- Acyl iodides in organic synthesis: I. Reactions with alcohols
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Reaction of acyl iodides RC(O)I (R = Me, Ph) with alcohols R′OH (R′ = Me, Et, i-Pr, t-Bu, CH2= CHCH2, HC≡CCH2) provides in the corresponding organyl iodides R′I. Unlike that 2-chloroethanol and phenol (R′ = CH 2CH2Cl, Ph) react with RC(O)I in the same way as with acyl chlorides yielding esters RCO2R′. This reaction path occurs partially also with methanol and ethanol.
- Voronkov,Trukhina,Vlasova
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- Direct Synthesis of trans-1,4-Diacetoxycyclohexa-2,5-diene by Electrochemical Reduction of r-1,t-4-Diacetoxy-t-2,c-3-dibromocyclohex-5-ene
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Electrochemical reduction of r-1,t-4-diacetoxy-t-2,c-3-dibromocyclohex-5-ene 1 gives only trans-1,4-diacetoxycyclohexa-2,5-diene 2 in good yield while the commonly used Zn reduction gives a product mixture containing 2 and acetoxybenzene 3 derived from acetoxy elimination.
- Kelebekli, Latif,Demir, Uemit,Kara, Yunus
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- A sulfonated Schiff base dimethyltin(iv) coordination polymer: Synthesis, characterization and application as a catalyst for ultrasound- or microwave-assisted Baeyer-Villiger oxidation under solvent-free conditions
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The synthesis and crystal structure of the new dimethyltin(iv) compound [SnMe2(HL)(CH3OH)]n·(0.5nCH3OH) (1) derived from the Schiff base 2-[(2,3-dihydroxyphenyl)methylideneamino]benzenesulfonic acid (H3L) are described. Despite having six potentially donating centres (one imine nitrogen, two phenoxo and three sulfonate oxygen atoms), the monoprotonated dianionic ligand (HL2-) behaves as an O,O,O-tridentate chelator. Single crystal X-ray diffraction revealed that 1 is a 1D coordination polymer with every tin(iv) ion bound to two methyl groups, a methanol molecule, two Ophenoxo and one μ-Osulfonate atom from HL2-. The coordination polymer 1 was applied as a heterogeneous catalyst for the Baeyer-Villiger oxidation of ketones to esters or lactones, using aqueous hydrogen peroxide as oxidant, under ultrasound (US) or microwave (MW) irradiation and solvent- and additive-free conditions. Overall conversions up to 76/82, 98/93, 93/89, 91/94, 83/90, 68/62 and 81/87% under US/MW irradiations were obtained with 3,3-dimethyl-2-butanone, cyclopentanone, 2-methylcyclopentanone, cyclohexanone, 3-methylcyclohexanone, benzophenone and acetophenone, respectively. The catalyst can be recycled up to five cycles without losing appreciable activity.
- Martins, Luísa M.D.R.S.,Hazra, Susanta,Guedes Da Silva, M. Fátima C.,Pombeiro, Armando J. L.
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- Chemistry of anti-o,o'-dibenzene
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A new and efficient preparation of anti-o,o'-dibenzene 1 has been achieved in three steps from cis-3,5-cyclohexadiene-1,2-diol 25. Utilizing a method for deoxygenation of 1,2-diols developed in our laboratory, anti-tetraol 23 was converted to 1 in 65% yield on a 0.5 g scale; This has allowed us to explore the chemistry of anti-dibenzenes extensively. The kinetics for thermal reversion of 1 to benzene have been studied in three different solvents. The direct photolysis of 1 to benzene has been found to form excited benzene in unit efficiency. This high efficiency of adiabatic photon up-conversion in the singlet manifold is unprecedented. No light was detected in the thermal dissociation of 1 in solution using various sensitizers. The chemiluminescence spectrum from the thermolysis of 1 in the presence of perylene has been recorded and found to correspond to the emission of perylene excimer. Although the efficiency of the chemiluminescent process was very low, it has proven to be one of a very few examples of chemiluminescent reactions from pure hydrocarbons. The possible mechanisms were discussed. Benzene 1,4-endoperoxide 36 was formed during the photolysis of monoperoxide 34 at low temperature. Peroxide 36 underwent a quantitative concerted retrocycloaddition to benzene and singlet oxygen. The half-life of 36 was determined to be 29 min at -30°C.
- Noh, Taehee,Gan, Hong,Halfon, Sharon,Hrnjez, Bruce J.,Yang, Nien-Chu C.
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- Baeyer-Villiger oxidation of ketones with a silica-supported peracid in supercritical carbon dioxide under flow conditions
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[2-Percarboxyethyl]-functionalized silica reacts with ketones in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions to yield the corresponding esters and lactones. The solid reagent can be easily recycled through treatment with 70% hydrogen peroxide in the presence of an acid at 0°C. This procedure not only simplifies the isolation of the reaction products, but has the advantage of using only water and carbon dioxide as solvents under mild conditions.
- Mello, Rossella,Olmos, Andrea,Parra-Carbonell, Javier,Gonzalez-Nunez, Maria Elena,Asensio, Gregorio
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- Acyl iodides in organic synthesis: II. Reactions with acyclic and cyclic ethers
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Reaction of acyl iodides RCOI (R = Me, Ph) was studied with acyclic and cyclic ethers (Et2O, MeCHCH2(O), ClCH2CHCH 2(O), THF, O(CH2CH2)2O, EtOCH 2CH2OH, EtOCH=CH2, PhOEt]. The reaction occurred with the rupture of one or two CO bonds furnishing the corresponding iodides and esters.
- Voronkov,Trukhina,Vlasova
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- BIPHASE AND TRIPHASE CATALYSIS. ARSONATED POLYSTYRENES AS CATALYSTS IN THE BAEYER-VILLIGER OXIDATION OF KETONES BY AQUEOUS HYDROGEN PEROXIDE.
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Arsonated polystyrene resins, prepared by a novel procedure, proved to be versatile catalysts for the Baeyer-Villiger oxidation of ketones by hydrogen peroxide. The insoluble beads of the catalyst can be quantitatively separated from the reaction mixture and recycled. Extensive hydrolysis of the lactone and ester products is prevented. In solvents miscible with aqueous hydrogen peroxide (biphase system), the catalysts facilitate oxidation of medium size cycloalkanones (C//4-C//7) and their alkyl and aryl derivatives, steroid ketones, and branched-chain aliphatic ketones. Larger size cycloalkanones, acetophenone, and straight-chain aliphatic ketones react very slowly or not at all. The arsonated polystyrene beads are effective catalysts and phase transfer agents in solvents immiscible with aqueous hydrogen peroxide. This represents the first example of triphase catalysis in oxidations by hydrogen peroxide.
- Jacobson,Mares,Zambri
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- Platinum and palladium complexes containing cationic ligands as catalysts for arene H/D exchange and oxidation
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Cationic catalysts in HD: Palladium(II) and platinum(II) complexes of pyridinium-substituted bipyridine ligands are highly active and stable catalysts for H/D exchange and oxidation of aromatic C-H bonds (TONs up to 3200, TOFs up to 0.1 s-1; se
- Emmert, Marion H.,Gary, J. Brannon,Villalobos, Janette M.,Sanford, Melanie S.
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- Baeyer-Villiger oxidation with potassium peroxomonosulfate supported on acidic silica gel
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Potassium peroxomonosulfate deposited onto silica SiO2· KHSO5 efficiently reacts with ketones in dichloromethane at room temperature to give the corresponding esters or lactones in quantitative yields. This method avoids hydrolysis of the reaction products. The Baeyer-Villiger reaction is catalyzed by potassium hydrogensulfate present in the supported reagent.
