- Solvolysis of o-methylbenzenediazonium tetrafluoroborate in acidic methanol-water mixtures. Further evidence for nucleophilic attack on a solvent separated aryl cation
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Rate constants for dediazoniation product formation and arenediazonium ion loss and product yields of solvolysis of o-methylbenzenediazonium tetrafluoroborate in acidic methanol-water mixtures at T = 35 °C are reported. Observed rate constants for diazonium ion loss and product formation are the same, increasing about 45% ongoing from water to methanol, and are not affected by added electrolytes like HCl, NaCl, and CuCl2. Only three dediazoniation products are detected, o-cresol, o-chlorotoluene, and o-anisole. All data are consistent with a rate-determining step formation of an aryl cation that reacts immediately with available nucleophiles. The selectivity of the reaction toward nucleophiles, S, which can be is low and essentially constant upon changing solvent composition, suggesting that the nucleophilic attack takes place on a solvent separated aryl cation.
- Pazo-Llorente,Sarabia-Rodriguez,Gonzalez-Romero,Bravo-Diaz
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Read Online
- N,N,N',N',N' '-pentamethyldipropylenetriamine (PMDPTA): A versatile auxiliary for site selective lithiation reactions
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Efficient lithiation processes were developed with PMDPTA, a tridentate ligand of butyllithium reagent for site selective metallation of aromatic and heteroaromatic compounds.
- Thurner, Angelika,Faigl, Ferenc,Agai, Bela,Toke, Laszlo
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Read Online
- Impact of oxygen vacancies in Ni supported mixed oxide catalysts on anisole hydrodeoxygenation
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The hydrodeoxygenation (HDO) activity of anisole has been investigated over Ni catalysts on mixed metal oxide supports containing Nb–Zr and Ti–Zr in 1:1 and 1:4 ratios. XRD patterns indicate the incorporation of Ti (or Nb) into the ZrO2 framewo
- Ali, Hadi,Kansal, Sushil Kumar,Lauwaert, Jeroen,Saravanamurugan, Shunmugavel,Thybaut, Joris W.,Vandevyvere, Tom
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- Trialkylammonium salt degradation: Implications for methylation and cross-coupling
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Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
- Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
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p. 6949 - 6963
(2021/06/02)
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- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
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Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
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supporting information
p. 20391 - 20399
(2021/08/13)
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- Optimizing the carburization conditions of supported rhenium carbide for guaiacol conversion
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The present work evaluates the effect of ethylene content of a carburization mixture on the formation of carburized rhenium supported on activated carbon. The resulting catalysts were characterized by N2 physisorption, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed reduction, and the results show a strong effect on the final phase obtained. A high amount of ethylene inhibited the carburization process, resulting in carbon formation, while a lower amount (≤ 35 %) of ethylene was favorable to the formation of the carbide phase. The catalysts were evaluated for the hydrodeoxygenation (HDO) of guaiacol, a bio-oil model compound, and a high yield of benzene (50 %), a desirable aromatic compound, was obtained at complete conversion over the catalysts containing the carbide phase.
- Blanco, Elodie,Dongil, Ana Belén,Escalona, Néstor,García-Fierro, Jose Luis,Ghampson, I. Tyrone
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- Ceramic boron carbonitrides for unlocking organic halides with visible light
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Photochemistry provides a sustainable pathway for organic transformations by inducing radical intermediates from substrates through electron transfer process. However, progress is limited by heterogeneous photocatalysts that are required to be efficient, stable, and inexpensive for long-term operation with easy recyclability and product separation. Here, we report that boron carbonitride (BCN) ceramics are such a system and can reduce organic halides, including (het)aryl and alkyl halides, with visible light irradiation. Cross-coupling of halides to afford new C-H, C-C, and C-S bonds can proceed at ambient reaction conditions. Hydrogen, (het)aryl, and sulfonyl groups were introduced into the arenes and heteroarenes at the designed positions by means of mesolytic C-X (carbon-halogen) bond cleavage in the absence of any metal-based catalysts or ligands. BCN can be used not only for half reactions, like reduction reactions with a sacrificial agent, but also redox reactions through oxidative and reductive interfacial electron transfer. The BCN photocatalyst shows tolerance to different substituents and conserved activity after five recycles. The apparent metal-free system opens new opportunities for a wide range of organic catalysts using light energy and sustainable materials, which are metal-free, inexpensive and stable. This journal is
- Yuan, Tao,Zheng, Meifang,Antonietti, Markus,Wang, Xinchen
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p. 6323 - 6332
(2021/05/19)
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- 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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- Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water
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Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.
- Chen, Chun,Gong, Wanbing,Han, Miaomiao,Wang, Dongdong,Wang, Guozhong,Zhang, Haimin,Zhang, Jifang,Zhang, Yunxia,Zhao, Huijun
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p. 2027 - 2037
(2021/09/02)
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- Synthetic method of benzofuranone
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The invention provides a synthetic method of benzofuranone. According to the method, o-cresol which is relatively easy to obtain is used as an initial raw material, and the target product benzofuranone is prepared through four-step reaction; and the whole preparation process is mild in condition, high in yield, easy to operate, small in environmental pollution and suitable for large-scale industrial production.
