyl-ethanol into DMF to be stirred and uniformly mixed; adding K2CO3; controlling the temperature to be 60to 80 DEG C; adding the RuCl3-Al2O3 composite catalyst prepared in the step (1); performing microwave radiation for 20 to 30min; next, continuously performing stirring reaction for 1 to 2h; after thereaction is completed, performing filtering; adding a sodium hydroxide solution for washing; collecting an organic phase; performing distillation separation to obtain 2,3-dihydrobenzofuran. The preparation method provided by the invention has the advantages that the cost is lower; the operation is simple; the reaction conditions are mild; the byproducts are few; the product purity is high; the product yield is higher.
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Paragraph 0021; 0028; 0032-0038; 0042; 0049
(2018/05/16)
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- A Practical and Chemoselective Ammonia-Free Birch Reduction
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A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. A broad range of aromatic and heteroaromatic compounds is reduced with excellent yields.
- Lei, Peng,Ding, Yuxuan,Zhang, Xiaohe,Adijiang, Adila,Li, Hengzhao,Ling, Yun,An, Jie
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supporting information
p. 3439 - 3442
(2018/06/26)
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- Novel electronic salt system and method for reducing unsaturated hydrocarbon compound
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The invention discloses an electronic salt system and a method for reducing unsaturated hydrocarbon compounds by using the electronic salt system, belongs to the field of organic synthesis, and solvesthe problems such as complicated operation, harsh conditions, easy generation of complex over-reduction products of methods for reducing the unsaturated hydrocarbon compounds in the prior art. An electron salt may be synthesized by an alkali metal reagent, an ether and an alcohol, the ether can be a crown ether or a cryptand; and the method adopts the electronic salt system, the unsaturated hydrocarbon compounds is reduced by the electronic salt system in an organic solvent. The method for reducing the unsaturated hydrocarbon compounds is used for reducing the unsaturated hydrocarbon compounds.
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Paragraph 0159-0163
(2018/09/08)
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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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- Titanium(III)-Oxo Clusters in a Metal-Organic Framework Support Single-Site Co(II)-Hydride Catalysts for Arene Hydrogenation
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Titania (TiO2) is widely used in the chemical industry as an efficacious catalyst support, benefiting from its unique strong metal-support interaction. Many proposals have been made to rationalize this effect at the macroscopic level, yet the underlying molecular mechanism is not understood due to the presence of multiple catalytic species on the TiO2 surface. This challenge can be addressed with metal-organic frameworks (MOFs) featuring well-defined metal oxo/hydroxo clusters for supporting single-site catalysts. Herein we report that the Ti8(μ2-O)8(μ2-OH)4 node of the Ti-BDC MOF (MIL-125) provides a single-site model of the classical TiO2 support to enable CoII-hydride-catalyzed arene hydrogenation. The catalytic activity of the supported CoII-hydride is strongly dependent on the reduction of the Ti-oxo cluster, definitively proving the pivotal role of TiIII in the performance of the supported catalyst. This work thus provides a molecularly precise model of Ti-oxo clusters for understating the strong metal-support interaction of TiO2-supported heterogeneous catalysts.
- Ji, Pengfei,Song, Yang,Drake, Tasha,Veroneau, Samuel S.,Lin, Zekai,Pan, Xiandao,Lin, Wenbin
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p. 433 - 440
(2018/01/17)
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- Ru-Catalyzed Transfer Hydrogenation of Nitriles, Aromatics, Olefins, Alkynes and Esters
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This paper reports the preparation of new ruthenium(II) complexes supported by a pyrazole-phosphine ligand and their application to transfer hydrogenation of various substrates. These Ru complexes were found to be efficient catalysts for the reduction of nitriles and olefins. Heterocyclic compounds undergo transfer hydrogenation with good to moderate yields, affording examples of unusual hydrogenation of all-carbon-rings. Internal alkynes with bulky substituents show selective reduction to olefins with the unusual E–selectivity. Esters with strong electron-withdrawing groups can be reduced to the corresponding alcohols, if ethanol is used as the solvent. Possible mechanisms of hydrogenation and olefin isomerization are suggested on the basis of kinetic studies and labelling experiments.
