- Magnetic d-penicillamine-functionalized cellulose as a new heterogeneous support for cobalt(II) in green oxidation of ethylbenzene to acetophenone
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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
- Keshipour, Sajjad,Adak, Kamran
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- Sodium percarbonate: A mild reagent for conversion of tosylhydrazones and nitroalkanes to carbonyl compounds
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Sodium percarbonate has been found to be a good reagent for oxidative regeneration of carbonyl compounds from tosyl hydrazones and nitroalkanes.
- Narayana,Reddy,Kabalka
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- Debromination of α-Bromo Ketones using Polymer-supported Triphenylphosphine
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An effective method for the debromination of α-bromo ketones using polymer-supported triphenylphosphine is described.
- Dhuru, Sameer P.,Padiya, Kamlesh J.,Salunkhe, M. M.
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- Atomically dispersed cobalt on graphitic carbon nitride as a robust catalyst for selective oxidation of ethylbenzene by peroxymonosulfate
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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
- Li, Jiaquan,Zhao, Shiyong,Yang, Shi-Ze,Wang, Shaobin,Sun, Hongqi,Jiang, San Ping,Johannessen, Bernt,Liu, Shaomin
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- Vinyl Triflimides—A Case of Assisted Vinyl Cation Formation
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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.
- Schroeder, Sebastian,Strauch, Christina,Gaelings, Niklas,Niggemann, Meike
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- SUBSTITUENT EFFECTS ON THE GAS PHASE BASICITIES OF METHYL BENZOATES. EFFECTS OF RESONANCE DEMAND ON SUBSTITUENT EFFECTS
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The gas phase basicities of m,p-substituted methyl benzoates have been determined by means of the pulsed ICR mass spectrometer.LArSR analysis of the substituent effect provides a smaller r+ of 0.45 compared to that of acetophenone basicities, indicating a reduced resonance demand of the conjugate acid ion of methyl benzoate.
- Mishima, Masaaki,Fujio, Mizue,Tsuno, Yuho
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- Origin of enantioselection in chiral alcohol oxidation catalyzed by Pd[(-)-sparteine]Cl2
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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.
- Mueller, Jaime A.,Cowell, Anne,Chandler, Bert D.,Sigman, Matthew S.
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- Photoredox Catalysis Using Heterogenized Iridium Complexes**
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Heterogenized photoredox catalysts provide a path for sustainable chemical synthesis using highly tunable, reusable constructs. Here, heterogenized iridium complexes as photoredox catalysts were assembled via covalent attachment to metal oxide surfaces (I
- Materna, Kelly L.,Hammarstr?m, Leif
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- Influence of induced steric on the switchover reactivity of mononuclear Cu(II)-alkylperoxo complexes
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Coordination and steric environment around a metal center plays an indispensable role in its reactivity. In this report we have synthesized two bispidine based Cu(II)-OOR (R = tBu) complexes [Cu(L1)(OOtBu)]+ and [Cu(L2)(OOtBu)]+ having different steric environment around the metal center and characterized by various spectroscopic techniques. These Cu(II)-OOR species show reactivity towards oxygen atom transfer and aldehyde deformylation reactions. In contrast to the previously reported nucleophilic oxidation, aldehyde deformylation reaction by these complexes proceed via an initial H-atom abstraction with KIE of 12 and 8 respectively. It has been observed that more steric bulk at N3 and N7 position of bispidine ligand prefers the oxygen atom transfer reaction while it hinders the H-atom abstraction for Cu(II)-alkylperoxo complexes.
- Nag, Sayanta Sekhar,Mukherjee, Gourab,Barman, Prasenjit,Sastri, Chivukula V.
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- Synthesis of new hybrid hydroquinone/cobalt schiff base catalysts: Efficient electron-transfer mediators in aerobic oxidation
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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
- Purse, Byron W.,Tran, Lien-Hoa,Piera, Julio,Akermark, Bjoern,Baeckvall, Jan-Erling
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- On the Mechanism of the reduction of α-Halo-Ketones by Several Models for NADH. Reduction by a SET-Hydrogen Atom Abstraction Chain Reaction
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The mechanism for the reduction of the α-haloacetophenones by four dihydronicotinamides (DHNA's) procceds by free radical chain whose initiation and propagation sequences both contain single electron transfer reactions.The use of DHNA's as models for the role of NADH in enzyme-mediated reductions is discussed.
