- On the way to biofuels from furan: Discriminating Diels-Alder and ring-opening mechanisms
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We performed kinetics experiments and quantum calculations to investigate the reaction of furan to benzofuran catalyzed by the acidic zeolite HZSM-5, which is a key step in the conversion of biomass to biofuels through catalytic fast pyrolysis. The reaction was studied experimentally by placing the zeolite in contact with solution-phase furan and detecting the benzofuran product over the temperature range 270-300 C, yielding an apparent activation energy of 72 ± 3 kJ/mol. The reaction was modeled in gas and zeolite phases to determine the energetics of the following two competing pathways: a Diels-Alder mechanism often assumed in interpretations of experimental data and a ring-opening pathway predicted by the chemoinformatic software RING. Quantum calculations on the zeolite/guest system were performed using the ONIOM embedded cluster approach. We computed the energetics of reactants, products, and all intermediate steps. Locating relevant transition states fell beyond our computational resources because of system size and the ruggedness of the energy landscape. The Diels-Alder mechanism in the gas phase was found to pass through a high-energy intermediate roughly 380 kJ/mol above the reactant energy, which reduces to approximately 200 kJ/mol in HZSM-5. In contrast, the ring-opening mechanism passes through a gas-phase intermediate roughly 500 kJ/mol above the reactant energy, which falls to approximately 50 kJ/mol in HZSM-5. The energy of the ring-opening mechanism over HZSM-5 fits into the experimentally determined energy budget of 72 ± 3 kJ/mol. These experimental and computational results highlight the importance of the ring-opening mechanism for this key step in making biofuels. Our results strongly indicate that, in the cavities of HZSM-5, the condensation of two furan molecules to form benzofuran and water does not proceed by a Diels-Alder reaction between the reactants.
- Vaitheeswaran,Green, Sara K.,Dauenhauer, Paul,Auerbach, Scott M.
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- Thermal Decomposition of Chroman. Reactivity of o-Quinone Methide
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The gas phase thermal decomposition of 3,4-dihydro-2H-1-benzopyran (chroman, 1) has been studied between 760 and 1110 K in different bath gases and hydrogen donors. In nitrogen, the unimolecular rate parameters are k1 (s-1) = 1015.3 exp(-263 (kJ mol-1)/RT). The activation energy is slightly higher than the bond dissociation energy (BDE) of the phenoxylic C - O bond. The decomposition starts with elimination of ethene and formation of 6-methylene-2,4-cyclohexadien-1-one (o-quinone methide, 2). Quinone methides are important intermediates in the chemistry of lignin. In the high temperature range (860-980 K) 2 decomposes cleanly into CO, benzene, and small amounts of fulvene, obeying k2 (s-1) = 1014.8 exp(-281 (kJ mol-1)/RT. Reverse radical disproportionation of 2 with toluene is mainly responsible for o-cresol formation. In cis-2-butene at 770 K, exclusively cis-2,3-dimethylchroman is formed. This stereospecificity suggests a concerted retro-Diels - Alder mechanism and is not compatible with the high Arrhenius parameters, indicative of a stepwise, biradical mechanism.
- Dorrestijn, Edwin,Pugin, Raphae?l,Nogales, M. Victoria Ciriano,Mulder, Peter
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- 3-Nitrocoumarins as Dienophiles in the Diels-Alder Reaction in Water. An Approach to the Synthesis of Nitrotetrahydrobenzo[c]chromenones and Dihydrodibenzo[b,d]furans
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The [4 + 2] cycloadditions of 3-nitrocoumarin (1a), 6-chloro-3-nitrocoumarin (1b), and 6-, 7-, and 8-hydroxy-3-nitrocoumarins (1c, 5, and 6) with (E)-piperylene (7), isoprene (8), 2,3-dimethyl-1,3-butadiene (9), 2-methoxy-1,3-butadiene (10), 2,3-dimethoxy-1,3-butadiene (11), and cyclopentadiene (12) were investigated in aqueous medium, in organic solvent and under solventless conditions. The reactions performed in water occurred in heterogeneous phase but were faster than those executed in toluene or dichloroethane (DCE). 1a-c, 5, and 6 behaved as 2π components in the Diels-Alder cycloadditions with 7-10 and 12, and exo adducts were preferentially or exclusively produced. Surprisingly 1a, behaved as a 4π component in the cycloaddition in water with 11 and 4-substituted 3-nitrochromanones 20 and 21 were isolated. The cycloadditions of hydroxy-3-nitrocoumarins 1c, 5, and 6 with 1,3-diene 9 did not work in water or in organic solvent, but did work under solventless conditions. Nitrotetrahydrobenzo[c]chromenones 13-16, 24, and 25, originating from the normal electron-demand Diels-Alder reactions, were converted into dihydrodibenzo[b,d]furans 27-31 in water, via one-pot Nef-cyclodehydration reactions.
- Amantini, David,Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando,Vaccaro, Luigi
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- Biomass to drugs: Green production of salicylic acid from 2-furoic acid in two steps
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Salicylic acid, generally produced by chemical synthesis based on petrochemical products, is a vital organic acid and widely used in the pharmaceutical synthesis. This work developed a new and green route for the production of salicylic acid from biomass-derived 2-furoic acid in two steps. Firstly, 2 mmol 2-furoic acid was creatively converted to 2,3-benzofuran using HZSM-5 (Si/Al=130) at 280 °C for 1.5 h under 100 psi N2; and then the oxidation of 2,3-benzofuran to salicylate was conducted with tert?butyl hydroperoxide under basic condition without metal catalyst at 120 °C for 1 h. The stability of the catalyst for the first step and the possible reaction pathway for the second step based on the control experiments was properly envisioned. Regardless of limited salicylic acid yield (16%) from 2-furoic acid, this work paves a potentially feasible pathway for the preparation of drugs from biomass.