- Alshakova, Iryna D.,Gabidullin, Bulat,Nikonov, Georgii I.
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p. 4860 - 4869
(2018/10/02)
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- Selective hydrogenation of aromatic compounds using modified iridium nanoparticles
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Till now, Ionic liquid-stabilized metal nanoparticles were investigated as catalytic materials, mostly in the hydrogenation of simple substrates like olefins or arenes. The adjustable hydrogenation products of aromatic compounds, including quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes, are always of special interest, since they provide more choices for additional derivatization. Iridium nanoparticles (Ir NPs) were synthesized by the H2 reduction in imidazolium ionic liquid. TEM indicated that the Ir NPs is worm-like shape with the diameter around 12.2?nm and IR confirmed the modification of phosphine-functionalized ionic liquids (PFILs) to the Ir NPs. With the variation of the modifier, solvent and reaction temperature, substrate like quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes could be hydrogenated by Ir NPs with interesting adjustable catalytic activity and chemoselectivity. Ir NPs modified by PFILs are simple and efficient catalysts in challenging chemoselective hydrogenation of quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes. The activity and chemoselectivity of the Ir NPs could be obviously impacted or adjusted by altering the modifier, solvent and reaction temperature.
- Jiang, He-Yan,Xu, Jie,Sun, Bin
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- Liquid phase hydrodeoxygenation of anisole, 4-ethylphenol and benzofuran using Ni, Ru and Pd supported on USY zeolite
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The objective of this work is to understand the role of metals on the hydrodeoxygenation (HDO) reaction pathways of three bio-oil model compounds. Ni, Ru and Pd were impregnated on USY zeolite, and the catalysts were characterized to determine metal reduction profile, surface concentration and nanoparticle size. Ru-USY and Pd-USY were completely reduced at a temperature below 450 °C, but Ni-USY still contained surface metal oxides after reduction. There was no indication of strong interactions between the metals and USY support. Anisole, 4-ethylphenol and benzofuran were used as bio-oil model compounds, in order to determine the effects of each metal on deoxygenation of methoxy-, phenol and furan functional groups, respectively. Pd-USY was the most effective HDO catalyst, exhibiting the highest turnover frequency for HDO of all three model compounds, in addition to and high selectivity to deoxygenated products. A mechanism was proposed for each model compound, and the kinetics of hydrogenation, dehydration, C–C coupling and ring-opening reactions were determined.
- Gamliel, David P.,Karakalos, Stavros,Valla, Julia A.
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- Highly Selective Hydrogenation with Ionic Liquid Stabilized Nickel Nanoparticles
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Abstract: Nickel nanoparticles (Ni NPs) were conveniently synthesized from the reduction of nickel(II) salt with NaBH4 or hydrazine in the presence of the ionic liquid 1-butyl-2,3-dimethylimidazolium (S)-2-pyrrolidinecarboxylic acid salt. UV/Vis spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were employed to characterize the interaction between the metal and the ionic liquid. The face-centered cubic structure of the Ni NPs(0) was confirmed by X-ray diffraction characterization. Transmission electron microscopy images revealed well-dispersed Ni particles of approximately 5.1?nm in average diameter. The ionic liquid immobilized Ni NPs were employed as highly efficient catalysts in chemoselective hydrogenation of quinoline and relevant compounds, as well as aromatic nitro compounds under mild reaction conditions. The Ni NPs can be efficiently recovered and reused. Graphical Abstract: [Figure not available: see fulltext.]
- Jiang, He-yan,Zhang, Si-shi,Sun, Bin
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p. 1336 - 1344
(2018/03/26)
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- Reversible Dehydrogenation and Hydrogenation of N-Heterocycles Catalyzed by Bimetallic Nanoparticles Encapsulated in MIL-100(Fe)
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Pd?Ni bimetallic nanoparticles (BMNPs) encapsulated in MIL-100(Fe) (Pd-Ni@MIL-100(Fe) was fabricated and employed as an efficient catalyst for the reversible dehydrogenation/hydrogenation of N-Heterocycles derivatives in water under mild conditions. Excellent catalytic performance for both reactions endows Pd-Ni@MIL-100(Fe) great potential value in organic chemistry. Alloying Pd with Ni can enhance the catalytic performance due to the bimetallic synergy. Both Lewis acidity and ordered mesoporous structure of MIL-100(Fe) are beneficial to the performance of the catalyst owing to its stabilization of BMNPs, reduction of the electron density of Pd atoms and enhancement of substrates adsorption capacity.
