- SELECTIVE PROTECTION OF CARBONYL GROUPS BY TAKING ADVANTAGE OF A COMBINATION OF SOLID SUPPORT AND GIRARD'S REAGENT.
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Some Girard's derivatives of 4-phenylbenzophenone were prepared in ethanol solution, in the presence of Amberlite IRC-50 as a catalyst. Supported samples of the derivatives were then prepared by addition of silica gel to the solution, followed by evaporat
- Chihara,Waniguchi,Wakabayashi,Taya
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Read Online
- The Stereoselective Oxidation of para-Substituted Benzenes by a Cytochrome P450 Biocatalyst
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The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol-CYP)?1.min?1) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S-oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.
- Chao, Rebecca R.,Lau, Ian C.-K.,Coleman, Tom,Churchman, Luke R.,Child, Stella A.,Lee, Joel H. Z.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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supporting information
p. 14765 - 14777
(2021/09/14)
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- Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity
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Aerobic alcohol oxidations catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which CuII and the aminoxyl participate together to mediate alcohol oxidation. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alcohol is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixture by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NOx-based redox cycle for oxidation of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alcohol oxidation chemoselectivity and functional group compatibility.
- Mao, Kaining,Nutting, Jordan E.,Stahl, Shannon S.
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p. 10565 - 10570
(2021/07/28)
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- A highly effective green catalyst Ni/Cu bimetallic nanoparticles supported by dendritic ligand for chemoselective oxidation and reduction reaction
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The highly active Ni/Cu bimetallic nanoparticles (NPs) of the different molar ratios of Ni and Cu (1:1, 1:3, 3:1) assisted by dendritic ligand 2,4,6-Tris (di-4-chlorobenzamido)-1,3-diazine were synthesized successfully confirmed by Scanning Electron Microscopy (SEM), Electron Diffraction X-ray (EDX), X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) analysis. These NPs were studied as a heterogeneous catalyst for the chemoselective oxidation of alcohol to the corresponding aldehyde at 30?min and chemoselective reduction of aromatic nitro substituents to the corresponding amino substituents at 20?min, while the Ni/Cu (3:1) NPs were found to be the most effective among other Ni/Cu?(1:1)?and Ni/Cu?(1:3)?NPs at room temperature under mild conditions. The Ni/Cu (3:1) NPs can be recycled for at least five successive runs with no perceptible decrease in catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
- Islam, Md. Sayedul,Khan, Md. Wahab
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p. 2353 - 2369
(2021/01/07)
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Controlled Aerobic Oxidation of Primary Benzylic Alcohols to Aldehydes Catalyzed by Polymer-Supported Triazine-Based Dendrimer-Copper Composites
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A controlled aerobic oxidation of primary benzylic alcohols to the corresponding benzaldehydes by using polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported triazine-based polyethyleneamine dendrimer-copper complexes [PS-PEG-TD2-Cu(II)] was developed. In particular, PS-PEG-TD2-Cu(OAc) 2 efficiently catalyzed the aerobic oxidation of benzylic alcohols in the presence of a catalytic amount of TEMPO under atmospheric conditions to give the corresponding aldehydes in up to quantitative yield. The catalyst was readily recovered by simple filtration and reused four times without significant loss of its catalytic activity.
- Pan, Shiguang,Yan, Shuo,Osako, Takao,Uozumi, Yasuhiro
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supporting information
p. 1152 - 1156
(2018/04/16)
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- Studies on Iron-Catalyzed Aerobic Oxidation of Benzylic Alcohols to Carboxylic Acids
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A comprehensive study on aerobic oxidation of benzylic alcohols to carboxylic acids with a catalytic amount each of Fe(NO 3) 3 ·9H 2 O, TEMPO, and KCl is conducted. Various synthetically useful functional groups are well tolerated in the reaction. Distinct electronic and steric effects are observed in the reaction: electron-withdrawing groups accelerate the reaction while electron-donating groups make the reaction slower, and ortho -substituted substrates react slower than meta -substituted substrates. Several large-scale reactions (100 mmol) are conducted using a slow air flow of 30 mL/min to demonstrate the practicality of this method in an academic laboratory.
