- An experimental and computational evaluation of the energetics of the isomeric methoxyphenylcarbenes generated in carbon atom reactions
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Carbon atom reactions with anisole and methoxybenzaldehyde demonstrate the reversible ring expansion of methoxyphenylcarbene (CH3O-C6H4-C-H). Trapping with HBF4 yields the methoxytropylium ion, analogous to the
- Geise, C. Michael,Hadad, Christopher M.,Zheng, Fengmei,Shevlin, Philip B.
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- Reaction of triaryloxonium salts with bases via dehydroarenes
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Tri-p-tolyloxonium tetrafluoroborate reacts with NaOH in water yielding a mixture of m- and p-cresls (1:1) use of MeOH as solvent rsults in a mixture of m- and p-crescols (1:1), use of MeOH as solvent results in a mixture of m- and p-methoxytoluenes (1:5:1). This result proves this reaction to proceed via 3,4-dehydrotoluene.
- Tolstaya, Tatiana P.,Tsariev, Dmitry A.,Luzikov, Yury N.
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- Design and Synthesis of Natural Product Inspired Libraries Based on the Three-Dimensional (3D) Cedrane Scaffold: Toward the Exploration of 3D Biological Space
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A chemoinformatic method was developed to extract nonflat scaffolds embedded in natural products within the Dictionary of Natural Products (DNP). The cedrane scaffold was then chosen as an example of a nonflat scaffold that directs substituents in three-dimensional (3D) space. A cedrane scaffold that has three orthogonal handles to allow generation of 1D, 2D, and 3D libraries was synthesized on a large scale. These libraries would cover more than 50% of the natural diversity of natural products with an embedded cedrane scaffold. Synthesis of three focused natural product-like libraries based on the 3D cedrane scaffold was achieved. A phenotypic assay was used to test the biological profile of synthesized compounds against normal and Parkinson's patient-derived cells. The cytological profiles of the synthesized analogues based on the cedrane scaffold revealed that this 3D scaffold, prevalidated by nature, can interact with biological systems as it displayed various effects against normal and Parkinson's patient-derived cell lines.
- Tajabadi, Fatemeh Mazraati,Pouwer, Rebecca H.,Liu, Miaomiao,Dashti, Yousef,Campitelli, Marc R.,Murtaza, Mariyam,Mellick, George D.,Wood, Stephen A.,Jenkins, Ian D.,Quinn, Ronald J.
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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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- Competitive homolytic and heterolytic dediazoniation mechanisms: Rate constants and product distribution of methoxy-, hydroxy-, and hydro-dediazoniation of 3- and 4-methylbenzenediazonium salts in acidic MeOH/H2O mixtures
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The rates and product distribution for methoxy-, hydroxy- and hydro-dediazoniation and the rate constants for disappearance of 3- and 4-methylbenzenediazonium tetrafluoroborate in acidic MeOH/H2O mixtures, in the presence and absence of electrolytes like HCl, NaCl, and CuCl2, are reported. Data were obtained by using a combination of VIS-UV and HPLC techniques. The kinetics and product distributions are completely consistent with competitive homolytic and heterolytic mechanisms, the heterolytic one being predominant at any solvent composition. Heterolytic data are in agreement with the predictions of a DN+AN mechanism; that is, rate determining formation of an aryl cation that reacts immediately with available nucleophiles. Selectivity values, determined from product yields, are low and independent of solvent composition. Product formation is discussed in terms of a preassociation step between aryl cations and the nucleophile, which does not account for much of the trapping, and a nucleophilic attack on a `free' arenediazonium cation. Activation parameters were also determined at 99.5% MeOH: enthalpies of activation are high and entropies of activation are positive, and they are similar to those reported for pure water.