- Gonzalez-Nunez, Maria E.,Mello, Rossella,Olmos, Andrea,Asensio, Gregorio
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- Enhanced shape selective catalysis of mixed cyclic ketones in aerobic Baeyer-Villiger oxidation with magnetic Cu-Fe3O4 supported mesoporous silica microspheres
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Various strategies have been developed to improve the conversion for the Baeyer-Villiger oxidation. However, the catalytic effects of the Baeyer-Villiger oxidation for the mixed ketones are rarely reported, though it is also important for the natural and industrial separation processes. In this report, magnetite Cu modified Fe3O4 supported mesoporous silica microspheres (Cu-Fe3O4@mSiO2) have been successfully synthesized by two step direct hydrothermal method (DHT). Over 99% of cyclohexanone conversion was obtained with mild air oxidation and benzaldehyde as sacrificing agent over Cu-Fe3O4@mSiO2. The catalytic system also shows higher conversion rates for small molecular ketones in the mixed ketone reactants, which was attributed to the enhanced mass transfer effect and Fe-Cu composite active sites in the magnetite mesoporous silica microspheres. The catalyst could be recycled for four times with similar catalytic performance, which shows enhanced shape selectivity in aerobic Baeyer-Villiger oxidations for mixed cyclic ketones.
- Zheng, Chunming,Chang, Shubin,Yang, Chuanwu,Lian, Dongying,Ma, Chao,Zhang, Chunrong,Fan, Xiangrui,Xu, Shichao,Sun, Xiaohong
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- Remarkably high reactivity of Pd(OAc)2/pyridine catalysts: Nondirected C-H oxygenation of arenes
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Less is more: The rational optimization and general applicability of the catalytic system Pd(OAc)2/pyridine is described (see scheme). The catalyst shows excellent reactivity in the C-H oxygenation of simple aromatic substrates. The Pd/pyridine ratio is critical as the use of one equivalent of pyridine per Pd center leads to dramatic enhancements in both reactivity and site selectivity in comparison to Pd(OAc)2 alone.
- Emmert, Marion H.,Cook, Amanda K.,Xie, Yushu J.,Sanford, Melanie S.
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- Methyl formate as a carbonylating agent for the catalytic conversion of phenol to methyl phenyl carbonate
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Methyl formate was used as a green and efficient carbonylating agent in the synthesis of methyl phenyl carbonate from phenol. Methyl formate showed better performance compared to toxic CO gas and the ability to produce other useful carbonylated products, e.g., dimethyl carbonate and dimethyl oxalate.
- Yalfani, Mohammad S.,Lolli, Giulio,Wolf, Aurel,Mleczko, Leslaw,Mueller, Thomas E.,Leitner, Walter
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- Efficient Baeyer-Villiger oxidation of ketones using molecular iodine/H2O2 as heterogeneous catalytic system
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The use of molecular iodine as a catalyst for the oxidation of ketones using hydrogen peroxide in the presence of acetic acid at room temperature is reported. Copyright Taylor & Francis Group, LLC.
- Gaikwad, Digambar D.,Dake, Satish A.,Kulkarni, Ravibhushan S.,Jadhav, Wamanrao N.,Kakde, Shankar B.,Pawar, Rajendra P.
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- Reactivity of dehydrometallophthalocyanines and - Porphyrazines
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The zinc dehydrophthalocyanine 2 and zinc dehydrobenzoporhyrazine 8a were generated from the 1N-aminobenzotriazole-annulated zinc phtalocyanine 1 and zinc benzoporhyrazine 8, respectively, by oxidation with Pb(OAc)4 in different solvents, for example, diethyl ether, tetrahydrofuran, acetic acid, and benzene. The reactivity of 2 and 8a was studied in detail. These species not only easily undergo Diels-Alder additions with dienes, but also the used solvents can be added. Among the addition products with solvents ethoxy-, acetoxy-, acetoxybutyloxy-substituted and barrelen-fused phthalocyanines and benzoporpyrazines were isolated. No products resulting from the dimerization of two denydro species were observed either for 2 or 8a. Analysis of the reaction products in comparison with those obtained by oxidation of 1-aminobenzotriazole 15 under similar conditions proves a higher reactivity (electrophilicity) of the dehydro-PcZn 2 and dehydro-PzZn 8a in comparison with unsubstituted benzyne towards the solvents used, such as diethyl ether and benzene.
- Vagin, Sergei I.,Frickenschmidt, Antje,Kammerer, Bernd,Hanack, Michael
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- Palladium catalysts containing pyridinium-substituted pyridine ligands for the C-H oxygenation of benzene with K2S2O8
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This manuscript describes the development of Pd catalysts with pyridinium-substituted pyridine ligands for the C-H oxygenation of benzene with potassium persulfate. These new catalysts provide dramatically improved activity compared to simple Pd(OAc)2 in this transformation. Furthermore, the reaction proceeds with high selectivity for phenyl acetate over biphenyl. Preliminary investigations suggest that a key role for the cationic pyridinium ligand is to serve as a phase transfer catalyst for the K2S 2O8 oxidant.
- Gary, J. Brannon,Cook, Amanda K.,Sanford, Melanie S.
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- Mechanism of the palladium-catalyzed arene C-H acetoxylation: A comparison of catalysts and ligand effects
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This article describes detailed mechanistic studies focused on elucidating the impact of pyridine ligands on the Pd-catalyzed C-H acetoxylation of benzene. Three different catalysts, Pd(OAc)2, Pd(OAc)2/pyridine (1:1), and Pd(OAc)2/pyridine (1:2), are compared using a combination of mechanistic tools, including rate and order studies, Hammett analysis, detailed characterization of catalyst resting states, and isotope effects. The data from these experiments implicate C-H activation as the rate-limiting step in all cases. The major difference between the three catalysts is proposed to be the resting state of Pd. Under the reaction conditions, Pd(OAc)2 rests as an acetate bridged dimer, while the Pd(OAc)2/pyridine (1:2) catalyst rests as the monomer (pyridine)2Pd(OAc)2. In contrast, a variety of experiments suggest that the highly active catalyst generated from the 1:1 combination of Pd(OAc)2 and pyridine rests as the dimeric structure [(pyridine)Pd(OAc)2]2.
- Cook, Amanda K.,Sanford, Melanie S.
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- Nucleophilic Metal Complexes as Acylation Catalysts: Solvent-dependent Switch Mechanisms Leading to the First Catalyzed Staudinger Reaction
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(Matrix Presented) Catalytic acylation using complex transition metal salts MCo(CO)4 is demonstrated. Surprisingly, a solvent-dependent mechanistic "switch" results in a Lewis acid-based acylation mechanism in nonpolar media and a nucleophilic mechanism in polar organic media. These observations lead to the first example of a catalyzed Staudinger reaction to form β-lactams.
- Wack, Harald,Drury III, William J.,Taggi, Andrew E.,Ferraris, Dana,Lectka, Thomas
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- Formation of S-shaped disilicoicosatungstate and efficient Baeyer-Villiger oxidation with hydrogen peroxide
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Partial protonation of a divacant lacunary Keggin-type silicodecatungstate in an anhydrous organic solvent led to dehydrative condensation and formation of a novel S-shaped disilicoicosatungstate (see picture). The S-shaped cluster efficiently promotes Baeyer-Villiger oxidation of cycloalkanones with high turnover numbers (TONs, ≥ 1900) and high selectivities (≥ 90%) for the corresponding lactones. (Chemical Equation Presented).
- Yoshida, Akihiro,Yoshimura, Masayuki,Uehara, Kazuhiro,Hikichi, Shiro,Mizuno, Noritaka
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- Chemistry of diamino-ligated methylpalladium(II) alkoxides and aryloxides (Part II): Methoxide formation and carbonylation reactions
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Reaction of N-ligated methylpalladium(II) alkoxide and aryloxide complexes [Pd(Me)(OR)(N ~ N)] (R = Ph, CH(CF3)2; N ~ N = tmeda (N,N,N′,N′-tetramethylethylenediamine) or bpy (2,2′-bipyridyl)) with carbon monoxide produces the corresponding methylesters in high yields. The insertion takes place either into the Pd-Me bond (aryloxide complexes) or into the Pd-OR bond (alkoxide complexes). Methylpalladium(II) methoxide complexes [Pd(Me)(OMe)(N ~ N)] (N ~ N = tmeda, bpy) have been generated in situ by aryloxide- or alkoxide-methanol exchange reactions for which the equilibrium constants have been determined. The bpy-ligated methylpalladium methoxide complex undergoes insertion of CO producing either a methylpalladium methoxycarbonyl complex [Pd(Me)(CO2Me)(bpy)] (at -60°C) or an acylpalladium methoxycarbonyl complex [Pd(COMe)(CO2Me)(bpy)] (at -25°C); both carbonylated species could be isolated and characterized at low temperature.