- Tanner, Dennis D.,Singh, Harrbansh Kumar,Kharrat, Abdelmajid,Stein, Allan R.
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- A side-on Mn(iii)-peroxo supported by a non-heme pentadentate N3Py2ligand: Synthesis, characterization and reactivity studies
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A mononuclear manganese(iii)-peroxo complex [MnIII(N3Py2)(O2)]+ (1a) bearing a non-heme N,N′-dimethyl-N-(2-(methyl(pyridin-2-ylmethyl)amino)ethyl)-N′-(pyridin-2-ylmethyl)ethane-1,2-diamine (N3Py2) ligand was synthesized by the reaction of [Mn(N3Py2)(H2O)](ClO4)2 (1) with hydrogen peroxide and triethylamine in CH3CN at 25 °C. The reactivity of 1a in aldehyde deformylation using 2-phenyl propionaldehyde (2-PPA) was studied and the reaction kinetics was monitored by UV-visible spectroscopy. A kinetic isotope effect (KIE) = 1.7 was obtained in the reaction of 1a with 2-PPA and α-[D1]-PPA, suggesting nucleophilic character of 1a. The activation parameters ΔH? and ΔS? were determined using the Eyring plot while Ea was obtained from the Arrhenius equation by performing the reaction between 288 and 303 K. Hammett constants (σp) of para-substituted benzaldehydes p-X-Ph-CHO (X = Cl, F, H, and Me) were linear with a slope (ρ) = 3.0. Computational study suggested that the side-on structure of 1a is more favored over the end-on structure and facilitates the reactivity of 1a.
- Narulkar, Dattaprasad D.,Ansari, Azaj,Vardhaman, Anil Kumar,Harmalkar, Sarvesh S.,Lingamallu, Giribabu,Dhavale, Vishal M.,Sankaralingam, Muniyandi,Das, Sandip,Kumar, Pankaj,Dhuri, Sunder N.
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- Iridium-catalyzed B-H insertion of sulfoxonium ylides and borane adducts: A versatile platform to α-boryl carbonyls
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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.
- Zhang, Shang-Shi,Xie, Hui,Shu, Bing,Che, Tong,Wang, Xiao-Tong,Peng, Dongming,Yang, Fan,Zhang, Luyong
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- Selective oxidation of arylalkanes with N-Graphitic-Modified cobalt nanoparticles in water
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N-Graphitic-Modified cobalt nanoparticles supported on carbon powder (Co/phen@CB-800-L) were prepared and found to be efficient catalysts for selective oxidation of arylalkanes to aromatic ketones with tert-butyl hydroperoxide (TBHP) in water. A broad sco
- Tu, Dong-Huai,Li, Yang,Li, Jiangwei,Gu, Yu-Jie,Wang, Bo,Liu, Zhao-Tie,Liu, Zhong-Wen,Lu, Jian
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- Synthesis of efficient and reusable catalyst of size-controlled Au nanoparticles within a porous, chelating and intelligent hydrogel for aerobic alcohol oxidation
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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)
- Wang, Yao,Yan, Rui,Zhang, Jianzheng,Zhang, Wangqing
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- PREPARATION AND SOME REACTIONS OF HALOMAGNESIUM DIORGANOCUPRATES
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Bromomagnesium diphenylcuprate and iodomagnesium dimethylcuprate have been prepared, and their thermal stability and some of their reactions investigated.In diethyl ether, 50percent of the BrMgPh2Cu decomposes in 12 h at room temperature and 50percent of the IMgMe2Cu decomposes at 0 deg C in 14 h but the cuprates are more stable in THF at or below 0 deg C.They react with acid chlorides to give 16-76percent yields of the corresponding ketones.With bromine and iodine, BrMgPh2Cu gives bromobenzene and iodobenzene in 56 and 48percent yield, respectively.Oxidation of BrMgPh2Cu with nitrobenzeneor copper(II) chloride gives, respectively, 61 and 34percent of biphenyl.Reaction of BrMgPh2Cu with acetic or benzoic anhydride yields 46-55percent of the corresponding ketone and 34-37percent of the corresponding carboxylic acids.
- Rahman, M. T.,Hoque, A. K. M. M.,Siddique, I.,Chowdhury, D. A. N.,Nahar, S. K.,Saha, S. L.
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- Recyclable Bismuth Complex Catalyzed 1,6-Conjugate Addition of Various Nucleophiles to para-Quinone Methides: Expedient Access to Unsymmetrical Diaryl- and Triarylmethanes
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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.
