- Intramolecular propargyl transfer reaction catalyzed by electrogenerated nickel complexes
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The intramolecular transfer of the propargyl group of aryl propargyl ethers to a carbonyl group can be effected by a nickel-catalyzed electrochemical reaction. Homopropargyl alcohols with 2-hydroxyphenyl substituents can be obtained, using a magnesium anode in single compartment cells.
- Franco, Delphine,Dunach, Elisabet
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- Shape-selective oxidation of benzylic alcohols by a receptor functionalized with a dicopper(II) pyrazole complex
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A novel metallohost containing a substrate-binding site and two copper ions held by two bis-pyrazole ligand sets is described. The cavity of this molecule can bind dihydroxybenzene guests (association constants in chloroform are in the range Ka = 2000-3000 M-1). In the presence of benzylic alcohols the Cu(II) centers of the metallohost are reduced to Cu(I). During this process the alcohols are oxidized to aldehydes. Benzylic alcohols possessing phenolic hydroxyl functions are extremely effective in the reduction reaction. It is believed that they are bound in the cavity of the metallohost and are oriented in the correct position with respect to the copper centers. This results in a rate enhancement of at least 4 orders of magnitude for the oxidation reaction.
- Martens,Klein Gebbink,Feiters,Nolte
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- Indium as a reducing agent: Deprotection of 4-nitrobenzyl ethers and esters
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Indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters.
- Moody, Christopher J.,Pitts, Michael R.
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- An efficient and sustainable protocol for oxidation of alcohols to carbonyl compounds
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A simple and extremely efficient protocol is developed for oxidation of alcohols to carbonyl compounds at room temperature by using green solvent lactic acid and green oxidant H2O2. This protocol provides high conversion under catalyst free conditions. The easy work up procedure allows high selectivity and good to excellent yields of carbonyl compounds with purity. We have performed wide range of substrates in present study with primary focus on reusability of lactic acid.
- Wagh, Ravindra B.,Nagarkar, Jayashree M.
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- Oxidative deoximation to their parent carbonyl compounds with ammonium chlorochromate adsorbed on alumina
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A convenient method for the oxidative cleavage of oximes to their parent aldehydes and ketones with ammonium chlorochromate adsorbed on alumina is described.
- Zhang, Gui-Sheng,Yang, De-Hong,Chen, Mi-Feng,Cai, Kun
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- Prodrugs - Part 1. Formylphenyl esters of aspirin
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The synthesis and study of a novel series of potential prodrugs of aspirin is reported. 2-, 3- and 4-formylphenyl aspirins, as well as a series of 4-substituted 2-formylphenyl aspirins, have been prepared. A study of their alkaline hydrolysis indicates that these compounds act as true prodrugs of aspirin which hydrolyse to aspirin and the formylphenol. The rates of hydrolysis and activation parameters indicate that hydrolysis of the 2-formylphenyl esters employs an intramolecular catalytic route.
- Bowden,Huntington,Powell
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- Enantioselective precipitate of amines, amino alcohols, and amino acids via schiff base reaction in the presence of chiral ionic liquid
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Two novel chiral ionic liquids are synthesized as the chiral selector. Racemates of amines, amino alcohols, and amino acids could generate enantioselective precipitate with multicomponent self-assemblies under mild conditions. The approach allows for enan
- Wu, Datong,Cai, Pengfei,Zhao, Xiaoyong,Pan, Yuanjiang
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- Biooxidation of Primary Alcohols to Aldehydes through Hydrogen Transfer Employing Janibacter terrae
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Chemoselective oxidations still represent a challenge for chemists. Lyophilized cells of Janibacter terrae were employed for the chemoselective oxidation of primary alcohols to the corresponding aldehydes by hydrogen transfer with the use of acetaldehyde as the hydrogen acceptor. Secondary alcohol moieties were transformed at a much slower rate. The substrate spectrum encompasses substituted benzyl alcohols, whereby substrates with a substituent in the meta position were well tolerated, whereas only very small substituants were tolerated in the ortho position. Furthermore, nalkanols and allylic alcohols were transformed with good conversions. The biocatalyst was compatible with DMSO as a water miscible organic solvent up to 30 % v/v.
- Orbegozo, Thomas,De Vries, Johannes G.,Kroutil, Wolfgang
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- Homoallylic alcohols via a chemo-enzymatic one-pot oxidation-allylation cascade
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A chemo-enzymatic one-pot, two-step transformation of (hetero)-benzylic and cinnamic alcohols to yield the elongated homoallylic sec-alcohols in water in up to 96% isolated yield has been developed. The sequence comprised an enzymatic alcohol oxidation using galactose oxidase from Fusarium sp. NRRL 2903 to furnish the corresponding aldehydes, which were subjected directly to allylation via indium(0)-mediated Barbier-type coupling with allyl bromide or by addition of allylboronic acid pinacol ester. Copyright
- Fuchs, Michael,Schober, Markus,Pfeffer, Jan,Kroutil, Wolfgang,Birner-Gruenberger, Ruth,Faber, Kurt
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- A novel and efficient oxidation of benzyl alcohols to benzaldehydes with DMSO catalyzed by acids
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Oxidation of benzyl alcohols to the corresponding aldehydes was achieved by an acid catalyzed DMSO oxidation. When the oxidation was catalyzed by HBr, no side products were detected. In most cases, the yields were excellent. The oxidation rate depends on both the nature and the position of the substituents on the aromatic rings. A tentative mechanism is proposed for the oxidation.
- Li, Chunbao,Xu, Yanli,Lu, Ming,Zhao, Zhuxuan,Liu, Lanjun,Zhao, Zheyuan,Cui, Yi,Zheng, Pengwu,Ji, Xioujie,Gao, Guangjie
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- Solvent-free oxidation of alcohols with potassium persulphate in the presence of bronsted acidic ionic liquids
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An efficient conversion of alcohols to aldehydes was achieved using potassium persulphate and 3-methylimidazolinium methane sulfonate. Copyright Taylor & Francis Group, LLC.
- Chaskar,Bhandari,Patil,Sharma,Mayeker
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- Demand-based thiolate anion generation under virtually neutral conditions: Influence of steric and electronic factors on chemo- and regioselective cleavage of aryl alkyl ethers
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Thiolate anions have been generated in a "demand-based" fashion under virtually neutral conditions for chemoselective deprotection of aryl alkyl ethers. Solvents play the critical role in making the reaction effective and should have high values of ε (>30), molecular polarizabilities (>10), and DN (>27) and low values of AN (>14). However, it is the combined effect of all of these physical properties that make a particular solvent effective. The reaction rates of cleavage of various aryl alkyl ethers are dependent on the steric crowding around the O-alkyl carbon and follow the order propargyl ≈ allyl ≈ benzyl > methyl > ethyl. Electron-withdrawing substituents increase the rate of ether cleavage reaction. The influence of the steric and electronic factors have been successfully exploited for selective deprotection of aryl alkyl ethers during inter- and intramolecular competitions.
- Chakraborti, Asit K.,Sharma, Lalima,Nayak, Mrinal K.