- Kapteijn, Gerardus M.,Dervisi, Athanasia,Verhoef, Michel J.,Van Den Broek, M.A. Frederik H.,Grove, David M.,Van Koten, Gerard
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- Solvent-free Baeyer-Villiger oxidation with H2O2 as oxidant catalyzed by multi-SO3H functionalized heteropolyanion-based ionic hybrids
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Three novel multi-SO3H functionalized heteropolyanion-based ionic hybrids were synthesized and characterized, which as heterogeneous catalysts for Baeyer-Villiger oxidation using 35% aqueous H2O2 as oxidant show high catalytic activity under solvent-free conditions, the target lactones were obtained with yields of 69% to 88% in 3 h at 50 °C. Three ionic hybrids could be recovered readily and their catalytic activity almost completely retained after ten recycles.
- Li, Xinzhong,Cao, Rong,Lin, Qi
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- Study on the effect of di- and trifluoromethyl groups on the Baeyer-Villiger reaction
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Case studies of the Baeyer-Villiger reaction applied to di-and trifluoromethylketone derivatives and the effect of the fluoromethyl groups on the Baeyer-Villiger reaction, are described.
- Kitazume, Tomoya,Kataoka, Junichi
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- Poly(styryl)bipyridine: Synthesis and formation of transition-metal complexes and some of their physical, chemical, and catalytic properties
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Poly(styryl)bipyridine, 1, is produced from the reaction of lithiated polystyrene with bipyridine in tetrahydrofuran. Under our conditions, bipyridine becomes bound to 10-15% of the phenyl residues. The reaction of 1 with a variety of transition-metal salts can be carried out in a variety of swelling solvents and results in formation of polymer-bound bipyridine transition-metal complexes. The extent of metal incorporation depends on solvent, metal ion concentration, and the identity of the metal species. Zerovalent metal complexes such as&24C5;-Ph-bpy-M(CO)4 (M = Cr, Mo, W) are readily prepared from the reaction of 1 with the metal hexacarbonyl complexes. (Poly(styryl)bipyridyl)palladium acetate is an active catalyst for the hydrogenation of olefins at ambient pressure and temperature. It can also be used to catalyze the acetoxylation of benzene; however, the percent conversion in this case is rather low.
- Card, Roger J.,Neckers, Douglas C.
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p. 2345 - 2349,2347,2349
(1978)
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- O-arylation of carboxylic acids using (phenyl)[2-(trimethylsilyl)phenyl] iodonium triflate as a precursor of arynes
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Using (phenyl)[2-(trimethylsilyl)phenyl]iodonium triflate as a precursor of arynes, Larock's method for O-arylation of carboxylic acids and arynes was developed. A variety of acids including simple aliphatic carboxylic acids, aromatic carboxylic acids, allenoic acids, and p-toluenesulfonic acid under mild reaction conditions could generate the aryl esters. Copyright Taylor & Francis Group, LLC.
- Xue, Jian,Huang, Xian
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- Assessing the photocatalytic activity of europium doped TiO2 using liquid phase plasma process on acetylsalicylic acid
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In this study, europium (Eu) was precipitated in TiO2 powder using liquid phase plasma (LPP) process to prepare a photocatalyst with higher activity, even in the visible light range. Eu was uniformly deposited on the surface of TiO2 by the LPP method. It was observed that the amount of Eu precipitated on the TiO2 surface increased with increasing precursor concentration. XPS and EDS analysis showed that Eu was precipitated as europium oxide. The precipitation of Eu shifted the position of the Raman peak to a higher wavelength; with higher Eu content, the band gap energy decreased. Particularly, the photocatalytic efficiency of the Eu doped TiO2 photocatalyst (EDTP) in the visible light source was much higher than that of bare TiO2, and with higher Eu content, the photocatalytic activity was improved. Acetylsalicylic acid was attacked by HO? produced on the EDTP's surface and assumed to be finally mineralized to H2O and CO2 via two decomposition pathways, namely, decarboxylation and deacetylation.
- Bang, Hye-Jin,Ha, Hyung-Ho,Jung, Sang-Chul,Kim, Sun-Jae,Lee, Heon,Park, Young-Kwon,Yu, Young Hyun
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- Versatile mesoporous carbonaceous materials for acid catalysis
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Starbon mesoporous materials were synthesized after pyrolysis of expanded starch and subsequently functionalised with sulfonated groups, providing highly active and reusable materials in various acid catalysed reactions. The Royal Society of Chemistry.
- Budarin, Vitaly L.,Clark, James H.,Luque, Rafael,Macquarrie, Duncan J.
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- Chloroferrate(III) ionic liquid as recyclable catalyst for the acetylation of alcohols and phenols and for 1,1-Diacylation of aldehydes
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A Lewis acidic ionic liquid, [bmim][FeCl4], was employed to catalyze acetylation of alcohols and phenols, and the conversion of aldehydes to corresponding 1,1-diacetates without conventional organic solvents. The catalyst is easily available, water-tolerant, recoverable and easy to handle.
- Wanga, Dong-Sheng,Lib, Gui-Yun,Pengb, Yan-Qing
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- Efficient Baeyer–Villiger Oxidation Catalysed by Silver Nanoparticles Stabilized on Modified Montmorillonite
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Abstract: Silver nanoparticles supported on modified montmorillonite clay (Ag-NPs@mont), were utilized as catalyst for the Baeyer–Villiger oxidation of various ketones with hydrogen peroxide as an oxidant under solvent free condition at room temperature. The modification of Montmorillonite K10 clay was carried out with HCl under controlled conditions for generating a high surface area porous matrix which acts as support for the in situ generation of Silver nanoparticles. The synthesized nanocomposite material was characterized by UV–Visible spectroscopy, powder XRD, SEM-EDX, TEM and N2 adsorption–desorption analysis. The catalyst can be recycled and reused several times without significant loss of their catalytic activity. Graphical Abstract: [Figure not available: see fulltext.].
- Borah, Subrat Jyoti,Das, Diganta Kumar
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- Stabilized Fe3O4 magnetic nanoparticles into nanopores of modified montmorillonite clay: A highly efficient catalyst for the Baeyer-Villiger oxidation under solvent free conditions
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In situ generation of Fe3O4 magnetic nanoparticles (Fe3O4@AT-mont.) into the nanopores of modified montmorillonite (AT-mont.) clay has been carried out. Modification of the montmorillonite was done by acid (4 M HCl) activation under controlled conditions for generating nanopores, which act as a "host" for the Fe3O4 nanoparticles. The synthesized Fe3O4@AT-mont. was characterized by PXRD, TEM, SEM-EDX, XPS, VSM and surface area analysis. The average particle size of Fe3O4 nanoparticles was found to be around 10 nm and exhibit a face centered cubic (fcc) lattice geometry. Fe3O4@AT-mont. showed efficient catalytic activity for the Baeyer-Villiger oxidation of various cyclic and aromatic ketones in the presence of hydrogen peroxide as an oxidant at room temperature under solvent free conditions and exhibited conversion of up to 98%. The catalyst was magnetically recovered and recycled up to the third run without any significant loss of efficiency.
- Saikia, Pallab Kumar,Sarmah, Podma Pollov,Borah, Bibek Jyoti,Saikia, Lakshi,Saikia, Kokil,Dutta, Dipak Kumar
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- Reaction of carboxylic acid esters with phenolates in oil-in-water microemulsions based on cetyltrimethylammonium bromide
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A kinetic study of reactions of carboxylic acid esters with phenols activated with alkalis or amines in microemulsions based on cationic surfactants showed that the phenolates formed upon activation exhibit different nucleophilicity depending on the value of the negative charge on the oxygen atom, which is determined by the properties of the phenol, ionizing agent, and solvent. Pleiades Publishing, Inc., 2006.