- Jiang, Jun,Li, Teng,Sun, Guangyu,Wang, Yantao,Xiong, Lu,Yang, Weiran,Yu, Pengxin,Zheng, Boying
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- Characteristic flavor formation of thermally processed N-(1-deoxy-α-D-ribulos-1-yl)-glycine: Decisive role of additional amino acids and promotional effect of glyoxal
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The role of amino acids and α-dicarbonyls in the flavor formation of Amadori rearrangement product (ARP) during thermal processing was investigated. Comparisons of the volatile compounds and their concentrations when N-(1-deoxy-α-D-ribulos-1-yl)-glycine r
- Zhan, Huan,Cui, Heping,Yu, Junhe,Hayat, Khizar,Wu, Xian,Zhang, Xiaoming,Ho, Chi-Tang
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- Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
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The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
- Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
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supporting information
p. 7290 - 7296
(2021/03/01)
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- A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
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Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
- Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
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p. 6684 - 6690
(2021/05/31)
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- Direct Observation of Transmetalation from a Neutral Boronate Ester to a Pyridine(diimine) Iron Alkoxide
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Transmetalation of the neutral boronate esters, (2-benzofuranyl)BPin and (2-benzofuranyl)BNeo (Pin = pinacolato, Neo = neopentylglycolato), to a representative pyridine(diimine) iron alkoxide complex, (iPrPDI)FeOEt (iPrPDI = 2,6-(2,6-iPr2-C6H3Na? CMe)2C5H3N; R = Me, Et, SiMe3), to yield the corresponding iron benzofuranyl derivative was studied. Synthesis of the requisite iron alkoxide complexes was accomplished either by salt metathesis between (iPrPDI)FeCl and NaOR (R = Me, Et, SiMe3) or by protonation of the iron alkyl, (iPrPDI)FeCH2SiMe3, by the free alcohol R′OH (R′ = Me, Et). A combination of magnetic measurements, X-ray diffraction, NMR, and M?ssbauer spectroscopies and DFT calculations identified each (iPrPDI)FeOR compound as an essentially planar, high-spin, S = 3/2 compound where the iron is engaged in antiferromagnetic coupling with a radical anion on the chelate (STotal = 3/2; SFe = 2, SPDI =-1/2). The resulting iron benzofuranyl product, (iPrPDI)Fe(2-benzofuranyl), was characterized by X-ray diffraction and in combination with magnetic measurements, spectroscopic and computational data, was identified as an overall S = 1/2 compound, demonstrating that a net spin-state change accompanies transmetalation (SFe = 1, SPDI =-1/2). These findings may be relevant to further development of iron-catalyzed Suzuki-Miyaura cross-coupling with neutral boronate esters and alkoxide bases.
- Chirik, Paul J.,Peterson, Paul O.,Rummelt, Stephan M.,Stieber, S. Chantal E.,Wile, Bradley M.,Zhong, Hongyu
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supporting information
(2020/01/11)
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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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- Metal-free and base-free decarboxylation of substituted cinnamic acids in a deep eutectic solvent
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A metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene.
- Chen, Chen,Jian, Yuqing,Lei, Yuxin,Li, Bin,Peng, Caiyun,Sheng, Wen-Bing,Sumera, Yasmin,Wang, Wei,Zhang, Ming
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p. 558 - 563
(2020/01/24)
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- Catalytic Aerobic Dehydrogenatin of N-Heterocycles by N-Hydoxyphthalimide
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Catalytic methods for the aerobic dehydrogenation of N-heterocycles are reported. In most cases, indoles are accessed efficiently from indolines using catalytic N-hydroxyphthalimide (NHPI) as the sole additive under air. Further studies revealed an improved catalytic system of NHPI and copper for the preparation of other heteroaromatics, for example quinolines. (Figure presented.).
- Chen, Weidong,Tang, Hao,Wang, Weilin,Fu, Qiang,Luo, Junfei
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supporting information
p. 3905 - 3911
(2020/08/10)
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- Iron-Catalyzed Synthesis of 2-Aminofurans from 2-Haloketones and Tertiary Amines or Enamines
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The selective synthesis of heterocycles from readily available substrates and catalyzed by an abundant and environmental benign catalyst continues to be an attractive topic. In this communication, we report an interesting protocol for the synthesis of 2-aminofurans. Starting from 2-haloketones and tertiary amines, with abundant iron salt as the catalyst, various 2-aminofurans were produced in good yields. Control experiments were performed to understand the reaction pathway. Based on the identified reaction pathway, the substrates for this transformation can be extended from tertiary amines to enamines and even with better final yields. Finally, a formal three-component reaction can also be realized by forming the enamines in-situ from aldehydes and amines.
- Wang, Le-Cheng,Geng, Hui-Qing,Peng, Jin-Bao,Wu, Xiao-Feng
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p. 2605 - 2616
(2020/04/24)
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- Method for removing sulfinyl group in heteroaryl compound
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The invention discloses a method for removing a sulfinyl group in a heteroaryl compound. The method is characterized in that a heteroaryl cyclic sulfoxide compound represented by formula (Ia) or formula (Ib) and trimethylsilylphenyl trifluoromethanesulfonate represented by formula (II) used a substrate are reacted in the presence of cesium fluoride to obtain a sulfinyl group-removed heteroaryl compound represented by formula (IIIa) or (IIIb). The method can rapidly remove the sulfinyl group in the heteroaryl cyclic sulfoxide compound, does not need a metal catalyst with poor safety or highly toxic organic reagents, and is safe. The method has the advantages of mild conditions, strong compatibility with some sensitive benzenesulfonyl groups and Boc groups, simplicity in post-treatment, andsuitableness for industrial production.
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Paragraph 0049-0052
(2019/10/01)
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- Desulfurization of Diaryl(heteroaryl) Sulfoxides with Benzyne
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Two benzyne-enabled desulfurization reactions have been demonstrated which convert diaryl sulfoxides and heteroaryl sulfoxides to biaryls and desulfurized heteroarenes, respectively. The reaction accessing biaryls tolerates a variety of functional groups, such as halides, pseudohalides, and carbonyls. Mechanistic studies reveal that both reactions proceed via a common assembly process but divergent disassemblies of the generated tetraaryl(heteroaryl) sulfuranes.