- Zhang, Jia-Wei,Li, Dan-Dan,Lu, Guo-Ping,Deng, Tao,Cai, Chun
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p. 4980 - 4986
(2018/10/15)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0345-0346; 0348
(2019/01/07)
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- Effect of preparation temperature on the structures and hydrodeoxygenation performance of Ni2P/C catalysts prepared by decomposition of hypophosphites
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A novel method for preparing Ni2P/C-x (x = preparation temperature, °C) catalysts in a flowing N2 atmosphere by decomposition of hypophosphites was proposed, and the effect of preparation temperature on the hydrodeoxygenation performance of the catalysts was further investigated. X-ray diffraction (XRD), N2-adsorption specific surface area measurements, CO uptake, and X-ray photoelectron spectroscopy (XPS) were applied. The performances of the Ni2P/C-x catalysts prepared at different preparation temperatures were tested in the benzofuran hydrodeoxygenation (BF HDO) reaction. The diffraction peaks related to Ni2P can be seen when x ≧ 400 °C. With increasing x, the Ni2P crystallite size and CO uptake amount of the Ni2P/C-x catalysts increased, and the amount of phosphorous decreased. The BF conversion and yield of total O-free products over the Ni2P/C-x catalysts increased with increasing preparation temperature. The Ni2P/C-550 catalyst showed a BF HDO conversion of 91.6% and a yield of total O-free products of 70.2% under the reaction conditions of 300 °C, 3.0 MPa, a H2/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 4.0 h?1.
- Dai, Xueya,Song, Hua,Yan, Zijin,Li, Feng,Chen, Yanguang,Wang, Xueqin,Yuan, Dandan,Zhang, Jiaojing,Wang, Yuanyuan
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p. 19917 - 19923
(2018/12/13)
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- Production of monocyclic phenols by the liquid-phase hydrogenolysis of benzofuran and dibenzyl ether using in situ hydrogen production from methanol
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We herein report our study into the hydrogenolysis of benzofuran, a model compound for the poorly decomposable compounds derived from lignin, over Pt supported catalysts in methanol in the absence of gaseous hydrogen. In this in situ hydrogenolysis reaction system, it was elucidated that both hydrogen production from methanol and selective hydrogenolysis of the furan moiety proceeded simultaneously to yield monophenolic compounds and gaseous hydrogen. This in situ hydrogenolysis reaction was investigated at temperatures between 180 and 220 °C and with reaction times ranging from 1 to 48 h. We found that the hydrogenolysis reaction was accelerated with increased hydrogen concentrations in the solvent. The molar ratio of consumed hydrogen to net hydrogen production increased gradually upon increasing the reaction temperature and time. In addition, the in situ hydrogenolysis of benzofuran under a hydrogen gas atmosphere revealed that the hydrogen produced in situ was more effective in the reaction than gaseous hydrogen, likely due to the dissolution and diffusion resistances of the solvent. Furthermore, dibenzyl ether was hydrogenolyzed to give monocyclic aromatic compounds under the same reaction conditions, suggesting that this in situ hydrogenolysis process could be effective in converting the by-products obtained during lignin depolymerization into valuable aromatic compounds.
- Fujitsuka, Hiroyasu,Tamura, Masaki,Tago, Teruoki
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p. 213 - 218
(2017/09/06)
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- Cyclic ether synthesis from diols using trimethyl phosphate
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Cyclic ethers have been effectively synthesized via the intramolecular cyclization of diols using trimethyl phosphate and NaH. The present cyclization could proceed at room temperature to produce 5-7 membered cyclic ethers in good to excellent yields. Substrates possessing a chiral secondary hydroxy group were transformed into the corresponding chiral cyclic ethers along with the retention of their stereochemistries.
- Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 4787 - 4790
(2017/07/06)
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- Unique nanocages of 12CaO·7Al2O3 boost heterolytic hydrogen activation and selective hydrogenation of heteroarenes over ruthenium catalyst
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The chemoselective hydrogenation of heteroarenes is one of the most important synthetic reactions for the production of key intermediates in agrochemicals, pharmaceuticals and various fine chemicals. The development of new heterogeneous catalysts for the environmentally benign synthesis of heterocycle hydrogenated products is a fundamental objective for chemists. Here, we report that 12CaO·7Al2O3 with a unique sub-nanocage structure loaded with Ru nanoparticles exhibits higher activity, chemoselectivity and sustainability for the hydrogenation of heteroarenes in a solvent-free system than traditional oxide-supported metal catalysts. Conversion of >99% and a selectivity close to 99% were achieved for the hydrogenation of quinoline under mild conditions. This catalyst was also successfully applied to the hydrogenation of a variety of N- and O-heteroarenes with high yields. The superior catalytic performance can be attributed to a cooperative effect between the hydrogen-storage ability and large amount of strong basic sites on the surface of the support, which promotes heterolytic H2 cleavage and prevents poisoning of the metal surface caused by the adsorption of heteroarenes.
- Ye, Tian-Nan,Li, Jiang,Kitano, Masaaki,Hosono, Hideo
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p. 749 - 756
(2017/05/22)
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- Accelerated catalytic activity of Pd NPs supported on amine-rich silica hollow nanospheres for quinoline hydrogenation
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Tuning the catalytic performance of metal nanoparticles (NPs) is very important in nanocatalysis. Herein, we report that amine-rich mesoporous silica hollow nanospheres (HS-NH2) synthesized by one-pot condensation could efficiently stabilize ultra-small Pd NPs and also increase the surface electron density of Pd NPs due to the coordinating and electron-donating effects of the amine group. Pd NPs supported on HS-NH2 afford TOF as high as 5052 h-1 in quinoline hydrogenation reaction and are much more active than Pd/C with a TOF of 960 h-1 as well as most reported solid catalysts. The intrinsic activity of Pd NPs increases as the particle size of Pd decreases, revealing that quinoline hydrogenation is a structure-sensitive reaction. The results of TEM, XPS, CO adsorption and CO stripping voltammetry indicate that the high activity of Pd NPs supported on HS-NH2 is mainly attributed to their ultra-small particle size and high surface electron density. Our primary results demonstrate that the organo-modified silica nanospheres are promising solid supports for modifying the electronic properties of metal NPs supported and consequently tailoring their catalytic functions.
- Guo, Miao,Li, Can,Yang, Qihua
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p. 2221 - 2227
(2017/07/22)
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- A 2,3-Dihydrobenzofuran synthetic method (by machine translation)
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The invention discloses a 2,3-Dihydrobenzofuran synthesis method, which belongs to the field of organic chemical synthesis, using phenol sodium and 2-chloro ethyl alcohol as raw materials, adding copper chloride and ferric chloride mixed solid as catalyst, mixed reflux cooling and collecting organic layer after the reaction, the use of sodium hydroxide solution to obtain the 2- phenoxyethyl alcohol ; the 2- phenoxyethyl alcohol, mix, add and zinc chloride catalyst containing dichloride, heating reflux reaction, washing after adding sodium hydroxide solution is distilled under reduced pressure, collecting 88-90 °C fraction is 2,3-dihydrobenzofuran. The method of the invention to add copper chloride and ferric chloride and the mixture of the two manganese chloride as a catalyst, at the same time optimize the reaction process and reaction conditions, the reaction temperature can be effectively reduced, shortening the reaction time, reduce the reaction byproducts, improves the reaction yield, has higher economic benefits. (by machine translation)
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Paragraph 0050; 0054; 0055
(2016/11/28)
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- A Rhodium Nanoparticle-Lewis Acidic Ionic Liquid Catalyst for the Chemoselective Reduction of Heteroarenes
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We describe a catalytic system composed of rhodium nanoparticles immobilized in a Lewis acidic ionic liquid. The combined system catalyzes the hydrogenation of quinolines, pyridines, benzofurans, and furan to access the corresponding heterocycles, important molecules present in fine chemicals, agrochemicals, and pharmaceuticals. The catalyst is highly selective, acting only on the heteroaromatic ring, and not interfering with other reducible functional groups.
