- Self-assembled nanoporphyrins in the presence of gold bio-nanoparticles as heterogeneous nano-biocatalyst for green production of aldehydes and ketones
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We report a simple and facile self-assembly method for the successful fabrication of a biological macromolecule, MnTPPCl (manganese(III) chloride 5,10,15,20-tetraphenylporphyrin), intercalated into gold nanoparticles using the cooperative effects of Sesbania sesban plant. This biohybrid was characterized using various techniques for further investigation. The catalytic activity of this biological hybrid was considered in the production of aldehydes and ketones from primary and secondary alcohols, respectively. Excellent conversions and selectivties were obtained applying Au@MnTPPCl colloidal nanocomposite and NaIO4 as an oxygen donor in ethanol.
- Taheri Bazmi, Mahmoud,Naeimi, Atena,Saeednia, Samira,Hatefi Ardakani, Mehdi
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Read Online
- Efficient synthesis of acrylates bearing an aryl or heteroaryl moiety: One-pot method from aromatics and heteroaromatics using formylation and the horner-wadsworth-emmons reaction
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Acrylates bearing an aryl or heteroaryl moiety were efficiently prepared by a one-pot process employing a sequence of lithiation, formylation and the Horner-Wadsworth-Emmons reaction starting from aromatic and heteroaromatic compounds. This method can efficiently introduce an acrylate moiety into aromatic and heteroaromatic compounds.
- Yasukata, Tatsuro,Matsuura, Takaharu
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p. 527 - 533
(2021/03/22)
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- A tunable synthesis of either benzaldehyde or benzoic acid through blue-violet LED irradiation using TBATB
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In this paper, a highly efficient, metal-free, and homogeneous method for the selective aerobic photooxidation of alcohols and photooxidative-desilylation of tert-butyldimethylsilyl ethers (TBDMS) in the presence of tetrabutylammonium tribromide (TBATB) under irradiation of visible light was reported. The light source: blue (460 nm) and violet (400 nm) LED, can control selective oxidation to aldehyde or carboxylic acid.
- Mardani, Atefeh,Heshami, Marouf,Shariati, Yadollah,Kazemi, Foad,Abdollahi Kakroudi, Mazaher,Kaboudin, Babak
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- Visible-light-induced selective aerobic oxidation of sp3 C-H bonds catalyzed by a heterogeneous AgI/BiVO4 catalyst
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An efficient oxidation of sp3 C-H bonds to esters and ketones has been developed using AgI/BiVO4 as the photocatalyst and O2 as the oxidant in water. Various substrates can be transformed into the desired esters and ketones in moderate to good yields. The synthetic utility of this approach has been demonstrated by gram-level experiments and consecutive oxidation experiments. A plausible mechanism has been proposed.
- Jiang, Li-Ya,Ming, Jing-Jing,Wang, Lian-Yue,Jiang, Yuan-Yuan,Ren, Lan-Hui,Wang, Zi-Cheng,Cheng, Wen-Chen
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supporting information
p. 1156 - 1163
(2020/03/11)
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Method for synthesizing 2, 6-dichlorobenzaldehyde by hydrolysis
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The invention discloses a method for preparing 2, 6-dichlorobenzaldehyde by hydrolysis. The method comprises the following steps: heating 2, 6-dichlorobenzyl chloride to 120-160 DEG C, adding a pi complex formed by 0.05-6wt% of a metal salt and benzaldehyde or a benzaldehyde derivative as a catalyst, slowly dropwise adding water with the molar weight equal to that of the 2, 6-dichlorobenzyl chloride, stopping reaction when the content of the 2, 6-dichlorobenzyl chloride is lower than 0.05 wt% to obtain a 2, 6-dichlorobenzaldehyde crude product, and refining to obtain the 2, 6-dichlorobenzaldehyde. 2, 6-dichlorobenzyl chloride is used as a raw material, the used catalyst is the pi complex formed by the metal salt and benzaldehyde, the solubility of the reaction raw material 2, 6-dichlorobenzyl chloride is increased, a homogeneous reaction system is formed, the usage amount is small, a hydrolysis reaction can be initiated at a low temperature, and the reaction is stable. The method has the advantages of mild reaction conditions, high yield, few side reactions and environmental friendliness.
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Paragraph 0017-0019
(2020/10/14)
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- A Strategy for Accessing Aldehydes via Palladium-Catalyzed C?O/C?N Bond Cleavage in the Presence of Hydrosilanes
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We report the catalytic reduction of both active esters and amides by selective C(acyl)?X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)?N and C(acyl)?O bond cleavage. Carboxylic acid C(acyl)?O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)?O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)?N cleavage under the same reaction conditions.
- He, Zhanyu,Liu, Tingting,Ru, Junxiang,Wang, Yulin,Wang, Zijia,Zeng, Zhuo
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supporting information
p. 5794 - 5800
(2020/12/01)
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- Monodentate Transient Directing Group Enabled Pd-Catalyzed Ortho-C-H Methoxylation and Chlorination of Benzaldehydes
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We report Pd-catalyzed ortho-C-H methoxylation and chlorination of benzaldehydes by employing monodentate transient directing groups (TDGs) as an alternative strategy to bidentate TDGs. More importantly, a single crystal of benzaldehyde imine ortho-cyclopalladium intermediate was successfully obtained, and its structure was unambiguously determined by X-ray diffraction, which clearly showed that it was a binuclear palladium species bridged by a pyridone ligand. The utility of this approach was further demonstrated through the synthesis of key intermediates of natural products and drugs.