- Pazo-Llorente, Roman,Gonzalez-Romero, Elisa,Bravo-Diaz, Carlos
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- Steric Influences on Spin-Lattice Relaxation Rates of Methyl Protons in Substituted Aromatic Molecules
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Proton spin-lattice relaxation rates (R1 values) have been measured at 400 MHz for a series of substituted aromatic compounds to determine the steric effects of ortho substituents on the R1 values of the methyl groups.These values have been interpreted on the basis of differences in the barriers to methyl group rotation caused by the substituent, resulting in changes in the contributions from the dipolar and the spin-rotation relaxation mechanisms.A significant dynamic range of methyl R1 values has been observed, showing that these measurements are sensitive to the steric environment.
- Chazin, Walter J.,Colebrook, Lawrence D.
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- Mechanistic Aspects of Hydrodeoxygenation of p-Methylguaiacol over Rh/Silica and Pt/Silica
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The mechanism of p-methylguaiacol (PMG) hydrodeoxygenation (HDO) has been examined over two Rh/silica catalysts and a Pt/silica catalyst at 300 °C and 4 barg hydrogen. Sequential conversion of PMG to 4-methylcatechol is followed by m- and p-cresol formation and finally toluene production, although direct conversion of PMG to p-cresol is favored over a commercial Rh/silica catalyst. Dehydroxylation and hydrogenation are shown to occur over metal functions, while demethylation and demethoxylation are favored over the fumed silica support. A mechanistic pathway for HDO of PMG is proposed.
- Bouxin, Florent P.,Zhang, Xingguang,Kings, Iain N.,Lee, Adam F.,Simmons, Mark J. H.,Wilson, Karen,Jackson, S. David
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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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- The reduction of aromatic aldehydes to hydrocarbons with borohydride exchange resin (BER)-nickel acetate in methanol
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Aromatic aldehydes were reduced to the corresponding hydrocarbons with borohydride exchange resin (BER)-nickel acetate in methanol in excellent yields.
- Bandgar,Kshirsagar,Wadgaonkar
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- Stepwise Reduction of Acetals to the Corresponding Hydrocarbons. A Mild and Effective Transformation via Carbinyl Bromides
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Stepwise reduction of two alkoxy groups in acetal was effected by the action of triethylsilane along with acetyl bromide and SnBr2 and then of tributyltinhydride (or lithium aluminium hydride) providing methyl or methylene compounds in good yields under very mild conditions.
- Oriyama, Takeshi,Ichimura, Yuichi,Koga, Gen
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- Study of gas phase m-cresol alkylation with methanol on solid acid catalysts
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The gas-phase alkylation of m-cresol with methanol was studied at 523 K on Al-MCM-41 and zeolites ZnY, HBEA, HZSM5 and HMCM22. The acidity was determined by ammonia TPD and FTIR of adsorbed pyridine. On acid sites of moderate strength (Al-MCM-41), initially the O-alkylation rate was higher than the C-alkylation rate. In contrast, formation of dimethylphenols by C-alkylation was highly favored on ZnY and HMCM22 which have both strong acidity although different nature; Lewis (ZnY) and Bronsted and Lewis (HMCM22). High selectivity of 2,5-DMP was observed on HZSM5, probably due to diffusional constraint. All catalysts, except Al-MCM-41, showed deactivation by coke formation.
- Acevedo,Bedogni,Okulik,Padr
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- Simple and efficient one-step conversion of benzonitrile into methylarene under mild conditions
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A very simple and efficient method has been developed for the synthesis of various methylarenes from the corresponding benzonitriles under mild conditions. The protocol uses Pearlmans catalyst to achieve the transformation under an atmosphere of gaseous hydrogen and proceeds smoothly in many common solvents. A series of methylarenes were thus obtained in high yields and purities. Georg Thieme Verlag Stuttgart - New York.
- Ouellet, étienne,Poirier, Donald
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- Rate and Mechanism for the Reaction of the Nitrate Radical with Aromatic and Alkylaromatic Compounds in Acetonitrile
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The results of a laser photolysis study indicate that an electron transfer process occurs in the reaction of the nitrate radical with aromatic and alkylaromatic compounds.