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- Graphene oxide as a heterogeneous reagent promoted synthesis of 2-substituted 1,3-benzazoles in water
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An efficient chemical method for the synthesis of benzimidazoles, benzothiazoles, and benzoxazoles has been developed through the condensation of various aldehydes with o-phenylenediamine, o-aminothiophenol, and o-aminophenol using graphene oxide (GO) as an oxidant in water. These benzazoles are also prepared through a one-pot oxidation/condensation tandem process by reacting alcohols with 2-amino-(thio)phenol/aniline in the presence of GO in poly(ethylene glycol) as a safe media. Moreover, this carbonaceous material could be readily separated using a simple filtration.
- Khalili, Dariush,Banazadeh, Ali Reza
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- Potassium exchanged layered zirconium phosphate as base catalyst for the desilylation of phenol silyl ethers
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Layered zirconium hydrogen phosphonate exchanged with the potassium ion was found to be an efficient heterogeneous catalyst for the hydrolysis of sterically hindered phenolic silyl ethers.
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio,Rossi, Monia,Tsadjout, Andre
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- N-methyl piperidinium chlorochromate adsorbed on alumina: A new and selective reagent for the oxidation of benzylic alcohols to their corresponding carbonyl compounds
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N-Methyl piperidinium chlorochromate adsorbed on alumina oxidizes a wide variety of benzylic alcohols to the corresponding carbonyl compounds.
- Tajbakhsh, Mahmood,Ghaemi, Moosa,Sarabi, Siavosh,Ghassemzadeh, Mitra,Heravi, Majid M.
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- Practical organic solvent-free Cu(OAc)2/DMAP/TEMPO-catalyzed aldehyde and imine formation from alcohols under air atmosphere
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A highly efficient and practical organic solvent-free Cu(OAc)2/DMAP/TEMPO catalyst system for the selective aerobic oxidation of benzylic and allylic alcohols to aldehydes and phenones under an ambient air atmosphere was reported. A wide range of functional groups such as phenolic hydroxyl, amino, and methylthio are compatible with the catalyst system. The organic solvent-free aerobic oxidative imine synthesis from benzyl alcohol and amines was also achieved via the newly developed Cu(OAc)2/DMAP/TEMPO catalyst. 100 g-scale reactions for aldehyde and imine formation were achieved with over 90% yield using 0.5 mol% catalyst loading in 36 hours, presenting a potential valuable protocol for both economical and environmental considerations. This journal is
- Guan, Mingyu,Wang, Chao,Zhang, Jingyu,Zhao, Yingsheng
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- Palladium nanoparticles supported on Fe3O4/amino acid nanocomposite: Highly active magnetic catalyst for solvent-free aerobic oxidation of alcohols
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In this paper, Fe3O4 nanoparticles were coated by a number of amino acids, e.g. cysteine, serine, glycine and β-alanine, via a simple method. Because of the surface modification of the magnetic nanoparticles with amino acid, the obtained magnetic nanocomposite is able to trap palladium nanoparticles through a strong interaction between the metal nanoparticles and the functional groups of amino acids. Among the synthesized nanocomposites, Fe3O4/cysteine-Pd exhibited the highest catalytic performance and excellent selectivity in the solvent-free aerobic oxidation of various alcohols, along with high level of reusability.
- Zamani, Farzad,Hosseini, Seyed Mohsen
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- Chemoselective aryl alkyl ether cleavage by thiophenolate anion through its in situ generation in catalytic amount
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Catalytically in sutu generated alkali metal thiophenoxide in NMP (1-melhyl-2-pyrrolidinone) chemoselectively cleaves aryl alkyl elhers in high yields.
- Nayak, Mrinal K.,Chakraborti, Asit K.
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- Highly selective oxidation of alcohols using MnO2/TiO 2-ZrO2 as a novel heterogeneous catalyst
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MnO2/TiO2-ZrO2, which was synthesized by the adsorption method, demonstrated very high catalytic activity in the selective oxidation of benzyl alcohols to benzaldehydes with excellent yields and selectivity in short reaction times. The physical and chemical properties of MnO2/TiO2-ZrO2 were investigated by XRD, XRF, BET, FT-IR and SEM techniques. The influence of the catalyst support (SBA-15, ZSM-5, TiO2-ZrO2 and Y), type of metal oxide supported, method of loading and amount of manganese nitrate loading have been thoroughly investigated. Moreover, the catalyst has shown excellent reusability in the process.
- Massah, Ahmad Reza,Kalbasi, Roozbeh Javad,Azadi, Mohammad
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- Preparation and characterization of P4MVPMnO4/SBA-15 as an efficient heterogeneous oxidant: An organic-inorganic hybrid polymer
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This work is concerned about the preparation and characterization of MnO4- supported poly (4-methyl vinylpyridinium)/SBA-15 which was effectively employed as a heterogeneous oxidant for oxidation of aromatic alcohols. P4MVPMnO4/SBA-15 exhibited excellent activity and selectivity under mild and solvent-less conditions.
- Kalbasi, Roozbeh Javad,Kolahdoozan, Majid,Shahabian, Keinaz,Zamani, Farzad
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- Simple synthesis of the novel Cu-MOF catalysts for the selective alcohol oxidation and the oxidative cross-coupling of amines and alcohols
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A novel porous metal–organic framework {Cu2(bbda)0.5(Hbbda)1.5(OAc)1.5.8H2O} (UoB-5) was synthesized under ultrasound irradiation by employing a new Schiff base ligand H2bbda (4,4'(1,4-phenylene bis (azanylylidene)) bis (methanylylidene))dibenzoic acid) and was fully characterized. The microporous nature of UoB-5 was confirmed by gas-sorption measurements. This framework acted as a highly effective heterogeneous catalyst for the alcohol oxidation reaction with tert-butyl hydroperoxide (t-BuOOH) as an oxidant. The presence of coordinatively unsaturated metal sites in UoB-5 could be the reason for high performance in this reaction. Furthermore, using the long linker with the free -NC group and uncoordinated -N atom on the wall of the pores created UoB-5 an excellent candidate for the catalytic activities without activation of the framework. It was confirmed with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from benzyl alcohols and anilines. Eventually, the new Cu-MOF (UoB-5) could be an alternative catalyst as a more economically favorable and environmentally friendly in the catalysis field.
- Ghamari Kargar, Pouya,Aryanejad, Sima,Bagherzade, Ghodsieh
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- Copper(II) nanoparticles: an efficient and reusable catalyst in green oxidation of benzyl alcohols to benzaldehydes in water
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Copper(II) nanoparticles immobilized onto 3-aminopropyltriethoxysilane (APTES) supported on mesoporous silica KIT-5 nanocomposite (AK) was prepared. The APTES group on KIT-5 was manipulated as a suitable coordinating agent for copper(II) and fully characterized using FT-IR, SEM, EDX, ICP, TGA, XRD and UV–visible methods. Moreover, a quantitative description for metal–ligand interactions in the APTES-KIT-5 mesoporous silica-supported copper(II) acetate complex was assessed via quantum chemistry computations. This novel transition metal supported heterogeneous surface was used as an effective catalyst in low loading for selective oxidation of differently substituted benzylic alcohols in water, using H2O2 as oxidant to give the corresponding carbonyl compounds in high to excellent yields. This heterogeneous nanocatalyst can be recovered and reused several times without any significant loss of activity. Copyright
- Mirsafaei, Razieh,Heravi, Majid M.,Hosseinnejad, Tayebeh,Ahmadi, Shervin
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- N-Substituted 3(10H)-Acridones as Visible-Light, Water-Soluble Photocatalysts: Aerobic Oxidative Hydroxylation of Arylboronic Acids
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We disclosed a novel water-soluble photocatalyst that could promote aerobic oxidative hydroxylation of arylboronic acids to furnish phenols in excellent yields. This transformation uses visible-light irradiation under environmentally friendly conditions, that is, water-soluble catalyst, metal-free, green oxidant, room temperature.
