98-86-2Relevant articles and documents
Magnetic d-penicillamine-functionalized cellulose as a new heterogeneous support for cobalt(II) in green oxidation of ethylbenzene to acetophenone
Keshipour, Sajjad,Adak, Kamran
, (2017)
A new efficient heterogeneous catalyst is introduced for the oxidation of ethylbenzene. The catalyst was obtained in three steps: functionalization of cellulose with d-penicillamine, deposition of Fe3O4 nanoparticles on cellulose–d-p
Debromination of α-Bromo Ketones using Polymer-supported Triphenylphosphine
Dhuru, Sameer P.,Padiya, Kamlesh J.,Salunkhe, M. M.
, p. 56 (1998)
An effective method for the debromination of α-bromo ketones using polymer-supported triphenylphosphine is described.
Atomically dispersed cobalt on graphitic carbon nitride as a robust catalyst for selective oxidation of ethylbenzene by peroxymonosulfate
Li, Jiaquan,Zhao, Shiyong,Yang, Shi-Ze,Wang, Shaobin,Sun, Hongqi,Jiang, San Ping,Johannessen, Bernt,Liu, Shaomin
, p. 3029 - 3035 (2021)
The development of a highly efficient strategy for the activation of the C-H bond in hydrocarbons is one of the most challenging tasks facing the chemical industries. The synthesis of novel catalysts with atomically dispersed active centers is highly desi
Vinyl Triflimides—A Case of Assisted Vinyl Cation Formation
Schroeder, Sebastian,Strauch, Christina,Gaelings, Niklas,Niggemann, Meike
, p. 5119 - 5123 (2019)
A new concept for selectivity control in carbocation-driven reactions has been identified which allows for the chemo-, regio-, and stereoselective addition of nucleophiles to alkynes—assisted vinyl cation formation—enabled by a Li+-based supramolecular framework. Mechanistic analysis of a model complex (Li2NTf2+?3 H2O) confirms that solely the formation of a complex between the incoming nucleophile and the transition state of the alkyne protonation is responsible for the resulting selective N addition to the vinyl cation. Into the bargain, a general, operationally simple synthetic procedure to previously inaccessible vinyl triflimides is provided.
Origin of enantioselection in chiral alcohol oxidation catalyzed by Pd[(-)-sparteine]Cl2
Mueller, Jaime A.,Cowell, Anne,Chandler, Bert D.,Sigman, Matthew S.
, p. 14817 - 14824 (2005)
A kinetic investigation into the origin of enantioselectivity for the Pd[(-)-sparteine]Cl2-catalyzed aerobic oxidative kinetic resolution (OKR) is reported. A mechanism to account for a newly discovered chloride dissociation from Pd[(-)-sparteine]Cl2 prior to alcohol binding is proposed. The mechanism includes (1) chloride dissociation from Pd[(-)-sparteine]Cl2 to form cationic Pd(-)-sparteine]Cl, (2) alcohol binding, (3) deprotonation of Pd-bound alcohol to form a Pd-alkoxide, and (4) β-hydride elimination of Pd-alkoxide to form ketone product and a Pd-hydride. Utilizing the addition of (-)-sparteine HCl to control the [Cl -] and [H+] and the resulting derived rate law, the key microscopic kinetic and thermodynamic constants were extracted for each enantiomer of sec-phenethyl alcohol. These constants allow for the successful simulation of the oxidation rate in the presence of exogenous (-)-sparteine HCl. A rate law for oxidation of the racemic alcohol was derived that allows for the successful prediction of the experimentally measured krel values when using the extracted constants. Besides a factor of 10 difference between the relative rates of β-hydride elimination for the enantiomers, the main enhancement in enantiodetermination results from a concentration effect of (-)-sparteine HCl and the relative rates of reprotonation of the diastereomeric Pd-alkoxides.