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Paragraph 0057-0067
(2020/06/16)
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- Light assisted O-alkylation of phenols to ethers using layered double oxides catalyst under green and mild conditions
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O-alkylation of phenols with dialkyl carbonates to ethers over layered double oxides (LDOs) catalyst under light irradiation is described. A base additive is not required when using the longer-chain diethyl carbonate as an alkylating agent owing to the sufficient basicity provided by LDOs. The synergism of substrate phenols molecules absorbing light to reach the first excited states with acid–base pairs of catalyst enhanced the interaction of reactant molecules with the surface of LDOs, simultaneously accelerating the cleavage of phenolic hydroxyl groups. A variety of phenols are tolerated in this system. This work reports a simple and environmentally benign catalytic process for the dehydrogenation of phenolic hydroxyl groups.
- Wang, Ruiyi,Wang, Xiaoyu,Zheng, Zhanfeng
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- Exhaustive Reduction of Esters Enabled by Nickel Catalysis
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We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl derivatives. This is achieved by an organosilane-mediated ester hydrosilylation reaction and subsequent Ni/NHC-catalyzed hydrogenolysis. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require the use of hazardous metal hydrides. Applications in the synthesis of -CD3-containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other C-O bonds are demonstrated.
- Cook, Adam,Prakash, Sekar,Zheng, Yan-Long,Newman, Stephen G.
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supporting information
p. 8109 - 8115
(2020/05/20)
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- Decyanation method of nitrile organic compound
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The invention provides a decyanation method of a nitrile organic compound. The nitrile organic compound shown in a general formula (1), a sodium reagent, crown ether and a proton donor are subjected to decyanation reaction in an organic solvent I to generate an organic compound shown in a general formula (2). According to the method, a Na/15-crown-5/H2O system is adopted, so that nitrile organic matters can be converted into a decyanation product, and the generation of amine byproducts is inhibited. The new method does not need to use liquid ammonia as a solvent, and is safer and more convenient to operate. The required sodium dispersoid is low in price; and the 15-crown-5 can be recycled and repeatedly used. The method has the advantages of good chemical selectivity, wide substrate application range, good functional group compatibility and the like.
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Paragraph 0055-0058
(2020/02/10)
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- Synthesis, in vitro cytotoxicity and anti-platelet activity of new 1,3-bentzenedisulfonamides
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To obtain more active and selective anti-platelet candidate drugs, we tried to introduce a methyl group at the 5-position and 6-position of the parent benzene ring first time, respectively or simultaneously. The idea could inspect compound with tetra-substituted or penta-substituted characteristics rather than retained classical 1,3,4-position triple substitutions characteristic whether it continues to have anti-platelet activity in vitro. The biological evaluation revealed that most of compounds with this novel structure were more potent than the positive control drug Picotamide. At the concentration of 1.3 μmol/L, using Arachidonic acid as an inducer, it was found that the anti-platelet activity in vitro of five compounds 1a, 1b, 1c, 2f, and 3d was higher than that of Picotamide and the series 1 compounds were generally higher than that of the series 2 and 3. And with ADP as an inducer, the activity in vitro of nine compounds 2a, 2b, 2d, 2f, 2g, 2h, 3a, 3b, and 3c was more elevated than that of Picotamide and the compounds of series 2 and 3 were all evidently even more active than that of series 1. The proportion of newly designed target compounds with active is higher than that of previously developed series of compounds. Based on the in vitro activity results, a preliminary analysis of the structure–activity relationship was deduced. Meanwhile, cytotoxic effects in vitro of 11 target compounds 1b, 1c, 2f, 2a, 2b, 3a, 3b, 3c, 2d, 2g, and 2h on L-929 cells were analyzed, but the data analysis shows that at two concentrations, target compounds have higher effect on L-929 cells than that of control drug Picotamide. The reason or mechanism for obtaining higher in vitro activity and higher cytotoxicity of the target compound under tetra- or penta- substitutions requires further relevant research work before conclusion can be drawn.
- Xiu-jie, Liu,Zhi-hao, Zhang,Qing-song, Deng,Xin, Chen,Chao-qing, Wang
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p. 1864 - 1872
(2019/08/26)
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- Iron-catalyzed cross coupling of aryl chlorides with alkyl Grignard reagents: Synthetic scope and FeII/FeIV mechanism supported by x-ray absorption spectroscopy and density functional theory calculations
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A combination of iron(III) fluoride and 1,3-bis(2,6-diiso-propylphenyl)imidazolin-2-ylidene (SIPr) catalyzes the high-yielding cross coupling of an electron-rich aryl chloride with an alkyl Grignard reagent, which cannot be attained using other iron catalysts. A variety of alkoxy-or amino-substituted aryl chlorides can be cross-coupled with various alkyl Grignard reagents regardless of the presence or absence of β-hydrogens in the alkyl group. A radical probe experiment using 1-(but-3-enyl)-2-chlorobenzene does not afford the corresponding cyclization product, therefore excluding the intermediacy of radical species. Solution-phase X-ray absorption spectroscopy (XAS) analysis, with the help of density functional theory (DFT) calculations, indicates the formation of a high-spin (S = 2) heteroleptic difluorido organoferrate(II), [MgX][FeIIF2(SIPr)-(Me/alkyl)], in the reaction mixture. DFT calculations also support a feasible reaction pathway, including the formation of a difluorido organoferrate(II) intermediate which undergoes a novel Lewis acid-assisted oxidative addition to form a neutral organoiron(IV) intermediate, which leads to an FeII/FeIV cata-lytic cycle, where the fluorido ligand and the magnesium ion play key roles.