- Xie, Hong-Yan,Han, Li-Shuai,Huang, Shan,Lei, Xiantao,Cheng, Yong,Zhao, Wenfeng,Sun, Hongbin,Wen, Xiaoan,Xu, Qing-Long
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- Porphyrin-Metalation-Mediated Tuning of Photoredox Catalytic Properties in Metal-Organic Frameworks
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Photoredox catalytic activation of organic molecules via single-electron transfer processes has proven to be a mild and efficient synthetic methodology. However, the heavy reliance on expensive ruthenium and iridium complexes limits their applications for scale-up synthesis. To this end, photoactive metal-organic frameworks (MOFs) exhibit unique advantages as novel heterogeneous photocatalytic systems, yet their utilization toward organic transformations has been limited. Here we describe the preparation and synthetic applications of four isostructural porphyrinic MOFs, namely, UNLPF-10a, -10b, -11, and -12, which are composed of free base, InIII-, SnIVCl2-, and SnIV-porphyrin building blocks, respectively. We demonstrate that the metalation with high valent metal cations (InIII and SnIV) significantly modifies the electronic structure of porphyrin macrocycle and provides a highly oxidative photoexcited state that can undergo efficient reductive quenching processes to facilitate organic reactions. In particular, UNLPF-12 exhibits both outstanding photostability and efficient photocatalytic activities toward a range of important organic transformations including aerobic hydroxylation of arylboronic acids, amine coupling, and the Mannich reaction.
- Johnson, Jacob A.,Luo, Jian,Zhang, Xu,Chen, Yu-Sheng,Morton, Martha D.,Echeverría, Elena,Torres, Fernand E.,Zhang, Jian
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- Co-immobilization of Laccase and TEMPO in the Compartments of Mesoporous Silica for a Green and One-Pot Cascade Synthesis of Coumarins by Knoevenagel Condensation
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Co-immobilization of bio- and chemocatalysts produces sustainable, recyclable hybrid systems that open new horizons for green cascade approaches in organic synthesis. Here, the co-immobilization of laccase and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) in mesoporous silica was used for the one-pot aqueous synthesis of 30 coumarin-3-carboxylate derivatives under mild conditions through the condensation of in situ oxidized 2-hydroxybenzyl alcohols and malonate derivatives. A maximum yield was obtained after incubating at pH 6.0 and 45 °C for 24 h. An efficient organic synthesis was catalyzed by the hybrid catalyst in 10 % organic solvent. More than 95 % of the initial activity of the enzyme was preserved after 10 cycles, and no significant catalyst deactivation occurred after 10 runs. This new system efficiently catalyzed the in situ aerobic oxidation of salicyl alcohols, followed by Knoevenagel condensation, which confirmed the possibility of producing efficient hybrid catalysts by co-immobilization of catalytic species in mesoporous materials.
- Mogharabi-Manzari, Mehdi,Amini, Mohsen,Abdollahi, Mohammad,Khoobi, Mehdi,Bagherzadeh, Ghodsieh,Faramarzi, Mohammad Ali
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- Cleavage or acetyl-de-alkylation of 4-methoxybenzyl (mpm) ethers using acetic acid
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Aryl (4-methoxyphenyl)methyl (MPM) ethers are cleaved by heating with acetic acid for a few hours at 90°C, producing the corresponding phenols and (4-methoxyphenyl)methyl acetate. Under the same conditions alkyl MPM ethers are transformed directly into the corresponding alkyl acetates.
- Hodgetts,Wallace
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- A practical electromediated ipso-hydroxylation of aryl and alkyl boronic acids under an air atmosphere
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An efficient electromediated aerobic ipso-hydroxylation reaction of aryl and alkyl boronic acids has been developed. Furthermore, mechanistic insight into the role of superoxide anions in this reaction has also been provided based on electrochemical studies and experimental results.
- Jiang, Hao,Lykke, Lennart,Uttrup Pedersen, Steen,Xiao, Wen-Jing,Anker Jorgensen, Karl
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- Selective Conversion of m-Hydroxybenzyl Alcohol to m-Hydroxybenzaldehide
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Pt/C-CeCl3-Bi(SO4)3 catalyst system in aqueous methanol has been found to be effective for the selective oxygen oxidation of m-hydroxybenzyl alcohol to m-hydroxybenzaldehide.
- Oi, Ryu,Takenaka, Shinji
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- Catalytic wet air oxidation of m-cresol over a surface-modified sewage sludge-derived carbonaceous catalyst
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Sewage sludge-derived carbonaceous materials (SW) treated with different kinds of acids were used as catalysts for catalytic wet air oxidation (CWAO) of m-cresol. The SW catalysts were characterized by XRF, XRD, FTIR, XPS and TPD-MS. The results showed that SW treated with HNO3 (HNO3-SW) exhibited the best catalytic activity. When the initial concentration of m-cresol was 5000 mg L-1, the conversion of m-cresol reached 99.0% with HNO3-SW after 90 min at 160 °C and 0.66 MPa oxygen. Continuous experiments were carried out for 8 d to investigate the durability and catalytic performance of HNO3-SW in CWAO reaction. Some correlation was observed between the conversion of m-cresol and the content of carboxyl groups, indicating that the carboxyl group might play a key role in determining the catalytic activity of SW catalysts in CWAO reaction. Based on the intermediate products identified by GC-MS, HPLC-MS, IC and HRMS analyses, the oxidation pathways of m-cresol in CWAO were proposed.