- Karakulina, Alena,Gopakumar, Aswin,Ak?ok, Ismail,Roulier, Bastien L.,LaGrange, Thomas,Katsyuba, Sergey A.,Das, Shoubhik,Dyson, Paul J.
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supporting information
p. 292 - 296
(2016/01/25)
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- Single-Site Cobalt Catalysts at New Zr8(μ2-O)8(μ2-OH)4 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles
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We report here the synthesis of robust and porous metal-organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
- Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Urban, Ania,Greene, Francis X.,Lan, Guangxu,Lin, Wenbin
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supporting information
p. 12234 - 12242
(2016/09/28)
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- Intermolecular C-H Silylation of Arenes and Heteroarenes with HSiEt3 under Operationally Diverse Conditions: Neat/Stoichiometric and Acceptor/Acceptorless
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Efficient protocols for Rh-catalyzed intermolecular C-H silylation of unactivated arenes and heteroarenes are disclosed. The silylations are catalyzed by a Rh-complex (2 mol %) derived in situ from commercially available Rh(nbd)2BF4 and (S,S)-i-Pr-BPE (L3) with Et3SiH in the presence of hydrogen acceptor under either neat (excess of arene) or stoichiometric conditions. The regioselectivity is determined mainly by the steric bulk of the substituents and by the electronic effect as an ancillary factor. In addition, our preliminary result shows that the current protocol catalyzes the silylation of arenes in the absence of hydrogen acceptors.
- Lee, Kang-Sang,Katsoulis, Dimitris,Choi, Jongwook
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p. 1493 - 1496
(2016/03/15)
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- Synthesis of five- and six-membered heterocycles by dimethyl carbonate with catalytic amounts of nitrogen bicyclic bases
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A catalytic amount of a nitrogen bicyclic base, i.e., DABCO, DBU or TBD, is effective for the one-pot synthesis of heterocycles from 1,4-, 1,5-diols and 1,4-bifunctional compounds via dimethyl carbonate chemistry under neat conditions. Nitrogen bicyclic bases that were previously shown to have enhanced the reactivity of DMC in methoxycarbonylation reaction by a BAc2 mechanism are herein used for the first time as efficient catalysts for cyclization reactions encompassing both BAc2 and BAl2 pathways. This synthesis procedure was also applied to a large scale synthesis of cyclic sugars, isosorbide and isomannide, starting from d-sorbitol and d-mannitol, respectively. The resulting anhydro sugar alcohols were obtained as pure crystalline compounds that did not require any further purification or crystallization. This journal is
- Aricò,Evaristo,Tundo
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p. A1176 - A1185
(2015/03/04)
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- Phosphine-functionalized ionic liquid-stabilized rhodium nanoparticles for selective hydrogenation of aromatic compounds
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Phosphine-functionalized, ionic liquid-stabilized rhodium nanoparticles with an average size of about 3.5 nm are very active catalysts for the selective hydrogenation of aromatic compounds, including quinoline and its analogues, and aromatic nitro compounds. Their catalytic performance complements that of classic homogeneous and heterogeneous rhodium catalysis.
- Jiang, He-Yan,Zheng, Xu-Xu
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p. 118 - 123
(2015/09/28)
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- Lewis acid promoted ruthenium(II)-catalyzed etherifications by selective hydrogenation of carboxylic acids/esters
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Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity. An assist from Al: A bifunctional catalyst system consisting of a Ru/phosphine complex and aluminum triflate allows selective hydrogenation of esters to ethers. A variety of lactones were reduced to the desired products in good yields. The catalyst further provides a general method for the reduction of linear esters and reductive etherification of carboxylic acids with alcohols.
- Li, Yuehui,Topf, Christoph,Cui, Xinjiang,Junge, Kathrin,Beller, Matthias
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supporting information
p. 5196 - 5200
(2015/04/27)
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- Copper-Catalyzed Reductive Cross-Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides
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A copper-catalyzed reductive cross-coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost-effective construction of aryl-alkyl and alkyl-alkyl C=C bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo- or heterocycles, such as 2,3-dihydrobenzofuran and benzochromene derivatives.