- Chen, De-Li,Sun, Yan,Chen, Mengyuan,Li, Xiaojin,Zhang, Lei,Huang, Xin,Bai, Yihui,Luo, Fang,Peng, Bo
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supporting information
(2019/06/13)
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- Preparation method of benzofuran compound
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The invention relates to a preparation method of a benzofuran compound. The preparation method comprises the following steps: putting a furan compound, acetic acid and a Lewis acid catalyst in a reaction vessel, reacting for 0.5-24 h at 80-160 DEG C, and separating and purifying to obtain the benzofuran compound. According to the preparation method provided by the invention, the furan compound isused as a reaction raw material, an acetic acid water solution is used as a solvent, Lewis acid is used as a catalyst, and at a mild reaction temperature (80-160 DEG C), the benzofuran compound is directly obtained through one-step reaction. The preparation method provided by the invention can synthesize the benzofuran compound with a corresponding structure and functional groups based on the structure and functional groups of the furan compound as a raw material, the raw material components are simple , and the process is convenient to operate; wherein the selectivity of the obtained benzofuran is as high as 99% in the process of synthesizing benzofuran by using furan, so that the method has industrial application prospects.
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Paragraph 0114-0117
(2019/04/04)
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- Facile synthesis of inorganic–organic Fe2W18Fe4@NiO@CTS hybrid nanocatalyst induced efficient performance in oxidative desulfurization of real fuel
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In this work, a new nanocatalyst, Fe2W18Fe4@NiO@CTS, was synthesized by the reaction of sandwich-type polyoxometalate (Fe2W18Fe4), nickel oxide (NiO), and chitosan (CTS) via sol–gel method. The assembled nanocatalyst was systematically characterized by FT-IR, UV–vis, XRD, SEM, and EDX analysis. The catalytic activity of Fe2W18Fe4@NiO@CTS was tested on oxidative desulfurization (ODS) of real gasoline and model fuels. The experimental results revealed that the levels of sulfur content and mercaptan compounds of gasoline were lowered with 97% efficiency. Also, the Fe2W18Fe4@NiO@CTS nanocatalyst demonstrated an outstanding catalytic performance for the oxidation of dibenzothiophene (DBT) in the model fuel. The major factors that influence the desulfurization efficiency and the kinetic study of the ODS reactions were fully detailed and discussed. The probable ODS pathway was proposed via the electrophilic mechanism on the basis of the electrophilic characteristic of the metal-oxo-peroxo intermediates. The prepared nanocatalyst could be reused for 5 successive runs without any appreciable loss in its catalytic activity. As a result, the current study suggested the potential application of the Fe2W18Fe4@NiO@CTS hybrid nanocatalyst as an ideal candidate for removal of sulfur compounds from fuel.
- Rezvani, Mohammad Ali,Maleki, Zeynab
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- Decarbonylation of Aromatic Aldehydes and Dehalogenation of Aryl Halides Using Maghemite-Supported Palladium Catalyst
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A facile decarbonylation reaction of a variety of aromatic and heteroaromatic aldehydes using maghemite-supported palladium catalyst has been developed. The magnetic properties of catalyst facilitated an easy and efficient recovery of the catalyst from the reaction mixture using an external magnet. It was found that the catalyst could be reused up to four consecutive catalytic runs without a significant change in activity. In addition, the catalyst was also very effective in the dehalogenation of aryl halides. This is the first report on efficient utilization of directly immobilized Pd on maghemite in decarbonylation and dehalogenation reactions.
- Ajda?i?, Vladimir,Nikoli?, Andrea,Simi?, Stefan,Manojlovi?, Dragan,Stojanovi?, Zoran,Nikodinovic-Runic, Jasmina,Opsenica, Igor M.
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p. 119 - 126
(2017/12/27)
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- Palladium-Catalyzed Regioselective C-2 Arylation of Benzofurans with N′-Acyl Arylhydrazines
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A novel ligand-free palladium-catalyzed C-2 arylation of benzofurans has been developed using N′-acyl arylhydrazines as the coupling partners and TEMPO as an oxidant. This protocol features a wide functional-group tolerance and highly regioselective products with good to excellent yields.
- Cao, Jun,Chen, Zi-Li,Li, Shu-Min,Zhu, Gao-Feng,Yang, Yuan-Yong,Wang, Cong,Chen, Wen-Zhang,Wang, Jian-Ta,Zhang, Ji-Quan,Tang, Lei
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supporting information
p. 2774 - 2779
(2018/06/21)
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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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- Preparation method of 2-substituted-benzofuran compound
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The invention relates to a preparation method of a 2-substituted-benzofuran compound. The method comprises the following specific steps that at the room temperature, after salicylaldehyde and nitroethane are mixed, sodium bisulfite (NaHSO3/SiO2) loaded by silica gel is added, the temperature is increased to 70-80 DEG C for 6-8 h, and 2-methylbenzofuran is obtained. The compound is shown in the description.
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Paragraph 0025-0033
(2018/10/11)
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- Novel synthesis method of benzofuran ring
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The invention relates to a novel synthesis method of a benzofuran ring. The novel synthesis method comprises the following steps: carrying out a process shown in the description; after mixing salicylic aldehyde and nitromethane at room temperature; adding silica gel loaded sodium bisulfite (NaHSO3/SiO2); raising the temperature to 60 to 80 DEG C and reacting for 4 to 6h to obtain the benzofuran ring.