- Yu, Yang,Wei, Huangzhao,Yu, Li,Gu, Bin,Li, Xianru,Rong, Xin,Zhao, Ying,Chen, Lili,Sun, Chenglin
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- Size-specific catalytic activity of polymer-stabilized gold nanoclusters for aerobic alcohol oxidation in water
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Gold nanoclusters (φ = 1.3 nm) stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP NCs) readily oxidize benzylic alcohols to the corresponding aldehydes and/or carboxylic acids under ambient temperature in water. Kinetic measurement revealed that smaller Au:PVP NCs exhibit higher catalytic activity than larger (9.5 nm) homologues and, more surprisingly, than Pd:PVP NCs of comparable size (1.5 and 2.2 nm). On the basis of the marked difference in the kinetic isotope effect and activation energy between Au:PVP and Pd:PVP NCs, a reaction mechanism for alcohol oxidation catalyzed by Au:PVP NCs is proposed in which a superoxo-like molecular oxygen species adsorbed on the surface of the small Au NCs abstracts a hydrogen atom from the alkoxide. Copyright
- Tsunoyama, Hironori,Sakurai, Hidehiro,Negishi, Yuichi,Tsukuda, Tatsuya
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- Highly effective near-infrared activating tripleta-triplet annihilation upconversion for photoredox catalysis
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Organic triplet-triplet annihilation upconversion (TTA-UC) materials have considerable promise in areas as broad as biology, solar energy harvesting, and photocatalysis. However, the development of highly efficient near-infrared (NIR) light activatable TTA-UC systems remains extremely challenging. In this work, we report on a method of systematically tailoring an annihilator to attain such outstanding systems. By chemical modifications of a commonly used perylene annihilator, we constructed a family of perylene derivatives that have simultaneously tailored triplet excited state energy (T1) and singlet excited state energy (S1), two key annihilator factors to determine TTAUC performance. Via this method, we were able to tune the TTAUC system from an endothermic type to an exothermic one, thus significantly elevating the upconversion performance of NIR light activatable TTA upconversion systems. In conjunction with the photosensitizer PdTNP (10 μM), the upconversion efficiency using the optimal annihilator (100 μM) identified in this study was measured to be 14.1% under the low-power density of NIR light (100 mW/cm2, 720 nm). Furthermore, using such a low concentration of perylene derivative, we demonstrated that the optimal TTA-UC pair developed in our study can act as a highly effective light wavelength up-shifter to enable NIR light to drive a photoredox catalysis that otherwise requires visible light. We found that such an NIR driven method is highly effective and can even surpass directly visible light driven photoredox catalysis. This method is important for photoredox catalysis as NIR light can penetrate much deeper in colored photoredox catalysis reaction solutions, especially when done in a large-scale manner. Furthermore, this TTA-UC mediated photoredox catalysis reaction is found to be outdoor sunlight operable. Thus, our study provides a solution to enhance NIR activatable organic upconversion and set the stage for a wide array of applications that have previously been limited by the suboptimal efficiency of the existing TTA upconversion materials.
- Huang, Ling,Wu, Wenting,Li, Yang,Huang, Kai,Zeng, Le,Lin, Wenhai,Han, Gang
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- Chromium containing Fe3O4/polyacrylonitrile-ethylenediamine as a magnetically recoverable catalyst for alcohol oxidation
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A new chromium containing Fe3O4/polyacrylonitrile-ethylenediamine has been prepared through in situ polymerization of acrylonitrile onto the surface of magnetic nanoparticles. The polymer magnetic nanocomposite was utilized for the oxidation of a number of aromatic alcohols as a reusable catalyst. The corresponding aldehydes were obtained in high yields within short reaction time under mild conditions.
- Heidarnezhad, Arash,Zamani, Farzad
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- Metal-Free Electrocatalytic Aerobic Hydroxylation of Arylboronic Acids
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Hydroxylation of arylboronic acids to aryl alcohols was realized by a scalable electrocatalytic method. The present electrochemical hydroxylation employs low-cost methyl viologen as an organic cathodic electrocatalyst and involves O2 as a green and sustainable reactant. The electrochemical kinetic studies shown here can be a powerful tool to gain rich mechanistic and kinetic information and thus an in-depth understanding of the electrocatalytic mechanism.
- Luo, Jian,Hu, Bo,Sam, Alyssa,Liu, T. Leo
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- A mild and efficient method for the selective cleavage of tert-butyldimethylsilyl ethers to alcohols
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A mild and efficient method for the selective deprotection of primary allylic and homoallylic, primary benzylic and aryl tert-butyldimethylsilyl (TBDMS) ethers has been established using a combination of H2O and DMSO at 90°C. All other primary and secondary TBDMS ethers remained unaffected under the reaction condition. The method is very effective in deprotection of TBDMS ethers in the presence of other sensitive functional groups.
- Maiti, Gourhari,Roy, Subhas Chandra
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- Radiation chemical oxidation of benzaldehyde, acetophenone, and benzophenone
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Radiation chemical reactions of ·OH, O·-, and SO4·- with benzaldehyde, acetophenone, and benzophenone have been studied using both pulse and steady-state radiolysis techniques. The observed rates for the ·OH addition (k = (2.6-8.8)×109 M-1 s-1) are higher than those found for the SO4·- reaction (k = (0.7-4.0)×109 M-1 s-1). The rate for the reaction of O·- with benzaldehyde is higher than that found for ·OH, while a reverse trend is observed in the case of the two ketones. Optical absorption spectra of the intermediate transients formed in the reactions of ·OH and SO4·- with all three compounds are similar with a peak around 370-380 nm. The absorption spectra from the O·- reaction have shown a major peak at 310 nm and are somewhat different from those obtained in the reaction of ·OH. The yields of the phenolic products formed in the reaction of ·OH with benzaldehyde and acetophenone in the presence of 0.1 mM ferricyanide corresponded to only 30% and 50% ·OH yields, respectively. Benzoic acid is a major product formed with benzaldehyde in the reaction of ·OH as well as SO4·- with G values of 2.1 and 1.3 per 100 eV, respectively. The formation of the exocyclic OH adduct is a major pathway in the reactions of ·OH (by addition) and of SO4·- from hydrolysis of the initially formed radical cation (k = 2.4×104 s-1) with benzaldehyde. The exocyclic OH adduct undergoes disproportionation to give benzoic acid. The formation of the exocyclic OH adduct of acetophenone is possibly hindered owing to the bulky COCH3 group.
- Sharma,Mudaliar,Rao,Mohan,Mittal
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- Catalyst-Controlled Selectivity in Oxidation of Olefins: Highly Facile Success to Functionalized Aldehydes and Ketones
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The attractive challenge in green chemistry is exploring novel heterogeneous catalyst system for catalyst-controlled product selectivity for oxidation of olefins. Hence, we proposed efficient and green catalytic methods for the selective synthesis of alde
- Shen, Chao,Sun, Nabo,Wu, Huizhen,Xu, Hao,Yu, Wenbo,Zheng, Kai
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- A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
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A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
- You, Shengyong,Zhang, Rongli,Cai, Mingzhong
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p. 1962 - 1970
(2021/01/25)
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- Building a Pyrazole–Benzothiadiazole–Pyrazole Photosensitizer into Metal–Organic Frameworks for Photocatalytic Aerobic Oxidation
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Charge separation plays a crucial role in regulating photochemical properties and therefore warrants consideration in designing photocatalysts. Metal–organic frameworks (MOFs) are emerging as promising candidates for heterogeneous photocatalysis due to their structural designability and tunability of photon absorption. Herein, we report the design of a pyrazole–benzothiadiazole–pyrazole organic molecule bearing a donor–acceptor–donor conjugated π-system for fast charge separation. Further attempts to integrate such a photosensitizer into MOFs afford a more effective heterogeneous photocatalyst (JNU-204). Under visible-light irradiation, three aerobic oxidation reactions involving different oxygenation pathways were achieved on JNU-204. Recycling experiments were conducted to demonstrate the stability and reusability of JNU-204 as a robust heterogeneous photocatalyst. Furthermore, we illustrate its applications in the facile synthesis of pyrrolo[2,1-a]isoquinoline-containing heterocycles, core skeletons of a family of marine natural products. JNU-204 is an exemplary MOF platform with good photon absorption, suitable band gap, fast charge separation, and extraordinary chemical stability for proceeding with aerobic oxidation reactions under visible-light irradiation.