- Li, Feng,Zhou, Yirong,Yang, Heng,Wang, Ziqi,Yu, Qinqin,Zhang, Fang-Lin
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supporting information
p. 3692 - 3695
(2019/05/24)
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- Organosuperbase dendron manganese complex grafted on magnetic nanoparticles; heterogeneous catalyst for green and selective oxidation of ethylbenzene, cyclohexene and oximes by molecular oxygen
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Magnetic Fe3O4 nanoparticles as a support were modified with an amino-terminated organosilicon and cyanoric choloride ligands. The novel manganese complex was grafted on modified magnetic support (Mn(II)-Met@MMNPs). The nanocatalyst structure, particle size, morphology and surface properties was well characterized by elemental analysis, ICP-AES, AAS, EDS, FT-IR, SEM, TEM, DLS, VSM, TGA, XRD and XPS. In order to develop an effective heterogeneous nanocatalyst for eco-friendly aerobic, highly active and selective catalytic reactions, synthesized nanocatalyst was applied in oxidation of various organic compounds. The catalytic performance of the manganese nanocatalyst in the aerobic oxidation of ethylbenzene (EB), cyclohexene (CYHE) and various aldoximes and ketoxime were studied. Selective aerobic oxidation of EB and CYHE and various oximes were catalyzed by the Mn-nanocatalyst using N-hydroxyphthalimide (NHPI) with molecular oxygen as the green oxidant without the need of any reducing agent, and respectively the acetophenone (AcPO) as a benzylic product, 2-cyclohexene-1-one (CYHE[dbnd]O) as an allylic product and corresponding carbonyl compounds were obtained. The oxidation process has been optimized for Mn-nanocatalyst by considering the effect of different parameters such as the ratio and amount of Mn-nanocatalyst/NHPI, reaction time and solvent for achieving maximum conversion and selectivity to products. Due to their significant low cost, informal preparation, easy magnetically separation from reaction mixture, excellent catalytic performance, simple recovery and reusability without any metal leaching, the Mn-nanocatalyst has huge application prospect in selective and green oxidation process.
- Faraji, Ali Reza,Ashouri, Fatemeh,Hekmatian, Zahra,Heydari, Somayyeh,Mosazadeh, Sima
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- A primary or secondary alcohol aqueous phase oxidation method of preparing aldehyde ketone (by machine translation)
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The invention discloses an aqueous phase oxidation of a primary or secondary alcohol preparation can comprise solvents, including: to the DAPGS - 550 - M surfactant in aqueous solution with a primary or secondary alcohol, potassium sulfate, silver nitrate and sulfonic acid bismith trifluoromethanesulfonate, to 400 - 700 rpm stirring 1 - 24 H-, extracted with ethyl acetate after, steaming and, chromatography, to obtain the target product; said DAPGS - 550 - M shown as formula I: So that the primary or secondary alcohol class compounds can be converted into the aldehyde compound. The whole reaction at room temperature, to a very large extent of reaction that has solved the problem of energy consumption. The method is simple, high yield, purity of 98% or more. Mild condition, wide substrate range, is not only simple and a primary or zhongzhong kind compound can be suitable, complex natural product also can be modified by this method. The reaction system can be recycled, the solvent pollution problem. (by machine translation)
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Paragraph 0052-0055
(2018/08/03)
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- Chemoselective Reduction of Sterically Demanding N,N-Diisopropylamides to Aldehydes
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A sequential one-pot process for chemoselectively reducing sterically demanding N,N-diisopropylamides to aldehydes has been developed. In this reaction, amides are activated with EtOTf to form imidates, which are reduced with LiAlH(OR)3 [R = t-Bu, Et] to give aldehydes by hydrolysis of the resulting hemiaminals. The non-nucleophilic base 2,6-DTBMP remarkably improves reaction efficiency. The combination of EtOTf/2,6-DTBMP and LiAlH(O-t-Bu)3 was found to be optimal for reducing alkyl, alkenyl, alkynyl, and 2-monosubstituted aryl N,N-diisopropylamides. In contrast, EtOTf and LiAlH(OEt)3 in the absence of base were found to be optimal for reducing extremely sterically demanding 2,6-disubstituted N,N-diisopropylbenzamides. The reaction tolerates various reducible functional groups, including aldehyde and ketone. 1H NMR studies confirmed the formation of imidates stable in water. The synthetic usefulness of this methodology was demonstrated with N,N-diisopropylamide-directed ortho-metalation and C-H bond activation.
- Xiao, Peihong,Tang, Zhixing,Wang, Kai,Chen, Hua,Guo, Qianyou,Chu, Yang,Gao, Lu,Song, Zhenlei
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p. 1687 - 1700
(2018/02/23)
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- A TEMPO-like nitroxide combined with an alkyl-substituted pyridine: An efficient catalytic system for the selective oxidation of alcohols with iodine
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An efficient method for the oxidation of alcohols to aldehydes or ketones in a two-phase CH2Cl2/NaHCO3 (aq.) system, using iodine and catalytic amounts of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl and 2,4,6-trimethylpyridine, was developed. The performance of the method was demonstrated by the selective oxidation of 37 variously substituted alcohols in ≥90% yield, including the gram-scale synthesis of the important chemical 2,5-diformylfuran from biomass-derived 5-hydroxylmethylfurfural.
- Kashparova, Vera P.,Klushin, Victor A.,Zhukova, Irina Yu.,Kashparov, Igor S.,Chernysheva, Daria V.,Il'chibaeva, Irina B.,Smirnova, Nina V.,Kagan, Efim Sh.,Chernyshev, Victor M.