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Paragraph 0025; 0026; 0027; 0030
(2018/11/22)
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- Palladium-Catalyzed Reductive Conversion of Acyl Fluorides via Ligand-Controlled Decarbonylation
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Ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides were developed using a Pd(OAc)2/Et3SiH combination. When tricyclohexylphosphine (PCy3) was used as the ligand, aldehydes were obtained as simple reductive conversion products. The use of 1,2-bis(dicyclohexylphosphino)ethane (Cy2P(CH2)2PCy2, DCPE) as the ligand, however, favored the formation of hydrocarbons, which are decarbonylative reduction products.
- Ogiwara, Yohei,Sakurai, Yuka,Hattori, Hiroyuki,Sakai, Norio
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supporting information
p. 4204 - 4208
(2018/07/29)
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- Earth-Abundant Mixed-Metal Catalysts for Hydrocarbon Oxygenation
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The oxygenation of aliphatic and aromatic hydrocarbons using earth-abundant Fe and Cu catalysts and "green" oxidants such as hydrogen peroxide is becoming increasingly important to atom-economical chemical processing. In light of this, we describe that dinuclear CuII complexes of pyrrolic Schiff-base macrocycles, in combination with ferric chloride (FeCl3), catalyze the oxygenation of π-activated benzylic substrates with hydroperoxide oxidants at room temperature and low loadings, representing a novel design in oxidation catalysis. Mass spectrometry and extended X-ray absorption fine structure analysis indicate that a cooperative action between CuII and FeIII occurs, most likely because of the interaction of FeCl3 or FeCl4- with the dinuclear CuII macrocycle. Voltammetric measurements highlight a modulation of both CuII and FeIII redox potentials in this adduct, but electron paramagnetic resonance spectroscopy indicates that any Cu-Fe intermetallic interaction is weak. High ketone/alcohol product ratios, a small reaction constant (Hammett analysis), and small kinetic isotope effect for H-atom abstraction point toward a free-radical reaction. However, the lack of reactivity with cyclohexane, oxidation of 9,10-dihydroanthracene, oxygenation by the hydroperoxide MPPH (radical mechanistic probe), and oxygenation in dinitrogen-purge experiments indicate a metal-based reaction. Through detailed reaction monitoring and associated kinetic modeling, a network of oxidation pathways is proposed that includes "well-disguised" radical chemistry via the formation of metal-associated radical intermediates.
- Pankhurst, James R.,Curcio, Massimiliano,Sproules, Stephen,Lloyd-Jones, Guy C.,Love, Jason B.
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supporting information
p. 5915 - 5928
(2018/05/28)
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- Direct Catalytic Conversion of Biomass-Derived Furan and Ethanol to Ethylbenzene
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Herein, we report a synthetic strategy to convert biomass-derived unsubstituted furan to aromatics at high selectivity, especially to ethylbenzene via alkylation/Diels-Alder cycloaddition using ethanol, while greatly reducing the formation of the main side product, benzofuran, over zeolite catalysts. Using synchrotron X-ray powder diffraction and first-principles calculations, it is shown that the above methodology favors the formation of aromatic products due to ready alkylation of furan by the first ethanol molecule, followed by Diels-Alder cycloaddition with ethylene derived from the second ethanol molecule on a Br?nsted acid site in a one-pot synthesis. This gives a double-promoting effect: an alkyl substituent(s) on furan creates steric hindrance to inhibit self-coupling to benzofuran while an alkylated furan (diene) undergoes a Diels-Alder reaction more favorably due to higher HOMO energy.
- Teixeira, Ivo F.,Lo, Benedict T. W.,Kostetskyy, Pavlo,Ye, Lin,Tang, Chiu C.,Mpourmpakis, Giannis,Tsang, Shik Chi Edman
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p. 1843 - 1850
(2018/03/09)
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- A process for the preparation and synthetic ChondriamideA and ChondriamideC method (by machine translation)
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The invention provides a process for the preparation of synthetic Chondriamide A and Chondriamide C and method, wherein the invention provides a process for the preparation, including: formula (I) compounds of structure, palladium catalyst, phosphorus ligand, alkali and organic solvent at room temperature the illumination reaction, formula (II) structure obtained olefin; wherein through the selection of a particular phosphorus ligand; make the method of the invention can be under the photocatalysis, room temperature to realize high-efficient catalytic conversion, and the mild reaction conditions, simple operation, in line with the development of green environment-friendly chemical requirements, and the range of choice of substrate and functional group compatibility has more universal, and has outstanding chemical selectivity; and the method can be successfully applied to complex molecular introducing carbon-carbon double bond to the programme, to optimize a part of the drug molecular synthesis strategy, improve the synthesis efficiency, reduce the cost, with industrial synthetic value and prospects. (by machine translation)
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Paragraph 0093-0097; 0199-0202
(2018/09/13)
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- NITROGEN-CONTAINING BIOPOLYMER-BASED CATALYSTS, THEIR PREPARATION AND USES IN HYDROGENATION PROCESSES, REDUCTIVE DEHALOGENATION AND OXIDATION
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The present invention relates to a process for the preparation of a nitrogen containing biopolymer-based catalyst by pyrolysis of a metal complex with a nitrogen-containing biopolymer and to the nitrogen containing biopolymer-based catalysts obtainable by this process. In particular, the invention relates to a nitrogen containing biopolymer-based catalyst comprising metal particles and at least one nitrogen containing carbon layer. The invention also relates to the use of a nitrogen containing biopolymer-based catalyst in a hydrogenation process, preferably in a process for hydrogenation of nitroarenes, nitriles or imines; in a reductive dehalogenation process of C-X bonds, wherein X is CI, Br or I, preferably in a process for dehalogenation of organohalides or in a process for deuterium labelling of arenes via dehalogenation of organohalides; or in an oxidation process. Further, the invention relates to a metal complex with the nitrogen containing biopolymer, wherein the metal is a transition metal selected from the group consisting of manganese, ruthenium, cobalt, rhodium, nickel, palladium and platinum, preferably cobalt or nickel, and wherein the nitrogen containing biopolymer is selected from chitosan, chitin and a polyamino acid, preferably chitosan or chitin.