- Agata, Ryosuke,Takaya, Hikaru,Matsuda, Hiroshi,Nakatani, Naoki,Takeuchi, Katsuhiko,Iwamoto, Takahiro,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information
p. 381 - 390
(2019/02/25)
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- Reductive Cleavage of Unactivated Carbon-Cyano Bonds under Ammonia-Free Birch Conditions
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A general protocol for the reductive cleavage of unactivated carbon-cyano bonds in aliphatic nitriles has been achieved under single-electron-transfer conditions using Na/15-crown-5/H2O. Electron is supplied by the electride derived from bench-stable sodium dispersions and recoverable 15-crown-5. H2O provides the proton source and suppresses the reduction of aromatic moieties. Compared with the Na/NH3 electride system generated under traditional Birch conditions, this ammonia-free electride system is more practical and features better reactivity and chemoselectivity for the decyanations of a broad range of aliphatic nitriles.
- An, Jie,Ding, Yuxuan,Luo, Shihui,Ma, Lifu
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- Role of copper- or cerium-promoters on NiMo/Γ-Al2O3 catalysts in hydrodeoxygenation of guaiacol and bio-oil
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Effect of copper (Cu) or cerium (Ce) as promoters for nickel-molybdenum/γ-alumina (NiMo/γ-Al2O3) catalyst on the hydrodeoxygenation (HDO) of guaiacol (GUA), a model oxygenated compound found in a bio-oil derived from woody biomass, was comparatively investigated. The addition of Cu- or Ce-promoters affected the physicochemical properties of the NiMo catalyst. The NiMo catalyst promoted by Cu showed the higher reducibility, whilst the Ce-promoter (2–8 wt% based on γ-Al2O3 content) provided the NiMo catalyst with a higher distribution of active metals and induced a greater difficulty in the reduction under hydrogen (H2) atmosphere. For the HDO of GUA at a mild reaction condition (10 bar initial H2 pressure and 300 °C) in the absence of solvent, the Cu-promoter enhanced the hydrogenation activity of the NiMo catalyst to convert GUA to phenol and methylphenols, one-atomic oxygen species. Whereas, the addition of Ce obviously inhibited the formation of coke on the catalyst surface after a long reaction period (6 h) and gave a higher GUA conversion level with increasing yield of phenols. For the HDO of real bio-oil obtained from the fast pyrolysis of cassava rhizome, the NiMo catalysts promoted by Cu or Ce at 4 wt% based on the γ-Al2O3 content showed a higher performance at eliminating the oxygenated compounds in the bio-oil, reducing the oxygen/carbon (O/C) molar ratio by over seven-fold from 1.75 to 0.24–0.25. Moreover, the gross heating value of the bio-oil was improved from 21.5 to ca. 29.0 MJ/kg after the HDO process. However, the addition of the Cu or Ce promoter did not inhibit coke deposition, possibly due to the acidic properties of the bio-oil that deteriorated the catalyst performance by metal leaching.
- Sangnikul, Patiphat,Phanpa, Chanisara,Xiao, Rui,Zhang, Huiyan,Reubroycharoen, Prasert,Kuchonthara, Prapan,Vitidsant, Tharapong,Pattiya, Adisak,Hinchiranan, Napida
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p. 151 - 160
(2019/02/17)
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- Palladium-Catalyzed Methylation of Aryl, Heteroaryl, and Vinyl Boronate Esters
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A method for the direct methylation of aryl, heteroaryl, and vinyl boronate esters is reported, involving the reaction of iodomethane with aryl-, heteroaryl-, and vinylboronate esters catalyzed by palladium and PtBu2Me. This transformation occurs with a remarkably broad scope and is suitable for late-stage derivatization of biologically active compounds via the boronate esters. The unique capabilities of this method are demonstrated by combining carbon-boron bond-forming reactions with palladium-catalyzed methylation in a tandem transformation.
- Haydl, Alexander M.,Hartwig, John F.
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supporting information
p. 1337 - 1341
(2019/02/26)
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- Effect of Co incorporation and support selection on deoxygenation selectivity and stability of (Co)Mo catalysts in anisole HDO
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A series of supported Co modified Mo catalysts was prepared by varying the Co/Mo ratio in the range from 0 to 1 while maintaining the Mo loading at ca. 10 wt%. A sequential incipient wetness impregnation method, with Mo being introduced first, using aqueous solutions of the corresponding precursor salts was employed during the synthesis procedure. Three supports, i.e., Al2O3, ZrO2, and TiO2 differing in textural and acidic properties were investigated. Material physicochemical characteristics were evaluated through ICP-OES, N2-sorption, XRD, H2-TPR, NH3-TPD, O2-TPO, STEM-EDX and XPS techniques. The anisole HDO performance of these CoMo catalysts was evaluated at gas phase conditions in a fixed bed tubular reactor in plug flow regime. The catalysts performance is correlated with properties such as reducibility, acidity, and metal-support interactions. Cobalt addition enhanced the total HDO selectivity by 45% as compared to Mo catalysts. Alumina catalysts displayed higher initial activity (Xanisole≈97%) relative to titania and zirconia supported variants (Xanisole 5+ to be the main active phase while over-reduction to lower Mo states (Mo4+ and Mo3+) as well as carbon deposition are identified as the cause for catalyst activity decrease with TOS.