- Liang, Xianghao,Xu, Haiyan,Li, Hanlin,Chen, Lizhuang,Lu, Hongfei
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- Fe3O4 nanoparticles as a new efficient co-catalyst for Pd(ii) in Wacker oxidation of styrene using H2O2 as an oxidant
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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.
- Keshipour, Sajjad,Nadervand, Selda
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- Rapid determination of both the activity and enantioselectivity of ketoreductases
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(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.
- Truppo, Matthew D.,Escalettes, Franck,Turner, Nicholas J.
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- On the Mechanism of the Reduction of α-Halo Ketones by 1,3-Dimethyl-2-phenylbenzimidazoline. Reduction by a SET-Hydrogen Atom Abstraction Chain Mechanism
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A series of α-halocarbonyl compounds are dehalogenated by 1,3-dimethyl-2-phenylbenzimidazoline (DMBI) to give their corresponding carbonyl compounds.Contrary to the original proposal, the mechanism for these reductions was shown to proceed via a free-radi
- Tanner, Dennis D.,Chen, Jian Jeffrey
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- Silver catalyzed proto- and sila-Nakamura-type α-vinylation of silyl enol ethers with dichloroacetylene. Divergent formation of stereochemically pure tri- and tetrasubstituted olefins
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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.
- Li, Lun,Wasik, Kimberly A.,Frost, Brian J.,Geary, Laina M.
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- A Manganese(IV)-Hydroperoxo Intermediate Generated by Protonation of the Corresponding Manganese(III)-Superoxo Complex
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Earlier work revealed that metal-superoxo species primarily function as radicals and/or electrophiles. Herein, we present ambiphilicity of a MnIII-superoxo complex revealed by its proton- A nd metal-coupled electron-transfer processes. Specifically, a MnIV-hydroperoxo intermediate, [Mn(BDPBrP)(OOH)]+ (1, H2BDPBrP = 2,6-bis((2-(S)-di(4-bromo)phenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) was generated by treatment of a MnIII-superoxo complex, Mn(BDPBrP)(O2a￠) (2) with trifluoroacetic acid at-120 °C. Detailed insights into the electronic structure of 1 are obtained using resonance Raman and multi-frequency electron paramagnetic resonance spectroscopies coupled with density functional theory calculations. Similarly, the reaction of 2 with scandium(III) triflate was shown to give a Mn(IV)/Sc(III) bridging peroxo species, [Mn(BDPBrP)(OO)Sc(OTf)n](3-n)+ (4). Furthermore, it is found that deprotonation of 1 quantitatively regenerates 2, and that one-electron oxidation of the corresponding MnIII-hydroperoxo species, Mn(BDPBrP)(OOH) (3), also yields 1.
- Lin, Yen-Hao,Kutin, Yury,Van Gastel, Maurice,Bill, Eckhard,Schnegg, Alexander,Ye, Shengfa,Lee, Way-Zen
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- In situ spectroscopic studies related to the mechanism of the Friedel-Crafts acetylation of benzene in ionic liquids using AlCl3 and FeCl3
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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.
- Csihony, Szilard,Mehdi, Hasan,Homonnay, Zoltan,Vertes, Attila,Farkas, Oedoen,Horvath, Istvan T.
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- Mechanistic Aspects of Photocycloaddition Chemistry. An Interesting Relationship between Substituent Effects on 1,4-Biradical Closure-to-Cleavage Ratios and Photocycloaddition Regioselectivity
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The influence of β-substituents on closure-to-cleavage ratios of triplet 1,4-biradicals has been recorded and compared with how these substituents influence the regiochemistry of photocycloaddition of isobutylene and 5-substituted uracils.
- Savino, Thomas G.,Chenard, Lois Konicki,Swenton, John S.
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- Facile conversion of tosylhydrazones to carbonyl compounds by the potassium peroxymonosulfate-acetone system
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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.