- Jiang, Xingguo,Ma, Shengming
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p. 1629 - 1639
(2018/02/26)
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- Decomposition of a Β-O-4 lignin model compound over solid Cs-substituted polyoxometalates in anhydrous ethanol: acidity or redox property dependence?
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Production of aromatics from lignin has attracted much attention. Because of the coexistence of C–O and C–C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone (2-PAP), was investigated over several cesium-exchanged polyoxometalate (Cs-POM) catalysts. Decomposition of 2-PAP can follow two different mechanisms: an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox properties of the catalysts. The catalysts of POMs perform the following functions: promoting active hydrogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen liberation and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP (>99%) with excellent selectivities to the desired products (98.6% for phenol and 91.1% for acetophenone) can be achieved.
- Wu, Xuezhong,Jiao, Wenqian,Li, Bing-Zheng,Li, Yanming,Zhang, Yahong,Wang, Quanrui,Tang, Yi
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p. 1216 - 1228
(2017/07/10)
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- Fluorous bispidine: A bifunctional reagent for copper-catalyzed oxidation and knoevenagel condensation reactions in water
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Fluorous bispidine-type ligands have been developed to facilitate its recovery and reusability and to demonstrate its bifunctional property as a ligand and base in copper-catalyzed aerobic oxidation, the Knoevenagel condensation and tandem oxidation/Knoevenagel condensation in water under mild conditions. Application of the fluorous ligand was also extended to the surfactant-free copper-catalyzed allylic and benzylic sp3 C-H oxidation reaction in water. The fluorous ligands could be recovered using F-SPE with recovery ranging from 91-97% and could be reused five times with little loss of activity.
- Ang, Wei Jie,Chng, Yong Sheng,Lam, Yulin
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p. 81415 - 81428
(2015/10/06)
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- Simultaneous identification of Fenton degradation by-products of diclofenac, ibuprofen and ketoprofen in aquatic media by comprehensive two-dimensional gas chromatography coupled with mass spectrometry
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Diclofenac, ibuprofen and ketoprofen are anti-inflammatory drugs intensively used both in human and animal treatment. Due to their high stability these compounds are partially removed by wastewater treatment plants and from this reason the development of some alternative treatments such as advanced oxidative processes are necessary. The main problems in the optimization of an advanced oxidative process rise from the difficulties which appear in the identification of degradation by-products necessary for the establishment of degradation pathway. In this paper a developed method for the simultaneous identification of Fenton degradation by-products of the three above mentioned pharmaceuticals is presented. The obtained results show the comprehensive two-dimensional gas chromatography coupled with mass spectrometry as a proper method for the analysis of the complex mixture of compounds resulted from the Fenton degradation process. Moreover, some compounds never mentioned in the scientific literature were identified. (Chemical Equation Presented).
- Beldean-Galea, Mihail Simion,Coman, Virginia,Copaciu, Florina,Thiébaut, Didier,Vial, Jér?me
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p. 1021 - 1027
(2015/07/15)
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- Selective oxidations of activated alcohols in water at room temperature
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Allylic and benzylic alcohols can be selectively oxidized to their corresponding aldehydes or ketones in water containing nanoreactors composed of the designer surfactant TPGS-750-M. The oxidation relies on catalytic amounts of CuBr, bpy, and TEMPO, with N-methyl-imidazole; air is the stoichiometric oxidant. the Partner Organisations 2014.
- Lipshutz,Hageman,Fennewald,Linstadt,Slack,Voigtritter
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supporting information
p. 11378 - 11381
(2014/11/08)
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- A crystalline porous coordination polymer decorated with nitroxyl radicals catalyzes aerobic oxidation of alcohols
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A porous coordination polymer (PCP) has been synthesized employing an organic ligand in which a stable free radical, isoindoline nitroxide, is incorporated. The crystalline PCP possesses one-dimensional channels decorated with the nitroxyl catalytic sites. When O2 gas or air was used as the oxidant, this PCP was verified to be an efficient, recyclable, and widely applicable catalyst for selective oxidation of various alcohols to the corresponding aldehydes or ketones.