- Ranga, Chanakya,Alexiadis, Vaios I.,Lauwaert, Jeroen,L?deng, Rune,Thybaut, Joris W.
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- Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane
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Palladium oxide nanoparticles supported on graphene oxide - triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.
- Mirza-Aghayan, Maryam,Kalantari, Meisam,Boukherroub, Rabah
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- Controlled manipulation of selectivity between O- versus C-alkylation in methylation of phenol using ZrO2-WO3- SiO2 catalysts
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Anisole and o-cresol are very important chemicals which could prepared from phenol using different catalytic routes favoring either O- or C-alkylation. In the methylation of phenol with methanol, the selectivity to either anisole or o-cresol could be manipulated using a suitable tailor-made catalyst having a proper balance of acidic and basic sites. In the current work, a series of compositions based on zirconium, tungsten and silicon oxides (xZrO2-yWO3-SiO2) were prepared and employed as catalysts in fixed bed methylation of phenol. In the absence of silica as support, methylation of phenol over 20% WO3-ZrO2 and 40% WO3-ZrO2 favored predominantly C-alkylated product o-cresol. Among various combinations 10% ZrO2-30% WO3-SiO2 gave the best results and selectivity to the desired product anisole. Effect of various parameters affecting selectivity to anisole or o-cresol were studied systematically. The mechanism of formation of different products with reference to catalyst structure and functionality was explored in detail. The process parameters could be optimized to get the desired product. Thus, the proper choice can be made to choose the selectivity of O-versus C-alkylation using a single catalyst. The time on stream study was carried out for 16 h to find that the catalyst was stable and could be regenerated.
- Bhadra, Kalpesh H.,Yadav, Ganapati D.
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- Room Temperature Chemoselective Deoxygenation of Aromatic Ketones and Aldehydes Promoted by a Tandem Pd/TiO2 + FeCl3 Catalyst
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A rapid and practical protocol for the chemoselective deoxygenation of various aromatic ketones and aldehydes was described, which used a tandem catalyst composed of heterogeneous Pd/TiO2 + homogeneous FeCl3 with the green hydrogen source, polymethylhydrosiloxane (PMHS). The developed catalytic system was robust and scalable, as exemplified by the deoxygenation of acetophenone, which was performed on a gram scale in an atmospheric environment utilizing only 0.4 mol % Pd/TiO2 + 10 mol % FeCl3 catalyst to give the corresponding ethylbenzene in 96% yield within 10 min at room temperature. Furthermore, the Pd/TiO2 catalyst was shown to be recyclable up to three times without an observable decrease in efficiency and it exhibited low metal leaching under the reaction conditions. Insights toward the reaction mechanism of Pd-catalyzed reductive deoxygenation for aromatic ketones and aldehydes were investigated through operando IR, NMR, and GC-MS techniques.
- Dong, Zhenhua,Yuan, Jinwei,Xiao, Yongmei,Mao, Pu,Wang, Wentao
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p. 11067 - 11073
(2018/09/12)
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- 4,5-Dimethyl-2-Iodoxybenzenesulfonic Acid Catalyzed Site-Selective Oxidation of 2-Substituted Phenols to 1,2-Quinols
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A site-selective hydroxylative dearomatization of 2-substituted phenols to either 1,2-benzoquinols or their cyclodimers, catalyzed by 4,5-dimethyl-2-iodoxybenzenesulfonic acid with Oxone, has been developed. Natural products such as biscarvacrol and lacinilene C methyl ether could be synthesized efficiently under mild reaction conditions. Furthermore, both the reaction rate and site selectivity could be further improved by the introduction of a trialkylsilylmethyl substituent at the 2-position of phenols. The corresponding 1,2-quinols could be transformed into various useful structural motifs by [4+2] cycloaddition cascade reactions.
- Uyanik, Muhammet,Mutsuga, Tatsuya,Ishihara, Kazuaki
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supporting information
p. 3956 - 3960
(2017/03/27)
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- Characterization and photocatalytic behavior of 2,9-di(aryl)-1,10-phenanthroline copper(i) complexes
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The synthesis, characterization, photophysical properties, theoretical calculations, and catalytic applications of 2,9-di(aryl)-1,10-phenanthroline copper(i) complexes are described. Specifically, this study made use of di(aryl)-1,10-phenanthroline ligands including 2,9-di(4-methoxyphenyl)-1,10-phenanthroline (1), 2,9-di(4-hydroxyphenyl)-1,10-phenanthroline (2), 2,9-di(4-methoxy-3-methylphenyl)-1,10-phenanthroline (3), and 2,9-di(4-hydroxy-3-methylphenyl)-1,10-phenanthroline (4). The 2:1 ligand-to-metal complexes, as PF6- salts, i.e., ([Cu·(1)2]PF6, [Cu·(2)2]PF6, [Cu·(3)2]PF6, and [Cu·(4)2]PF6) have been isolated and characterized. The structures of ligands 1 and 2 and complexes [Cu·(1)2]PF6 and [Cu·(3)2]PF6 have been determined by single-crystal X-ray analysis. The photoredox catalytic activity of these copper(i) complexes was investigated in an atom-transfer radical-addition (ATRA) reaction and the results showed fairly efficient activity, with a strong wavelength dependence. In order to better understand the observed catalytic activity, photophysical emission and absorption studies, and DFT calculations were also performed. It was determined that when the excitation wavelength was appropriate for exciting into the LUMO+1 or LUMO+2, catalysis would occur. On the contrary, excitations into the LUMO resulted in no observable catalysis. In light of these results, a mechanism for the ATRA photoredox catalytic cycle has been proposed.