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Berge,Roberts
, p. 471 (1979)
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Synthesis of new hybrid hydroquinone/cobalt schiff base catalysts: Efficient electron-transfer mediators in aerobic oxidation
Purse, Byron W.,Tran, Lien-Hoa,Piera, Julio,Akermark, Bjoern,Baeckvall, Jan-Erling
, p. 7500 - 7503 (2008)
A study was conducted to demonstrate the use of efficient electron-transfer mediators in aerobic oxidation. These electron-transfer mediators were used in aerobic oxidation for synthesizing new hybrid hydroquinone and Cobalt Schiff base catalysts. These n
Spacer-Independent Intramolecular Triplet Energy Transfer in Diketones
Wagner, Peter J.,Giri, Brij. P.,Frerking, Harlan W.,DeFrancesco, James
, p. 8326 - 8327 (1992)
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Iridium-catalyzed B-H insertion of sulfoxonium ylides and borane adducts: A versatile platform to α-boryl carbonyls
Zhang, Shang-Shi,Xie, Hui,Shu, Bing,Che, Tong,Wang, Xiao-Tong,Peng, Dongming,Yang, Fan,Zhang, Luyong
, p. 423 - 426 (2020)
Iridium-catalyzed boron-hydrogen bond insertion reactions of trimethylamine-borane and sulfoxonium ylides have been demonstrated, furnishing α-boryl ketones in moderate to excellent yields in most cases (51 examples; up to 84%). This practical and scalable insertion reaction showed broad substrate scope, high functional-group compatibility and could be applied in late-stage modification of structurally complex drug compounds. Further synthetic applications were also demonstrated.
Synthesis of efficient and reusable catalyst of size-controlled Au nanoparticles within a porous, chelating and intelligent hydrogel for aerobic alcohol oxidation
Wang, Yao,Yan, Rui,Zhang, Jianzheng,Zhang, Wangqing
, p. 81 - 88 (2010)
Synthesis of size-controlled Au nanoparticles for aerobic alcohol oxidation within a porous, chelating and intelligent hydrogel of poly(N-isopropylacrylamide)-co-poly[2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxypropyl ester] (PNIPAM-co-PMACHE)
Recyclable Bismuth Complex Catalyzed 1,6-Conjugate Addition of Various Nucleophiles to para-Quinone Methides: Expedient Access to Unsymmetrical Diaryl- and Triarylmethanes
Liang, Xianghao,Xu, Haiyan,Li, Hanlin,Chen, Lizhuang,Lu, Hongfei
, p. 217 - 226 (2020)
An efficient method for the 1,6-conjugate addition of para-quinone methides with readily available nucleophiles was developed. This protocol provides a straightforward access to a class of diaryl and triarylmethane derivatives with good to excellent yields in the presence of (C4H12N2)2[BiCl6]Cl·H2O. Moreover, this bismuth catalyst can be recycled for several times.
Fe3O4 nanoparticles as a new efficient co-catalyst for Pd(ii) in Wacker oxidation of styrene using H2O2 as an oxidant
Keshipour, Sajjad,Nadervand, Selda
, p. 47617 - 47620 (2015)
A new highly selective and environment-friendly Wacker oxidation process employing PdCl2/Fe3O4 nanoparticles in H2O at 100°C using H2O2 as an oxidant has been developed. This approach has some advantages such as copper free reaction conditions, green solvent, high yield, excellent selectivity and green oxidant.
Rapid determination of both the activity and enantioselectivity of ketoreductases
Truppo, Matthew D.,Escalettes, Franck,Turner, Nicholas J.
, p. 2639 - 2641 (2008)
(Chemical Equation Presented) Fast and furious: A rapid and inexpensive assay for determining both the activity and enantioselectivity of ketoreductases (KREDs) has beendeveloped (see scheme; HRP = horseradish peroxidase, ABTS = 2,2′-azino-di(3-ethyl benzthiazoline-6-sulfonic acid). This assay, which employs an enantioselective alcohol oxidase as a reporter enzyme, was used to screen a panel of 17 KREDs in only 10 min using less than 0.5 mg substrate.
Silver catalyzed proto- and sila-Nakamura-type α-vinylation of silyl enol ethers with dichloroacetylene. Divergent formation of stereochemically pure tri- and tetrasubstituted olefins
Li, Lun,Wasik, Kimberly A.,Frost, Brian J.,Geary, Laina M.
, (2020)
The silver-catalyzed reaction of silyl enol ethers with dichloroacetylene (DCA) is described. When DCA was used as a solution in diethyl ether, we found that the silyl group was transferred to the vinyl group, resulting in stereochemically pure tetrasubstituted olefins. However, when DCA was used as a solution in the more polar acetonitrile, protonation was the major pathway, and trisubstituted olefins were the dominant products.