- Mirgorodskaya,Valeeva,Kudryavtseva,Vylegzhanina,Zuev
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- Air Oxidation of Benzene to Biphenyl - A Dual Catalytic Approach
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Facile oxidative homocoupling of benzenes to the respective biphenyls is effected under moderate conditions, using air or oxygen in the presence of catalytic PdCl2 and AcOH/AcONa as solvent. The fast regeneration of the active Pd2+ species is accomplished by combining several oxygen-binding catalysts, such as Zr(IV), Mn(II), and Co(II) acetates. In this way, it is possible to increase the content of active oxygen in solution so that the rate of catalyst regeneration is faster than the rate of aggregation of the spent catalyst , Pd(0), to palladium black. The effects of various process parameters are studied and some mechanistic implications are discussed.
- Mukhopadhyay, Sudip,Rothenberg, Gadi,Lando, Gilad,Agbaria, Kasim,Kazanci, Murat,Sasson, Yoel
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- Vinyl Phosphonic Acid Functionalized Silica Polymer Nanocomposites for the Acylation of Phenol
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Abstract: In order to overcome the corrosive problems of homogeneous vinyl phosphonic acid (VPA), ordered mesoporous silica (SBA-15) is functionalized with VPA via in situ radical polymerization method to achieve SBA/VPA nanocomposites with different amou
- Amit, Dubey,Verma, Savita
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p. 724 - 733
(2022/01/13)
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- Magnetically recyclable silica-coated ferrite magnetite-K10montmorillonite nanocatalyst and its applications in O, N, and S-acylation reaction under solvent-free conditions
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Novel silica-coated ferrite nanoparticles supported with montmorillonite (K10) have been prepared successfully by using a simple impregnation method. Further, these nanoparticles were characterized by using different analytical methods like FT-IR, PXRD, EDS, and FE-SEM techniques. In addition, these nanoparticles have been explored for their catalytic activity for the O, N, and S-acylation reactions under solvent-free conditions which gave moderate to excellent yields in a much shorter reaction time. Moreover, these nanoparticles could easily be separated out from the reaction medium after the reaction completion by using an external magnetic field and have been re-used for 10 cycles without any significant loss of the catalytic activity.
- Kumar, Pushpendra,Patil, Shripad M.,Tandon, Nitin,Tandon, Runjhun
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p. 21291 - 21300
(2021/07/01)
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- Green Oxidation of Ketones to Lactones with Oxone in Water
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Cyclic ketones were quickly and quantitatively converted to 5-, 6-, and 7-membered lactones, very important synthons, by treatment with Oxone, a cheap, stable, and nonpollutant oxidizing reagent, in 1 M NaH2PO4/Na2HPO4 water solution (pH 7). Under such simple and green conditions, no hydroxyacid was formed, thus making the adoption of more complex and non-eco-friendly procedures previously developed to avoid lactone hydrolysis unnecessary. With some changes, the method was successfully applied also to water-insoluble ketones such as adamantanone, acetophenone, 2-indanone, and the challenging cycloheptanone.
- Bertolini, Valentina,Appiani, Rebecca,Pallavicini, Marco,Bolchi, Cristiano
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p. 15712 - 15716
(2021/11/01)
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- 3D-Network porous polymer bonded metalloporphyrin: An efficient and reusable catalyst for the Baeyer-Villiger oxidation
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A new, green catalyst was prepared through immobilization of metalloporphyrin on the surface of 3D-network polymer based on calix[4]resorcinarene (PC4RA), which efficiently catalyze B-V oxidation reaction using O2/benzaldehyde. The catalyst demonstrated excellent activity, which is highly potential for cyclic aliphatic ketones oxidation under mild conditions. IR spectroscopy, UV-Vis spectroscopy, thermal gravimetric analysis, energy dispersive spectroscopy and scanning electron microscopy are some of the spectroscopic methods used to characterize the new synthesized solid support.
- Hamid, Sheida,Mouradzadegun, Arash
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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supporting information
p. 5022 - 5037
(2021/05/04)
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- Preparation method of O-methoxyacetophenone
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The invention relates to a preparation method of o-methoxyacetophenone. A composite catalyst containing heteropolyacid and Lewis acid is adopted and can effectively catalyze the reaction of dimethyl ether and o-hydroxyacetophenone so that the use of dimethyl sulfate and other highly toxic substances as reaction reagents is avoided, the production cost is lowered, the discharge of highly toxic substances is reduced, and the process is enabled to be greener and more environment-friendly.
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Paragraph 0027-0028
(2021/02/10)
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- Method for preparing o-methoxyacetophenone through catalytic distillation
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The invention relates to a method for preparing o-methoxyacetophenone by catalytic distillation. A composite dehydration catalyst containing heteropoly acid and Lewis acid is adopted and can effectively catalyze the reaction of methanol and o-hydroxyacetophenone so that the use of dimethyl sulfate and other highly toxic substances as reaction reagents is avoided, the production cost is reduced, and the emission of highly toxic substances is reduced and thus the process is more environment-friendly.
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Paragraph 0026-0027
(2021/02/10)
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- Development of pH-activatable fluorescent probes for rapid visualization of metastatic tumours and fluorescence-guided surgeryviatopical spraying
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A series of pH-activatable aza-BODIPY-based fluorescent probes were developed for rapid cancer visualization and real-time fluorescence-guided surgery by harnessing topical spraying. These probes exhibited good water-solubility, a tunable pKafrom 5.0 to 7.9, and stable intense NIR emission at ~725 nm under acidic conditions.AzaB5with a pKavalue of 6.7 was able to rapidly and clearly visualize pulmonary and abdominal metastatic tumours including tiny metastases less than 2 mmviatopical spraying, further improving intraoperative fluorescence-guided resection. We believe thatAzaB5is promising as a powerful tool to rapidly delineate a broad range of malignancies and assist surgical tumour resection.
- Cao, Wenwen,Li, Xiaoxin,Wu, Peng,Xiong, Hu
-
supporting information
p. 10636 - 10639
(2021/10/19)
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- An efficient, economical and eco-friendly acylation of alcohols and amines by alum doped nanopolyaniline under solvent free condition
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We report acylation of alcohols and amines employing acetic acid as an acylating agent in solvent free condition by using alum doped nanopolyaniline (NDPANI) as a catalyst. This environmentally benign method does not use corrosive acid anhydrides and acid chlorides for acylation and does not produce waste product. Also, a non-toxic potash alum was used for doping of polyaniline rather than corrosive acids. The reaction conditions represent an advance over established method not only in omitting the need for expensive catalysts or solvents but also in shortening the reaction time significantly. The advantages of this catalyst are non-hazardous, cheap, reusable, easy to prepare and handling.
- Behera, Satyaranjan,Patra, Braja N.
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- An efficient method to prepare aryl acetates by the carbonylation of aryl methyl ethers or phenols
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Synthesis of valuable chemicals from lignin based compounds is critical for the application of biomass. Here, we develop a method of preparing aryl acetates by the carbonylation of aryl methyl ethers or phenols under low CO pressure. Good to excellent yields of aryl acetates were obtained using different substrates, and a possible reaction mechanism was proposed by conducting a series of control experiments. This method may provide a potential way for the utilization of lignin.