- Cetin, M. Mustafa,Hodson, Roman T.,Hart, C. Robin,Cordes, David B.,Findlater, Michael,Casadonte, Dominick J.,Cozzolino, Anthony F.,Mayer, Michael F.
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p. 6553 - 6569
(2017/07/11)
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- Nucleophilic Amination of Methoxy Arenes Promoted by a Sodium Hydride/Iodide Composite
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A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution.
- Kaga, Atsushi,Hayashi, Hirohito,Hakamata, Hiroyuki,Oi, Miku,Uchiyama, Masanobu,Takita, Ryo,Chiba, Shunsuke
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p. 11807 - 11811
(2017/09/20)
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- Construction of Acid–Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol
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Novel Mg-bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid–base bifunctional catalysts, they achieve the liquid-phase selective methylation of phenol with methanol to produce o- and p-cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo- and regioselectivity (>95 % for p-product) was attained on the alkylation of phenol with bulky tert-butyl alcohol, rendering the first acid–base cooperative shape-selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape-selectivity come from the superior special acidic–basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.
- Xie, Jingyan,Zhuang, Wenxia,Zhang, Wei,Yan, Ning,Zhou, Yu,Wang, Jun
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p. 1076 - 1083
(2017/03/27)
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- Conversion of Cyclohexanones to Alkyl Aryl Ethers by Using a Pd/C–Ethylene System
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The conversion of cyclohexanone and substituted cyclohexanones into alkyl aryl ethers by using a Pd/C–ethylene system is discussed, with ethylene functioning as a hydrogen acceptor. The ether products are easily transformed into the corresponding phenols by treatment with BBr3. The direct conversion of cyclohexenone into phenol in the presence of a catalytic amount of Pd/C under an ethylene atmosphere is also described.
- El-Deeb, Ibrahim Yussif,Tian, Miaomiao,Funakoshi, Tatsuya,Matsubara, Ryosuke,Hayashi, Masahiko
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supporting information
p. 409 - 413
(2017/01/24)
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- Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
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The modification of benzylic quaternary, tertiary, and secondary carbon centers through palladium-catalyzed hydrogenolysis of C(sp3)–C(sp3) σ bonds is presented. When benzyl Meldrum's acid derivatives bearing quaternary benzylic centers are treated under mild hydrogenolysis conditions – palladium on carbon and atmospheric pressure of hydrogen – aromatics substituted with tertiary benzylic centers and Meldrum's acid are obtained with good to excellent yield. Analogously, substrates containing tertiary or secondary benzylic centers yield aromatics substituted with secondary benzylic centers or toluene derivatives, respectively. Furthermore, this strategy is used for the high yielding synthesis of diarylmethanes. The scope of the reductive dealkylation reaction is explored and the limitations with respect to steric and electronic factors are determined. A mechanistic analysis of the reaction is described that consisted of deuterium labelling experiments and hydrogenolysis of enantioenriched derivatives. The investigation shows that the C(sp3)–C(sp3) σ bond-cleaving events occur through a hybrid SN1/SN2 mechanism, in which the palladium center displaces a carbon-based leaving group, namely Meldrum's acid, with inversion of configuration, followed by reductive elimination of palladium to furnish a C?H bond. (Figure presented.).
- Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
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p. 3422 - 3434
(2016/11/13)
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- Synthesis of anisole by vapor phase methylation of phenol with methanol over catalysts supported on activated alumina
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The synthesis of anisole by vapor phase methylation of phenol with methanol over activated alumina (AA) supported catalysts was investigated in a fixed bed reactor. KH2PO4/AA gave the best performance among the eight tested catalysts. The catalyst was prepared by loading KH2PO4 on AA and then calcining at the optimized temperature of 700 °C for 8 h. In the vapor phase reaction, the level of anisole yield (LAY) has a maximum at 400-450 °C when the temperature varied from 300 to 500 °C, which decreased slightly with increasing WHSV and increased distinctly with increasing mole fraction of methanol. On comparing O-methylation and C-methylation of phenol, a low temperature, high WHSV (short residence time), and a low methanol concentration over the KH2PO4/AA catalyst with higher K contents were found to increase anisole selectivity by O-methylation of phenol. The reaction routes to the major products and the catalytic mechanism were suggested, and a 'K-acid' bifunctional process may be a critical factor to the formation of anisole.