- Baciocchi, E.,Giacco, T. Del,Murgia, S. M.,Sebastiani, G. V.
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- Carbon-carbon cross-coupling reactions catalyzed by a two-coordinate nickel(II)-Bis(amido) complex via observable NiI, NiII, and NiIII intermediates
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Recently, the development of more sustainable catalytic systems based on abundant first-row metals, especially nickel, for cross-coupling reactions has attracted significant interest. One of the key intermediates invoked in these reactions is a NiIII-alkyl species, but no such species that is part of a competent catalytic cycle has yet been isolated. Herein, we report a carbon-carbon cross-coupling system based on a two-coordinate Ni II-bis(amido) complex in which a NiIII-alkyl species can be isolated and fully characterized. This study details compelling experimental evidence of the role played by this NiIII-alkyl species as well as those of other key NiI and NiII intermediates. The catalytic cycle described herein is also one of the first examples of a two-coordinate complex that competently catalyzes an organic transformation, potentially leading to a new class of catalysts based on the unique ability of first-row transition metals to accommodate two-coordinate complexes.
- Lipschutz, Michael I.,Tilley, T. Don
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- Transition metal mediated asymmetric synthesis. X. Homochiral ?-complexes with planar chirality: synthetic equivalents of chiral cyclohexadiene dications
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Homochiral 6-methoxy-substituted dienyltricarbonyliron complexes have been obtained from 1-methylcyclohexa-1,3-diene-5,6-diol (available via microbial oxidation of toluene) by complexation and removal of an allylic substituent with acids or with triphenylcarbenium tetrfluoroborate.A variety of optically active tricarbonyliron complexes have been produced from these compounds.The optical purity of the product and the stereochemistry of the complexation reaction have been determined.The high efficiency of chirality transfer during complexation of 5,6-dimethoxy-substituted dienes makes this method suitable as a general route to resolved organoiron complexes.
- Howard, Philip, W.,Stephenson, G. Richard,Taylor, Stephen C.
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- The balance of acid, basic and redox sites in Mg/Me-mixed oxides: The effect on catalytic performance in the gas-phase alkylation of m-cresol with methanol
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The reactivity of Mg/Me-mixed oxides (Me = Fe, Cr, Al) in m-cresol gas-phase methylation with methanol was studied, with the aim of finding relationships between catalytic performance and surface/bulk features. All systems exhibit similar surface properties (basically due to the presence of basic and Lewis-type acid sites), but the presence of extra cations in the MgO framework affects greatly the products obtained in the mentioned catalytic reaction, depending on the possible co-presence of redox capacity. In particular, (i) the Mg/Al/O system, characterized by no redox capacity, shows catalytic behaviour quite similar to that of conventional Bronsted-type acid catalysts, though with the advantage of exhibiting almost no deactivation during use (a rather common problem for acid catalysts activating methanol for phenol attack); (ii) the Mg/Cr/O catalyst shows a reactivity typical of a basic catalyst, with high chemo- and regio-selectivity and the favoured formation of 2,5-dimethylphenol; (iii) the Mg/Fe/O system presents a catalytic behaviour closer to that of Mg/Cr/O, if referred to the distribution of phenolic products, but it also exhibits a better activity in methanol dehydrogenation to formaldehyde (that is the true electrophilic reactant for m-cresol ring methylation), and in the decomposition of formaldehyde into light compounds. This behaviour causes a poor selectivity to dimethylphenols with respect to converted methanol, whereas the selectivity with respect to converted m-cresol is not different from that shown by Mg/Cr/O system.