- Jin, Ji-Kang,Wu, Kun,Liu, Xin-Yi,Huang, Guo-Quan,Huang, Yong-Liang,Luo, Dong,Xie, Mo,Zhao, Yifang,Lu, Weigang,Zhou, Xiao-Ping,He, Jian,Li, Dan
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supporting information
p. 21340 - 21349
(2021/12/17)
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- Application of Electron-Rich Covalent Organic Frameworks COF-JLU25 for Photocatalytic Aerobic Oxidative Hydroxylation of Arylboronic Acids to Phenols
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Visible-light-driven organic reactions are environmentally friendly green chemical transformations among which photosynthetic oxidative hydroxylation of arylboronic acids to phenols has attracted increasing research interest during the very recent years. Given the efficiency and reusability of heterogeneous catalysts, COF-JLU25, an electron-rich COF-based photocatalyst constructed by integrating electron-donating blocks 1,3,6,8-tetrakis(4-aminophenyl)pyrene (PyTA) and 4-[4-(4-formylmethyl)-2,5-dimethoxyphenyl] benzaldehyde (TpDA), was selected as a photocatalyst for the oxidative hydroxylation of arylboronic acids. In our studies, COF-JLU25 demonstrated excellent photocatalytic activity with high efficiency, robust reusability, and low catalyst loading, showcasing an application potential of previously underexplored COF-based photocatalyst composed solely of electron-rich units.
- Xiao, Guangjun,Li, Wenqian,Chen, Tao,Hu, Wei-Bo,Yang, Hui,Liu, Yahu A.,Wen, Ke
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supporting information
p. 3986 - 3991
(2021/03/29)
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- Transforming a Fluorochrome to an Efficient Photocatalyst for Oxidative Hydroxylation: A Supramolecular Dimerization Strategy Based on Host-Enhanced Charge Transfer
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The development of non-covalent synthetic strategy to fabricate efficient photocatalysts is of great importance in theranostic and organic materials. Herein, a fluorochrome N,N′-dimethyl 2,5-bis(4-pyridinium)thiazolo[5,4-d]thiazolediiodide (MPT) was transformed into an efficient photocatalyst through supramolecular dimerization in the cavity of cucurbit[8]uril (CB[8]). The host-enhanced charge transfer interaction within the supramolecular dimer 2MPT-CB[8] dramatically promoted intersystem crossing to produce triplet. In addition, the staggered conformation of 2MPT-CB[8] facilitated the energy transfer and electron transfer of the triplet. As a result, 2MPT-CB[8] could serve as a high-efficiency photocatalyst for the oxidative hydroxylation of arylboronic acids. This supramolecular dimerization strategy enriches the supramolecular engineering of functional π-systems. It is anticipated that this strategy can be extended to fabricate various π-systems with tailor-made functions.
- Tang, Bohan,Xu, Weiquan,Xu, Jiang-Fei,Zhang, Xi
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supporting information
p. 9384 - 9388
(2021/03/22)
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- Catalytic study of the copper-based magnetic nanocatalyst on the aerobic oxidation of alcohols in water
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A copper-based magnetic nanocatalyst has been prepared by co-precipitation method and characterized by FESEM, EDS, TEM, XRD, XRF, ICP–OES, FTIR, and BET analysis. This new nanocatalyst displays a good activity toward the aerobic oxidation of a wide range of alcohols in water. Moreover, it is recyclable up to five following runs by simple filtration without any significant loss of its catalytic activity.
- Dehkordi, S. Saeid Saei,Albadi, Jalal,Jafari, Abbas Ali,Samimi, Heshmat Allah
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p. 2527 - 2538
(2021/03/24)
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- La(OH)3nanoparticles immobilized on Fe3O4@chitosan composites as novel magnetic nanocatalysts for sonochemical oxidation of benzyl alcohol to benzaldehyde
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This work introduces an eco-friendly method for immobilization of La(OH)3 nanoparticles on modified Fe3O4 nanoparticles. The structural and morphological characteristics of the nanocatalyst were determined by various analytical techniques including, FT-IR, EDS, FESEM, VSM and XRD. The catalytic efficiency of the Fe3O4@Cs/La(OH)3 composite as a heterogeneous nanocatalyst was evaluated by selective oxidation of benzylic alcohols to aldehydes. The optimum reaction conditions including time, temperature, nanocatalyst dosage, and solvent were investigated for ultrasound-assisted oxidation processes. Furthermore, the magnetic nanocatalyst was recovered up to seven times without considerable activity loss. Furthermore, the proposed nanocomposite had a remarkable effect on reducing the reaction time and enhancing the yield. This journal is
- Fadaeian, Manoochehr,Ghomi, Javad Safaei,Javidfar, Fereshteh
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p. 35988 - 35993
(2021/12/02)
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- Decarboxylative Hydroxylation of Benzoic Acids
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Herein, we report the first decarboxylative hydroxylation to synthesize phenols from benzoic acids at 35 °C via photoinduced ligand-to-metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation. The aromatic decarboxylative hydroxylation is synthetically promising due to its mild conditions, broad substrate scope, and late-stage applications.
- Ritter, Tobias,Su, Wanqi,Xu, Peng
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supporting information
p. 24012 - 24017
(2021/10/06)
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- Biocatalytic Cross-Coupling of Aryl Halides with a Genetically Engineered Photosensitizer Artificial Dehalogenase
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Devising artificial photoenzymes for abiological bond-forming reactions is of high synthetic value but also a tremendous challenge. Disclosed herein is the first photobiocatalytic cross-coupling of aryl halides enabled by a designer artificial dehalogenase, which features a genetically encoded benzophenone chromophore and site-specifically modified synthetic NiII(bpy) cofactor with tunable proximity to streamline the dual catalysis. Transient absorption studies suggest the likelihood of energy transfer activation in the elementary organometallic event. This design strategy is viable to significantly expand the catalytic repertoire of artificial photoenzymes for useful organic transformations.
- Fu, Yu,Huang, Jian,Wu, Yuzhou,Liu, Xiaohong,Zhong, Fangrui,Wang, Jiangyun
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supporting information
p. 617 - 622
(2021/02/03)
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- Aqueous extract of Shikakai; a green solvent for deoximation reaction: Mechanistic approach from experimental to theoretical
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This article describes a green method for regeneration of carbonyl compounds from various types of oxime compounds under microwave radiation using I2 and aqueous saponin solution isolated from Shikakai. Effect of saponin concentration on yield percentage of regenerated different types of carbonyl compounds has been discussed. A correlation has been established between saponin concentration and yield percentage of carbonyl compounds. Mechanism of interaction between oxime and saponin is established on the basis of density functional theory. In addition, the quantum chemical parameters for saponin have been determined. Furthermore, electrostatic surface analysis of the saponin is carried out to confirm the mechanism of interaction between saponin and oximes.
- Das, Debadutta,Kudrat-E-Zahan, Md.,Mahal, Ahmed,Mohapatra, Ranjan K.,Parhi, Pankaj K.,Sahu, Raghaba,Sarangi, Ashish K.
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- Solvent-free, microwave assisted oxidation of alcohols with 4-hydroxypyridinium chlorochromate functionalized silica gel
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4-Hydroxypyridinium chlorochromate functionalized silica gel was found to be an efficient and reusable oxidant for the very fast oxidation of primary and secondary alcohols to the corresponding carbonyl compounds under solventfree conditions and microwave irradiation in excellent yields.