- Dang, Dan,Wang, Ze,Lin, Weigang,Song, Wenli
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p. 720 - 726
(2016/05/19)
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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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supporting information
p. 131 - 135
(2015/12/26)
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- En Route to a Practical Primary Alcohol Deoxygenation
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A long-standing scientific challenge in the field of alcohol deoxygenation has been direct catalytic sp3 C-O defunctionalization with high selectivity and efficiency, in the presence of other functionalities, such as free hydroxyl groups and amines widely present in biological molecules. Previously, the selectivity issue had been only addressed by classic multistep deoxygenation strategies with stoichiometric reagents. Herein, we propose a catalytic late-transition-metal-catalyzed redox design, on the basis of dehydrogenation/Wolff-Kishner (WK) reduction, to simultaneously tackle the challenges regarding step economy and selectivity. The early development of our hypothesis focuses on an iridium-catalyzed process efficient mainly with activated alcohols, which dictates harsh reaction conditions and thus limits its synthetic utility. Later, a significant advancement has been made on aliphatic primary alcohol deoxygenation by employing a ruthenium complex, with good functional group tolerance and exclusive selectivity under practical reaction conditions. Its synthetic utility is further illustrated by excellent efficiency as well as complete chemo- and regio-selectivity in both simple and complex molecular settings. Mechanistic discussion is also included with experimental supports. Overall, our current method successfully addresses the aforementioned challenges in the pertinent field, providing a practical redox-based approach to the direct sp3 C-O defunctionalization of aliphatic primary alcohols.
- Dai, Xi-Jie,Li, Chao-Jun
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supporting information
p. 5433 - 5440
(2016/05/19)
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- DEUTERATED BENZOPYRAN COMPOUND AND APPLICATION THEREOF
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features as shown in Formula (I), or pharmaceutically acceptable salts or stereoisomers thereof, or prodrug molecules thereof. With excellent anti-inflammatory and analgesic effects and the capability to inhibit growth of tumor cells, such compounds are novel COX-2 selective inhibitors. The compounds and pharmaceutically acceptable salts thereof disclosed by the present application can be applied in preparing anti-inflammatory and analgesic drugs and drugs for treating or preventing tumors.
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Paragraph 0146-0147
(2015/03/18)
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- Deuterated Benzopyran Compounds and Application Thereof
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The present invention discloses deuterated benzopyran compounds having structure features as shown in Formula (I), or pharmaceutically acceptable salts or stereoisomers thereof, or prodrug molecules thereof. With excellent anti-inflammatory and analgesic effects and the capability to inhibit growth of tumor cells, such compounds are novel COX-2 selective inhibitors. The compounds and pharmaceutically acceptable salts thereof disclosed by the present application can be applied in preparing anti-inflammatory and analgesic drugs and drugs for treating or preventing tumors.
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Paragraph 0253; 0254; 0255; 0256; 0275; 0276; 0277; 0278
(2015/05/26)
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- Iron fluoride/N-heterocyclic carbene catalyzed cross coupling between deactivated aryl chlorides and alkyl grignard reagents with or without β-hydrogens
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High-yielding cross-coupling reactions of various combinations of aryl chlorides and alkyl Grignard reagents have been developed by using an iron(III) fluoride/1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene (SIPr) catalyst composite. The iron(III) fluoride/SIPr-catalyzed aryl-alkyl coupling demonstrates unprecedented scope for both aryl chlorides and alkyl Grignard reagents, thus enabling the first efficient coupling of electron-rich (deactivated) aryl chlorides with alkyl Grignard reagents without β-hydrogens. The present reaction is also effective for diverse alkyl Grignard reagents such as (trimethylsilyl)methyl, primary, and secondary alkyl Grignard reagents.
- Agata, Ryosuke,Iwamoto, Takahiro,Nakagawa, Naohisa,Isozaki, Katsuhiro,Hatakeyama, Takuji,Takaya, Hikaru,Nakamura, Masaharu
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p. 1733 - 1740
(2015/06/16)
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- Methylation of phenol and its derivatives with dimethyl carbonate in the presence of Mn2(CO)10, W(CO)6, and Co2(CO)8
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Aryl methyl ethers were synthesized by reactions of phenol, substituted phenols, and α- and β-naphthols with dimethyl carbonate in the presence of manganese, tungsten, and cobalt carbonyls. Optimal reactant and catalyst ratios and reaction conditions were found to ensure selective formation of aryl methyl ethers.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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p. 330 - 334
(2015/05/04)
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- A ligand-free, powerful, and practical method for methoxylation of unactivated aryl bromides by use of the CuCl/HCOOMe/MeONa/MeOH system
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A ligand-free, powerful, and practical method for mono and polymethoxylation of unactivated aryl bromides has been developed; CuCl was used as catalyst, HCOOMe as cocatalyst, and methanolic MeONa as both nucleophile and solvent. This eco-friendly procedure is characterized by operational simplicity, inexpensive substrates (unactivated mono to polybromoarenes), full conversion, and direct recovery of pure MeOH.
- Guo, Ying,Ji, Si-Zhe,Chen, Cheng,Liu, Hong-Wei,Zhao, Jian-Hong,Zheng, Yu-Lin,Ji, Ya-Fei
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p. 8651 - 8664
(2015/03/05)
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- Erbium trifluoromethanesulfonate catalyzed Friedel-Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation
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Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel-Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste.
- Tran, Phuong Hoang,Hansen, Poul Erik,Nguyen, Hai Truong,Le, Thach Ngoc
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p. 612 - 618
(2015/02/19)
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- Synthesis of deuterated benzopyran derivatives as selective COX-2 inhibitors with improved pharmacokinetic properties
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We designed a series of specifically deuterated benzopyran analogues as new COX-2 inhibitors with the aim of improving their pharmacokinetic properties. As expected, the deuterated compounds retained potency and selectivity for COX-2. The new molecules possess improved pharmacokinetic profiles in rats compared to their nondeuterated congeners. Most importantly, the new compounds showed pharmacodynamic efficacy in several murine models of inflammation and pain. The benzopyran derivatives were separated into their enantiomers, and the activity was found to reside with the S-isomers. To streamline the synthesis of the desired S-isomers, an organocatalytic asymmetric domino oxa-Michael/aldol condensation reaction was developed for their preparation.