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supporting information
p. 3517 - 3521
(2017/10/05)
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- Water as a proton mediator for dioxygen-selective oxidation of alcohols by a planar dinuclear butterfly-like CuCu bonding complex: A combined experimental and computational study
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The selective catalytic oxidation of alcohols is important both in laboratory and industrial production, and traditional oxidants cause environmentally lethal wastes. The development of dioxygen selective oxidation efficient has been pursued from atom-efficient, economic and environmental view of points. Using DFT calculation and ESI-MS experiments, we studied the activation of the CuCu bonded planar complex Cu2(ophen)2 to dioxygen and the application of the dioxygen-copper system for the selective oxidation of alcohols. For practical application and green chemistry, this catalytic system avoided the use of a large excess of base and expensive nitroxyl derivatives. In the cycle of oxidation, two oxidative dehydrogenation processes featuring superoxide/peroxide (I) and hydroperoxide (II) occurred along with a series of conformational changes of the butterfly-like Cu-complex from stretched to folded to stretched. Additionally, we characterized the role of the water molecule as a proton mediator in the dioxygen-copper system.
- Zhang, Lingjuan,Liu, Jie,Zhang, Fuqiang,Zhang, Xian-Ming
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- Method for synthesizing aromatic aldehyde, aromatic ketone and aromatic ester through catalytically oxidizing alkyl aromatic compound by iron
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The invention discloses a method for synthesizing aromatic aldehyde, aromatic ketone and aromatic ester through catalytically oxidizing an alkyl aromatic compound by iron, and belongs to the technical field of catalytic synthesis. According to the method, a low-cost and environment-friendly iron catalyst is used under a normal pressure; under the action of hydrogen and silicon reagents serving as an accelerant and an oxidant, a side chain of an aromatic hydrocarbon is oxidized into a carbonyl group for generating the corresponding aromatic aldehyde, aromatic ketone and aromatic ester. The method for preparing the aromatic aldehyde, the aromatic ketone and the aromatic ester through a catalytic oxidation reaction, which is provided by the invention, has numerous advantages that a catalyst, reaction raw materials, the oxidant and a silicon reagent are wide in sources and good in stability and is low-cost and environment-friendly; the alkyl aromatic compound is metered to participate in a reaction; the reaction condition is mild; the compatibility of functional groups is good; the scope of application is wide; the reaction selectivity is good; in an optimized reaction condition, the separation yield of a target product can be up to approximately 95 percent.
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Paragraph 0052; 0053
(2017/10/13)
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- Method for preparing 2,6-dichlorobenzaldehyde through continuous oxidization of 2,6-dichlorotoluene
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The invention discloses a method for preparing 2,6-dichlorobenzaldehyde through continuous oxidization of 2,6-dichlorotoluene, and belongs to the technical field of organic synthesis. The method is a technology that a 2,6-dichlorotoluene compound is adopted as a raw material, a metal ion complex of one or more of cobalt, molybdenum and bromine is adopted as a catalyst, hydrogen peroxide is adopted as an oxidizing agent, acetic acid is adopted as a solvent, and 2,6-dichlorotoluene is continuously oxidized in a tubular reactor to prepare 2,6-dichlorobenzaldehyde. The method is mild in condition, short in reaction time, high in raw material utilization rate, capable of achieving effective control in the reacting process, safe, stable, continuous in operation and high in production efficiency.
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Paragraph 0034; 0035; 0036; 0037; 0038; 0039-0060
(2017/08/28)
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- N-Propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) as a green and reusable heterogeneous nanocatalyst for the chemoselective preparation and deprotection of acylals
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Abstract: N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) was simply synthesized and used as a highly efficient, environmentally friendly, and chemoselective catalyst for the synthesis of 1,1-diacetates (acylals) from the one-pot condensation reaction of various aromatic aldehydes with acetic anhydride, in high yield of products (86–96%) and short reaction time (20–60?min) under solvent-free conditions at room temperature. In addition to these results, we further studied the possibility of deprotection of the resulting acylals into benzaldehyde derivatives in this catalytic system by the addition of water. More importantly, noteworthy advantages of this study are non-use of toxic organic solvents and catalysts, simple work-up procedure, short reaction time, high yield of products, and recovery and reusability of MNPs-PSA by an external magnet. Graphical Abstract: A simple and highly efficient procedure for the protection of various aldehydes with acetic anhydride in the presence of N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) is reported. We further studied the possibility of deprotection of the resulting acylals into benzaldehyde derivatives in this catalytic system by the addition of water as a green solvent. The catalyst was reused several times without loss of its catalytic activity.
- Sajjadifar, Sami,Nasri, Parastoo
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p. 6677 - 6689
(2017/10/06)
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- Citric acid catalyzed deprotection of carbonyl compounds from phenylhydrazones, semicarbazones and oximes under microwave irradiations
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Deprotection of phenylhydrazones, semicarbazones and oximes to their corresponding carbonyl compounds have been carried out in good to excellent yields (83-96 %) by using citric acid as organic catalyst in water as a medium of reaction under microwave irradiation.