- Li, Liangchun,Matsuda, Ryotaro,Tanaka, Iku,Sato, Hiroshi,Kanoo, Prakash,Jeon, Hyung Joon,Foo, Maw Lin,Wakamiya, Atsushi,Murata, Yasujiro,Kitagawa, Susumu
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supporting information
p. 7543 - 7546
(2014/06/10)
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- Tetra-n-butylammonium bromide: A simple but efficient organocatalyst for alcohol oxidation under mild conditions
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A simple but efficient organocatalytic system with 5 mol% tetra-n-butylammonium bromide (TBAB) as the catalyst has been identified for alcohol oxidation for the first time. This organocatalytic system is compatible with a broad range of benzylic/allylic alcohols with various catalytically reactive groups. Besides, it shows excellent selectivity for secondary benzylic alcohols over aliphatic alcohols, and good selectivity over the primary benzylic alcohol site in 4-(1-hydroxyethyl)benzyl alcohol. Thus, the features of simplicity, high efficiency, selectivity and mildness of reaction conditions associated with this TBAB organocatalytic system suggest its potential for widespread use in synthetic chemistry.
- Ma, Xinyi,Li, Zhongfeng,Liu, Feijie,Cao, Shengli,Rao, Honghua
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supporting information
p. 1741 - 1746
(2014/06/09)
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- Methodology for in situ protection of aldehydes and ketones using trimethylsilyl trifluoromethanesulfonate and phosphines: Selective alkylation and reduction of ketones, esters, amides, and nitriles
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A methodology for selective transformations of ketones, esters, Weinreb amides, and nitriles in the presence of aldehydes has been developed. The use of a combination of PPh3-trimethylsilyl trifluoromethanesulfonate (TMSOTf) promotes selective transformation of aldehydes to their corresponding, temporarily protected, O,P-acetal type phosphonium salts. Because, hydrolytic work-up following ensuing reactions of other carbonyl moieties in the substrates liberates the aldehyde moiety, a sequence involving aldehyde protection, transformation of other carbonyl groups, and deprotection can be accomplished in a one-pot manner. Furthermore, the use of PEt3 instead of PPh 3 enables ketones to be converted in situ to their corresponding O,P-ketal type phosphonium salts and, consequently, selective transformations of esters, Weinreb amides, and nitriles in the presence of ketones can be performed. This methodology is applicable to various dicarbonyl compounds, including substrates that possess heteroaromatic skeletons and hydroxyl protecting groups.
- Yahata, Kenzo,Minami, Masaki,Yoshikawa, Yuki,Watanabe, Kei,Fujioka, Hiromichi
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p. 1298 - 1307
(2014/01/06)
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- RuCl 3-DCHA catalyst system: A selective aerobic oxidation of primary benzylic alcohols under mild conditions
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The aerobic oxidation of benzylic alcohols to their corresponding aldehydes was performed in a RuCl3 · 3H2O-dicyclohexylamine (DCHA) catalyst system under ambient atmosphere at room temperature. It is noteworthy that the RuCl3 · 3H2O-DCHA system displayed a preference for the primary versus secondary benzylic alcohols in both intermolecular and intramolecular competition experiments.
- Yu, Kaihui,Ye, Dongnai,Shu, Lei,Zhang, Shiyong,Hu, Qiaosheng,Liu, Liangxian
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experimental part
p. 2318 - 2326
(2012/06/18)
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- Selective aerobic oxidation of alcohols by using manganese oxide nanoparticles as an efficient heterogeneous catalyst
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Manganese oxide (Mn3O4) nanoparticles have been successfully innovated to be efficient catalysts not only for the aerobic oxidation of various alcohols to aldehydes or ketones, but also for the selective aerobic oxidation of mixed alcohols. Copyright
- Sun, Hua-Yin,Hua, Qing,Guo, Feng-Feng,Wang, Zhi-Yong,Huang, Wei-Xin
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experimental part
p. 569 - 573
(2012/04/17)
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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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scheme or table
p. 428 - 436
(2012/07/28)
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- Reversing the reactivity of carbonyl functions with phosphonium salts: Enantioselective total synthesis of (+)-centrolobine
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Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric total synthesis of (+)-centrolobine with the highest overall yield reported to date.
