- Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
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Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
- Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
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p. 14177 - 14183
(2021/08/16)
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- Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids
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Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
- Tiburcio, Estefanía,Greco, Rossella,Mon, Marta,Ballesteros-Soberanas, Jordi,Ferrando-Soria, Jesús,López-Haro, Miguel,Hernández-Garrido, Juan Carlos,Oliver-Meseguer, Judit,Marini, Carlo,Boronat, Mercedes,Armentano, Donatella,Leyva-Pérez, Antonio,Pardo, Emilio
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p. 2581 - 2592
(2021/02/16)
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- Aerobic Oxidation of Diverse Primary Alcohols to Carboxylic Acids with a Heterogeneous Pd-Bi-Te/C (PBT/C) Catalyst
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Heterogeneous catalytic aerobic oxidation methods represent a near-ideal approach for the conversion of primary alcohols to carboxylic acids. Here, we report that a heterogeneous catalyst composed of Pd, Bi, and Te supported on activated carbon is highly effective for the oxidation of diverse benzylic and aliphatic primary alcohols, including 5-(hydroxymethyl)furfural (HMF) and substrates bearing heterocycles and other important functional groups. In many cases, the desired carboxylic acid product is obtained in >90% yield. Additionally, the catalyst has been demonstrated in a continuous-flow packed-bed reactor for the oxidation of benzyl alcohol, achieving near-quantitative yield while undergoing over 30 000 turnovers.
- Ahmed, Maaz S.,Mannel, David S.,Root, Thatcher W.,Stahl, Shannon S.
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supporting information
p. 1388 - 1393
(2017/09/22)
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- Catalytic Conversion of Alcohols to Carboxylic Acid Salts and Hydrogen with Alkaline Water
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A [RuH(CO)(py-NP)(PPh3)2]Cl (1) catalyst is found to be effective for catalytic transformation of primary alcohols, including amino alcohols, to the corresponding carboxylic acid salts and two molecules of hydrogen with alkaline water. The reaction proceeds via acceptorless dehydrogenation of alcohol, followed by a fast hydroxide/water attack to the metal-bound aldehyde. A pyridyl-type nitrogen in the ligand architecture seems to accelerate the reaction.
- Sarbajna, Abir,Dutta, Indranil,Daw, Prosenjit,Dinda, Shrabani,Rahaman, S. M. Wahidur,Sarkar, Abheek,Bera, Jitendra K.
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p. 2786 - 2790
(2017/05/31)
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- ALKYLATION OF PHENOLIC COMPOUNDS
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The invention relates to a process for O-alkyiation of a phenolic compound comprising at least two hydroxyl groups bonded to an aromatic hydrocarbon, the process comprising reacting the phenolic compound with an alkylating agent in the presence of a base, at a suitable reaction temperature and for a suitable time period, thereby alkylating the at least two hydroxy] groups. The invention also relates to O-alkylaled phenolic compounds produced by this process.
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Page/Page column 37
(2015/04/28)
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- Photoracemization of Blestriarene C and Its Analogs
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Two analogs of blestriarene C (4,4'-dimethoxy-1,1'-biphenanthrene-2,2',7,7'-tetraol) bearing no 7,7'-dihydroxy (3) and 4,4'-dimethoxy groups 4 were prepared. Unlike blestriarene C (1), compounds 3 and 4, as well as 1,1'-biphenanthrene-2,2'-diol (5), do not racemize under fluorescent lamp illumination. Cyclic voltammetry analysis reveals that compound 1 has a lower half-wave potential (E1/2) than compounds 3, 4, 5, suggesting that a redox cycle is involved in the racemization. Compound 1 racemizes by absorbing UV light corresponding to the 1Lb band. During the reaction, no side products are observed. The racemization is significantly inhibited under nitrogen. Based on these observations, we propose a feasible mechanism for the easy racemization of compound 1, which is mediated by a cation radical generated in situ by a reversible photo-induced oxygen oxidation. Chirality 27:479-486, 2015.