- Abd El Rahman, Naglaa M.,Nasreen, Aayesha
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p. 2030 - 2035
(2017/10/19)
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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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- Diverse ortho-C(sp2)-H functionalization of benzaldehydes using transient directing groups
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Pd-catalyzed C-H functionalizations promoted by transient directing groups remain largely limited to C-H arylation only. Herein, we report a diverse set of ortho-C(sp2)-H functionalizations of benzaldehyde substrates using the transient directing group strategy. Without installing any auxiliary directing group, Pd(II)-catalyzed C-H arylation, chlorination, bromination, and Ir(III)-catalyzed amidation, could be achieved on benzaldehyde substrates. The transient directing groups formed in situ via imine linkage can override other coordinating functional groups capable of directing C-H activation or catalyst poisoning, significantly expanding the scope for metal-catalyzed C-H functionalization of benzaldehydes. The utility of this approach is demonstrated through multiple applications, including late-stage diversification of a drug analogue.
- Liu, Xi-Hai,Park, Hojoon,Hu, Jun-Hao,Hu, Yan,Zhang, Qun-Liang,Wang, Bao-Long,Sun, Bing,Yeung, Kap-Sun,Zhang, Fang-Lin,Yu, Jin-Quan
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supporting information
p. 888 - 896
(2017/05/16)
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- Synergistic catalysis within TEMPO-functionalized periodic mesoporous organosilica with bridge imidazolium groups in the aerobic oxidation of alcohols
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Anchoring 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) within the nanospaces of a periodic mesoporous organosilica with bridged imidazolium groups led to an unprecedented powerful bifunctional catalyst (TEMPO@PMO-IL-Br), which showed enhanced activity in the metal-free aerobic oxidation of alcohols. The catalyst and its precursors were characterized by N2 adsorption-desorption analysis, transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), thermal gravimetric analysis (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), solid state electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, transmission electron microscopy (TEM) and high resolution TEM. It was clearly found that the catalytic activity of SBA-15-functionalized TEMPO (TEMPO@SBA-15) not bearing IL, TEMPO@PMO-IL-Cl, PMO-IL-AMP, or individual catalytic functionalities (PMO-IL/TEMPO@SBA-15) was inferior as compared with those obtained from TEMPO@PMO-IL-Br in the metal-free aerobic oxidation of benzyl alcohol, suggesting the critical role of co-supported TEMPO and imidazolium bromide in obtaining high catalytic activity in the described catalyst system. Our observation clearly points to the fact that the combination of imidazolium bromide units in close proximity to TEMPO moieties in the nanospaces of TEMPO@PMO-IL-Br might be indeed one of the key factors explaining the enhanced catalytic activity observed for this catalyst in the oxidation of benzyl alcohol, possibly through a synergistic catalysis relay pathway. A proposed model was suggested for the observed synergistic effect.
- Karimi, Babak,Vahdati, Saleh,Vali, Hojatollah
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p. 63717 - 63723
(2016/07/19)
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- Experimental and theoretical investigations into the stability of cyclic aminals
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Background: Cyclic aminals are core features of natural products, drug molecules and important synthetic intermediates. Despite their relevance, systematic investigations into their stability towards hydrolysis depending on the pH value are lacking. Results: A set of cyclic aminals was synthesized and their stability quantified by kinetic measurements. Steric and electronic effects were investigated by choosing appropriate groups. Both molecular mechanics (MM) and density functional theory (DFT) based studies were applied to support and explain the results obtained. Rapid decomposition is observed in acidic aqueous media for all cyclic aminals which occurs as a reversible reaction. Electronic effects do not seem relevant with regard to stability, but the magnitude of the conformational energy of the ring system and pKa values of the N-3 nitrogen atom. Conclusion: Cyclic aminals are stable compounds when not exposed to acidic media and their stability is mainly dependent on the conformational energy of the ring system. Therefore, for the preparation and work-up of these valuable synthetic intermediates and natural products, appropriate conditions have to be chosen and for application as drug molecules their sensitivity towards hydrolysis has to be taken into account.
- Sawatzky, Edgar,Drakopoulos, Antonios,R?lz, Martin,Sotriffer, Christoph,Engels, Bernd,Decker, Michael
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supporting information
p. 2280 - 2292
(2016/11/17)
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- New application of cross-linked poly(N -bromoacrylamide) and poly(N -bromosuccinimide) as highly efficient and chemoselective heterogeneous polymeric catalysts for deprotection of 1,3-dithianes and 1,3-dithiolanes under mild conditions
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Cross-linked poly(N-bromoacrylamide) (PNBA) and poly(N- bromosuccinimide) as the mild and efficient heterogeneous polymeric catalysts were applied for selective deprotection of 1,3-dithianes and 1,3-dithiolanes to their corresponding carbonyl compounds. They were also effective as a reagent in aqueous media. These methods are very simple and the polymer catalysts could be recycled several times. Deprotection of thioacetal and thioketal without enolizable hydrogens proceeded very well to give only the corresponding aldehyde and ketone in high to excellent yield. Nevertheless, in the case of thioketals carrying enolizable hydrogens, deprotection accompanied with the formation of a minor ring-expanded product is observed. However, using the PNBA/H2O system, ring expansion of these thiolketals with enolizable hydrogen was not detected. These methods provide advantages, such as chemoselectivity, easy preparation, simple work up, excellent yields, and the ability to recycle the catalyst, which makes this method more useful compared to other known methodologies.