In situ spectroscopic studies related to the mechanism of the Friedel-Crafts acetylation of benzene in ionic liquids using AlCl3 and FeCl3
Csihony, Szilard,Mehdi, Hasan,Homonnay, Zoltan,Vertes, Attila,Farkas, Oedoen,Horvath, Istvan T.
, p. 680 - 685 (2002)
Several aspects of the mechanism of the Friedel-Crafts acetylation of benzene were studied by in situ spectroscopic methods in ionic liquids, prepared from MCl3 (M = Al or Fe) and 1-butyl-3-methylimidazolium chloride ([bmim]Cl). Moessbauer measurements have revealed that the addition of FeCl3 to [bmim]Cl leads to an equilibrium mixture that contains solid FeCl3, [bmim][Fe2Cl7], and Fe2Cl6 and/or [bmim][FeCl4], depending on the molar ratio of FeCl3 and [bmim]Cl. The formation of [(CH3CO)2CHCO]+[MCl4] -, a potential side product in the Friedel-Crafts acetylation of benzene, was shown to require the presence of both the acetylium ion [CH3CO]+[MCl4]- and free acetyl chloride. We have confirmed that [(CH3CO)2CHCO]+[MCl4]- does not involve in the Friedel-Crafts acetylation of benzene. Experimental data and theoretical calculations indicate that the acetylium ion [CH3CO]+[MCl4]- is the key intermediate in the Friedel-Crafts acetylation of benzene and the reaction proceeds through an ionic mechanism.
Facile conversion of tosylhydrazones to carbonyl compounds by the potassium peroxymonosulfate-acetone system
Jung,Kim,Kim
, p. 1583 - 1587 (1992)
Tosylhydrazones of carbonyl compounds were found to be readily cleaved into the corresponding carbonyl compounds in good yields under the mild conditions by treatment with dimethyldioxirane which is generated in situ from the reaction of acetone with potassium peroxymonosulfate.
Mechanistic studies of magnetically recyclable Pd-Fe3O4 heterodimeric nanocrystal-catalyzed organic reactions
Byun, Sangmoon,Chung, Jooyoung,Kwon, Jungmin,Moon Kim
, p. 982 - 988 (2015)
Recently, we have reported several catalytic applications of new Pd-Fe3O4 heterodimeric nanocrystals as magnetically separable catalysts. Successful applications of the nanocrystals towards various useful organic reactions such as Suzuki, Heck, and Sonogashira coupling reactions, direct C-H arylation, and Wacker oxidation have been recorded. However, detailed mechanistic courses of the reactions have not been delineated, and it was not clear whether these processes proceeded through a homogeneous or heterogeneous mechanism. Here, we report detailed mechanistic investigations of the reactions employing the Pd-Fe3O4 nanoparticle catalysts. Suzuki coupling and Wacker oxidation reactions were chosen as two representative heterogeneous reactions employing the Pd-Fe3O4 catalysts, and general kinetic studies, hot filtration tests, and three-phase tests were carried out for the two reactions. The studies showed that the reactions most probably proceed via a solution-phase mechanism.
Kinetics of acetophenone reduction to (R)-1-phenylethanol by a whole-cell Pichia capsulata biocatalyst
Homola, Patrik,Kurák, Tomá?,Illeová, Viera,Polakovi?, Milan
, p. 323 - 332 (2015)
(R)-1-phenylethanol is an important substance in fragrance and flavor industry. In this work, the reduction of acetophenone to (R)-1-phenylethanol in an aqueous medium was examined using Pichia capsulata as a whole-cell biocatalyst. Progress curve and initial rate measurements were used to obtain kinetic data. The experiments were carried out at pH 5, temperature of 25 °C, and in the presence of glucose to maintain in vivo regeneration of NADH. A model of the reversible reaction kinetics considering the substrate inhibition of the forward reaction was developed. Five kinetic parameters of this model were determined by a simultaneous fit of a reaction rate dependence on substrate concentration and 18 substrate and product concentration progress curves with very good accuracy. Equilibrium constant of the reaction and equilibrium conversion of acetophenone to (R)-1-phenylethanol were 13.7 and 93%, respectively.
Transition-Metal-Free N-O Reduction of Oximes: A Modular Synthesis of Fluorinated Pyridines
Huang, Huawen,Cai, Jinhui,Xie, Hao,Tan, Jing,Li, Feifei,Deng, Guo-Jun
, p. 3743 - 3746 (2017)
An NH4I-based reductive system has been explored to promote the oxime N-O bond cleavage and thereby enable a modular synthesis of a broad range of pharmacologically significant fluorinated pyridines. Compared with traditional condensation methods for pyridine assembly, this protocol was found to be highly regio- and chemoselective and presented broad functional group tolerance.