- Liu, Jing-Hui,Yang, Chu-Ting,Lu, Xiao-Yu,Zhang, Zhen-Qi,Xu, Ling,Cui, Mian,Lu, Xi,Xiao, Bin,Fu, Yao,Liu, Lei
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supporting information
p. 15334 - 15338
(2016/02/18)
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- Oxacycle synthesis via intramolecular reaction of carbanions and peroxides
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The intramolecular reaction of dialkyl peroxides with carbanions, generated via chemoselective metal-heteroatom exchange or deprotonation, provides a new approach to cyclic ethers. Applied in tandem with C-C bond formation, the strategy enables a one-step annelation to form oxaospirocycles.
- Willand-Charnley, Rachel,Puffer, Benjamin W.,Dussault, Patrick H.
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p. 5821 - 5823
(2014/05/20)
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- Titania-promoted carboxylic acid alkylations of alkenes and cascade addition-cyclizations
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Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C-C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner.
- Manley, David W.,McBurney, Roy T.,Miller, Phillip,Walton, John C.,Mills, Andrew,O'Rourke, Christopher
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p. 1386 - 1398
(2014/03/21)
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- Quenched skeletal Ni as the effective catalyst for selective partial hydrogenation of polycyclic aromatic hydrocarbons
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Quenched skeletal Ni is an active and selective catalyst for selective partial hydrogenation of polycyclic aromatic hydrocarbons (PAHs). The molecular structure of PAHs significantly dominate the hydrogenation process and furthermore, the distribution of hydrogenated products.
- Liu, Chengyun,Rong, Zeming,Sun, Zhuohua,Wang, Yong,Du, Wenqiang,Wang, Yue,Lu, Lianhai
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p. 23984 - 23988
(2013/11/19)
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- Structure-activity relationship of human glutaminyl cyclase inhibitors having an N-(5-methyl-1H-imidazol-1-yl)propyl thiourea template
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In an effort to design inhibitors of human glutaminyl cyclase (QC), we have synthesized a library of N-aryl N-(5-methyl-1H-imidazol-1-yl)propyl thioureas and investigated the contribution of the aryl region of these compounds to their structure-activity relationships as cyclase inhibitors. Our design was guided by the proposed binding mode of the preferred substrate for the cyclase. In this series, compound 52 was identified as the most potent QC inhibitor with an IC50 value of 58 nM, which was two-fold more potent than the previously reported lead 2. Compound 52 is a most promising candidate for future evaluation to monitor its ability to reduce the formation of pGlu-Aβ and Aβ plaques in cells and transgenic animals.
- Lee, Jeewoo,Tran, Phuong-Thao,Hoang, Van-Hai,Thorat, Shivaji A.,Kim, Sung Eun,Ann, Jihyae,Chang, Yu Jin,Nam, Dong Woo,Song, Hyundong,Mook-Jung, Inhee,Lee, Jiyoun
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p. 3821 - 3830
(2013/07/19)
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- Synthesis of five-membered cyclic ethers by reaction of 1,4-diols with dimethyl carbonate
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The reaction of 1,4-diols with dimethyl carbonate in the presence of a base led to selective and high-yielding syntheses of related five-membered cyclic ethers. This synthetic pathway has the potential for a wide range of applications. Distinctive cyclic ethers and industrially relevant compounds were synthesized in quantitative yield. The reaction mechanism for the cyclization was investigated. Notably, the chirality of the starting material was maintained. DFT calculations indicated that the formation of five-membered cyclic ethers was energetically the most favorable pathway. Typically, the selectivity exhibited by these systems could be rationalized on the basis of hard-soft acid-base theory. Such principles were applicable as far as computed energy barriers were concerned, but in practice cyclization reactions were shown to be entropically driven. Copyright
- Aricó, Fabio,Tundo, Pietro,Maranzana, Andrea,Tonachini, Glauco
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experimental part
p. 1578 - 1586
(2012/10/07)
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- General and practical one-pot synthesis of dihydrobenzosiloles from styrenes
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A one-pot synthesis of dihydrobenzosiloles from styrenes has been developed. The reaction involves the nickel-catalyzed hydrosilylation of styrene with diphenylsilane, followed by the iridium-catalyzed dehydrogenative cyclization. This method is efficient for both electron-rich and -deficient styrenes and exhibits good functional group tolerance, as well as excellent regioselectivity. The forming dihydrobenzosiloles can be efficiently converted into valuable benzosiloles or 2-hydroxyphenethyl alcohols.