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Page/Page column 19
(2018/07/29)
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- Dendrimer-Stabilized Metal Nanoparticles as Efficient Catalysts for Reversible Dehydrogenation/Hydrogenation of N-Heterocycles
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Nanoparticles (Pd, Pt, Rh) stabilized by G4OH PAMAM dendrimers and supported in SBA-15 (MNPs/SBA-15 with M = Pd, Pt, Rh) were efficiently used as catalysts in the acceptorless dehydrogenation of tetrahydroquinoline/indoline derivatives in toluene (release of H2) at 130 °C. These catalysts are air stable, very active, robust, and recyclable during the process. The reverse hydrogenation reaction of quinoline derivatives (H2 storage) was also optimized and successfully performed in the presence of the same catalysts in toluene at 60 °C under only 1 atm of hydrogen gas. Such catalysts may be essential for the adoption of organic hydrogen-storage materials as an alternative to petroleum-derived fuels. Hot filtration test confirmed that the reaction follows a heterogeneous pathway. Moreover, PdNPs/SBA-15 was an excellent catalyst for the direct arylation at the C-2 position (via C-H activation) of indole in water in the presense of a hypervalent iodine oxidant. Thus, a one-pot dehydrogenation/direct arylation cascade reaction between indoline and an arylated agent was efficaciously performed in water, demonstrating the potential of the system to catalyze tandem heterogeneous/homogeneous processes by choice of the appropriate oxidant/reductant.
- Deraedt, Christophe,Ye, Rong,Ralston, Walter T.,Toste, F. Dean,Somorjai, Gabor A.
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p. 18084 - 18092
(2017/12/26)
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- A Biomass-Derived Non-Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides
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Hydrodehalogenation is a straightforward approach for detoxifications of harmful anthropogenic organohalide-based pollutants, as well as removal of halide protecting groups used in multistep syntheses. A novel sustainable catalytic material was prepared from biowaste (chitosan) in combination with an earth-abundant cobalt salt. The heterogeneous catalyst was fully characterized by transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy measurements, and successfully applied to hydrodehalogenation of alkyl and (hetero)aryl halides with broad scope (>40 examples) and excellent chemoselectivity using molecular hydrogen as a reductant. The general usefulness of this method is demonstrated by successful detoxification of non-degradable pesticides and fire retardants. Moreover, the potential of the catalyst as a deprotection tool is demonstrated in a multistep synthesis of (±)-peronatin B (alkaloid).
- Sahoo, Basudev,Surkus, Annette-Enrica,Pohl, Marga-Martina,Radnik, J?rg,Schneider, Matthias,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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supporting information
p. 11242 - 11247
(2017/09/02)
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- Selective Reductive Removal of Ester and Amide Groups from Arenes and Heteroarenes through Nickel-Catalyzed C?O and C?N Bond Activation
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An inexpensive nickel(II) catalyst and a hydrosilane were used for the efficient reductive defunctionalization of aryl and heteroaryl esters through a decarbonylative pathway. This versatile method could be used for the removal of ester and amide functional groups from various organic molecules. Moreover, a scale-up experiment and a synthetic application based on the use of a removable carboxylic acid directing group highlight the usefulness of this reaction.
- Yue, Huifeng,Guo, Lin,Lee, Shao-Chi,Liu, Xiangqian,Rueping, Magnus
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supporting information
p. 3972 - 3976
(2017/03/27)
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- Effect of the nature of sulfur compounds on their reactivity in the oxidative desulfurization of hydrocarbon fuels with oxygen over a modified CuZnAlO catalyst
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The reactivity of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT), which are the representatives of the main classes of sulfur compounds that are the constituents of diesel fractions, was studied in the course of their oxidative desulfurization with oxygen on a CuO/ZnO/Al2O3 catalyst modified with boron and molybdenum additives. At T ≥ 375°C, the reactivity increased in the order thiophene 2 from hydrocarbon fuel, which was simulated by a solution of 4,6-DMDBT in toluene, was 80%. Under the assumption of a first order reaction with respect to sulfur compound and oxygen, the apparent activation energies of the test processes were calculated. An attempt was made to reveal the role of the adsorption of sulfur compounds in the overall process of oxidative desulfurization with the use of X-ray diffraction analysis, X-ray photoelectron spectroscopy, and differential thermal and thermogravimetric analysis with the massspectrometric monitoring of gas phase composition.
- Yashnik,Salnikov,Kerzhentsev,Saraev,Kaichev,Khitsova,Ismagilov,Yamin,Koseoglu
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- Palladium Nanoparticles Supported on Fibrous Silica (KCC-1-PEI/Pd): A Sustainable Nanocatalyst for Decarbonylation Reactions
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A practical and convenient decarbonylation of a variety of aromatic, heteroaromatic, and alkenyl aldehydes by using palladium nanoparticles supported on novel, fibrous nanosilica, named KCC-1-PEI/Pd, has been developed. Complete conversion of aldehyde functionalities into deformylated products was achieved in all cases and in nearly all cycles tested by reusing the catalyst systems. This method eliminates further purification of products after their isolation. Syntheses of at least three different deformylated products have been shown in sequence with the same catalyst system, which neither requires use of any additives, such as oxidants and bases, nor CO scavengers.
- Kundu, Pintu K.,Dhiman, Mahak,Modak, Atanu,Chowdhury, Arindam,Polshettiwar, Vivek,Maiti, Debabrata
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p. 1142 - 1146
(2016/11/23)
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- A Pincer Ruthenium Complex for Regioselective C-H Silylation of Heteroarenes
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A pincer Ru(II) catalyst for the highly efficient undirected silylation of O- and S-heteroarenes with (TMSO)2MeSiH and Et3SiH is described, producing heteroarylsilanes with exclusive C2-regioselectivity, good functional-group tolerance, and high turnover numbers (up to 1960). The synthetic utility of the silylated products is demonstrated by Pd-catalyzed Hiyama-Denmark cross-coupling under mild conditions. One-pot, two-step silylation and coupling procedures have been also developed.