- Fujioka, Hiromichi,Yahata, Kenzo,Kubo, Ozora,Sawama, Yoshinari,Hamada, Tomohito,Maegawa, Tomohiro
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supporting information; experimental part
p. 12232 - 12235
(2012/01/30)
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- Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols
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Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.
- Hoover, Jessica M.,Stahl, Shannon S.
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supporting information; experimental part
p. 16901 - 16910
(2011/12/04)
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- Chemoselective oxidation of primary alcohols catalysed by Ce(iii)-complex intercalated LDH using molecular oxygen at room temperature
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Herein we describe the preparation of an efficient heterogeneous catalyst consisting of an anionic Ce(iii)-complex immobilized Zn/Al-layered double hydroxide (LDH) and its use in the catalytic liquid phase oxidation of primary alcohols using molecular O2 at room temperature. Various primary alcohols could be transformed to their corresponding aldehydes in good to excellent yields using the set of optimal conditions. The heterogeneous catalytic system can also be recovered and reused for several cycles without a significant loss of catalytic activity. The Royal Society of Chemistry 2011.
- Singha, Sudarshan,Sahoo, Mitarani,Parida
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experimental part
p. 11838 - 11844
(2011/12/13)
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- Dialkylaluminum N, O -dimethylhydroxylamine complex as a reagent to mask reactive carbonyl groups in situ from nucleophiles
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Aluminum complexes of N,O-dimethylhydroxylamine are effective reagents to mask carbonyl groups in situ from nucleophilic addition by organolithiums, Grignard reagents, and borohydrides. The utility of this process by selectively adding nucleophiles into carbonyl groups on a variety of structures as well as distinguishing between carbonyl groups on a sensitive natural product is demonstrated. 1H NMR analysis supports the in situ masking of the more reactive carbonyl group.
- Barrios, Francis J.,Zhang, Xuechao,Colby, David A.
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supporting information; experimental part
p. 5588 - 5591
(2011/02/23)
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- Aerobic oxidation of primary alcohols catalyzed by copper salts and catalytically active μ-hydroxyl-bridged trinuclear copper intermediate
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We have developed a new protocol involving the "copper(II) chloride-cesium carbonate" system for the aerobic oxidation of primary alcohols. Cesium carbonates and the solvents such as toluene and 1,2-dichloroethane play important roles to form a catalytica
- Liang, Lei,Rao, Guodong,Sun, Hao-Ling,Zhang, Jun-Long
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experimental part
p. 2371 - 2377
(2010/12/25)
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- One-pot synthesis of symmetrical 1,3-diarylureas or substituted benzamides directly from benzylic primary alcohols and effective oxidation of secondary alcohols to ketones using phenyliodine diacetate in combination with sodium azide
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Benzylic primary alcohols can be directly converted into symmetrical 1,3-diarylureas or substituted benzamides via an one-pot oxidative reaction using the combined reagent of phenyliodine diacetate and sodium azide. This new reaction constitutes a step-economical way to prepare symmetric 1,3-diarylureas or substituted benzamides depending upon the substituents on the phenyl rings of starting alcohols. The sodium acetate generated in situ from the ligand exchange between phenyliodine diacetate and sodium azide plays the pivotal role in the formation of 1,3-diarylureas. In addition, it is also found that various secondary alcohols can be readily oxidized to their corresponding ketones in excellent yields using the same reagent system of phenyliodine diacetate and sodium azide. Generally, secondary alcohols are preferentially oxidized to the corresponding ketones in the presence of primary ones with the limited amounts of phenyliodine diacetate and sodium azide.
- Li, Xiao-Qiang,Wang, Wei-Kun,Han, Yi-Xin,Zhang, Chi
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experimental part
p. 2588 - 2598
(2010/12/25)
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- Creation of highly stable monomeric Pd(II) species in an anion-exchangeable hydroxy double salt interlayer: Application to aerobic alcohol oxidation under an air atmosphere
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An active Pd(II) catalyst supported on the Ni-Zn mixed basic salt (NiZn), which is classified by the anion-exchangeable layered hydroxy double salts, was synthesized by simple intercalation of the anionic Pd(II) hydroxyl complex. The divalent Pd species in the interlayer of NiZn maintained their original monomeric structure during the aerobic alcohol oxidation, due to the strong electrostatic interaction between the NiZn host and anionic Pd(II) species. This catalyst could be reused without any loss of the catalytic activity and selectivity in the aerobic alcohol oxidation.