- AHMADI, Sayed Ali,GHALEHBANDI, Shermineh Sadat,GHAZANFARI, Dadkhoda,SHEIKHHOSSEINI, Enayatollah
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p. 283 - 289
(2020/10/06)
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- Photo-oxidation coupled Kabachnik-Fields and Bigenelli reactions for direct conversion of benzyl alcohols to α-aminophosphonates and dihydropyrimidones
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A tandem one-pot solvent free approach for the direct conversion of benzyl alcohols to α-amino phosphonates and dihydropyrimidones is reported. The method relies on a metal free photo-oxidation of benzyl alcohols to benzaldehydes under UV irradiation using ammonium perchlorate followed by Kabachnik-Fields and Biginelli reactions. The reaction conditions are moderate and metal free with good substrate scope. The control experiments were performed to investigate the role of the ammonium perchlorate and molecular oxygen as oxidants. The quenching experiments in the presence of TEMPO and other radical quenchers suggest radical based mechanism.
- Ali, Gazunfor,Ara, Tabassum,Dangroo, Nisar A.,Naqvi, Tahira,Raheem, Shabnam,Rizvi, Masood Ahmad
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p. 195 - 202
(2020/04/01)
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- Efficient solvent- And temperature-tuned access to aldoxime ethers and phenolic functions by Pd-catalyzed C-O cross-coupling of aldoximes with aryl bromides and bromo-chalcones
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A single method with a functionality switching option was developed for the first time for the Pd-catalyzed C-O cross-coupling of aryl bromides and bromo-chalcones with aldoximes. The ligand tBuXPhos (L2) was found to be an effective supporting ligand for the Pd-catalyzed coupling of aldoximes with bromo coupling partners. The functionality switching from oxime ethers to a phenolic or hydroxy group was driven by solvent or temperature. This method offers the products in good to excellent yields in short reaction times.
- Reeta,Rangarajan,Kaushik, Kumar,Singh, Rishi Pal,Singh, Manjula,Singh, Raj Pal
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supporting information
p. 1326 - 1336
(2020/02/11)
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- Production of (S)-β-Nitro Alcohols by Enantioselective C?C Bond Cleavage with an R-Selective Hydroxynitrile Lyase
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Hydroxynitrile lyase (HNL)-catalysed stereoselective synthesis of β-nitro alcohols from aldehydes and nitroalkanes is considered an efficient biocatalytic approach. However, only one S-selective HNL—Hevea brasiliensis (HbHNL)—exists that is appropriate for the synthesis of (S)-β-nitro alcohols from the corresponding aldehydes. Further, synthesis catalysed by HbHNL is limited by low specific activity and moderate yields. We have prepared a number of (S)-β-nitro alcohols, by kinetic resolution with the aid of an R-selective HNL from Arabidopsis thaliana (AtHNL). Optimization of the reaction conditions for AtHNL-catalysed stereoselective C?C bond cleavage of racemic 2-nitro-1-phenylethanol (NPE) produced (S)-NPE (together with benzaldehyde and nitromethane, largely from the R enantiomer) in up to 99 % ee and with 47 % conversion. This is the fastest HNL-catalysed route known so far for the synthesis of a series of (S)-β-nitro alcohols. This approach widens the application of AtHNL for the synthesis not only of (R)- but also of (S)-β-nitro alcohols from the appropriate substrates. Without the need for the discovery of a new enzyme, but rather by use of a retro-Henry approach, it was used to generate a number of (S)-β-nitro alcohols by taking advantage of the substrate selectivity of AtHNL.
- Rao, D. H. Sreenivasa,Padhi, Santosh Kumar
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p. 371 - 378
(2019/01/08)
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- Coenzyme A-Conjugated Cinnamic Acids – Enzymatic Synthesis of a CoA-Ester Library and Application in Biocatalytic Cascades to Vanillin Derivatives
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We present a bioorthogonal method for the ligation of coenzyme A (CoA) with cinnamic acids. The reaction, which is the initial step in the biosynthesis of a multitude of bioactive secondary metabolites, is catalyzed by a promiscuous plant ligase and yields CoA conjugates with different functionalization in high purity and without formation of by-products. Its applicability in biosynthetic cascades is shown for the direct transformation of cinnamic acids into natural benzaldehydes (like vanillin) or artificial derivatives (e. g. ethylvanillin). (Figure presented.).
- Dippe, Martin,Bauer, Anne-Katrin,Porzel, Andrea,Funke, Evelyn,Müller, Anna O.,Schmidt, Jürgen,Beier, Maria,Wessjohann, Ludger A.
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p. 5346 - 5350
(2019/11/29)
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- A mild aerobic oxidation of benzyl alcohols and oxidative decarboxylation of phenylacetic acids by cellulose-supported Ag-Ag2S nanoparticles
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Synthesis, characterization and catalytic activity of Ag-Ag2S nanoparticles supported on environmentally benign cellulose matrix has been discussed. The nanoparticles carry out controlled oxidation of benzylic alcohols to aldehydes at room temperature. Same nanoparticles also carry out oxidative decarboxylation of phenylacetic acid and decarboxylation of mandelic acid derivatives to corresponding aldehydes under comparatively milder conditions. Stability and recyclability of the catalyst has been studied. The advantages of the catalyst developed in this work over other previous reports include room temperature or comparatively low temperature reaction, shorter reaction times, no requirement of stoichiometric oxidant or ligands, use of green solvents, functional group tolerance, and recyclability.
- Hussain, Farhaz Liaquat,Suri, Mrinaly,Namdeo, Ashutosh,Borah, Geetika,Dutta, Dipanka,Goswami, Tridip,Pahari, Pallab
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- A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium
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A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study.
- Thiruvengetam, Prabaharan,Chakravarthy, Rajan Deepan,Chand, Dillip Kumar
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p. 123 - 133
(2019/07/19)
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- Synthesizing method of 4-(4-bromo-3-aldehyde-phenoxyl)-benzonitrile
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The invention provides a synthesizing method of 4-(4-bromo-3-aldehyde-phenoxyl)-benzonitrile. The synthesizing method comprises the following steps of using 3-methylphenol as the starting raw material, and reacting with acid anhydride to prepare 3-methyl-benzene ester; enabling the 3-methyl-benzene ester and sulfonyl chloride to react, so as to prepare a mixture of 3-chloromethyl-benzene ester and3-dichloromethyl-benzene ester; adding ulotropine, and hydrolyzing, so as to obtain 3-hydroxyl-benzaldehyde; performing brominating reaction, so as to obtain 4-bromo-3-hydroxyl-benzaldehyde; adding 4-fluorobenzonitrile, and performing condensation reaction, so as to obtain the 4-(4-bromo-3-aldehyde-phenoxyl)-benzonitrile. The synthesizing method has the advantages that the prices of the reactionraw materials are low, the obtaining is easy, the reaction steps are fewer, the production cost is low, the technology is simple, the product purity is high and reaches 99.0% or above, and the synthesizing method is suitable for industrialized production.
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Paragraph 0025; 0059; 0065-0068; 0069-0073
(2019/01/14)
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- Dichlorophenobarbital: An efficient and selective reagent for deoximation of oximes to the carbonyl compounds
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A simple, fast and efficient procedure for the cleavage of a wide of range ketoximes and al-doximes to the corresponding compounds using a safe and low-cost reagent, N,N′-dichlorophenobarbital, under mild reaction conditions at room temperature is described.