- Fang, Huaquan,Guo, Le,Zhang, Yuxuan,Yao, Wubing,Huang, Zheng
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supporting information
p. 5624 - 5627
(2016/11/17)
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- Enhancement of hydrocarbon production and catalyst stability during catalytic conversion of biomass pyrolysis-derived compounds over hierarchical HZSM-5
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In order to promote hydrocarbon production and catalyst stability in catalytic fast pyrolysis (CFP) of biomass, HZSM-5 catalysts were treated with alkali solutions to introduce mesopores into the microporous system. Parent and hierarchical catalysts were tested in catalytic conversion of furan as an important intermediate from biomass fast pyrolysis (BFP). Controlled desilication with mole concentration of NaOH of 0.3 M resulted in sheet-like mesopores on the external sphere, enhancing mass transfer in the catalyst, and it specifically promoted the carbon yield of hydrocarbons by 21.6%. Though the coke content on these HZSM-5-0.3M catalysts increased gradually by 11.6%, the tolerance toward deactivation by coke deposition was improved. Cyclic tests of catalysis-regeneration process over hierarchical HZSM-5-0.3M over 20 cycles revealed that it can withstand long-running with a stable yield of hydrocarbons being achieved. Thus, hierarchical HZSM-5 is a suitable catalyst for CFP of biomass and its derivatives to hydrocarbons by this simple synthetic process.
- Shao,Zhang,Shen,Xiao
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p. 44313 - 44320
(2016/06/09)
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- Effects of water and alcohols on the polymerization of furan during its acid-catalyzed conversion into benzofuran
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Furan, an important product from catalytic pyrolysis of biomass, has the potential to be further converted into value-added chemicals or biofuels. This study investigated the conversion of furan into benzofuran over a Br?nsted acid catalyst (Amberlyst 70) at 140-190°C in various solvents. With water as the solvent, furan could barely make its way to benzofuran as its polymerization dominated. With methanol as the solvent, the polymerization of furan was suppressed and benzofuran formation was enhanced substantially. This is because in methanol, the reactive intermediates (i.e., aldehydes) were stabilized and their involvement in polymerization reactions was suppressed. Other alcohols showed similar effects on suppressing polymerization. In dimethyl sulfoxide (DMSO), the polymerization of furan was also effectively suppressed. However, furan was not converted to benzofuran but to levulinic acid via a distinct reaction route.
- Hu, Xun,Jiang, Shengjuan,Kadarwati, Sri,Dong, Dehua,Li, Chun-Zhu
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p. 40489 - 40501
(2016/05/24)
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- Total synthesis of the 2-arylbenzo[b]furan-containing natural products from Artocarpus
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In this study, 2-arylbenzo[b]furan-containing derivatives moracin C (1) and moracin M (4), the natural products from Artocarpus, have been synthesized in highest overall yield to date (1, 7 steps with an overall yield of 41.9%; 4, 6 steps with an overall yield of 56.3%), and we also report the first total synthesis of artoindonesianin B-1 (2), another member of this family, in the same route (8 steps with an overall yield of 11.3%). This discovery provides a concise route for preparing enough amounts of 1, 2, and 4 as well as 2-arylbenzo[b]furan-containing natural product-like analogs (71-74) to explore the biological potential.
- Wu, Deyan,Mei, Hanbing,Tan, Ping,Lu, Weiqiang,Zhu, Jin,Wang, Wei,Huang, Jin,Li, Jian
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supporting information
p. 4383 - 4387
(2015/06/22)
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- Zeolite-catalyzed synthesis of 2,3-unsubstituted benzo[b]furans via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals
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An efficient and environmentally benign heterogeneous catalytic process for the synthesis of 2,3-unsubstituted benzo[b]furans has been established via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals. By utilizing tin-exchanged H-β zeolite (Sn-β) as catalyst, a wide range of functionalized 2,3-unsubstituted benzo[b]furans could be prepared in good to excellent yields. The Sn-β zeolite catalyst also exhibited excellent shape selectivity on the cyclization of meta-substituted 2-aryloxyacetaldehyde acetals, and 6-substituted isomers were preferably formed up to 97% regio-selectivity. Moreover, Sn-β zeolite could be easily recovered and reused without any noticeable activity loss.
- Sun, Nan,Huang, Peng,Wang, Yifan,Mo, Weimin,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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p. 4835 - 4841
(2015/07/27)
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- Palladium-Catalyzed Aerobic Oxidative Dehydrogenation of Cyclohexenes to Substituted Arene Derivatives
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A palladium(II) catalyst system has been identified for aerobic dehydrogenation of substituted cyclohexenes to the corresponding arene derivatives. Use of sodium anthraquinone-2-sulfonate (AMS) as a cocatalyst enhances the product yields. A wide range of functional groups are tolerated in the reactions, and the scope and limitations of the method are described. The catalytic dehydrogenation of cyclohexenes is showcased in an efficient route to a phthalimide-based TRPA1 activity modulator.
- Iosub, Andrei V.,Stahl, Shannon S.
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p. 3454 - 3457
(2015/03/30)
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- Iridium Pincer-Catalyzed Dehydrogenation of Ethers Featuring Ethylene as the Hydrogen Acceptor
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We describe efficient methods to dehydrogenate ethers by using iridium pincer complexes (iPr4Anthraphos)-Ir(H)(Cl), 4, iPr4PC(sp3)P-Ir(H)(Cl), 5, and (iPr4PCP)-Ir(H)(Cl), 6. At 120°C, cyclic ethers were dehydrogenated with tert-butylethylene as the hydrogen acceptor with high turnover numbers (over 400 in many cases). Acyclic ethers such as diethyl ether can also be dehydrogenated catalytically with TONs up to 90. The efficient dehydrogenation of cyclic and acyclic ethers using ethylene as a more practical hydrogen acceptor has been demonstrated for the first time. (Figure Presented)
- Lyons, Thomas W.,Bzier, David,Brookhart, Maurice
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p. 4058 - 4062
(2015/09/01)
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- Acetylenes from Aldehydes. Preparation of Ethynylphenols and Phenylacetylenes by Flash Vacuum Pyrolysis of Isoxazolones
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The flash vacuum pyrolysis method of synthesis of acetylenes from aldehydes via isoxazolones is a convenient method for the preparation of a variety of derivatives, including kinetically unstable, sensitive compounds such as the ethynylphenols.