- Zhang, Dejin,Yang, Guoqiang,Xiong, Junping,Liu, Jia,Hu, Xingbang,Zhang, Zhibing
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p. 2683 - 2687
(2021/02/16)
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- Revisiting the Structural Evolution of Hydrotalcite-Derived Mixed Metal Oxides upon Alkali Metal Doping and Its Impact on Base Catalysis
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The structural evolution of classic coprecipitation-derived Mg?Al mixed oxide (MMO) upon doping of different alkali metals in a wide level (1–20 wt.%) was revisited. The pristine lateral MMO of aggregates into particulates, accompanied with the dramatic loss of the surface areas and the formation of aluminates. These phenomena become severer with the decrease of the atomic radius. The formation of NaAlO2 likely occurs via the gradual dealumination of the MMO, which is highly dependent on both the dopant content and the activation temperature. This leads to ultimately a new ensemble with MgO as the core decorated by NaAlO2 in the outer surfaces at high Na doping level and above 973 K. When evaluated in the base-catalyzed transesterification and acylation model reactions, the Na-doped MMO show enhanced performance and a plateau at increasing doping that might be explained by an interplay between the number and strength of strong basicity.
- Ding, Yunjie,Lin, Ronghe,Lv, Yali,Mou, Xiaoling,Yu, Qing
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- Method for promoting acylation of amine or alcohol by carbon dioxide
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The invention relates to a method for promoting acylation of amine or alcohol by carbon dioxide, which comprises the following steps of: mixing an amine compound, carboxylate or thiocarboxylate compound and a reaction solvent under the action of carbon dioxide, and reacting to obtain an amide compound, or under the action of carbon dioxide, mixing the alcohol compound, the thiocarboxylate compound and the reaction solvent [gamma]-valerolactone, and reacting to obtain the ester compound. According to the invention, under the promotion action of carbon dioxide, carboxylate or thiocarboxylate is used as an acylation reagent, and amine and alcohol are converted into amide and ester compounds in the absence of a transition metal catalyst, so that acylation reagents such as acyl chloride or anhydride with irritation and corrosivity are avoided; and the method has the advantages of simple operation, mild reaction conditions, high tolerance of substrate functional groups, strong applicability and high yield, and provides an efficient, reliable and economical preparation method for synthesis of amide and ester compounds.
- -
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Paragraph 0039-0041
(2021/05/29)
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- Tropolonate salts as acyl-transfer catalysts under thermal and photochemical conditions: Reaction scope and mechanistic insights
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Acyl-transfer catalysis is a frequently used tool to promote the formation of carboxylic acid derivatives, which are important synthetic precursors and target compounds in organic synthesis. However, there have been only a few structural motifs known to efficiently catalyze the acyl-transfer reaction. Herein, we introduce a different acyl-transfer catalytic paradigm based on the tropolone framework. We show that tropolonate salts, due to their strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
- Mai, Binh Khanh,Koenigs, Rene M.,Nguyen, Thanh Vinh,Lyons, Demelza J.M.,Empel, Claire,Pace, Domenic P.,Dinh, An H.
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p. 12596 - 12606
(2020/11/18)
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- Synthesis and anti-inflammatory activity of 2-oxo-2H-chromenyl and 2H-chromenyl-5-oxo-2,5-dihydrofuran-3-carboxylates
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Cycloaddition reaction of 4-chloro-2-oxo-2H-chromene-3-carbaldehydes (3a-g) and 4-chloro-2H-chromene-3-carbaldehydes (7a-h) with activated alkynes (4a-b) provided the 2-oxo-2H-chromenyl-5-oxo-2,5-dihydrofuran-3-carboxylates (5a-n) and 2H-chromenyl-5-oxo-2,5-dihydrofuran-3-carboxylates (8a-p). All the prepared compounds were screened for anti-inflammatory activity. In vitro anti-inflammatory activity data demonstrated that the compounds 5g, 5i, 5k-l and 8f are effective among the tested compounds against TNF-α (1.108 ± 0.002, 0.423 ± 0.022, 0.047 ± 0.001, 0.070 ± 0.002 and 0.142 ± 0.001 μM) in comparison with standard compound Prednisolone (0.033 ± 0.002 μM). Based on in vitro results, three compounds (5i, 5k and 8f) have been selected for in vivo experiments and these compounds are identified as better compounds with respect to anti-inflammatory activity in LPS induced mice model. Compound 5i was identified as potent and showed significant reduction in TNF-α and IL-6.
- Bhimapaka, China Raju,Karri, Shailaja,Kuncha, Madhusudana,Kurma, Siva Hariprasad,Sistla, Ramakrishna
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- Method for preparing p-Hydroxyacetophenone and cosmetic composition containing p-Hydroxyacetophenone
-
A disclosed method for producing p-hydroxyacetophenone includes: a first step of preparing phenylacetate; and a second step of obtaining p-hydroxyacetophenone through distillation under reduced pressure after making the phenylacetate react using an acid catalyst set in a solvent selected from a mixture of haloalkyl ethers, alkyl acetates, haloalkyl ethers and alkyl acetates.
- -
-
Paragraph 0040-0042
(2020/09/30)
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- Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
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Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
- Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7683 - 7689
(2020/04/22)
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- Environmentally benign decarboxylative: N-, O-, and S-Acetylations and acylations
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An operationally simple and general method for acetylation and acylation of a wide variety of substrates (amines, alcohols, phenols, thiols, and hydrazones) has been reported. Meldrum's acid and its derivatives have been used as an air-stable, non-volatile, cost-effective, and easy to handle acetylating/acylating agent. Easily separable byproducts (CO2 and acetone) allowed the isolation of analytically pure acetylated products without the requirement of work-up and any chromatography. This journal is
- Ghosh, Santanu,Purkait, Anisha,Jana, Chandan K.
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supporting information
p. 8721 - 8727
(2020/12/30)
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- Substrate substitution effects in the Fries rearrangement of aryl esters over zeolite catalysts
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The catalytic transformation of aryl esters to hydroxyacetophenones via Fries rearrangement over solid acids is of interest to avoid the use of corrosive and toxic Lewis and Br?nsted acids traditionally applied. Microporous zeolites are known to catalyze the reaction of simple substrates such as phenyl acetate, but their application to substituted derivatives has received limited attention. To refine structure-activity relationships, here we examine the impact of various parameters including the solvent polarity, water content, acidic properties, and framework type on the reaction scheme in the Fries rearrangement of p-tolyl acetate over common solid acids. The results confirm the importance of providing a high concentration of accessible Br?nsted acid sites, with beta zeolites exhibiting the best performance. Extension of the substrate scope by substituting methyl groups in multiple positions identifies a framework-dependent effect on the rearrangement chemistry and highlights the potential for the transformation of dimethylphenyl acetates. Kinetic studies show that the major competitive path of cleavage of the ester C-O bond usually occurs in parallel to the Fries rearrangement. The possibility of sequentially acylating the resulting phenol depends on the substrate and reaction conditions.
- Bonrath, Werner,Létinois, Ulla,Lin, Ronghe,Medlock, Jonathan,Mitchell, Sharon,Netscher, Thomas,Pérez-Ramírez, Javier,Stemmler, René T.
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p. 4282 - 4292
(2020/07/30)
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- Acylation of Phenols, Alcohols, Thiols, Amines and Aldehydes Using Sulfonic Acid Functionalized Hyper-Cross-Linked Poly(2-naphthol) as a Solid Acid Catalyst
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Abstract: The hyper-cross-linked porous poly(2-naphthol) fabricated by the Friedel–Crafts alkylation of 2-naphthol has been functionalized with sulfonic acid to obtain a solid acid catalyst. The catalyst is applied for the protection of phenol, alcohols, thiols, amines and aldehydes with acetic anhydride at room temperature. The catalytic protection using the new solid acid is featured by achieving high yield at neat condition, needing no aqueous work-up and/or chromatographic separation, and showing excellent recycling efficiency, suggesting the potential of this sulfonated porous polymers as a new protection protocol in a wide range of sustainable chemical reactions. Graphical Abstract: [Figure not available: see fulltext.].