- Shiri, Azam,Khoramabadi-Zad, Ahmad,Esmaili-Nezhad, Fateme
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p. 833 - 837
(2018/11/06)
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- A synthesis method of benzaldehyde (by machine translation)
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The invention provides a synthesis method of benzaldehyde, the method comprises: (1) the hydroxy benzoic acid as the raw material, N, N - dimethyl formamide or N, N - dimethyl acetamide as catalyst, in the presence of acyl, to carry out the following formula 1 shown between the acyl chloride reaction in order to produce hydroxy benzoyl chloride; and (2) in the presence of hydrogen, in the presence of a catalyst, in the step (1) the resulting hydroxy benzoyl chloride of the following carried out 2 is shown between the hydrogenation reduction reaction of benzaldehyde. According to the method of the present invention mild condition, few steps, synthetic high yield, production process has no waste water, compared with the traditional method, the advantages of environmental protection, energy-saving high-efficiency, small equipment footprint, the product quality is in quality. [Formula 1] [Formula 2] (by machine translation)
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Paragraph 0028; 0031-0032; 0037-0038; 0043-0044; 0049-0134
(2018/09/21)
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- Deprotection of durable benzenesulfonyl protection for phenols — efficient synthesis of polyphenols
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A robust protection method for phenol was demonstrated by the use of durable benzenesulfonyl group, which survives various harsh reaction conditions using Grignard reagent, organolithium reagent, metal alkoxide, phosgene, mineral, and Lewis acids. A facile deprotection condition utilizing pulverized KOH (5 equiv) and t-BuOH (10 equiv) in hot toluene makes this protocol as a practical method, which can be applied to the multistep synthesis of biologically and medicinally important polyphenol compounds.
- Alam, Mohammad Shariful,Koo, Sangho
-
supporting information
p. 247 - 254
(2018/01/08)
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- Temperature-Directed Biocatalysis for the Sustainable Production of Aromatic Aldehydes or Alcohols
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The biosynthesis of aromatic aldehydes and alcohols from renewable resources is currently receiving considerable attention because of an increase in demand, finite fossil resources, and growing environmental concerns. Here, a temperature-directed whole-cell catalyst was developed by using two novel enzymes from a thermophilic actinomycete. Ferulic acid, a model lignin derivative, was efficiently converted into vanillyl alcohol at a reaction temperature at 30 °C. However, when the temperature was increased to 50 °C, ferulic acid was mainly converted into vanillin with a productivity of 1.1 g L?1 h?1. This is due to the fact that the redundant endogenous alcohol dehydrogenases (ADHs) are not active at this temperature while the functional enzymes from the thermophilic strain remain active. As the biocatalyst could convert many other renewable cinnamic acid derivatives into their corresponding aromatic aldehydes/alcohols, this novel strategy may be extended to generate a vast array of valuable aldehydes or alcohols.
- Ni, Jun,Gao, Yan-Yan,Tao, Fei,Liu, Hong-Yu,Xu, Ping
-
supporting information
p. 1214 - 1217
(2018/01/27)
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- A gold catalytic oxidation of benzyl alcohol synthesis method (by machine translation)
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The present invention provides a kind of organic synthesis in the oxidation of benzyl alcohol synthesis method, the reaction formula is as follows, in the formula 1 containing different substituents is benzyl alcohol, in the formula 2 is triphenylcarbinol compound. The required reaction of gold catalyst is Ph3 PAuCl, Ph3 PAuNTf2 , HAuCl4 , NaAuCl4 , Ph3 PAuOTf, Ph3 PAuSbF6 , IPrAuCl, gold. The required reaction medium is: solvent-free, toluene, are three-toluene, 1, 2 - dichloroethane, tetrahydrofuran, acetonitrile, acetone. The reaction implementing microwave heating of reactor, the method of the invention the oxidizing agent triphenylcarbinol for commercial products, cheap, and simple experimental operation, substrate and wide range of application. (by machine translation)
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Paragraph 0034-0037; 0041; 0042-0044
(2017/08/25)
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- Palladium-Catalyzed Formylation of Aryl Iodides with HCOOH as CO Source
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A facile and practical method for the synthesis of aromatic aldehydes by palladium-catalyzed reductive carbonylation starting from aryl iodides and HCOOH is described. Compared to the known formylation procedure, HCOOH serves not only as the most convenient and environmental-friendly C1 source but also as the reviving agent in the reductive elimination process of a Pd-catalyst. Furthermore, this procedure is also applied successfully to the modification of natural products, such as vindoline, tabersonin, and vincamine, to obtain the corresponding products in good yields.
- Sun, Guanglong,Lv, Xue,Zhang, Yinan,Lei, Min,Hu, Lihong
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supporting information
p. 4235 - 4238
(2017/08/23)
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- One-pot Three-component Synthesis of Furan-based Heterocycles from Benzyl Halides
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An efficient and a novel approach for the synthesis of furochromene and furopyran scaffolds are described. Benzyl halides undergo oxidation in Kornblum conditions to give the corresponding aldehydes, which in turn undergo [4?+?1] cycloaddition reaction with isocyanide to afford the corresponding furan derivatives. The significant attraction of this protocol is simple procedure, mild reaction condition, and good yield.
- Beerappa, Mallappa,Shivashankar, Kalegowda
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p. 2197 - 2205
(2017/07/25)
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- Novel CuCl2-cryptand-[2.2.Benzo] complex: A base free and oxidant free catalyst for Ipso-Hydroxylation of aryl/heteroaryl-boronic acids in water at room temperature
-
A novel cryptand and its copper complex was synthesised, which found to have enormous catalytic activity towards ipso-hydroxylation of aryl or heteroarylboronic acids and esters in water without using H2O2 or other oxidising agent and base at room temperature. This newly developed method efficiently converts aryl boronic acids and esters as well as heteroaryl boronic acids to their corresponding phenols with high yields within a very short reaction time. This protocol has found to be well-matched with a wide variety of functional groups. High yields, very short reaction time, easy separation, recyclability up to 6th time are the advantages of this method.
- Bora, Sankar Jyoti,Chetia, Bolin
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supporting information
p. 52 - 56
(2017/09/19)
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- Highly efficient and green oxidation of alkanes and alkylaromatics with hydrogen peroxide catalysed by silver and vanadyl on mesoporous silica-coated magnetite
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A heterogeneous catalyst (FeSi/Ag/VO) based on silver and vanadyl as active sites and mesoporous silica-coated nanospheres of magnetite (Fe3O4@m-SiO2) as support was successfully prepared by deposition of Ag nanoparticles and the covalent grafting of vanadyl(IV) acetylacetonate on Fe3O4@m-SiO2. The catalyst exhibited excellent activity for the oxidation of alkanes, benzene and alkylaromatics using green oxidant H2O2 and oxalic acid in acetonitrile at 60?°C.