- Zhang, Yanmei,Tortorella, Micky D.,Wang, Yican,Liu, Jianqi,Tu, Zhengchao,Liu, Xiaorong,Bai, Yang,Wen, Dingsheng,Lu, Xin,Lu, Yongzhi,Talley, John J.
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supporting information
p. 1162 - 1166
(2014/12/10)
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- Selective reductive cleavage of inert aryl C-O bonds by an iron catalyst
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Breaking point: An effective reductive cleavage of inert aryl C-O bonds with an inexpensive iron catalyst has been developed. During this process, the reduction of the arene rings was not observed. This catalytic system also enabled the selective cleavage of the β-O-4 linkage of lignin model compounds under an atmosphere of hydrogen, thus offering an opportunity for the depolymerization of lignin. Copyright
- Ren, Yunlai,Yan, Mengjie,Wang, Jianji,Zhang, Z. Conrad,Yao, Kaisheng
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supporting information
p. 12674 - 12678
(2013/12/04)
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- Metal-free reductive cleavage of benzylic esters and ethers: Fragmentations result from single and double electron transfers
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The mechanisms for the reductive cleavage of benzylic esters and ethers by neutral organic electron donor 1 are different (see scheme). Products isolated from the cleavage of benzylic ethers result from the transfer of two electrons, without the intermediacy of benzyl radicals, which are believed to be intermediates in the reductive cleavage of benzylic esters. Copyright
- Doni, Eswararao,O'Sullivan, Steven,Murphy, John A.
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p. 2239 - 2242
(2013/03/28)
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- Efficient palladium-catalyzed C-O hydrogenolysis of benzylic alcohols and aromatic ketones with polymethylhydrosiloxane
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A simple method has been developed for the reductive deoxygenation of aromatic ketones and benzylic alcohols in the presence of polymethylhydrosiloxane (PMHS). The reductive deoxygenation of aromatic ketones and benzylic alcohols, including secondary alcohols, to the corresponding methylene hydrocarbons has been achieved in good to excellent yields using palladium chloride (PdCl2) as catalyst and PMHS as hydride source. Such deoxygenations were successfully with aryl alkyl ketones and diaryl ketones, as exemplified by the reductive deoxygenation of acetophenone and benzopheneone, respectively. The corresponding benzylic alcohols and secondary alcohol analogues could also be converted into their respective methylene hydrocarbons by the PdCl2/PMHS system.
- Wang, Hu,Li, Li,Bai, Xing-Feng,Shang, Jun-Yan,Yang, Ke-Fang,Xu, Li-Wen
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supporting information
p. 341 - 347
(2013/05/08)
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- Iridium-catalyzed direct dehydroxylation of alcohols
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Iridium-catalyzed direct dehydroxylation of alcohols with hydrazine was developed through a combination of the oxidation of alcohols and the Wolff-Kishner reduction. This protocol is simple to perform and highly efficient for a series of primary, benzylic and allylic alcohols. Iridium-catalyzed direct dehydroxylation of alcohols with hydrazine is developed through a combination of the oxidation of alcohols and Wolff-Kishner reduction. This protocol is simple to perform and highly efficient for a series of primary alcohols, especially benzylic and allylic ones. Copyright
- Huang, Jian-Lin,Dai, Xi-Jie,Li, Chao-Jun
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supporting information
p. 6496 - 6500
(2013/11/06)
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- Exploiting the lithiation-directing ability of oxetane for the regioselective preparation of functionalized 2-aryloxetane scaffolds under mild conditions
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Oxetane nudges in the DoM direction! Regioselective ortho-lithiation induced by an oxetane ring has been achieved. The reaction provides easy access to ortho-functionalized 2-aryloxetanes also through a lithiation/borylation Suzuki-Miyaura cross-coupling. The lithiation-directing ability of oxetane and the proton transfer mechanism have been investigated by competitive metalation and kinetic isotope effect studies. Copyright
- Coppi, Donato Ivan,Salomone, Antonio,Perna, Filippo Maria,Capriati, Vito
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supporting information; scheme or table
p. 7532 - 7536
(2012/09/10)
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- A convenient and practical synthesis of anisoles and deuterated anisoles by palladium-catalyzed coupling reactions of aryl bromides and chlorides
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Synthesis of anisole: Aryl and heteroaryl halides undergo selective C-O cross-coupling reactions with methanol in the presence of a Pd(OAc) 2/L3 catalyst system. The corresponding ethers were obtained under mild conditions in good yields. The catalytic methodology was also used for the synthesis of labeled deuterated anisoles in good yields (see scheme). Copyright
- Gowrisankar, Saravanan,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 2498 - 2502
(2012/03/27)
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- C,N-chelated organotin(IV) compounds as catalysts for transesterification and derivatization of dialkyl carbonates
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The potential catalytic activity of selected C,N-chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMC) and diethyl carbonate (DEC) was investigated. Some tri-, di- and monoorganotin(IV) species (LCN(n-Bu)2SnCl (1), LCN(n-Bu)2SnCl.HCl (1a), LCN(n-Bu) 2SnI (2), LCNPh2SnCl (3), LCNPh 2SnI (4), LCN(n-Bu)SnCl2 (5), L CNSnBr3 (6) and [LCNSn(OC(O)CF 3)]2(μ-O)(μ-OC(O)CF3)2 (7)) bearing the LCN moiety (LCN = 2-(N,N-dimethylaminomethyl) phenyl-) were assessed as catalysts for reactions of both DMC and DEC with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMC with p-substituted phenols were studied for comparison with the standard base K2CO3/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, GC and GC-MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. Copyright
- Weidlich, Tomas,Dusek, Libor,Vystrcilova, Barbora,Eisner, Ales,Svec, Petr,Ruzicka, Ales
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p. 293 - 300
(2012/10/07)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan, S.