- Wentrup, Curt,Wiedenstritt, Maria,Winter, Hans-Wilhelm
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p. 1233 - 1236
(2015/08/18)
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- Practical, modular, and general synthesis of 3-coumaranones through gold-catalyzed intermolecular alkyne oxidation strategy
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A gold-catalyzed intermolecular alkyne oxidation for the preparation of 3-coumaranones has been developed. Using 8-isopropylquinoline N-oxides as oxidants, the reactions of o-ethynylanisoles afford versatile 3-coumaranones in moderate to good isolated yields. The synthetic utility of this chemistry is also indicated by the synthesis of the natural product sulfuretin.
- Shu, Chao,Liu, Rongfu,Liu, Shuang,Li, Jian-Qiao,Yu, Yong-Fei,He, Qiao,Lu, Xin,Ye, Long-Wu
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- NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles
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The pair NaBH4-TMEDA as hydride source and a palladium catalyst in THF prove to be an efficient system for the hydrodehalogenation of halogenated heterocycles with one or more heteroatoms. In general, Pd(OAc) 2-PPh3 rapidly hydrodehalogenates reactive halo-heterocycles such as bromo-pyridines, -quinolines, -thiophenes, -indoles, -imidazoles, etc., at room temperature in very good yields, whereas in most cases PdCl2(dppf) reduces less reactive halides such as chloro-pyridines, -quinolines, -pyrimidines and bromo-indoles, -benzofurans, etc. Moreover, PdCl2(tbpf) shows to be even more active removing the 2- and 5-chlorine from both thiophene and thiazole rings. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene and nitrile substituents. Moreover, with a proper selection of the catalyst it is also possible to obtain a good control in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Figus, Susanna
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p. 191 - 209
(2014/07/21)
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- Selective catalytic transfer dehydrogenation of alkanes and heterocycles by an iridium pincer complex
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Catalytic alkane dehydrogenation is a reaction with tremendous potential for application. We describe a highly active PSCOP-pincer iridium catalyst for transfer dehydrogenation of cyclic and linear alkanes. The dehydrogenation of linear alkanes occurs under relatively mild conditions with high regioselectivity for a-olefin formation. In addition, the catalyst system is very effective in the dehydrogenation of heterocycles to form heteroarenes and olefinic products.
- Yao, Wubing,Zhang, Yuxuan,Jia, Xiangqing,Huang, Zheng
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supporting information
p. 1390 - 1394
(2014/03/21)
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- Preparation of functional styrenes from biosourced carboxylic acids by copper catalyzed decarboxylation in PEG
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A general protocol for the copper-catalyzed decarboxylation of α,β-unsaturated carboxylic acids in PEG, particularly of biosourced cinnamic acid analogues, is reported. Moderate to high isolated yields (31-96%) towards the styrene derivatives were obtained. For the first time, decarboxylation of α-amino acids to the corresponding amines was successfully performed with good to high yields and extended to the decarboxylation of a few condensed heterocyclic compounds. Both the use of PEG as a green solvent and direct separation of the pure product of the reaction by distillation permitted the reuse of the solvent and the Cu-based catalytic system over several cycles without deactivation. This was extended to the synthesis of 4-vinylguaiacol on the laboratory scale in an average 92% yield. This journal is the Partner Organisations 2014.
- Cadot, Stephane,Rameau, Nelly,Mangematin, Stephane,Pinel, Catherine,Djakovitch, Laurent
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supporting information
p. 3089 - 3097
(2014/06/10)
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- Protodecarboxylation of carboxylic acids over heterogeneous silver catalysts
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A heterogeneous supported Ag catalyst for the protodecarboxylation of aromatic carboxylic acids has been developed. Control of the metal particle size proved extremely important. The highest activity was achieved with a silver loading of 10 wt%, which had relatively big metal crystallites of 40 nm. It is inferred that the adsorption of the aromatic moiety requires terrace sites rather than edges or corners at the metal nanoparticle. The amphoteric support, γ-Al2O3, gave the most active catalysts. Oxygen coverage of the surface is essential for catalytic activity. A mechanism has been proposed with the critical steps (1) formation of a benzoyl anion by reaction with a base in the reaction medium, (2) binding of the anionic species at the Ag+ surface sites with (3) extrusion of CO2 and (4) proton transfer from another molecule of carboxylic acid, followed by desorption of the decarboxylated species and binding of the benzoate to the active site to complete the catalytic cycle. With 2-nitrobenzoic acid as substrate, the catalyst had a turnover frequency (TOF) of 216 h-1. The catalyst showed good activity for benzoic acid with nitro, methoxy and halogen substituents at the ortho-position as well as for heteroaromatic carboxylic acids. The Royal Society of Chemistry.
- Toy, Xiu Yi,Roslan, Irwan Iskandar Bin,Chuah, Gaik Khuan,Jaenicke, Stephan
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p. 516 - 523
(2014/02/14)
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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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- Copper-catalyzed decarboxylative intramolecular C-O coupling: Synthesis of 2-arylbenzofuran from 3-arylcoumarin
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A copper-catalyzed decarboxylative intramolecular C-O coupling reaction was established. Under aerobic conditions in the presence of cupric chloride/1,10-phenathroline, a variety of 2-arylbenzofurans were prepared from 3-arylcoumarins in one-pot with yields from 26% to 84%. The Royal Society of Chemistry 2014.