- Nouri, Seyed Hadi,Hosseini-Monfared, Hassan
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- Bimetallic Cu-Pd Nanoparticles Supported on Bio-silica as an Efficient Catalyst for Selective Aerobic Oxidation of Benzylic Alcohols
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A new bimetallic heterogeneous catalyst consisting of copper and palladium nanoparticles supported on bio-silica is presented. The use of TEMPO as co-catalyst allowed the aerobic oxidation of primary benzylic alcohols into the corresponding aldehydes with excellent selectivity and good activity. The methodology could be applied to the oxidation of allylic and heterobenzylic alcohols. The catalyst is easy to prepare from commercial starting materials and can be recovered and reused without apparent loss of activity.
- Buxaderas, Eduardo,Graziano-Mayer, Marilyn,Volpe, María Alicia,Radivoy, Gabriel
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p. 1387 - 1393
(2017/03/11)
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- N,N-Dicarboxymethyl hydrazine: An old but neglected reagent for chemoselective derivatization of carbonyl compounds
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N,N-Dicarboxymethyl hydrazine (DCMH) was found to be a chemoselective derivatization reagent of carbonyl compounds and its potential applications in organic synthesis was investigated for the first time. DCMH could be employed as a chemoselective protective reagent of aldehydes and gave the parent aldehydes in satisfactory yields. In proof-of-concept systems, DCMH could play the role of a scavenger to remove aldehydes in the presence of ketones. It was also used as a tagging reagent in the selective isolation of aldehyde from the complex mixture.
- Zhen, Maomin,Peng, Yanqing
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supporting information
p. 3443 - 3449
(2016/04/09)
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- MAGNETICALLY SEPARABLE IRON-BASED HETEROGENEOUS CATALYSTS FOR DEHYDROGENATION OF ALCOHOLS AND AMINES
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The present invention discloses an iron-based nitrogen doped graphene catalyst, process for preparation thereof and use of said catalyst in oxidant-free catalytic dehydrogenation of alcohols and amines to the corresponding carbonyl compounds, amines and N-heterocylic compounds with extraction of molecular hydrogen as the only by-product.
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Page/Page column 15; 16; 17
(2016/12/22)
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- Selective Enzymatic Transformation to Aldehydes in vivo by Fungal Carboxylate Reductase from Neurospora crassa
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The enzymatic reduction of carboxylic acids is in its infancy with only a handful of biocatalysts available to this end. We have increased the spectrum of carboxylate-reducing enzymes (CARs) with the sequence of a fungal CAR from Neurospora crassa OR74A (NcCAR). NcCAR was efficiently expressed in E. coli using an autoinduction protocol at low temperature. It was purified and characterized in vitro, revealing a broad substrate acceptance, a pH optimum at pH 5.5–6.0, a Tmof 45 °C and inhibition by the co-product pyrophosphate which can be alleviated by the addition of pyrophosphatase. The synthetic utility of NcCAR was demonstrated in a whole-cell biotransformation using the Escherichia coli K-12 MG1655 RARE strain in order to suppress overreduction to undesired alcohol. The fragrance compound piperonal was prepared from piperonylic acid (30 mM) on gram scale in 92 % isolated yield in >98% purity. This corresponds to a productivity of 1.5 g/L/h. (Figure presented.).
- Schwendenwein, Daniel,Fiume, Giuseppe,Weber, Hansj?rg,Rudroff, Florian,Winkler, Margit
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p. 3414 - 3421
(2016/11/13)
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- Exploring the synthetic applicability of a new carboxylic acid reductase from Segniliparus rotundus DSM 44985
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A new carboxylic acid reductase (CAR) gene from Segniliparus rotundus DSM 44985 was overexpressed in Escherichia coli. The recombinant enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids. Especially, it effectively reduced 4-hydroxybenzoic acid (8a) and 4-nitrobenzoic acid (19a), toward which the known Nocardia CAR exhibited no or little activity. The recombinant E. coli cells co-expressing the Segniliparus CAR and Nocardia PPTase genes catalyzed the reductions of vanillic acid (20a) and 3,4-dihydroxyphenylacetic acid (25a) to give vanillyl alcohol (20c) and 3-hydroxytyrosol (25c) with high yield, respectively. The endogenous aldehyde reductases of E. coli should be responsible for the further reduction of the produced aldehydes. These results demonstrated that Segniliparus CAR was a useful addition to the biocatalyst tool-box for the reduction of carboxylic acids and might find applications in the synthesis of valuable bio-based chemicals from renewable resources.
- Duan, Yitao,Yao, Peiyuan,Chen, Xi,Liu, Xiangtao,Zhang, Rui,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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- Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism
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The second-order rate constants for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (4a-4f) and Y-substituted-phenyl-4-nitrobenzenesulfonates (5a-5f) with N3- ion have been measured spectrophotometrically. The reactions of 4a-4f proceed through S-O and C-O bond fission pathways competitively. Fraction of the S-O bond fission decreases rapidly as the substituent X in the benzenesulfonyl moiety changes from an electron-withdrawing group to an electron-donating group. The Hammett plots for reactions of 4a-4f are linear with ρX=1.87 and 0.56 for the S-O and C-O bond fission, respectively. The fact that the substituent X is further away from the reaction site of the C-O bond fission than that of the S-O bond fission is one reason for the smaller ρX value. The nature of the reaction mechanism (i.e., a stepwise mechanism in which expulsion of the leaving group occurs after the rate-determining step) is also responsible for the smaller ρX value obtained from the C-O bond fission. The Bronsted-type plot for the reactions of 5a-5f is linear with βlg=-0.63, which is typical for reactions reported previously to proceed through a concerted mechanism. Effects of substituents X and Y on regioselectivity and reaction mechanism are discussed in detail.
- Moon, Ji-Hyun,Kim, Min-Young,Han, So-Yeop,Um, Ik-Hwan
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p. 1360 - 1365
(2015/07/15)
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- NOVEL METAL FREE PROCESS FOR ALLYLIC OXIDATION
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The patent discloses a novel metal free process for the preparation of corresponding phenol and ketone via allylic oxidation of substituted cyclohexenes. Air is used as oxidant in the present process and can be used as such or optionally selected from pure oxygen or atmospheric oxygen. Moreover, the process of the present invention utilizes easily available starting materials and is a green eco-friendly, convenient and economical process with high yield of >60 % and high selectivity
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Page/Page column 10
(2015/02/25)
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- Fe(III)-catalyzed trityl benzyl ether formation and disproportionation cascade reactions to yield benzaldehydes
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During investigating water-compatible Lewis acids catalyzed etherifications using alcohols as alkylating reagents directly, we developed Fe(III)-catalyzed trityl benzyl ether formations irradiated by microwave. Then an in situ trityl benzyl ether formation and disproportionation cascade reaction was achieved to yield the benzaldehyde products with good functional group tolerances under neat conditions at relative higher temperatures. The substituent effects of the substrates on the etherification and disproportionation were explored by changing the substitutions on benzyl alcohols and triarylmethanols using chemical kinetic plots methods and the mechanism of the transformation was studied by crossover experiments. The etherification and disproportionation cascade process could be conveniently scaled up in laboratory without losing much efficiency.
- Wang, Xiaoyu,Du, Chuan,Shi, Hui,Pang, Yadong,Jin, Shengfei,Hou, Yuqian,Wang, Yanshi,Peng, Xiaoshi,Xiao, Jianyong,Liu, Yang,Liu, Yongxiang,Cheng, Maosheng
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p. 6744 - 6748
(2015/08/24)
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