- Ebrahimzadeh, Farzaneh
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- Aldehyde and Ketone Synthesis by P450-Catalyzed Oxidative Deamination of Alkyl Azides
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Heme-containing proteins have recently attracted increasing attention for their ability to promote synthetically valuable transformations not found in nature. Following the recent discovery that engineered variants of myoglobin can catalyze the direct conversion of organic azides into aldehydes, we investigated the azide oxidative deamination reactivity of a variety of hemoproteins featuring different heme coordination environments. Our studies show that although several heme-containing enzymes possess basal activity in this reaction, an engineered variant of the bacterial cytochrome P450 CYP102A1 constitutes a particularly efficient biocatalyst for promoting this transformation, and it exhibits a broad substrate scope along with high catalytic activity (up to 11 300 turnovers), excellent chemoselectivity, and enhanced reactivity toward secondary alkyl azides to yield ketones. Mechanistic studies and Michaelis–Menten analyses provided insight into the mechanism of the reaction and the impact of active-site mutations on the catalytic properties of the P450. Altogether, these studies demonstrate that engineered P450 variants represent promising biocatalysts for the synthesis of aryl aldehydes and ketones through the oxidative deamination of alkyl azides under mild reaction conditions.
- Giovani, Simone,Alwaseem, Hanan,Fasan, Rudi
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p. 2609 - 2613
(2016/08/30)
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- A TEMPO-free copper-catalyzed aerobic oxidation of alcohols
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The copper-catalyzed aerobic oxidation of primary and secondary alcohols without an external N-oxide co-oxidant is described. The catalyst system is composed of a Cu/diamine complex inspired by the enzyme tyrosinase, along with dimethylaminopyridine (DMAP) or N-methylimidazole (NMI). The Cu catalyst system works without 2,2,6,6-tetramethyl-l-piperidinoxyl (TEMPO) at ambient pressure and temperature, and displays activity for un-activated secondary alcohols, which remain a challenging substrate for catalytic aerobic systems. Our work underscores the importance of finding alternative mechanistic pathways for alcohol oxidation, which complement Cu/TEMPO systems, and demonstrate, in this case, a preference for the oxidation of activated secondary over primary alcohols.
- Xu, Boran,Lumb, Jean-Philip,Arndtsen, Bruce A.
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supporting information
p. 4208 - 4211
(2015/04/14)
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- AIBN/NaBr-promoted aerobic oxidation of benzylic alcohols via a radical process
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An economic and practical AIBN-initiated aerobic oxidation system of benzylic alcohols, hetero aryl alcohols and allyl alcohols was developed for the first time. Moderate to excellent yields were obtained with a broad substrate scope. Moreover, a proposed mechanism of a radical process was assumed and confirmed by the key intermediate detected.
- Liu, Chengkou,Fang, Zheng,Yang, Zhao,Li, Qingwen,Guo, Shiyu,Guo, Kai
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supporting information
p. 577 - 581
(2016/01/12)
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- Highly practical sodium(i)/azobenzene catalyst system for aerobic oxidation of benzylic alcohols
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An economic, environmental and practical aerobic oxidation of benzylic alcohols and hetero aryl alcohols to the corresponding carbonyl compounds with good substrate scope is disclosed for the first time. Good to excellent yields were obtained by employing economic and commercially available sodium bromide and a catalytic amount of azobenzene under metal-free and ligand-free conditions. Moreover, aldehydes and acids, the oxidation products of benzylic 1° alcohols, could be obtained using sodium bromide and sodium hydroxide as the co-catalyst respectively in high yields.
- Liu, Chengkou,Fang, Zheng,Yang, Zhao,Li, Qingwen,Guo, Shiyu,Guo, Kai
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p. 79699 - 79702
(2015/10/06)
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- Highly practical oxidation of benzylic alcohol in continuous-flow system with metal-free catalyst
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Oxidation of benzylic alcohol to ketone or aldehyde is one of the most challenging reactions in terms of green chemistry. We report herein that employing H2O2, catalytic amount of Br- and acid in continuous-flow system to realize oxidation of benzylic alcohols with broad substrate scope and high selectivity. More importantly, no over oxidation to acid was obtained and it showed higher selectivity to 2° hydroxyl groups rather than 1°.
- Liu, Chengkou,Fang, Zheng,Yang, Zhao,Li, Qingwen,Guo, Shiyu,Zhang, Kai,Ouyang, Pingkai,Guo, Kai
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p. 5973 - 5976
(2015/10/28)
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- A novel and active catalyst Ag/ZnO for oxidant-free dehydrogenation of alcohols
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Nano Ag/ZnO catalysts were prepared by varying load of Ag on ZnO supports using a new and very simple method. The structure of nano Ag/ZnO has been confirmed by various techniques. The Ag/ZnO with 7.4 × 10-5 mol% of Ag has pore size distribution about 2.74 nm and this nano Ag/ZnO is found to be the best catalyst for oxidation of primary and secondary benzyl alcohols into corresponding aldehydes and ketones in oxidant-free at the atmospheric pressure. The influence of various parameters such as: solvent, base, temperature, time of reaction, etc. has been systematically studied on nano Ag/ZnO catalyst.
- Hosseini-Sarvari, Mona,Ataee-Kachouei, Tahereh,Moeini, Fatemeh
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- Efficient conversion of primary azides to aldehydes catalyzed by active site variants of myoglobin
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The oxidation of primary azides to aldehydes constitutes a convenient but underdeveloped transformation for which no efficient methods are available. Here, we demonstrate that engineered variants of the hemoprotein myoglobin can catalyze this transformation with high efficiency (up to 8500 turnovers) and selectivity across a range of structurally diverse aryl-substituted primary azides. Mutagenesis of the 'distal' histidine residue was particularly effective in enhancing the azide oxidation reactivity of myoglobin, enabling these reactions to proceed in good to excellent yields (37-89%) and to be carried out at a synthetically useful scale. Kinetic isotope effect, isotope labeling, and substrate binding experiments support a mechanism involving heme-catalyzed decomposition of the organic azide followed by alpha hydrogen deprotonation to generate an aldimine which, upon hydrolysis, releases the aldehyde product. This work provides the first example of a biocatalytic azide-to-aldehyde conversion and expands the range of non-native chemical transformations accessible through hemoprotein-mediated catalysis.