- Jung,Kim,Kim
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- Nucleophilic versus Electrophilic Reactivity of Bioinspired Superoxido Nickel(II) Complexes
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The formation and detailed spectroscopic characterization of the first biuret-containing monoanionic superoxido-NiII intermediate [LNiO2]? as the Li salt [2; L=MeN[C(=O)NAr)2; Ar=2,6-iPr2C6H3)] is reported. It results from oxidation of the corresponding [Li(thf)3]2[LNiIIBr2] complex M with excess H2O2 in the presence of Et3N. The [LNiO2]? core of 2 shows an unprecedented nucleophilic reactivity in the oxidative deformylation of aldehydes, in stark contrast to the electrophilic character of the previously reported neutral Nacnac-containing superoxido-NiII complex 1, [L′NiO2] (L′=CH(CMeNAr)2). According to density-functional theory (DFT) calculations, the remarkably different behaviour of 1 versus 2 can be attributed to their different charges and a two-state reactivity, in which a doublet ground state and a nearby spin-polarized doublet excited-state both contribute in 1 but not in 2. The unexpected nucleophilicity of the superoxido-NiII core of 2 suggests that such a reactivity may also play a role in catalytic cycles of Ni-containing oxygenases and oxidases.
- Panda, Chakadola,Chandra, Anirban,Corona, Teresa,Andris, Erik,Pandey, Bhawana,Garai, Somenath,Lindenmaier, Nils,Künstner, Silvio,Farquhar, Erik R.,Roithová, Jana,Rajaraman, Gopalan,Driess, Matthias,Ray, Kallol
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- Mechanistic studies of magnetically recyclable Pd-Fe3O4 heterodimeric nanocrystal-catalyzed organic reactions
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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.
- Byun, Sangmoon,Chung, Jooyoung,Kwon, Jungmin,Moon Kim
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- Mononuclear manganese-peroxo and bis(m-oxo)dimanganese complexes bearing a common N-methylated macrocyclic ligand
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Mononuclear MnIII-peroxo and dinuclear bis(μ-oxo)Mn III2 complexes that bear a common macrocyclic ligand were synthesized by controlling the concentration of the starting MnII complex in the reaction of H2O2 (i.e., a Mn III-peroxo complex at a low concentration (≤ 1 mM) and a bis(μ-oxo)MnIII2 complex at a high concentration (≥30mM)). These intermediates were successfully characterized by various physicochemical methods such as UV-visible spectroscopy, ESI-MS, resonance Raman, and X-ray analysis. The structural and spectroscopic characterization combined with density functional theory (DFT) calculations demon-strated unambiguously that the peroxo ligand is bound in a side-on fashion in the MnIII-peroxo complex and the Mn2O2 diamond core is in the bis(μ-oxo)MnIII2 complex. The reactivity of these intermediates was investigated in electrophilic and nucleophilic reactions, in which only the MnIII-peroxo complex showed a nucleophilic reactivity in the deformylation of aldehydes.
- Kang, Hyeona,Cho, Jaeheung,Cho, Kyung-Bin,Nomura, Takashi,Ogura, Takashi,Nam, Wonwoo
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- Kinetics of acetophenone reduction to (R)-1-phenylethanol by a whole-cell Pichia capsulata biocatalyst
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(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.
- Homola, Patrik,Kurák, Tomá?,Illeová, Viera,Polakovi?, Milan
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- Rapid and selective removal of Hg(II)ions and high catalytic performance of the spent adsorbent based on functionalized mesoporous silica/poly(m-aminothiophenol)nanocomposite
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The toxic Hg(II)being released excessively into the water body from various sources has threatened the environment and human health. The aim of this study is to design a rapid and selective adsorbent, and propose an alternative way to dispose the spent ad
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- Transition-Metal-Free N-O Reduction of Oximes: A Modular Synthesis of Fluorinated Pyridines
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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.
- Huang, Huawen,Cai, Jinhui,Xie, Hao,Tan, Jing,Li, Feifei,Deng, Guo-Jun
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- Ruthenium-Catalyzed Flash Oxidation of Allenes to α,α′-Dihydroxyketones
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The ruthenium-catalyzed flash oxidation of β-allenic esters 1 furnishes α,α′-dihydroxyketones 2 in 24-72% yield. In the case of the chiral allene 1e, the oxidation proceeds with good diastereoselectivity (88% de), i.e. with efficient axis to center chirality transfer. The flash oxidation can also be used for the synthesis of corticosteroids, as exemplified by the transformation of allenic steroid 4 into dihydroxyketone 5.
- Laux, Michael,Krause, Norbert
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- 'Amphiphilic' cleavage of γ-stannyl ketones with ATPH/RLi: Application to enone fragmentation by the conjugate addition - Cleavage sequence
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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).