- Pu, Wen-Chen,Mu, Guan-Min,Zhang, Guo-Lin,Wang, Chun
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p. 903 - 906
(2014/01/06)
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- Gold(I)-catalyzed protodecarboxylation of (Hetero)aromatic carboxylic acids
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Readily available, inexpensive and easy to handle, carboxylic acids have been shown to be very effective, greener coupling partners compared to costly organometallic reagents for the formation of C-C bonds. The use of well-defined gold complexes furnished 3 in slightly better yield with butyric acid, and in quantitative yield with adamantane-1-carboxylic acid. All reactions reached completion within 16 h. As with silver systems, this reactivity trend highlights, as previously observed, the benefits of potential coordinating groups in the ortho position to the gold binding site, which possibly facilitate the decarboxylation step. Additional reaction time and increased temperatures were necessary to afford the gold aryl products in satisfactory yields. Yet, some substrates such as 2-nitrobenzoic acids reacted poorly and could only be transformed in 50% yield.
- Dupuy, Stéphanie,Nolan, Steven P.
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supporting information
p. 14034 - 14038
(2013/11/19)
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- Acceptorless dehydrogenation of C-C single bonds adjacent to functional groups by metal-ligand cooperation
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Unprecedented direct acceptorless dehydrogenation of C-C single bonds adjacent to functional groups to form α,β-unsaturated compounds has been accomplished by using a new class of group 9 metal complexes. Metal-ligand cooperation operated by the hydroxycyclopentadienyl ligand was proposed to play a major role in the catalytic transformation.
- Kusumoto, Shuhei,Akiyama, Midori,Nozaki, Kyoko
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supporting information
p. 18726 - 18729
(2014/01/06)
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- Aerobic one-step oxidation of benzene to phenol on copper exchanged HZSM5 zeolites: A mechanistic study
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Various Cu/HZSM5-zeolites were prepared and their catalytic properties were investigated by product analysis via GC/MS chromatography in order to trace down the mechanism of the gas phase one-step oxidation of benzene to phenol with molecular oxygen. Comparison of Cu free and Cu containing zeolites showed that the activation of O2 takes place at copper centers of the zeolite and high copper loadings lead to high yields of deep oxidation products (CO, CO2). No phenol was formed in the absence of Br?nsted acid sites, i.e. on Cu/KZSM5, revealing the bifunctionality of the Cu/HZSM5 zeolite. The yields of the various oxidation products and thus the selectivity toward phenol can be influenced by variation of the relative O2 concentration in the reaction mixture, indicating the possibility of a stoichiometric use of O2. The role of the superoxide radical ion O2- as a reactive intermediate is discussed and a radical ionic reaction mechanism is suggested.
- Tabler, Andreas,H?usser, Anette,Roduner, Emil
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p. 139 - 145
(2013/09/23)
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- Production of targeted aromatics by using Diels-Alder classes of reactions with furans and olefins over ZSM-5
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In this paper we study the co-feeding of olefins (ethylene and propylene) with a series of furanic compounds (furan, 2-methylfuran, furfural, and furfuryl alcohol) over ZSM-5 catalyst in a continuous flow fixed-bed reactor at a temperature range of 450-600 °C. We show the importance of Diels-Alder cycloaddition reactions when olefins are co-fed with furanics over ZSM-5. Co-feeding propylene with furan (C4 diene) increased the toluene aromatic selectivity from 22% to 59%. Similarly, co-feeding propylene with 2-methylfuran (C5 diene) increased the xylenes aromatic selectivity from 9% to 27%. Co-feeding of ethylene with furans did not change the aromatics selectivity. The increase of toluene selectivity was also observed in the co-feeding of propylene with furfural and fufuryl alcohol. Furfural and furfuryl alcohol both underwent decarbonylation reactions to produce CO and furan. The reaction conditions that maximize Diels-Alder products were a propylene to 2MF molar ratio of 1 at 450 °C. Increasing the temperature to 600 °C increased the selectivity of benzene, toluene and CO. Decreasing the temperature to 300 °C increased the coke yield and decreased the xylene yield. The xylene selectivity went through a maximum at a propylene to 2-methylfuran molar ratio of 1:1.
- Cheng, Yu-Ting,Huber, George W.
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supporting information
p. 3114 - 3125
(2013/01/15)
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- Dehydrogenative aromatization of saturated aromatic compounds by graphite oxide and molecular sieves
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Graphite oxide (GO) has attracted much attention of material and catalysis chemists recently. Here we describe a combination of GO and molecular sieves for the dehydrogenative aromatization. GO prepared through improved Hummers method showed high oxidative activity in this reaction. Partially or fully saturated aromatic compounds were converted to their corresponding dehydrogenated aromatic products with fair to excellent conversions and selectivities. As both GO and molecular sieves are easily available, cheap, lowly toxic and have good tolerance to various functional groups, this reaction provides a facile approach toward aromatic compounds from their saturated precursors. Copyright
- Zhang, Xuan,Xu, Liang,Wang, Xitao,Ma, Ning,Sun, Feifei
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experimental part
p. 1525 - 1530
(2012/09/08)
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- Room-temperature hydrodehalogenation of halogenated heteropentalenes with one or two heteroatoms
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The pair NaBH4-TMEDA as a hydride source and catalytic PdCl 2(dppf) in THF prove to be an efficient system for the hydrodehalogenation of bromo(chloro)-heteropentalenes with one or two heteroatoms, while Pd(OAc)2/PPh3 is able to reduce reactive haloheteropentalenes, and PdCl2(tbpf) allows the removal of the 2-chlorine from a thiophene ring. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene, and nitrile substituents and also showing good efficiency in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Baldino, Salvatore,Ruiu, Andrea
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p. 9921 - 9925,5
(2012/12/12)
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