- Kalla, Reddi Mohan Naidu,Reddy, Sirigireddy Sudharsan,Kim, Il
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p. 2696 - 2705
(2019/05/28)
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- Fe3O4@PEG core/shell nanoparticles as magnetic nanocatalyst for acetylation of amines and alcohols using ultrasound irradiations under solvent-free conditions
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Abstract: Ultrasound irradiation was used to prepare one-pot Fe3O4@PEG core/shell nanostructure for the first time. The morphology, structure, and physicochemical properties were specified by different analytical techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray powder diffraction, and vibrating sample magnetometer. For acetylation of phenols, alcohols, and amines, the synthesized Fe3O4@PEG core/shell nanoparticles were used as an efficient heterogeneous and green catalyst with acetic anhydride under sonication applying mild reaction conditions. Different electron-withdrawing and electron-donating substrates indicate a prominent yield of desired products with the merit of reusability of Fe3O4@PEG nanocatalyst and magnetic separation. Graphical Abstract: [Figure not available: see fulltext.].
- Veisi, Hojat,Nikseresht, Ahmad,Rostami, Afsaneh,Hemmati, Saba
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p. 507 - 520
(2018/10/24)
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- Preparation method for phenyl acetate compound
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The invention discloses a preparation method for a phenyl acetate compound. The preparation method comprises the following steps: taking substituted phenol shown as formula (I) and acetic anhydride asreaction raw materials, taking a sodium hydroxide aqueous solution as a solvent, and performing esterification reaction in a tubular reactor, thereby acquiring the phenyl acetate compound shown as formula (II). The reaction formula is as follows. In formula (I) and formula (II), substituent group R is hydrogen, C1-C6 alkyl, nitro, cyano group, halogen, carboxyl or C1-C12 alkoxycarbonyl. The manner of approximate plug flow tubular reaction is adopted by the invention, so that materials in tubular reaction almost are free from back mixing, mass and heat transfer efficiency is high, happening ofside reaction is obviously reduced and product yield and purity are both higher.
- -
-
Paragraph 0015; 0016; 0021-0032
(2019/04/10)
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- 4-Imidazol-1-yl-butane-1-sulfonic acid ionic liquid: Synthesis, structural analysis, physical properties and catalytic application as dual solvent-catalyst
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4-Imidazol-1-yl-butane-1-sulfonic acid (ImBu-SO3H) has been successfully synthetized and fully characterized by FT-IR and high-resolution NMR spectroscopy (1H, 13C). The “plausible” alternative structures of ImBu-SO3H were discussed on the basis of its NMR data. The ionic liquid showed interesting dual solvent-catalyst property, which was studied experimentally for the acetylation of a variety of functionalized alcohols, phenols, thiols, amines and α-tocopherol (α-CTP) as the most active form of vitamin E with acetic anhydride and which provided good yields within a short reaction time. ImBu-SO3H was successfully recycled by product extraction with an average recovered yield of 82% for 5 subsequent runs. The catalytic activity of the recycled ImBu-SO3H showed almost no loss even after five consecutive runs.
- Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie,Juan, Joon Ching
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p. 866 - 878
(2019/07/12)
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- Synthesis of phenyl esters using SiO2-SO3H catalyst in conventional heating and microwave-irradiated esterification processes
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A SiO2-SO3H amorphous catalyst containing a small surface area of 115.0 m2g-1 and 1.32 mmol H+/g was prepared from fine construction sand and sodium carbonate and sulfonated with H2SO4. In a 10% (w/w) basis, it is very efficient for catalyzing the esterification of carboxylic acids with phenol. The reaction processes were performed using conventional heating and under microwave irradiation. The yields were higher in the microwave-irradiated esterification. The catalyst could be used for three esterification sequences in both processes.
- Barbosa, Sandro L.,Ottone, Myrlene,De Freitas, Milton,Lima, Camila D.,Nelson, David L.,Clososki, Giuliano C.,Caires, Franco J.,Klein, Stanlei I.,Hurtado, Gabriela R.
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p. 3663 - 3668
(2019/05/08)
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- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- Highly-chemoselective step-down reduction of carboxylic acids to aromatic hydrocarbons: Via palladium catalysis
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Aryl carboxylic acids are among the most abundant substrates in chemical synthesis and represent a perfect example of a traceless directing group that is central to many processes in the preparation of pharmaceuticals, natural products and polymers. Herein, we describe a highly selective method for the direct step-down reduction of carboxylic acids to arenes, proceeding via well-defined Pd(0)/(ii) catalytic cycle. The method shows a remarkably broad substrate scope, enabling to direct the classical acyl reduction towards selective decarbonylation by a redox-neutral mechanism. The utility of this reaction is highlighted in the direct defunctionalization of pharmaceuticals and natural products, and further emphasized in a range of traceless processes using removable carboxylic acids under mild, redox-neutral conditions orthogonal to protodecarboxylation. Extensive DFT computations were conducted to demonstrate preferred selectivity for the reversible oxidative addition and indicated that a versatile hydrogen atom transfer (HAT) pathway is operable.
- Liu, Chengwei,Qin, Zhi-Xin,Ji, Chong-Lei,Hong, Xin,Szostak, Michal
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p. 5736 - 5742
(2019/06/18)
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- Unprecedented acetylation of phenols using a catalytic amount of magnesium powder
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The acetylation of phenols with acetic anhydride was achieved using a catalytic amount of magnesium metal powder under air and solvent-free conditions to afford corresponding phenyl acetates in excellent yield (up to 98%).
- Bajracharya, Gan B.,Shrestha, Suryaman Sama
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supporting information
p. 1688 - 1693
(2018/06/15)
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- Werner transition-metal complex (WTMC)-mediated mild and efficient chemo-selective acylation of phenols and anilines under solvent-free condition
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Werner-type transition-metal complexes (WTMC) such as [Co(NH3)5Cl]Cl2, Cu[(NH3)4]SO4, Mn(acac)3, Ni[(NH3)6]Cl2, Ni[(en)3]S2O3, and Hg[Co(SCN)4] efficiently promote the chemoselective acetylation of phenols and anilines under solvent-free condition. The results of this study clearly shows that the optimal condition for the acetylation of anilines/phenols (1 mmol) (2a–r) with acetic anhydride (1.2 mmol) in the presence of WTMC (1 mmol) and two drops of H3PO4 on heating for 10 min under solvent-free condition gives the corresponding acetanilides/phenyl acetate (3a–r) in good to excellent yield. Furthermore, the method is simple, efficient, chemoselective, and eco-friendly under solvent-free condition for the acetylation of anilines and phenols promoted by WTMC by using acetic anhydrate as the acetylating agent. The simple preparation of the catalyst, easy procedure of the acetylation reaction, and simple work-up indicate the importance of WTMC for such reactions.
- Sarief, Abdulla,Haque, SK Manirul,Feroze, Syed Mudabbir,Arifuddin, Mohammed
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p. 1104 - 1109
(2018/09/27)
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- Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and Recyclable Nanocatalyst for Acetylation of Alcohols and Amines Under Solvent-Free Conditions
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To fabricate SiO2/PDA–SO3H nanocatalyst, a suitable method is designed for the loading of sulfonic acid groups on the surface of polydopamine (PDA)-encapsulated SiO2 nanoparticles. To bridge the gap between heterogeneous and homogeneous catalysis, surface functionalization of silica gel is an elegant procedure. The morphology, structure, and physicochemical features were specified using different analytical techniques including field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FT-IR), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy (XPS), and back titration. The SiO2/PDA–SO3H nanoparticles are efficient nanocatalysts for the acetylation of many alcohols, phenols, and amines with acetic anhydride under solvent-free conditions in good to excellent yields. Moreover, the reuse and recovery of the catalyst was shown seven times without detectible loss in activity. Graphical Abstract: [Figure not available: see fulltext.]
- Veisi, Hojat,Vafajoo, Saba,Bahrami, Kiumars,Mozafari, Bita
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p. 2734 - 2745
(2018/07/30)
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- Na 2 CO 3-Catalyzed O-Acylation of Phenols for the Synthesis of Aryl Carboxylates with Use of Alkenyl Carboxylates
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Inorganic base-catalyzed O-acylation of phenol and its derivatives has been developed. The procedure provides an efficient catalysis system for the preparation of aryl carboxylates with alkenyl carboxylates as acyl reagents. The reaction proceeded smoothly by using ?-Na 2 CO 3 as the catalyst in MeCN to produce the corresponding aryl carboxylates in good to excellent yields.