- Hara, Takayoshi,Ishikawa, Masakazu,Sawada, Junya,Ichikuni, Nobuyuki,Shimazu, Shogo
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body text
p. 2034 - 2040
(2010/06/19)
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- A chemoselective aerobic oxidation of benzylic azides catalyzed by molybdenum xanthate in an aqueous medium
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A mild molybdenum-catalyzed, aerobic, chemoselective oxidation of benzylic azides to the corresponding aldehydes in an aqueous medium that tolerates a variety of functional groups including alcohols, esters, ketones, halides and olefins is described.
- Maddani, Mahagundappa,Prabhu, Kandikere Ramaiah
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p. 4526 - 4530
(2008/09/21)
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- Mild and selective hydrozirconation of amides to aldehydes using Cp 2Zr(H)Cl: Scope and mechanistic insight
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An investigation of the use of Cp2Zr(H)Cl (Schwartz's reagent) to reduce a variety of amides to the corresponding aldehydes under very mild reaction conditions and in high yields is reported. A range of tertiary amides, including Weinreb's amides, can be converted directly to the corresponding aldehydes with remarkable chemoselectivity. Primary and secondary amides proved to be viable substrates for reduction as well, although the yields were somewhat diminished as compared to the corresponding tertiary amides. Results from NMR experiments suggested the presence of a stable, 18-electron zirconacycle intermediate that presumably affords the aldehyde upon water or silica gel workup. A series of competition experiments revealed a preference of the reagent for substrates in which the lone pair of the nitrogen is electron releasing and thus more delocalized across the amide bond by resonance. This trend accounts for the observed excellent selectivity for tertiary amides versus esters. Experiments regarding the solvent dependence of the reaction suggested a kinetic profile similar to that postulated for the hydrozirconation of alkenes and alkynes. Addition of p-anisidine to the reaction intermediate resulted in the formation of the corresponding imine mimicking the addition of water that forms the aldehyde.
- Spletstoser, Jared T.,White, Jonathan M.,Tunoori, Ashok Rao,Georg, Gunda I.
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p. 3408 - 3419
(2007/10/03)
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- Heterotrimetallic RuMnMn species on a hydrotalcite surface as highly efficient heterogeneous catalysts for liquid-phase oxidation of alcohols with molecular oxygen
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(Chemical Equation Presented) Robust and structurally defined on the atomic scale: A heterotrimetallic RuIV-MnIVMnIV species coordinated to a hydrotalcite surface is a highly efficient heterogeneous catalyst for the liquid-phase oxidation of various alcohols with 1 atm O2 as the sole oxidant (see scheme).
- Ebitani, Kohki,Motokura, Ken,Mizugaki, Tomoo,Kaneda, Kiyotomi
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p. 3423 - 3426
(2007/10/03)
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- Selective oxidation of alcohols at the benzylic position by benzeneseleninic anhydride
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Benzeneseleninic anhydride in the presence of tert-butyl hydroperoxide in chlorobenzene at about 70°C is an effective oxidizing agent for the selective oxidation of alcohols at the benzylic position.