- Crocella,Cerrato,Magnacca,Morterra,Cavani,Cocchi,Passeri,Scagliarini,Flego,Perego
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- Phosphoric acid-modified commercial kieselguhr supported palladium nanoparticles as efficient catalysts for low-temperature hydrodeoxygenation of lignin derivatives in water
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Efficient production of high value-added chemicals and biofuels via low-temperature chemoselective HDO of lignin derivatives in water is still a challenge. Here, we construct a low-cost, active and stable Pd/PCE catalyst using phosphoric acid-modified commercial Celite (PCE) as the support, and this catalyst exhibits excellent activity in low-temperature HDO of vanillin as well as other lignin derivatives in water. The superior catalytic performance is due to the presence of P species on the surface of Pd/PCE, accelerating the selective conversion of the intermediate into the final product. Detailed experimental and mechanistic studies reveal that the rapid conversion of the intermediate to the final product proceeds via a free-radical process in an interfacial microenvironment created by intimate interacting between the P species and Pd NPs. The insights of this work provide a new low-cost catalytic system for efficient production of valuable chemicals and future biofuels from lignin derivatives. This journal is
- Cui, Yuntong,Liu, Zhaohui,Ran, Jiansu,Wang, Jianjian,Yangcheng, Ruixue
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p. 1570 - 1577
(2022/03/14)
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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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- Investigation on the stoichiometry of carbon dioxide in isotope-exchange reactions with phenylacetic acids
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The functionalization of carbon dioxide (CO 2) as a C1 building block has attracted enormous attention. Carboxylation reactions, in particular, are of major interest for applications in isotope labeling. Due to the inexpensive nature of CO 2, information about its stoichiometric use is generally unavailable in the literature. Because of the rarity and limited availability of CO 2isotopomers, this parameter is of concern for applications in carbon-isotope labeling. We investigated the effects of the stoichiometry of labeled CO 2on carbon isotope exchange of phenyl? acetic acids. Both thermal and photocatalytic procedures were studied, providing insight into product outcome and isotope incorporation. Preliminary results on isotope-dilution effects of carbonate bases in photocatalytic carboxylation reactions have also been obtained.
- Audisio, Davide,Goudet, Amelie,Sallustrau, Antoine,Talbot, Alex,Taran, Frederic
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supporting information
(2021/08/10)
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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 0059-0062
(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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- 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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- Photocatalytic carbanion generation-benzylation of aliphatic aldehydes to secondary alcohols
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We present a redox-neutral method for the photocatalytic generation of carbanions. Benzylic carboxylates are photooxidized by single electron transfer; immediate CO2 extrusion and reduction of the in situ formed radical yields a carbanion capable of reacting with aliphatic aldehydes as electrophiles giving the Grignard analogous reaction product.
- Donabauer, Karsten,Maity, Mitasree,Berger, Anna Lucia,Huff, Gregory S.,Crespi, Stefano,K?nig, Burkhard
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p. 5162 - 5166
(2019/06/05)
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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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- Synthesis method of musk ambrette
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The invention provides a synthesis method of musk ambrette. The synthesis method comprises the following steps of (1) mixing m-cresol, a phase transfer catalyst, a water solution of strong alkali and chloromethane, reacting and then generating m-methoxytoluene; and (2) mixing a catalyst and a solvent, dropwise adding the m-methoxytoluene for 0.5-2h, dropwise adding tert-butyl chloride for 0.5-2h, then reacting for 3-5h and generating tertiary butyl methoxyl methylbenzene. According to the synthesis method of the musk ambrette, methylanisole (replenishing sodium hydroxide to an aqueous alkaline solution, filtering out sodium chloride and then recycling) is synthesized by m-cresol and chloromethane in the water solution of strong alkali, so that compared with a traditional production technology, the yield is improved, treatment of waste water is reduced, manpower resource is saved, energy consumption is reduced and the synthesis method is safer and more reliable.
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Paragraph 0029; 0034; 0037; 0039
(2017/12/29)
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- The selective hydrogenolysis of C-O bonds in lignin model compounds by Pd-Ni bimetallic nanoparticles in ionic liquids
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β-O-4 and α-O-4 linkages can be selectively cleaved by Pd-Ni bimetallic nanoparticles in ionic liquids using hydrogen gas as the hydrogen donor under ambient pressure and neutral conditions. No hydrogenation of the benzene ring takes place in the catalytic system. An obvious improvement in activity is found compared with single nickel and palladium catalysts based on the results of experiments and characterization. After the reaction, the catalytic system still remains in the reactor by simple extraction, which can be reused without further treatment.