- Giovani, Simone,Singh, Ritesh,Fasan, Rudi
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p. 234 - 239
(2015/12/30)
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- Green and Efficient: Iron-Catalyzed Selective Oxidation of Olefins to Carbonyls with O2
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A mild and operationally simple iron-catalyzed protocol for the selective aerobic oxidation of aromatic olefins to carbonyl compounds is described. Catalyzed by a Fe(III) species bearing a pyridine bisimidazoline ligand at 1 atm of O2, α- and β-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance, including those containing radical-sensitive groups. With α-halo-substituted styrenes, the oxidation took place with concomitant halide migration to afford α-halo acetophenones. Various observations have been made, pointing to a mechanism in which both molecular oxygen and the olefinic substrate coordinate to the iron center, leading to the formation of a dioxetane intermediate, which collapses to give the carbonyl product. (Chemical Equation).
- Gonzalez-De-Castro, Angela,Xiao, Jianliang
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supporting information
p. 8206 - 8218
(2015/07/15)
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- A mild and highly efficient laccase-mediator system for aerobic oxidation of alcohols
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With the aid of the highly active nitroxyl radical AZADO (2-azaadamantane N-oxyl), a simple method for the aerobic catalytic oxidation of alcohols is presented. The oxidations could typically proceed under practical ambient conditions (room temperature, air atmosphere, no moisture effect, metal-free, etc.) with a broad generality of the alcohol substrates, and especially for the oxidation of complex and highly functionalized alcohols. An ionic mechanism is proposed for the present system.
- Zhu, Chenjie,Zhang, Zhi,Ding, Weiwei,Xie, Jingjing,Chen, Yong,Wu, Jinglan,Chen, Xiaochun,Ying, Hanjie
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supporting information
p. 1131 - 1138
(2014/03/21)
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- TEMPO-mediated oxidation of primary alcohols to aldehydes under visible light and air
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A homogeneous visible light photoredox TEMPO-mediated selective oxidation of primary alcohols to the corresponding carbonyl compounds was developed using molecular oxygen from air as the terminal oxidant. Ru(bpy)3(PF 6)2 (bpy: bipyridyl) and Ir(dtb-bpy)(ppy) 2(PF6) (dtb-bpy: 4,4′-di-tert-butyl-2,2′- bipyridyl; ppy: 2-phenylpyridine) were used as the sensitizers. A homogeneous visible light photoredox TEMPO-mediated selective oxidation of primary alcohols to the corresponding carbonyl compounds was developed. Molecular oxygen from air was the terminal oxidant. Copyright
- Liu, Dongwang,Zhou, Hongxia,Gu, Xiangyong,Shen, Xiaoqin,Li, Pixu
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supporting information
p. 117 - 122
(2014/03/21)
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- SBA-15-Functionalized 3-Oxo-ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal-Free Conditions
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The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.
- Karimi, Babak,Farhangi, Elham,Vali, Hojatollah,Vahdati, Saleh
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p. 2735 - 2741
(2016/12/23)
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- Nanoparticle-supported and magnetically recoverable organic-inorganic hybrid copper(ii) nanocatalyst: A selective and sustainable oxidation protocol with a high turnover number
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A magnetically recoverable copper-based nanocatalyst was prepared from inexpensive starting materials. With a particle size between 20 to 30 nm, it was shown to catalyze the oxidation of benzylic alcohols. The catalyst exhibited a high turnover number (TON) and excellent selectivity. The catalyst was characterized by several techniques, such as XRD, HR-TEM, SAED, EDS, FT-IR, VSM, and BET surface area. Factors affecting the reaction parameters, such as the substrate to oxidant molar ratio, weight of the catalyst, reaction time, etc., were investigated in detail. The reusability of the catalyst was examined by conducting repeat experiments with the same catalyst; it was observed that the catalyst displayed no significant changes in its activity even after seven cycles for the aerobic, as well as for the peroxide, oxidation of benzyl alcohol. Furthermore, the heterogeneous nature, easy recovery, and reusability, makes the present protocol highly beneficial for addressing environmental concerns and industrial requirements. This journal is
- Rathore, Puran Singh,Patidar, Rajesh,Thakore, Sonal
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p. 41111 - 41121
(2014/12/10)
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- Manganese nanocatalyst and N-hydroxyphthalimide as an efficient catalytic system for selective oxidation of ethylbenzene, cyclohexene and oximes under aerobic condition
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The catalytic activity of the nano-manganese-catalyst in the aerobic oxidation of ethylbenzene, cyclohexene and oximes were evaluated without the need of any reducing agent, using N-hydroxyphthalimide (2-Hydroxy-1H-isoindole- 1,3-dione; NHPI) under oxygen pressure. The oxidation of ethylbenzene and cyclohexene to acetophenone and 2-cyclohexene-1-one using N-hydroxyphthalimide (2-Hydroxy-1H-isoindole-1,3-dione; NHPI) under oxygen atmosphere in the presence of a SiO2/Al2O3-supported manganese catalyst occurs with conversions of 95 and 99% and selectivities of 99%. The supported manganese is also a suitable and efficient catalyst for the oxidative deprotection of oximes to the corresponding carbonyl compounds. A mild and efficient method has been optimized for manganese catalysts by considering the effect of various parameters such as the reaction time and the amount of catalyst, the temperature and the reusability of the catalyst after several runs without modification. Moreover, some possible mechanisms for the oxidation of ethylbenzene, cyclohexene and oximes have been proposed.