- Toki, Naotoshi,Satoh, Tsuyoshi
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p. 1009 - 1012
(2007/10/03)
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- Catalytic Conversions in Water. Part 23: Steric Effects and Increased Substrate Scope in the Palladium-Neocuproine Catalyzed Aerobic Oxidation of Alcohols in Aqueous Solvents
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The steric influence of substituents on the 2-and 9-positions of phenanthroline in the (2,9-R2-1,10-phenanthroline)palladium(II)- catalyzed aerobic oxidation of 2-hexanol was investigated by means of high throughput experimentation. (Neocuproine)Pd-(OAc)2 (R=CH 3) was found to be a highly active catalyst for alcohol oxidation in 1:1 water/DMSO mixtures. The catalyst is unique in that it tolerates water, polar co-solvents and a wide variety of functional groups in the alcohol. Turn-over frequencies of > 1500 h-1 were achieved and a series of alcohols was oxidised with 0.1 to 0.5 mol % of catalyst.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
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p. 1341 - 1352
(2007/10/03)
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- Scope, kinetics, and mechanistic aspects of aerobic oxidations catalyzed by ruthenium supported on alumina
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The Ru/Al2O3 catalyst was prepared by modification of the preparation of Ru(OH)3·nH2O. The present Ru/Al 2O3 catalyst has high catalytic activities for the oxidations of activated, nonactivated, and heterocyclic alcohols, diols, and amines at 1 atm of molecular oxygen. Furthermore, the catalyst could be reused seven times without a loss of catalytic activity and selectivity for the oxidation of benzyl alcohol. A catalytic reaction mechanism involving a ruthenium alcoholate species and β-hydride elimination from the alcoholate has been proposed. The reaction rate has a first-order dependence on the amount of catalyst, a fractional order on the concentration of benzyl alcohol, and a zero order on the pressure of molecular oxygen. These results and kinetic isotope effects indicate that β-elimination from the ruthenium alcoholate species is a rate-determining step.
- Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 4353 - 4361
(2007/10/03)
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- Catalytic Conversions in Water. Part 21: Mechanistic Investigations on the Palladium-Catalysed Aerobic Oxidation of Alcohols in Water
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Water-soluble complexes of palladium(II) with phenanthroline-derivatives are stable, recyclable catalysts for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic liquid-liquid system. The active catalyst is a dihydroxy-bridged palladium dimer. Kinetics of the reaction, ligand and anion effects are discussed.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Sheldon, Roger A.
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p. 355 - 369
(2007/10/03)
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- A very mild and chemoselective oxidation of alcohols to carbonyl compounds
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matrixpresented Efficient oxidation of primary alcohols and β-amino alcohols to the corresponding aldehydes and α-amino aldehydes can be carried out at room temperature and in methylene chloride, using trichloroisocyanuric acid in the presence of catalytic TEMPO: aliphatic, benzylic, and allylic alcohols, and β-amino alcohols are rapidly oxidized without no overoxidation to carboxylic acids. Secondary carbinols are slowly oxidized so that the reaction is highly chemoselective.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 3041 - 3043
(2007/10/03)
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- Potassium ferrate on wet alumina: Preparation and reactivity
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The use of a wet alumina/potassium ferrate system for the oxidation of a range of activated alcohols is described. Studies are presented which delineate the scope and limitation of the procedure and include a new carbon-carbon bond cleavage reaction. (C) 2000 Elsevier Science Ltd.
- Caddick,Murtagh,Weaving
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p. 9365 - 9373
(2007/10/03)
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- Efficient and highly selective oxidation of Primary alcohols to aldehydes by N-chlorosuccinimide mediated by oxoammonium salts
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2,2,6,6-Tetramethyl-1-piperidinyloxy catalyzes efficient oxidation of primary alcohols to aldehydes by N-chlorosuccinimide, in a biphasic dichloromethane - aqueous pH 8.6 buffer system in the presence of tetrabutylammonium chloride. Aliphatic, benzylic, and allylic alcohols are readily oxidized with no overoxidation to carboxylic acids. Secondary alcohols are oxidized to ketones with a much lower efficiency. Very high chemoselectivities are observed when primary alcohols are oxidized in the presence of secondary ones. Primary - secondary diols are selectively transformed into hydroxy aldehydes, with, in some cases, no detectable formation of the isomeric keto alcohols.