- Sun, Kang-Kang,Lu, Guo-Ping,Zhang, Jia-Wei,Cai, Chun
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p. 11884 - 11889
(2017/09/18)
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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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- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
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The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
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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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- A Mild and Selective Method for the Catalytic Hydrodeoxygenation of Cyanurate Activated Phenols in Multiphasic Continuous Flow
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A low-energy, high-selectivity approach to the catalytic hydrodeoxygenation of phenols is reported using batch or continuous flow methods to react 3 equiv of phenol with cyanuric chloride then hydrogenolyzing the triarylcyanurate intermediate to give 3 equiv of deoxo aromatic. The use of cyanuric chloride compares favorably with existing activation methods, showing improved scalability, atom efficiency, and economics. The scope of both the activation and hydrogenolysis stages are explored using lignin-related phenols. Initial development has identified that continuous stir tank reactors (CSTRs) enable a multiphasic process for converting guaiacol to anisole and at steady state overcome the catalyst deactivation issues observed in batch, seemingly caused by the cyanurate byproduct. Green chemistry aspects and the potential for industrial adoption are discussed.
- Zhao, Yuhan,King, Georgina,Kwan, Maria H.T.,Blacker, A. John
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supporting information
p. 2012 - 2018
(2017/02/10)
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- Acid-catalysed carboxymethylation, methylation and dehydration of alcohols and phenols with dimethyl carbonate under mild conditions
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Dimethyl carbonate (DMC) chemistry has been extended to include acid-catalysed reactions of different aliphatic alcohols and phenols. For the first time, p-toluenesulfonic acid (PTSA), H2SO4, AlCl3 and FeCl3 have been shown to aid carboxymethylation for primary aliphatic alcohols at catalytic loadings with quantitative conversion and selectivity. For carboxymethylation of secondary alcohols, stoichiometric PTSA and catalytic AlCl3 both gave quantitative conversion and selectivity. Stoichiometric FeCl3 and H2SO4 promoted dehydration of linear aliphatic alcohols. Additionally FeCl3 catalysed methylation of cyclohexanol, whilst AlCl3 resulted in methylation of phenolic compounds. This research expands the range of potential application for DMC in green chemistry.
- Jin, Saimeng,Hunt, Andrew J.,Clark, James H.,McElroy, Con Robert
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supporting information
p. 5839 - 5844
(2016/11/06)
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- Masked N-Heterocyclic Carbene-Catalyzed Alkylation of Phenols with Organic Carbonates
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An easily prepared masked N-heterocyclic carbene, 1,3-dimethylimidazolium-2-carboxylate (DMI-CO2), was investigated as a “green” and inexpensive organocatalyst for the alkylation of phenols. The process made use of various low-toxicity and renewable alkylating agents, such as dimethyl- and diethyl carbonate, in a focused microwave reactor. DMI-CO2 was found to be a very active catalyst and excellent yields of a range of aryl alkyl ethers were obtained under relatively benign conditions. The observed difference in the conversion behavior of phenol methylation, in the presence of either the carbene or 1,8-diazabicycloundec-7-ene (DBU) catalyst, was rationalized on the basis of mechanistic investigations. The primary mode of action for the N-heterocyclic carbene is nucleophilic catalysis. Activation of the dialkyl carbonate electrophile results in concomitant evolution of an organo-soluble alkoxide, which deprotonates the phenolic starting material. In contrast, DBU is initially protonated by the phenol and thus consumed. Subsequent regeneration and participation in nucleophilic catalysis only becomes significant after some phenolate alkylation occurs.