- Kuznetsov, Alexey,Gevorgyan, Vladimir
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supporting information; experimental part
p. 914 - 917
(2012/05/05)
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- Intramolecular condensation of 1,2-C6H4(CH 2RH)2 (R = O, S, and NH) to yield heterocyclic compounds over halide-cluster catalysts
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1,2-Benzenedimethanol was reacted under a helium stream in the presence of [(Nb6Cl12)Cl2(H2O) 4]·4H2O supported on silica gel. When the temperature was raised above 200 °C, catalytic activity of the cluster for cyclization appeared, yielding 1,3-dihydroisobenzofuran in 91% selectivity at 350 °C. The corresponding halide clusters of tantalum and tungsten also catalyzed the reaction. cis-1,2-Cyclohexanedimethanol and 1,4-butanediol exclusively produced the corresponding furans. 1,2-Benzenedimethanamine and 1,2-benzenedimethanethiol selectively afforded isoindoline and 1,3-dihydrobenzo[c]thiophene, respectively.
- Nagashima, Sayoko,Kamiguchi, Satoshi,Kudo, Kentaro,Sasaki, Tomoaki,Chihara, Teiji
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scheme or table
p. 78 - 80
(2011/05/07)
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- An efficient copper-catalyzed etherification of aryl halides
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An efficient and mild copper-catalyzed ether formation from aryl halides and aliphatic alcohols has been developed. The key to the successful coupling is the use of lithium alkoxide, directly or in situ generated by lithium tert-butoxide, and the corresponding alcohol as solvent. Georg Thieme Verlag Stuttgart - New York.
- Huang, Jinkun,Chen, Ying,Chan, Johann,Ronk, Mike L.,Larsen, Robert D.,Faul, Margaret M.
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scheme or table
p. 1419 - 1422
(2011/07/30)
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- Copper(I)-catalyzed aryl bromides to form intermolecular and intramolecular carbon-oxygen bonds
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(Chemical Equation Presented) A highly efficient Cu-catalyzed C-O bond-forming reaction of alcohol and aryl bromides has been developed. This transformation was realized through the use of copper(I) iodide as a catalyst, 8-hydroxyquinoline as a ligand, and K3PO4 as a base. A variety of functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields.
- Niu, Jiajia,Guo, Pengran,Kang, Juntao,Li, Zhigang,Xu, Jingwei,Hu, Shaojing
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supporting information; scheme or table
p. 5075 - 5078
(2009/10/17)
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- CYCLIC ETHERS
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A process of preparing cyclic ethers is described. The process involves the reaction of at least one organic compound such as a dioi or a polyol which it has at least one pair of hydroxyl groups separated by 4 or 5 carbon atoms, and which is capable of being converted into an ether linkage, with an organic carbonate in the presence of a base. The base is an alkoxy, a carbonate or a hydroxide base or is a mixture of such bases. At least one of the hydroxyl groups of the organic compound is not a tertiary hydroxyl group.
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Page/Page column 10; 14; 15
(2009/03/07)
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- Catalytic activation of the leaving group in the SN2 reaction
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A novel catalytic activation of the leaving group in the SN2 reaction is achieved as an extension of our mercuric triflate-catalyzed reactions. Derivatives of anilinoethyl 4-pentynoate reacted smoothly with catalytic amounts of Hg(OTf)2 to give indoline derivatives in excellent yield with efficient catalytic turnovers under very mild conditions. The reaction of optically pure secondary alcohol derivatives resulted in inversion of stereochemistry, which is a definitive feature of the S N2 reaction. The procedure is applicable for benzoazepine synthesis.
- Yamamoto, Hirofumi,Pandey, Ghanshyam,Asai, Yumiko,Nakano, Mayo,Kinoshita, Atsushi,Namba, Kosuke,Imagawa, Hiroshi,Nishizawa, Mugio
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p. 4029 - 4032
(2008/02/10)
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