- Kondo, Yuichiro,Kon-i, Kana,Iwasaki, Atsuko,Ooi, Takashi,Maruoka, Keiji
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- A novel manganese(III)-peroxo complex bearing a proline-derived pentadentate aminobenzimidazole ligand
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Manganese(III)-peroxo complexes are invoked as key intermediates in the enzymatic cycles of Mn-containing enzymes, and the synthesis of reactive manganese(III)-peroxo complexes with rationally designed ligand has been of great interest in the communities of bioinorganic and biomimetic chemistry. Herein, we designed a novel pentadentate aminobenzimidazole ligand and obtained its manganese(II) complex, which was successfully applied in the synthesis of a reactive manganese(III)-peroxo complex by treatment with hydrogen peroxide in the presence of triethylamine. The manganese(III)-peroxo complex was well characterized with various spectroscopic techniques, including ultraviolet–visible (UV-vis) spectrophotometry, coldspray ionization time-of-flight mass spectrometry (CSI-TOF MS), and continuous wave electron paramagnetic resonance (CW-EPR) spectroscopy. Besides, its reactivity in aldehyde deformylation was investigated, demonstrating second-order kinetics in the reaction with 2-phenylpropionaldehyde and affording acetophenone as the sole product.
- Du, Junyi,Miao, Chengxia,Xia, Chungu,Sun, Wei
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- Structure-based enzyme tailoring of 5-hydroxymethylfurfural oxidase
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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.
- Dijkman, Willem P.,Binda, Claudia,Fraaije, Marco W.,Mattevi, Andrea
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- Hypervalent iodine in synthesis XIV-facile conversion of tosylhydrazones to carbonyl compounds with phenyliodine (III) diacetate (PID)
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Treatment of tosylhydrazones of ketones with PID in wet acetonitrile affords the corresponding parent ketones in excellent yields under mild conditions.
- Zeng,Chen
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- Hydration of phenylacetylene on sulfonated carbon materials: Active site and intrinsic catalytic activity
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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
- Yan, Pengqiang,Xie, Zailai,Tian, Siyuan,Li, Fan,Wang, Dan,Su, Dang Sheng,Qi, Wei
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- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
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Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
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- 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
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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.
- Chen, Chong,Ji, Lijun,Lu, Qiuting,Shi, Guojun,Yuan, Enxian,Zhou, Hongyu
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- A Nanographene-Based Two-Dimensional Covalent Organic Framework as a Stable and Efficient Photocatalyst
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Synthesis of covalent organic frameworks (COFs) with desirable organic units furnishes advanced materials with unique functionalities. As an emerging class of two-dimensional (2D) COFs, sp2-carbon-conjugated COFs provide a facile platform to build highly stable and crystalline porous polymers. Herein, a 2D olefin-linked COF was prepared by employing nanographene, namely, dibenzo[hi,st]ovalene (DBOV), as a building block. The DBOV-COF exhibits unique ABC-stacked lattices, enhanced stability, and charge-carrier mobility of ≈0.6 cm2 V?1 s?1 inferred from ultrafast terahertz photoconductivity measurements. The ABC-stacking structure was revealed by the high-resolution transmission electron microscopy and powder X-ray diffraction. DBOV-COF demonstrated remarkable photocatalytic activity in hydroxylation, which was attributed to the exposure of narrow-energy-gap DBOV cores in the COF pores, in conjunction with efficient charge transport following light absorption.
- Jin, Enquan,Fu, Shuai,Hanayama, Hiroki,Addicoat, Matthew A.,Wei, Wenxin,Chen, Qiang,Graf, Robert,Landfester, Katharina,Bonn, Mischa,Zhang, Kai A. I.,Wang, Hai I.,Müllen, Klaus,Narita, Akimitsu
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supporting information
(2021/12/22)
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- Two-step sequential energy transfer of molecular assemblies based on host-guest interactions for the construction of photochemically catalyzed artificial light-harvesting systems
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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
- Jiang, Man,Li, Xing-Long,Liu, Hui,Wang, Rong-Zhou,Wang, Ying,Xing, Ling-Bao,Yu, Shengsheng,Zhang, Ming-Hui
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- AuCu/ZnO heterogeneous photocatalysts: Photodeposited AuCu alloy effect on product selectivity in alkene epoxidation
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AuCu metal alloy nanoparticles were photodeposited on ZnO nanorods (ZnO_NRs) which proved to be effective photocatalysts for alkene epoxidation. The alloy nanoparticles were photodeposited onto ZnO nanorods with controlled ratios of gold and copper, with the deposition monitored in situ by UV-Vis spectroscopy. The alloy catalyst hybrids were tested for activity toward styrene epoxidation and HMF oxidative esterification, where the photoreactions were both optimized for time, temperature, and metal ratio content of the catalyst. The Au0.54Cu1/ZnO_NR alloy catalysts showed excellent photocatalytic activity and were most effective for conversion of styrene to styrene epoxide, where the product selectivity could be controlled by varying the metal ratio. Cu content in the alloy NP was essential to this process, as shown by the extrema in terms of metal content, using Au/ZnO only, where 100% benzaldehyde was obtained as the product. Au/ZnO evidenced best photocatalytic activity for HMF esterification, with conversion rapidly diminishing upon alloying of Au with Cu. A detailed XPS study was carried out to investigate reaction mechanism based on these studies, in particular, mechanisms are proposed for styrene epoxidation and oxidation cycles using the AuCu/ZnO_NR photocatalysts.