- Lui, Matthew Y.,Yuen, Alexander K. L.,Masters, Anthony F.,Maschmeyer, Thomas
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p. 2312 - 2316
(2016/10/24)
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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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- 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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- One-pot primary aminomethylation of aryl and heteroaryl halides with sodium phthalimidomethyltrifluoroborate
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A one-pot primary aminomethylation of aryl halides, triflates, mesylates, and tosylates via Suzuki-Miyaura cross-coupling reactions with sodium phthalimidomethyltrifluoroborate followed by deamidation with ethylenediamine is reported.
- Murai, Norio,Miyano, Masayuki,Yonaga, Masahiro,Tanaka, Keigo
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supporting information; experimental part
p. 2818 - 2821
(2012/07/17)
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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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- 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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- A practical synthesis of sarpogrelate hydrochloride and in vitro platelet aggregation inhibitory activities of its analogues
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A convenient approach for the preparation of sarpogrelate hydrochloride was developed. Two series of sarpogrelate hydrochloride analogues were designed and synthesized in order to improve their platelet aggregation inhibitory activities, biological tests suggested that these compounds have platelet aggregation inhibitory activities to some extent.
- Chen, Guo Hua,Wang, Sheng,Wu, Fei Hua
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scheme or table
p. 287 - 289
(2010/12/20)
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- Synthesis of novel structurally simplified estrogen analogues with electron-donating groups in ring A
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A library of 25 novel estrogen analogues were prepared in five to eight steps from mostly commercially available substituted anisoles via bromination, formylation, Corey-Fuchs reaction, elimination, and Sonogashira reaction. Georg Thieme Verlag Stuttgart.
- Tietze, Lutz F.,Vock, Carsten A.,Krimmelbein, Ilga K.,Nacke, Linda
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experimental part
p. 2040 - 2060
(2009/12/27)
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- Sequential ortho-lithiations; The sulfoxide group as a relay to enable meta-substitution
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Sulfoxides are known to be powerful directing groups for ortho-lithiation, even in competition with other directors. This has been utilised to introduce substituents meta- to a methoxy-group by sequential lithiation, reaction with Me tert-butylsulfinate,
- Flemming, Jonathan P.,Berry, Malcolm B.,Brown, John M.
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experimental part
p. 1215 - 1221
(2008/10/09)
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- Efficient method for the reduction of carbonyl compounds by triethylsilane catalyzed by PdCl2
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The versatility of the palladium(II) chloride and triethylsilane system has been tested in the reduction of aromatic carbonyl compounds. The reaction takes place under mild conditions. This facile and efficient method affords high yields for the reduction of aldehydes and ketones to the corresponding alkanes.
- Mirza-Aghayan, Maryam,Boukherroub, Rabah,Rahimifard, Mahshid
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scheme or table
p. 3567 - 3570
(2009/02/07)
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- A practical palladium catalyzed dehalogenation of aryl halides and α-haloketones
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A practical and high-yielding protocol for the dehalogenation of aromatic halides is presented. In the presence of palladium acetate, triphenylphosphine, and potassium carbonate, a number of highly functionalized aromatic halides as well as α-haloketones were dehalogenated with alcohols as hydrogen donors.
- Chen, Jingbo,Zhang, Yushun,Yang, Liquan,Zhang, Xiang,Liu, Jianping,Li, Liang,Zhang, Hongbin
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p. 4266 - 4270
(2007/10/03)
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- [1,2]-Wittig rearrangement from chloromethyl ethers
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The reaction of different chloromethyl ethers 1 with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (2.5 mol %) in THF at 0 °C leads to the corresponding α-lithiomethyl ether intermediates, through a chlorine-lithium exchange, which spontaneously undergo a clean [1,2]-Wittig rearrangement affording the expected homobenzylic alcohols 2. This is the first version of this rearrangement starting from easily available chloromethyl ethers.