- Habibi,Faraji,Arshadi,Veisi,Gil
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- Sub-stoichiometric oxidation of benzylic alcohols with commercially available activated MnO2 under oxygen atmosphere: A green modification of the benzylic oxidation
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Benzylic and allylic alcohols were readily converted into aldehydes and ketones in the presence of sub-stoichiometric amounts of activated MnO 2 under oxygen atmosphere. No over-oxidation to carboxylic acid happened. The present procedure dramatically reduces the amounts of MnO 2 necessary for the oxidation and provides a greener modification of widely used oxidation method.
- Kamimura, Akio,Komatsu, Hiroyuki,Moriyama, Takaaki,Nozaki, Yuichiro
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p. 5968 - 5972
(2013/07/27)
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- Regioselective formylation of 1,3-disubstituted benzenes through in situ lithiation
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A facile method of regioselective formylation of disubstituted benzene via in situ deprotonation/metalation using n-BuLi/TMEDA/DIPA has been developed. Effect of different electron withdrawing and electron donating substituents in 1,3-interrelated aromatic system was studied; the metalation mostly occurred at the 2-position to afford the desired products in high yields.
- Wang, Le,Wang, Yan,Guo, Fangxu,Zheng, Yue,Bhadury, Pinaki S.,Sun, Zhihua
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supporting information
p. 6053 - 6056
(2013/10/22)
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- Phosphonium salts and aldehydes from the convenient, anhydrous reaction of aryl acetals and triphenylphosphine hydrobromide
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The reactions of aryl acetals/ketals and triphenylphosphine hydrobromide gave the corresponding aldehydes/ketones and alkyl phosphonium bromides. This reaction was applied to convert acetals/ketals to the corresponding aldehydes/ketones under an anhydrous
- Ramanathan, Mani,Hou, Duen-Ren
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- Efficient catalytic systems based on cobalt for oxidation of ethylbenzene, cyclohexene and oximes in the presence of N-hydroxyphthalimide
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The selective oxidation of ethylbenzene and cyclohexene to acetophenone and 2-cyclohexene-1-one using N-hydroxyphthalimide (NHPI) under oxygen atmosphere in the presence of an SiO2/Al2O3-supported cobalt catalyst occurs with conversions of 83 and 75% and selectivities of 99%. The supported cobalt is also a suitable and efficient catalyst for the oxidative deprotection of oximes to the corresponding carbonyl compounds. The reaction conditions have been optimized considering the effect of various parameters such as reaction time, amount of catalyst, temperature and reusability of the catalyst after several runs. Moreover, some possible mechanisms for the oxidation of ethylbenzene, cyclohexene and oximes have been proposed.
- Habibi,Faraji,Arshadi,Heydari,Gil
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p. 282 - 292
(2015/03/06)
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- Continuous flow oxidation of alcohols and aldehydes utilizing bleach and catalytic tetrabutylammonium bromide
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We report a method for the oxidation of a range of alcohols and aldehydes utilizing a simple flow system of alcohols in EtOAc with a stream of 12.5% NaOCl and catalytic Bu4NBr. Secondary alcohols are oxidized to ketones, aldehydes are oxidized directly to methyl esters in the presence of methanol, and benzylic alcohols are oxidized to either benzaldehydes or methyl esters, depending on the conditions used. The reaction conditions are mild and generally provide complete conversion in 5-30 min.
- Leduc, Andrew B.,Jamison, Timothy F.
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supporting information; experimental part
p. 1082 - 1089
(2012/08/27)
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- Synthesis and characterization of alkyl-imidazolium-based periodic mesoporous organosilicas: A versatile host for the immobilization of perruthenate (RuO4-) in the aerobic oxidation of alcohols
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The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3- trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10 % imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols.
- Karimi, Babak,Elhamifar, Dawood,Yari, Omolbanin,Khorasani, Mojtaba,Vali, Hojatollah,Clark, James H.,Hunt, Andrew J.
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p. 13520 - 13530
(2012/11/07)
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- Straightforward synthesis of aromatic imines from alcohols and amines or nitroarenes using an impregnated copper catalyst
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The impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines. This catalyst does not require any type of expensive and difficult to handle organic ligand or typical transition metals, and provides excellent yields achievable under mild reaction conditions. Moreover, the catalyst is very easy to remove from the reaction medium by simply using a magnet. The one-pot process of dehydrogenation of alcohols in the presence of aniline followed by aqueous hydrolysis gave pure alcohols in excellent yields. In addition to amines, nitroarenes could be used as the nitrogen-containing reagent. In the case of primary amines the expected imines were successfully prepared under similar reaction conditions. The impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines or nitroarenes. A similar synthesis of imines was accomplished using only primary amines. This catalyst avoids the use of expensive organic ligands and other transition metals while enabling excellent yields under mild reaction conditions. Copyright
- Perez, Juana M.,Cano, Rafael,Yus, Miguel,Ramon, Diego J.