'Amphiphilic' cleavage of γ-stannyl ketones with ATPH/RLi: Application to enone fragmentation by the conjugate addition - Cleavage sequence
Kondo, Yuichiro,Kon-i, Kana,Iwasaki, Atsuko,Ooi, Takashi,Maruoka, Keiji
, p. 414 - 416 (2000)
The use of a combined Lewis acid/base system consisting of aluminum tris(2,6-diphenylphenoxide) (ATPH) and MeLi has allowed the electrophilically activated nucleophilic ('amphiphilic') cleavage of C(α)-C(β) bonds in γ- stannyl ketones. Through combination with the conjugate addition of α- stannyl carbanion to enone, this approach constitutes a novel two-step conjugate addition-cleavage sequence that leads to functionalized ketones (see reaction).
Structure-based enzyme tailoring of 5-hydroxymethylfurfural oxidase
Dijkman, Willem P.,Binda, Claudia,Fraaije, Marco W.,Mattevi, Andrea
, p. 1833 - 1839 (2015)
5-Hydroxymethylfurfural oxidase (HMFO) is a flavin-dependent enzyme that catalyzes the oxidation of many aldehydes, primary alcohols, and thiols.The three-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is relevant for the industrial production of biobased polymers.The remarkable wide substrate scope of HMFO contrasts with the enzymes precision in positioning the substrate to perform catalysis.We have solved the crystal structure of HMFO at 1.6 ? resolution, which guided mutagenesis experiments to probe the role of the active-site residues in catalysis.Mutations targeting two active-site residues generated engineered forms of HMFO with promising catalytic features, namely enantioselective activities on secondary alcohols and improved 2,5-furandicarboxylic acid yields.
Hydration of phenylacetylene on sulfonated carbon materials: Active site and intrinsic catalytic activity
Yan, Pengqiang,Xie, Zailai,Tian, Siyuan,Li, Fan,Wang, Dan,Su, Dang Sheng,Qi, Wei
, p. 38150 - 38156 (2018)
A series of sulfonated carbon materials (sulfonated glucose-derived carbon, carbon nanotubes, activated carbon and ordered mesoporous carbon, denoted as Sglu, SCNT, SAC and SCMK, respectively) were synthesized and applied as acid catalysts in phenylacetyl
A highly efficient transformation from cumene to cumyl hydroperoxide via catalytic aerobic oxidation at room temperature and investigations into solvent effects, reaction networks and mechanisms
Chen, Chong,Ji, Lijun,Lu, Qiuting,Shi, Guojun,Yuan, Enxian,Zhou, Hongyu
, (2021/12/04)
Cumyl hydroperoxide (CHP) is an important intermediate for the production of phenol/acetone, but suffers from severe reaction conditions and a low yield industrially. Here, an efficient transformation from cumene to CHP was developed. Different solvents were modulated for cumene oxidation catalyzed by NHPI/Co, and reaction network and mechanisms were investigated methodically. Hexafluoroisopropanol (HFIP) markedly promoted the transformation from cumene to CHP compared to other solvents at room temperature. A cumene conversion high up to 64.3% were observed with a selectivity to CHP of 71.7%. The solvent HFIP exhibited a significant promotion on cumene oxidation due to its contribution to the enhancement of the concentration of PINO radicals. Moreover, cumyl, cumyl oxyl and methyl radicals were captured by TEMPO and analyzed by HRMS, and the reaction paths and mechanisms from cumene to products were inferred. The preparation method discovered in this work may open an access to the production of CHP.
Two-step sequential energy transfer of molecular assemblies based on host-guest interactions for the construction of photochemically catalyzed artificial light-harvesting systems
Jiang, Man,Li, Xing-Long,Liu, Hui,Wang, Rong-Zhou,Wang, Ying,Xing, Ling-Bao,Yu, Shengsheng,Zhang, Ming-Hui
, (2022/01/14)
In the present work, a highly efficient artificial light-harvesting system with a two-step sequential energy transfer process based on host-guest interactions between cyano-substituted p-phenylenevinylene derivative (PPTA) and cucurbit [7]uril (CB [7]) ha