- Zhou, Xiao-Yu,Chen, Xia
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supporting information
p. 2321 - 2325
(2018/10/20)
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- Synthetic method of medicine intermediate phenyl acetate
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The invention discloses a synthetic method of medicine intermediate phenyl acetate. The synthetic method adopts phenol and acetyl chloride as raw materials, adopts cyclohexane as a solvent, wherein the ratio of amount of substance of the phenol to acetyl chloride is 1 to (1.15 to 1.3), the reaction temperature is 20 DEG C, and the reaction time is 5h. The synthetic method has the advantages of moderate reaction conditions, easiness for getting raw materials, simplicity in operation, high product yield, easiness for controlling the reaction and the like, and facilitates the industrialized production.
- -
-
Paragraph 0009; 0010
(2018/04/03)
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- Reusable rhodium catalyst for the selective transvinylation of sp2-C linked carboxylic acid
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The vinyl benzoate derivatives were successfully synthesized by the transvinylation reactions that vinyl group transferred from vinyl acetate to aromatic carboxylic acids with the recoverable catalyst RhCl3·3H2O. This catalyst features air stable and tolerance of water, good reusable ability, meanwhile, shows high selectivity for aromatic carboxylic acid in the presence of phenolic hydroxyl. With this method, a variety of vinyl benzoate derivatives can be produced with up to 95% yield.
- Jiang, Ruihang,Chen, Zhangpei,Zhan, Kun,Liu, Lei,Zhou, Junjie,Ai, Yongjian,Li, Shuang,Bao, Hongjie,Hu, Ze'nan,Qi, Li,Wang, Jingting,Sun, Hong-bin
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p. 3279 - 3282
(2018/07/21)
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- A PdII Carbene Complex with Anthracene Side-Arms for π-Stacking on Reduced Graphene Oxide (rGO): Activity towards Undirected C–H Oxygenation of Arenes
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An N-heterocyclic carbene palladium(II) complex containing two anthracene side arms was immobilized on the surface of reduced graphene oxide (rGO) by π-stacking. The activity of the homogeneous analogue and the supported complex in undirected C–H acetoxylation reaction of arenes was studied. The results show that the catalytic efficiency in acetoxylation of benzene is improved in the immobilized materials compared to the homogeneous analogue. According to XPS analysis, the immobilized catalyst maintains the original oxidation state of PdII after the catalytic reaction.
- Majeed, Maitham H.,Shayesteh, Payam,Persson, Axel R.,Wallenberg, L. Reine,Schnadt, Joachim,Wendt, Ola F.
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supporting information
p. 4742 - 4746
(2018/11/27)
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- Protection of COOH and OH groups in acid, base and salt free reactions
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We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction.
- Zhu, Xiaotao,Qian, Bo,Wei, Rongbiao,Huang, Jian-Dong,Bao, Hongli
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supporting information
p. 1444 - 1447
(2018/04/12)
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- A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
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Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
- Crovak, Robert A.,Hoover, Jessica M.
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p. 2434 - 2437
(2018/02/28)
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- PREPARATION OF PHENOLIC (METH)ACRYLATES
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A method for preparation of phenolic (meth)acrylates. The method comprises contacting acetic anyhydride, a phenolic compound and (meth)acrylic acid to form a reaction mixture.
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Page/Page column 3; 4
(2018/06/12)
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- "Click Chemistry" Mediated Functional Microporous Organic Nanotube Networks for Heterogeneous Catalysis
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The synthesis of azide functional microporous organic nanotube networks (N3-MONNs) via a Friedel-Crafts hyper-cross-linking reaction is reported. Subsequently, a general method for obtaining heterogeneous catalysts through a Cu-catalyzed alkyne-azide reaction is presented. The small-molecule catalysts such as 2,2,6,6,-tetramethylpiperidine-1-oyl and 4-(N,N-dimethylamino)pyridine can be anchored into the MONNs. Owing to the hierarchically porous structure and high surface area, these catalysts show high activity in selective oxidation of alcohols and acylation reaction, respectively.
- Yu, Wei,Zhou, Minghong,Wang, Tianqi,He, Zidong,Shi, Buyin,Xu, Yang,Huang, Kun
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supporting information
p. 5776 - 5779
(2017/11/10)
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- Diazepinium perchlorate: a neutral catalyst for mild, solvent-free acetylation of carbohydrates and other substances
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Diazepinium perchlorate, an essentially neutral organic salt possessing excellent stability, has been found to be well suited for the acetylation of free as well as partially protected sugars, phenols, thiophenols, thiols and other alcohols as well as amines. The diazepinium perchlorate-catalyzed acetylation is mild, organic and solvent-free and leaves acid sensitive protecting groups such as TBDMS/TBDPS/Tr ethers and isopropylidene/benzylidene acetals present on a substrate unaffected. Regioselective hydroxyl protection in partially protected carbohydrate derivatives/polyhydroxylic compounds was possible and was proved to be a convenient time-saving alternative to the conventional synthesis of such compounds. Easy preparation of the catalyst, mild reaction conditions and an environmentally benign protocol are some of the notable features of this reaction. The results obtained on the acetylation of phenols and thiophenols could be rationalized through their local nucleophilicity index obtained from DFT calculations.
- Giri, Santosh Kumar,Gour, Rajesh,Kartha, K. P. Ravindranathan
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p. 13653 - 13667
(2017/03/11)
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- Exploring the catalytic activity of Lewis-acidic uranyl complexes in the nucleophilic acyl substitution of acid anhydrides
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The catalytic activities of several uranyl complexes, such as N,N′-disalicylidene-o-phenelyenediaminato(ethanol)dioxouranium(vi) (UO2(salophen)EtOH), bis(dibenzoylmethanato)(ethanol)dioxouranium(vi) (UO2(dbm)2EtOH), pentakis(N,N-dimethylformamide)dioxouranium(vi) ([UO2(DMF)5]2+), and tetrakis(triphenylphosphine oxide)dioxouranium(vi) ([UO2(OPPh3)4]2+), were examined in the nucleophilic acyl substitution of acid anhydrides. Among them, [UO2(OPPh3)4]2+ was the most efficient to give ethyl acetate and acetic acid from acetic anhydride (Ac2O) and ethanol, and was resistant towards decomposition during the catalytic reaction. Several nucleophiles were also subjected to the catalytic acylation reaction using acetic and pivalic anhydride. Kinetic and spectroscopic studies suggested that [UO2(OPPh3)4]2+ interacts with Ac2O to form [UO2(Ac2O)(OPPh3)3]2+. Interaction of this actual catalyst with additional Ac2O determines the rate of the overall nucleophilic acyl substitution reaction.
- Takao, Koichiro,Akashi, Shin
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p. 12201 - 12207
(2017/03/08)
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- Copper-Catalyzed C-S Bond Formation via the Cleavage of C-O Bonds in the Presence of S8 as the Sulfur Source
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Useful and applicable methods for one-pot and odorless synthesis of unsymmetrical and symmetrical diaryl sulfides via C-O bond activation are presented. First, a new efficient procedure for the synthesis of unsymmetrical sulfides using the cross-coupling reaction of phenolic esters such as acetates, tosylates, and triflates and with arylboronic acid or triphenyltin chloride as the coupling partners is reported. Depending on the reaction, S 8 /KF or S 8 /NaO t -Bu system is found to be an effective source of sulfur in the presence of copper salts and in poly(ethylene glycol) as a green solvent. Then, the synthesis of symmetrical diaryl sulfides from phenolic compounds by using S 8 as the sulfur source and NaO t -Bu in anhydrous DMF at 120 °C under N 2 is described. By these protocols, the synthesis of a variety of unsymmetrical and symmetrical sulfides become easier than the available protocols in which thiols and aryl halides are directly used for the preparation of the sulfides.