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p. 4914 - 4917,4
(2012/12/12)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan
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p. 4914 - 4917
(2013/01/14)
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- Diiron complexes with pendant phenol group(s) as mimics of the diiron subunit of [FeFe]-hydrogenase: Synthesis, characterisation, and electrochemical investigation
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Four diiron hexacarbonyl complexes, [Fe2(μ-SCH 2-o-C6H4OMe)2(CO)6] (4a), [Fe2{μ-SCH2-o,m-C6H3(OMe) 2}2-(CO)6] (4b), [Fe2{μ-SCH 2-o,o′-C6H3(CO2Me)(OMe)} 2(CO)6] (4c) and the demethylated form of complex 4a, [Fe2(μ-SCH2-o-C6H4OH) 2(CO)6] (5a), were synthesised and fully characterised. Complexes 4b and 4c were also structurally analysed. Electrochemical investigations revealed that the integrity of the bridging linkages of the examined diiron complexes significantly affect their reduction reversibility and catalysis through a coupled chemical reaction in a unique ECE mechanism, widely adopted by complexes with the core {Fe2(CO)4-6}. Demethylation of complexes 4a and 1Me, [Fe2(μ-SCH 2)2CMe(CH2-o-C6H4OMe)(CO) 6], by BBr3 led to complexes (5a and 1H, [Fe 2(μ-SCH2)2CMe(CH2-o-C 6H4OH)-(CO)6]) with pendant phenol group(s), a weak acid. Deprotonation of the two complexes produced the pendant phenolate, which instantly intramolecularly substitutes the bound CO to yield species of the coordination form FeI-OR (R = phenolic moiety). Electrochemical investigation revealed that the pendant phenol groups in complexes 1H and 5a do not seem to improve their catalytic efficiency in proton reduction in the medium acetic acid/dichloromethane.
- Tang, Ying,Wei, Zhenhong,Zhong, Wei,Liu, Xiaoming
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experimental part
p. 1112 - 1120
(2011/06/10)
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- Palladium chloride-catalyzed reductive cleavage of benzylic acetal, ketal and ether compounds with triethylsilane
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Reductive cleavage of benzylic acetal, ketal and ether compounds to the corresponding alkanes using triethylsilane and a catalytic amount of palladium(II) chloride is described. The reductive reaction took place under mild conditions, affording high yields of the corresponding alkane compounds in short reaction times.
- Mirza-Aghayan,Boukherroub,Rahimifard,Zadmard
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experimental part
p. 570 - 573
(2012/06/16)
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- Synthesis and characterization of chroman-containing compounds and their preliminary assessment of cytotoxicity toward two human cancer cell lines
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A series of chroman derivatives were synthesized by employing o-methyl phenol as a precursor. These compounds were fully characterized using IR, NMR spectroscopic techniques, and elemental analysis. Mechanisms for the formation of the chroman moiety of these compounds were also proposed. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to estimate their cytotoxicity toward two cancer cell lines: human ovarian cancer (A2780) and human cervical cancer (Hela).
- Tang, Ying,Wei, Jie,Zhong, Wei,Liu, Xiaoming
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experimental part
p. 423 - 429
(2011/07/08)
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- A rare bond between a soft metal (FeI) and a relatively hard base (RO-, R = phenolic moiety)
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Reacting a bidentate ligand H2L, 2-(2-methoxybenzyl)-2- methylpropane-1,3-dithiol, with Fe3(CO)12 formed a diiron hexacarbonyl complex (1Me) from which a diiron hexacarbonyl complex (1H) pendant with a phenolic group was derived via in-situ demethylation. Further deprotonation of complex 1H gave a diiron pentacarbonyl species (1) in which a rare bond between the soft metal FeI and the relatively hard base phenolate formed, FeI-OR (R = phenolic moiety). This bonding may be a suitable mimic of the bonding feature, {FeIFeI}R-OH/ OH2 found in the [FeFe]-hydrogenase.
- Zhong, Wei,Tang, Ying,Zampella, Giuseppe,Wang, Xiufeng,Yang, Xinlei,Hu, Bin,Wang, Jiang,Xiao, Zhiyin,Wei, Zhenhong,Chen, Huanwen,De Gioia, Luca,Liu, Xiaoming
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scheme or table
p. 1089 - 1092
(2011/01/11)
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- SYNTHETIC METHODS AND COMPOSITIONS
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The invention provides synthetic methods that utilize bromo or chloro substituents as blocking groups during the functionalization of aromatic rings, as well as compounds that are prepared from such methods.
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Page/Page column 4; 5
(2011/01/11)
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