- Natori, Koichi,Iwayama, Taizo,Yamabe, Osamu,Kitamoto, Yuichi,Ikeda, Hiroshi,Sakamoto, Kenkichi,Hattori, Tetsutaro,Miyano, Sotaro
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p. 479 - 486
(2015/08/03)
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- Nitromethane in polyphosphoric acid- A new reagent for carboxyamidation and carboxylation of activated aromatic compou
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A new method of carboxyamidation of aromatic compounds based on their reaction with nitromethane in polyphosphoric acid has been developed. Upon the hydrolysis of benzamides during the reaction mixture workup, the corresponding benzoic acids can be obtained. Taylor & Francis Group, LLC.
- Aksenov, Alexander V.,Aksenov, Nicolai A.,Nadein, Oleg N.,Aksenova, Inna V.
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experimental part
p. 541 - 547
(2011/11/29)
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- Synthesis of novel azo-resveratrol, azo-oxyresveratrol and their derivatives as potent tyrosinase inhibitors
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Ten azo compounds including azo-resveratrol (5) and azo-oxyresveratrol (9) were synthesized using a modified Curtius rearrangement and diazotization followed by coupling reactions with various phenolic analogs. All synthesized compounds were evaluated for their mushroom tyrosinase inhibitory activity. Compounds 4 and 5 exhibited high tyrosinase inhibitory activity (56.25% and 72.75% at 50 μM, respectively). The results of mushroom tyrosinase inhibition assays indicate that the 4-hydroxyphenyl moiety is essential for high inhibition and that 3,5-dihydroxyphenyl and 3,5-dimethoxyphenyl derivatives are better for tyrosinase inhibition than 2,5-dimethoxyphenyl derivatives. Particularly, introduction of hydroxyl or methoxy group into the 4-hydroxyphenyl moiety diminished or significantly reduced mushroom tryosinase inhibition. Among the synthesized azo compounds, azo-resveratrol (5) showed the most potent mushroom tyrosinase inhibition with an IC50 value of IC50 = 36.28 ± 0.72 μM, comparable to that of resveratrol, a well-known tyrosinase inhibitor.
- Song, Yu Min,Ha, Young Mi,Kim, Jin-Ah,Chung, Ki Wung,Uehara, Yohei,Lee, Kyung Jin,Chun, Pusoon,Byun, Youngjoo,Chung, Hae Young,Moon, Hyung Ryong
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p. 7451 - 7455
(2013/02/22)
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- Efficient and rapid method for the oxidation of electron-rich aromatic aldehydes to carboxylic acids using improved basic hydrogen peroxide
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An efficient and rapid method for oxidation of electron-rich aromatic aldehydes to their corresponding carboxylic acids in excellent yields was developed. It is based on the oxidation of methoxy-substituted benzaldehydes in methanol with an improved aqueous basic hydrogen peroxide system. Benzaldehydes with electronwithdrawing substituents are oxidized to the corresponding carboxylic acid in excellent yields under mild reaction conditions. Copyright Taylor & Francis Group, LLC.
- Cong, Zhi-Qi,Wang, Chun-Ian,Chen, Tie,Yin, Bing-Zhu
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p. 679 - 683
(2007/10/03)
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- BISMUTH MEDIATED OXIDATIONS
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The invention relates to a process for the oxidation of a substrate comprising a benzylic alkyl moiety, said process comprising incubating the substrate with a bismuth complex comprising bismuth and a ligand and a stoichiometric source of oxygen.
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Page/Page column 9-10
(2008/06/13)
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- Bismuth-catalyzed benzylic oxidations with tert-butyl hydroperoxide
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(Chemical Equation Presented) Oxidation of alkyl and cycloalkyl arenes with tert-butyl hydroperoxide catalyzed by bismuth and picolinic acid in pyridine and acetic acid gave the corresponding benzylic ketones (48-99%). Alternatively, oxidation of methyl arenes gave the corresponding substituted benzole acids (50-95%). Preliminary mechanistic studies were consistent with a radical mechanism rather than a bismuth(III)-bismuth(V) cycle.