- Brock, Aidan J.,Deshan, Athukoralalage Don K.,Sarina, Sarina,Waclawik, Eric R.,Weerathunga, Helapiyumi,Zhu, Huai-Yong
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- Synthesis of SCF3-Substituted Sulfonium Ylides from Sulfonium Salts or α-Bromoacetic Esters
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A metal-free direct trifluoromethylthiolation of sulfonium ylides with an electrophilic trifluoromethylthiolating reagent has been established, in which sulfonium salt or α-bromoacetic ester is employed as sulfonium ylide precursors. This trifluoromethylthiolation enables the straightforward construction of SCF3-substituted sulfonium ylides from a wide range of substrates, including ketones, esters, and even PEGylated substrates. Moreover, the application of this approach in large-scale preparation and the fluorescence and fluorine-19 magnetic resonance imaging capabilities of the product are also explored. (Figure presented.).
- Huang, Jinfeng,Jia, Yimin,Jiang, Mou,Jiang, Zhong-Xing,Li, Xiangyu,Xiao, Yushan,Yang, Zhigang,Zhang, Jing,Zhou, Xin,Zhou, Zhiwen
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supporting information
(2022/01/11)
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- Enhancing the Catalytic Performance of Group I, II Metal Halides in the Cycloaddition of CO2to Epoxides under Atmospheric Conditions by Cooperation with Homogeneous and Heterogeneous Highly Nucleophilic Aminopyridines: Experimental and Theoretical Study
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Compared to metal-organic complexes and transition-metal halides, group I metal halides are attractive catalysts for the crucial cycloaddition reaction of CO2to epoxides as they are ubiquitously available and inexpensive, have a low molecular weight, and are not based on (potentially) endangered metals, especially for the case of sodium and potassium. Nevertheless, given their low intrinsic catalytic efficiency, they require the assistance of additional catalytic moieties. In this work, we show that by exploiting the high nucleophilicity of opportunely designed aminopyridines, catalytic systems based on alkaline metals can be formed, which allow the cycloaddition of CO2to epoxides to proceed under atmospheric pressure at moderate temperatures. Importantly, the aminopyridine nucleophiles can be applied in their heterogenized form, leading to a recyclable catalytic system. An investigation of the reaction mechanism by density functional theory calculations shows that metal halide complexes and nucleophilic pyridines can work as a dual cooperative catalytic system where the use of aminopyridines leads to lower energy barriers for the opening of the epoxide ring, and halide-adducts are involved in the subsequent steps of CO2insertion and ring closure.
- Natongchai, Wuttichai,Posada-Pérez, Sergio,Phungpanya, Chalida,Luque-Urrutia, Jesús Antonio,Solà, Miquel,D'Elia, Valerio,Poater, Albert
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p. 2873 - 2886
(2022/02/10)
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- Selective Activation of Unstrained C(O)-C Bond in Ketone Suzuki-Miyaura Coupling Reaction Enabled by Hydride-Transfer Strategy
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A Rh(I)-catalyzed ketone Suzuki-Miyaura coupling reaction of benzylacetone with arylboronic acid is developed. Selective C(O)-C bond activation, which employs aminopyridine as a temporary directing group and ethyl vinyl ketone as a hydride acceptor, occurs on the alkyl chain containing a β-position hydrogen. A series of acetophenone products were obtained in yields up to 75%.