- Einhorn, Jacques,Einhorn, Cathy,Ratajczak, Fabien,Pierre, Jean-Louis
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p. 7452 - 7454
(2007/10/03)
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- Alkyliron and Alkylcobalt Reagents, IV.- Aldehyde-Selective Cyanoalkylation with Cyanalkyl Derivatives of Iron(II) and Other Transition Metals
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For the transfer of the cyanomethyl residue with high aldehydes vs. ketone selectivity, the Fe reagent 3a is a good alternative to the known Ti reagent 1a, whereas analogous reagents with the metals Mn, Co, Ni or Cu are unfavorable.For the aldehyde- vs. k
- Kauffmann, Thomas,Kieper, Hansjoerg,Pieper, Hans
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p. 899 - 906
(2007/10/02)
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- Thiazolidinedione hypoglycemic agents
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Hypoglycemic thiazolidine-2,4-dione derivatives of the formula STR1 wherein the dotted line represents a bond or no bond; A and B are each independently CH or N, with the proviso that when A or B is N, the other is CH; X is S, SO, SO2, CH2, CHOH or CO; n is 0 or 1; Y is CHR1 or NR2, with the proviso that when n is 1 and Y is NR2, X is SO2 or CO; Z is CHR3, CH2 CH2, CH=CH, STR2 OCH2, SCH2, SOCH2 or SO2 CH2 ; R, R1, R2 and R3 are each independently hydrogen or methyl; and X1 and X2 are each independently hydrogen, methyl, trifluoromethyl, phenyl, benzyl, hydroxy, methoxy, phenoxy, benzyloxy, bromo, chloro or fluoro; a pharmaceutically-acceptable cationic salt thereof; or a pharmaceutically-acceptable acid addition salt thereof when A or B is N.
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- Selective reduction of less reactive carbonyl groups in the presence of diborane and sodium bisulfite on silica gel
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The less reactive carbonyl group of a mixture of reducible groups of carbonyl compounds was preferentially reduced with diborane on silica gel by first forming the adduct of the more reactive carbonyl group with sodium bisulfite.For example, 4-acetylbenzaldehyde could be converted to 4-(1-hydroxylethyl)benzaldehyde in 93percent selectivity; in a mixture of 4-phenyl-acetophenone and 4-phenylbenzaldehyde, biphenylethanol was preferentially formed in 95percent yield with 16percent yield of 4-phenylbenzyl alcohol.Silica gel and sodium bisulfite were essential for this selective reaction.Aliphatic and aromatic aldehydes and unhindered cyclohexanones could be selectively protected by this method.
- Chihara, Teiji,Wakabayasi, Tamie,Taya, Kazuo,Ogawa, Haruo
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p. 720 - 724
(2007/10/02)
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- Cerium or Ruthenium Catalyzed Oxidation of Alcohols to Carbonyl Compounds by Means of Sodium Bromate
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Sodium bromate has been found to be effective oxidant for oxidation of alcohols in the presence of cerium or ruthenium compounds in biphase reaction.Selective oxidation of secondary alcohols was performed in the presence of primary ones using cerium(IV) ammonium nitrate (CAN) or cerium(IV) sulfate (CS) as catalyst.For instance, treatment of 1,10-undecanediol with CS/NaBrO3 provided 11-hydroxy-2-undecanone in 82percent yield.Ruthenium catalyzed biphase oxidation of alcohols with sodium bromate provided the corresponding aldehydes or ketones in good to excellent yields.
- Kanemoto, Shigekazu,Tomioka, Hiroki,Oshima, Koichiro,Nozaki, Hitosi
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p. 105 - 108
(2007/10/02)
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- CERIUM CATALYZED SELECTIVE OXIDATION OF SECONDARY ALCOHOLS IN THE PRESENCE OF PRIMARY ONES
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The combination of (NH4)2Ce(NO3)6-NaBrO3 or Ce(SO4)2.2H2SO4-NaBrO3 has been found to be effective for the title selective oxidation.
- Tomioka, Hiroki,Oshima, Koichiro,Nozaki, Hitosi
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p. 539 - 542
(2007/10/02)
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- APPLICATION OF THE COMBINATION OF SODIUM BISULFITE AS A PROTECTIVE REAGENT AND SOLID SUPPORTS IN THE SELECTIVE REDUCTION OF 4-ACETYLBENZALDEHYDE WITH DIBORANE
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4-Acetylbenzaldehyde (2) has been selectively reduced by using a combination of protective group and solid supports.The formyl group of 2 was protected by addition of sodium bisulfite.The adduct, supported on silica gel, was then selectively reduced to 4-
- Chihara, Teiji,Wakabayashi, Tamie,Taya, Kazuo
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p. 1657 - 1660
(2007/10/02)
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