- Bonvin, Yannick,Callens, Emmanuel,Larrosa, Igor,Henderson, David A.,Oldham, James,Burton, Andrew J.,Barrett, Anthony G. M.
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p. 4549 - 4552
(2007/10/03)
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- New chiral diamide ligands containing redox-active hydroquinone groups. Synthesis and results in the palladium(II)-catalyzed 1,4-diacetoxylation of 1,3-dienes
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Chiral ligands 8-11, 22 and 23 were synthesized from different chiral diamines as a new class of ligands for the Pd(II)-catalyzed 1,4-diacetoxylation of 1,3-dienes. The synthesis from the diamines and protected benzoic acids was performed in a few simple steps and gave the ligands in high overall yields. The hydroquinone groups present in the ligands are in situ oxidized to benzoquinone to give the active ligands. Application of these ligands in the 1,4-diacetoxylation reaction afforded the oxidation product with high regio- and diastereoselectivity and an enantiomeric excess up to 42% was obtained. Possible coordination modes of the metal to the ligand are discussed, and experiments were made to investigate the coordination by varying the reaction conditions or making changes to the ligands.
- Verboom, Renzo C.,Plietker, Bernd J.,B?ckvall, Jan-E.
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p. 508 - 517
(2007/10/03)
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- Directed ortho-metalation, a new insight into organosodium chemistry
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Finely dispersed metallic sodium in combination with an alkyl chloride RCcan replace organolithium reagents in the ortho-metalation of aromatic compounds (see scheme). The in situ generated base is consumed as soon as it is formed, which avoids Wurtz coupling, the usual side reaction, and the handling and storage of highly reactive alkyl sodium bases. Reaction conditions are mild, the reaction is easy to scale up, and the reagents needed are inexpensive.
- Gissot, Arnaud,Becht, Jean-Michel,Desmurs, Jean Roger,Pevere, Virginie,Wagner, Alain,Mioskowski, Charles
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p. 340 - 343
(2007/10/03)
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- Method for orthometalation of a carbocyclic aromatic derivative bearing at least an electron donor group
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The invention concerns a method for orthometalation of a carbocyclic aromatic derivative bearing at least an electron donor group, characterised in that it consists in reacting said carbocyclic aromatic derivative with an efficient amount of at least one alkaline metal in the presence of a compound of formula (I): RX, wherein: R represents a hydrocarbon radical having 1 to 20 carbon atoms which can be a saturated or unsaturated, linear or branched, acyclic aliphatic radical; a saturated or unsaturated, monocyclic or polycyclic cycloaliphatic radical; a saturated or unsaturated, linear or branched aliphatic radical bearing a cyclic substituent; and X represents a bromine or chlorine atom.
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Page column 9
(2010/01/31)
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- Selenium(IV) oxide catalyzed oxidation of aldehydes to carboxylic acids with hydrogen peroxide
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A convenient method for oxidative transformation of aromatic, heteroaromatic and aliphatic aldehydes into carboxylic acids is presented. It is based on the oxidation of aldehydes in THF using 30% hydrogen peroxide in the presence of 5 molar % of selenium(IV) oxide. The scope and limitation of the method are discussed.
- Brzaszcz,Kloc,Maposah,Mlochowski
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p. 4425 - 4434
(2007/10/03)
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- Re2O7-catalyzed carbon-carbon bond cleavage of ketones into carboxylic acids with aq. TBHP
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A mild and efficient catalytic method for the C-C bond cleavage of ketones to corresponding carboxylic acids in good yields is described using a catalytic amount of Re2O7 and 70% tert. butyl hydroperoxide (TBHP) as oxidant.