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p. 4548 - 4554
(2012/11/07)
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- Study of Co(AAOPD) and Cu(AAOPD) schiff-base catalysts effect in oxidation oximes and carboxylic acids derivatives
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Oximes and carboxylic acids derivatives have a wide range in medical, pharmaceutical, agriculture industrials. Thus they have significant effects on these fields. Base-promoted or (RC=N-) groups of cobalt and nickel groups. These were examined for oxidative process of oximes and carboxylic acids. This process is absolutely selective and in this procedure oximes transforms to aldehyde and ketone derivatives with high yield, without more oxidative process on Aldehyde group. In this mechanism high amounts of various oximes transforms into carbonyi group. However, obtained results showed that oxidative process for oximes and carboxylic acid with presence of Base-Promoted such as Co(AAOPD) and Cu(AAOPD) because of higher speed and yield. For more evaluation of reaction progress and identification of products through different methods like were used: Thin Layer Chromatography (TLC), Gas Chromatography, FT-IR, UV-Vis and elemental analysis. Carboxylic acids;. Carboxylic acids;. Oximes;. Schiff-Base.
- Soleymani, Reza,Taheri, Milad,HOSEYNALIBEYGl, Marziye,Daryani, Mehdi
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p. 857 - 866,10
(2020/08/24)
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- Nanocrystalline magnesium oxide stabilized palladium(0): An efficient reusable catalyst for room temperature selective aerobic oxidation of alcohols
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Nanocrystalline magnesium oxide-stabilized palladium(0) [NAP-Mg-Pd(0)], as an efficient catalytic system has been employed for the selective oxidation of alcohols using atmospheric oxygen as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using a set of optimal conditions. NanoActive Magnesium Oxide Plus, [NAP-MgO] with its three-dimensional structure and well-defined shape acts as an excellent support for well dispersed palladium(0) nanoparticles. This catalyst can be recovered and reused for several cycles without any significant loss of catalytic activity.
- Layek, Keya,Maheswaran,Arundhathi,Kantam, M. Lakshmi,Bhargava, Suresh K.
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supporting information; experimental part
p. 606 - 616
(2011/04/25)
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- A highly recyclable magnetic core-shell nanoparticle-supported TEMPO catalyst for efficient metal- and halogen-free aerobic oxidation of alcohols in water
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The selective oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is one of the most challenging reactions in organic chemistry. Many oxidizing reagents such as stoichiometric CrVI salts, DMSOcoupled reagents, and hypervalent iodine have been traditionally used to accomplish this transformation. However, these reagents show poor atom efficiency and are often toxic; their widespread use thereby causes significant environmental concerns that render them impractical. As a consequence, due to ever-increasing environmental standards and economic pressures, there is substantial interest towards the use of heterogeneous and recyclable catalysts to achieve the efficient oxidation of alcohols with molecular oxygen or air as the oxidant. Whereas methodologies for the improvement of catalytic activities and selectivities have been developed considerably, they may possibly leave toxic traces of heavy metals in the products. Moreover, many of the metal-based catalyst systems are often deactivated because of the occupation of coordination sites with the by-produced water and so they generally require the use of organic solvents. Therefore, it seems that there is still a great interest in developing efficient and non-metallic catalysts for the aerobic oxidation of alcohols from the viewpoint of socalled green and sustainable chemistry. Of particular interest in this area is the application of the stable nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in combination with various types of non-metallic, stoichiometric co-oxidants as an alternative to metal-based oxidants.
- Karimi, Babak,Farhangi, Elham
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supporting information; experimental part
p. 6056 - 6060
(2011/06/26)
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- Biomimetic catalytic decarboxylation of phenylacetic acid derivatives by manganese(III) complex
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Bis(2-hydroxyacetophenone)ethylendiimine as a quadridentate Schiff base ligand and its Mn(III) were synthesized and characterized by analytical and spectral data. An efficient homogeneous oxidative decarboxylation of some carboxylic acids was performed by catalytic amount of Mn(III) complex in chloroform, using tetrabutylamonium periodate as oxidant at room temperature.
- Montazerozohori,Nasr-Esfahani,Joohari,Akhlaghi,Dehghani
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experimental part
p. 1081 - 1084
(2011/12/16)
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- Manganese(III) porphyrin covalently bound to sol-gel derived silica (Mn(III) porphyrinosilica): A reusable and green heterogeneous photocatalyst for oxidative decarboxylation of &α-arylacetic acids with H 2O2
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Manganese(III) (5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin)chloride, MnIII(TDCPP)Cl, was chemically (covalently) bound to a silica matrix by a sol-gel method and used as a new reusable heterogeneous photocatalyt for the selective and efficient oxidative decarboxylation of α-arylacetic acids with H2O2 as a mild and clean oxidant at room temperature. The activity of this heterogeneous photocatalytic system is higher than that of a corresponding homogeneous systems and the catalyst can be reused several times without loss of its activity and selectivity.
- Farhadi, Saeid,Zabardasti, Abedien,Rahmati, Mohammad Hosien
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experimental part
p. 157 - 160
(2011/07/29)
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- A green procedure for the oxidation of benzyl halides to aromatic aldehydes or ketones in aqueous media
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Green oxidation of benzyl halides to the corresponding aldehydes or ketones was achieved in aqueous media using trimethylamine N-oxide generated in situ from trimethylamine and H2O2. The yield of the reaction was excellent and the workup was simple. Copyright
- Zheng, Pengwu,Yan, Li,Ji, Xiujie,Duan, Xuemin
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experimental part
p. 16 - 19
(2011/02/27)
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