- Gómez, Cecilia,Maciá, Beatriz,Lillo, Victor J.,Yus, Miguel
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p. 9832 - 9839
(2007/10/03)
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- Facile and regioselective dealkylation of alkyl aryl ethers using niobium(V) pentachloride
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A simple and facile method for the cleavage of carbon-oxygen bonds promoted by niobium pentachloride(V) is described. Excellent yields and regioselectivities were observed with various alkyl aryl ethers to give the phenols. NMR studies revealed the formation of monoaryloxy niobium salt(V), and a neighboring-group effect may play a significant role in the regioselectivity. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Sudo, Yukinori,Arai, Shigeru,Nishida, Atsushi
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p. 752 - 758
(2007/10/03)
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- Continuous chemoselective methylation of m-cresol and phenol with supercritical methanol over solid acid and base metal oxide catalysts
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The chemoselective methylation of m-cresol and phenol with supercritical methanol (scCH3OH) promoted by metal oxide catalysts (MgO, ZrO 2, Cs-P-Si and Fe-V/SiO2) was investigated in a continuous flow fixed bed reactor. The use of scCH3OH as a carrier medium led to a significant change in the product selectivity compared to that attained in the gas phase reaction, and caused a marked suppression of the degradation of CH3OH during the reaction, resulting in an improvement in the catalyst lifetime. The chemoselective outcome of the reaction was highly influenced by the acid-base character on the solid catalysts examined under supercritical conditions.
- Oku, Tomoharu,Arita, Yoshitaka,Ikariya, Takao
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p. 1553 - 1557
(2007/10/03)
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- Catalytic Friedel-Crafts acylation of aromatic ethers using Sml3
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10% mol Sml3 catalysed the Friedel-Crafts acylation of aromatic ethers by acyl chlorides in acetonitrile with the yields of 48-82%. Reactions of various substituted aromatic ethers with acyl chloride were studied. The structures of compounds were established by IR and 1H NMR. The main product obtained with anisole is the para-substituted compound with only a trace (3, a pattern repeated with the other aromatic ethers used.
- Chen, Xiaohang,Yu, Mingxin,Wang, Meijun
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- Process for performing an in-situ-quench reaction
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Method for carrying out in-situ quench (ISQ) reaction, by producing reactive intermediate in presence of reaction partner comprises (a) supplying a mixture of a precursor(PR), RP and optionally inert diluent to microreactor; (b) mixing in reactor with highly reactive reagent (RR) which converts PR into RI; and (c) isolating final product formed by reaction of RI with RP (optionally after flowing through a residence time unit). A method for carrying out an in-situ quench (ISQ) reaction, by producing a reactive intermediate (RI) in presence of a reaction partner (RP), involves: (a) supplying a mixture of a precursor(PR), RP and optionally an inert diluent to a microreactor; (b) mixing in the reactor with a highly reactive reagent (RR) which converts PR into RI; and (c) isolating the final product formed by the reaction of RI with RP (optionally after flowing through a residence time unit). An independent claim is included for use of a microreactor for carrying out an ISQ reaction, by supplying a mixture of PR, RP and optionally an inert diluent to the microreactor and mixing with RR.
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Page/Page column 9
(2008/06/13)
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- The tertiary sulfonamide as a latent directed-metalation group: Ni 0-catalyzed reductive cleavage and cross-coupling reactions of aryl sulfonamides with Grignard reagents
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A mild method for the Ni0-catalyzed hydrodesulfamoylation (see scheme, B) of aryl sulfonamides (1→2) with iPr2Mg or iPrMgCl as β-hydride transfer sources can be linked with directed ortho metalation (A and C) to give meta-substituted aromatics 2. Cross-coupling process with alkyl and aryl Grignard reagents furnish disubstituted benzenes and bi- and teraryl compounds.
- Milburn, Robert R.,Snieckus, Victor
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p. 888 - 891
(2007/10/03)
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- Acceleration of tributyltin hydride reduction of phenethyl iodide and m-methoxybenzyl bromide by a strong magnetic field
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Reduction reactions of phenethyl iodide and m-methoxybenzyl bromide with tributyltin hydride are accelerated by a strong (9.4 T) magnetic field.