- Rostami, Abed,Rostami, Amin,Ghaderi, Arash,Gholinejad, Mohammad,Gheisarzadeh, Sajedeh
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p. 5025 - 5038
(2017/10/06)
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- Continuous Production of Biorenewable, Polymer-Grade Lactone Monomers through Sn-Β-Catalyzed Baeyer–Villiger Oxidation with H2O2
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The Baeyer–Villiger oxidation is a key transformation for sustainable chemical synthesis, especially when H2O2 and solid materials are employed as oxidant and catalyst, respectively. 4-substituted cycloketones, which are readily available from renewables, present excellent platforms for Baeyer–Villiger upgrading. Such substrates exhibit substantially higher levels of activity and produce lactones at higher levels of lactone selectivity at all values of substrate conversion, relative to non-substituted cyclohexanone. For 4-isopropyl cyclohexanone, which is readily available from β-pinene, continuous upgrading was evaluated in a plug-flow reactor. Excellent selectivity (85 % at 65 % conversion), stability, and productivity were observed over 56 h, with over 1000 turnovers (mol product per mol Sn) being achieved with no loss of activity. A maximum space–time yield that was almost twice that for non-substituted cyclohexanone was also obtained for this substrate [1173 vs. 607 g(product) kg(catalyst)?1 cm?3 h?1]. The lactone produced is also shown to be of suitable quality for ring opening polymerization. In addition to demonstrating the viability of the Sn-β/H2O2 system to produce renewable lactone monomers suitable for polymer applications, the substituted alkyl cyclohexanones studied also help to elucidate steric, electronic, and thermodynamic elements of this transformation in greater detail than previously achieved.
- Yakabi, Keiko,Mathieux, Thibault,Milne, Kirstie,López-Vidal, Eva M.,Buchard, Antoine,Hammond, Ceri
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p. 3652 - 3659
(2017/09/13)
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- Preparation of acetates catalyzed by boric acid and/or tungstophosphoric acid-modified zirconia obtained employing polyethylene glycols as pore-forming agents
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Zirconia modified with boric acid and/or tungstophosphoric acid calcined at 320 °C were prepared, characterized and used as catalysts in the production of acetates from diverse alcohols and phenols. Polyethylene glycol (PEG) of different molecular weight (400, 2000, 6000 Da) were added as low cost pore-forming agents during zirconia synthesis using zirconyl chloride as precursor and ammonium hydroxide as precipitating agent. The zirconias were impregnated with aqueous solutions of boric acid and/or tungstophosphoric acid (TPA). The borated zirconias, zirconias modified with TPA and zirconias doped with both boron and TPA were amorphous mesoporous materials with very strong acid sites, and specific surface areas SBET of around 200, 100, and 150 m2/g, respectively. The FT-IR spectra of borated zirconias exhibited the bands of boron species, while the zirconias modified with TPA presented the characteristic bands of tungstophosphate anion, and the zirconias doped with both boron and TPA showed a degradation of the TPA anion, confirmed by 31P MAS-NMR. The borated zirconias and the zirconias modified with TPA gave excellent selectivity and yield in the 2-phenylethanol esterification with acetic acid. The use of these materials allows obtaining higher or similar results than those reported in the literature. Zirconias doped with both boron and TPA gave lower values, due to the transformation of the [PW12O40]3? Keggin anion in to the [P2W21O71]6? and [PW11O39]7? species. The reactivity towards acetylation with acetic acid of different alcohols and phenols using the best catalyst was ordered according to: primary alcohols > secondary alcohols > phenols. The reactivity difference of the alcohols and phenols was correlated with the electronic density on the oxygen atom and steric effects.
- Osiglio, Lilian,Sathicq, Gabriel,Pizzio, Luis,Romanelli, Gustavo,Blanco, Mirta
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- Zirconocene-catalyzed direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio under solvent-free conditions
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A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C-Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.
- Tang, Zhi,Jiang, Qiutao,Peng, Lifen,Xu, Xinhua,Li, Jie,Qiu, Renhua,Au, Chak-Tong
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supporting information
p. 5396 - 5402
(2017/11/22)
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- Electrophilic RhI catalysts for arene H/D exchange in acidic media: Evidence for an electrophilic aromatic substitution mechanism
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A series of new rhodium (I) complexes supported by bidentate nitrogen-donor ligands with varying electronic and steric properties were synthesized in situ and evaluated for catalytic arene C–H/D activation. In trifluoroacetic acid (HTFA), these complexes are proposed to mediate H/D exchange of arene C–H/D bonds by an electrophilic aromatic substitution mechanism that involves Rh-mediated activation of HTFA (or DTFA). DFT calculations support the proposed pathway for the H/D exchange reactions.
- Webster-Gardiner, Michael S.,Piszel, Paige E.,Fu, Ross,McKeown, Bradley A.,Nielsen, Robert J.,Goddard, William A.,Gunnoe, T. Brent
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p. 381 - 388
(2016/12/16)
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- Polymer-Supported Palladium(II) Carbene Complexes: Catalytic Activity, Recyclability, and Selectivity in C?H Acetoxylation of Arenes
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Heterogeneous catalysts for selective oxidation of C?H bonds were synthesized by co-polymerization of new N-heterocyclic carbene-palladium(II) (NHC-PdII) monomers with divinylbenzene. The polymer-supported NHC-PdII-catalysed undirect
- Majeed, Maitham H.,Shayesteh, Payam,Wallenberg, L. Reine,Persson, Axel R.,Johansson, Niclas,Ye, Lei,Schnadt, Joachim,Wendt, Ola F.
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supporting information
p. 8457 - 8465
(2017/06/28)
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- S,O-Ligand-Promoted Palladium-Catalyzed C-H Functionalization Reactions of Nondirected Arenes
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Pd(II)-catalyzed C-H functionalization of nondirected arenes has been realized using an inexpensive and easily accessible type of bidentate S,O-ligand. The catalytic system shows high efficiency in the C-H olefination reaction of electron-rich and electron-poor arenes. This methodology is operationally simple, scalable, and can be used in late-stage functionalization of complex molecules. The broad applicability of this catalyst has been showcased in other transformations such as Pd(II)-catalyzed C-H acetoxylation and allylation reactions.
- Naksomboon, Kananat,Valderas, Carolina,Gómez-Martínez, Melania,álvarez-Casao, Yolanda,Fernández-Ibá?ez, M. ángeles
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p. 6342 - 6346
(2017/09/15)
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- Regioselective Baeyer-Villiger oxidation of lignin model compounds with tin beta zeolite catalyst and hydrogen peroxide
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Lignin depolymerization represents a promising approach to the sustainable production of aromatic molecules. One potential approach to the stepwise depolymerization of lignin involves oxidation of the benzylic alcohol group in β-O-4 and β-1 linkages, followed by Baeyer-Villiger oxidation (BVO) of the resulting ketones and subsequent ester hydrolysis. Towards this goal, BVO reactions were performed on 2-adamantanone, a series of acetophenone derivatives, and lignin model compounds using a tin beta zeolite/hydrogen peroxide biphasic system. XRD, 119Sn MAS NMR spectroscopy, DRUVS and XPS were used to determine tin speciation in the catalyst, the presence of both framework Sn and extra framework SnO2 being inferred. Conversion of ketones to BVO products was affected by electron donation as well as steric hindrance, 4′-methoxyacetophenone affording the highest yield of ester (81%). As the size and complexity of the ketone increased, excess hydrogen peroxide was typically needed for successful BVO. Yields of ester products derived from β-O-4 and β-1 lignin models were modest due to the formation of polymeric material stemming from direct ring hydroxylation.
- Jennings, John A.,Parkin, Sean,Munson, Eric,Delaney, Sean P.,Calahan, Julie L.,Isaacs, Mark,Hong, Kunlun,Crocker, Mark
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p. 25987 - 25997
(2017/07/07)
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- TiCl4/Et3N-Mediated Condensation of Acetate and Formate Esters: Direct Access to β-Alkoxy- and β-Aryloxyacrylates
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A methodology to build (E)-β-alkoxy- and (E)-β-aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl4/Et3N system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation.
- álvarez-Calero, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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supporting information
p. 6344 - 6347
(2016/12/23)
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