- Gurunath,Sudalai
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p. 559 - 560
(2007/10/03)
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- SYNTHESIS OF HEXADECYLTETRACYANOQUINODIMETHANE
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In order to obtain tetracyanoquinodimethane derivatives containing a long-chain substituent, a new procedure was developed for the synthesis of 1,4-cyclohexanedione derivatives by the reduction of 1,5-dimethoxybenzoic acid.The first synthesis of hexadecyltetracyanoquinodimethane is reported.
- Khodorkovskii, V. Yu.,Batese, A. E.,Valter, R. E.,Utinan, M. F.,Karlivan, G. A.,Neiland, O. Ya.
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p. 1170 - 1173
(2007/10/02)
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- 3,6-DIMETHOXYBENZOCYCLOBUTENONE: A REAGENT FOR QUINONE SYNTHESIS
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3,6-Dimethoxybenzocyclobutenone 4 is prepared in four efficient steps from 2,5-dimethoxybenzoic acid 8.The derived benzocyclobutenol 13 undergoes electrocyclic ring opening at 110-115 deg C to give the hydroxy-o-quinone dimethide 21, which reacts with dienophiles to give 5,8-dimethoxy-1,2,3,4-tetrahydro-1-naphthol derivatives stereoselectively.Since the ketone 4 can be functionalised at C-5 using electrophiles and at C-2 via homolytic bromation, the ring opening and cycloaddition sequence offers a flexible route to linear fused hydroquinone and quinone derivatives.In model studies, the benzocyclobutenol derivative 48 underwent thermal electrocyclic ring opening and intramolecular cycloaddition to give 49, while the analogous reaction with 52 failed due to adverse steric effects during the cycloaddition step.In photochemical experiments, attempts to generate the silyl ether 57 by in situ silylation of the dienol 55 and to prepare the benzocyclobutenol 62 via irradiation of the o-phthalaldehyde monoacetal 60 were unsuccessful.
- Azadi-Ardakani, Manouchehr,Wallace, Timothy W.
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p. 5939 - 5952
(2007/10/02)
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- Synthesis and Properties of Dinitromethylated Arenes. Reinvestigation of the Ponzio Reaction
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Several title compounds have been prepared by the modified Ponzio procedure and their IR, 1 H and 13 C NMR data are presented.In some cases trinitromethylated arenes were obtained as a by-product.Oxidative cleavage to parent aldehydes and oxidation to carboxylic acids were the major competing reactions. 9-Anthracenecarbaldehyde oxime and 10-methyl-9-anthracenecarbaldehyde oxime reacted with nitrogen dioxide in an unexpected way, giving 10-nitro-9-anthracenecarbonitrile oxide and 10-methyl-10-nitro-9-anthrone as the respective main products.Nitration of (dinitromethyl)benzene has also been examined under various conditions.
- Suzuku, Hitomi,Takaoka, Hiroshi,Yamamoto, Hidetoshi,Ogawa, Takuji
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p. 2927 - 2932
(2007/10/02)
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- Anodic Oxidation of 1,4-Dimethoxy Aromatic Compounds. A Facile Route to Functionalized Quinone Bisketals.
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The anodic oxidation of 12 functionalized 1,4-dimethoxybenzene derivatives and 8 functionalized 1,4-dimethoxynaphthalenes has been studied under a variety of conditions.Many substituted 1,4-dimethoxy aromatics afford high yields of the respective quinone bisketals by single-cell anodic oxidation without accurate control of the electrode potential.Oxidizable groups offen complicate the anodic oxidation; however, in some cases protected derivatives of these functionalities can be converted to the bisketals in good yields.Aromatics containing reducible functions can besmoothly oxidized to quinone bisketals by the use of a divided cell.The current efficiencies and the effect of electrode material on selected systems are reported and discussed.
- Henton, Daniel R.,McCreery, Richard L.,Swenton, John S.
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p. 369 - 378
(2007/10/02)
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