- Fukuyoshi, Shu-ichi,Kusumi, Takenori
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p. 230 - 231
(2007/10/03)
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- Palladium-Catalyzed Cross-Coupling Reaction of Organoindiums with Aryl Halides in Aqueous Media
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(matrix presented) Diaryl-, divinyl-, and dialkylindium proved to be stable in aqueous media and to undergo a palladium-catalyzed cross-coupling reaction with aryl halides in aqueous THF. Treatment of 3-iodophenol with diphenylindium compound, generated from indium trichloride and two equimolar amounts of a phenyl Grignard reagent, in aqueous media under palladium catalysis provided the corresponding coupling product in excellent yield. Divinyl- and diethlindium can be used for the coupling reaction in the presence of water. A wide range of functional groups, including a hydroxy group and a formyl group, are compatible with this reaction.
- Takami, Kazuaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
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p. 1997 - 1998
(2007/10/03)
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- The positional δ(18O) values of extracted and synthetic vanillin
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The positional δ(18O) values of vanillin (1) of different origins have been determined from the global values of 2-methoxy-4-methylphenol (4), obtained from 1 upon Clemensen reduction, and of 3-methylanisole (5), obtained from 4 by removal of the phenolic O-atom. By these means, it is possible to differentiate samples of 1 of synthetic origin from those extracted from Vanilla plants or produced from lignin by chemical oxidation. The main difference between the samples derived from guaiacol and those possessing the aromatic moiety of natural origin is in the enrichment values of the O-atoms at C(3) and C(4), while the extractive materials from the pods are distinguished from the product from lignin on the basis of the carbonyl oxygen δ(18O) values, ranging from + 25.5 and + 26.2 in the natural material to + 19.7‰ in the lignan-based sample. The values for the phenolic O-atom vary from + 8.9 and + 12‰ of the synthetic materials to + 6.5, + 5.3, and + 6.3‰, respectively, of the sample from lignin and the two samples from Vanilla pods, whereas the MeO O-atoms show the following values for the same compounds: - 2.9, - 3.2, + 3.5, + 3.1, and + 2.3‰, respectively. This study indicates the significance of the positional δ(18O) values of polyoxygenated compounds for the definition of their origin.
- Fronza, Giovanni,Fuganti, Claudio,Serra, Stefano,Burke, Andrew,Guillou, Claude,Reniero, Fabiano
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p. 351 - 359
(2007/10/03)
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- Photocleavage of Benzyl-Sulfide Bonds
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The nucleoside transport inhibitor 6--9-(β-D-ribofuranosyl)purine, NBMPR, has been used successfully in photoaffinity labeling.We have studied the mechanism for photocleavage of the benzyl-sulfur bond by using substituted benzyl phenyl sulfides as analogues of NBMPR.This has enabled us to enhance the photoreactivity of the benzyl-sulfur bond.We have also performed "radical clock" studies with a hexenyl side chain to trap reactive intermediates.The mechanistic interpretation from the substituent and side chain studies is that the benzyl-sulfur moiety is photocleaved via a homolytic pathway.
- Fleming, Steven A.,Jensen, Anton W.
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p. 7135 - 7137
(2007/10/02)
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- ortho-Substituted Unsymmetrical Biaryls from Aryl tert-Butyl Sulfones
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Nickel-catalysed coupling of arylmagnesium halides with aryl tert-butyl sulfones, and in particular with those bearing ortho-substituents introduced by ortholithiation, gives ortho-substituted unsymmetrical biaryls.
- Clayden, Jonathan,Julia, Marc
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p. 1682 - 1683
(2007/10/02)
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- Correlation of Reaction Rates with a Substituent Constant Scale Derived from Calculated Electron Densities for a Computer Control Algorithm
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A new ? substituent scale based on electron density calculations by the AM1 quantum mechanical model has been established and used to correlate rates of O-methylation of substituted phenols, as part of a chemical artificial intelligence to control a fully automated apparatus for methyl iodide labeling.
- Cork, David G.,Hayashi, Nobuyoshi
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p. 1583 - 1585
(2007/10/02)
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