- Zhong, Jing,Zhou, Wuxin,Yan, Xufei,Xia, Ying,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 1372 - 1377
(2022/02/23)
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- One-Dimensional Organic Conjugated Polymers as Recyclable Heterogeneous Photocatalysts
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Organic conjugated polymers with long-range conjugation generally have strong light absorption capacity in the visible light region and impressive performance in charge transfer, which endows them great application potential in the field of opto-electronic materials. However, there are few reports on their use in photocatalytic reactions. At present, it has been reported that a variety of donor-acceptor (D?A) type organic dyes can be used in efficient organic photocatalytic transformations. We designed and synthesized one-dimensional organic conjugated polymers pPhCzBP-Th and pPhCzBP-DTh with D?A structure, and proved that they are good heterogeneous photo-redox catalysts, which can photocatalyze hydrodehalogenation reduction of α-bromoacetophenone and its derivatives. Due to the strong reducibility of the excited state, pPhCzBP-Th can also efficiently reduce α-chloroacetophenone. Furthermore, by simply wrapping the catalyst powder, high-efficient separation of products and catalysts recycling can be achieved.
- Lei, Zhexuan,Liu, Yiming,Ma, Yuguo,Mo, Yitian,Tong, Yujie
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supporting information
(2022/03/18)
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- Cu/N-Oxyl-catalyzed aerobic oxidative esterification to oxalic acid diesters from ethylene glycol via highly selective intermolecular alcohol oxidation
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One of the ideal green esterification reactions is aerobic oxidative esterification using only a stoichiometric amount of different alcohols via intermolecular selective alcohol oxidation followed by hemiacetal formation by the addition of the other alcohol and hemiacetal oxidation to esters. However, oxalic acid diester synthesis via oxidative esterification has not been reported to date, possibly owing to the difficulty of selectivity control of intermolecular alcohol oxidation and the chelating effects of ethylene glycol-derived alcohols/hemiacetals on inhibiting oxidation catalysts. Herein, using a CuCl/tetramethylethylenediamine/1,5-dimethyl-9-azanoradamantane N-oxyl catalyst, we describe a highly efficient aerobic oxidative esterification reaction of ethylene glycol to various oxalic acid diesters via selective oxidation of ethylene glycol-derived alcohols/hemiacetals even in the presence of other aliphatic primary alcohols. Notably, the green reaction works well using an ideal stoichiometric ratio of ethylene glycol and primary/secondary alcohols. Thorough experimental investigation and theoretical calculations revealed that highly selective oxidative esterification is enabled by the preferential bidentate coordination of ethylene glycol-derived alcohols/hemiacetals to the Cu(ii) species, followed by efficient two-electron/one-proton transfer.
- Morino, Yusuke,Suzuki, Kosuke,Yamaguchi, Kazuya,Yatabe, Takafumi
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supporting information
p. 2017 - 2026
(2022/04/07)
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- Method for preparing aldehyde ketone compound through olefin oxidation
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The invention provides a method for preparing an aldehyde ketone compound by olefin oxidation, which relates to an olefin oxidative cracking reaction in which oxygen participates. The method comprises the following specific steps: in the presence of a solvent and an oxidant, carrying out oxidative cracking on an olefin raw material to obtain a corresponding aldehyde ketone product. Compared with the traditional method, the method does not need to add any catalyst or ligand, does not need to use high-pressure oxygen, has the advantages of simple and mild reaction conditions, environment friendliness, low cost, high atom economy and the like, is wide in substrate application range and high in yield, and has a wide application prospect in the aspects of synthesis of aldehyde ketone medical intermediates and chemical raw materials.
- -
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Paragraph 0019
(2021/04/07)
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- Poly(ethylene glycol) dimethyl ether mediated oxidative scission of aromatic olefins to carbonyl compounds by molecular oxygen
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A simple, and practical oxidative scission of aromatic olefins to carbonyl compounds using O2as the sole oxidant with poly(ethylene glycol) dimethyl ether as a benign solvent has been developed. A wide range of monosubstituted,gem-disubstituted, 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins was successfully converted into the corresponding aldehydes and ketones in excellent yields even with gram-scale reaction. Some control experiments were also conducted to support a possible reaction pathway.
- Yu, Tao,Guo, Mingqing,Wen, Simiaomiao,Zhao, Rongrong,Wang, Jinlong,Sun, Yanli,Liu, Qixing,Zhou, Haifeng
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p. 13848 - 13852
(2021/04/22)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method includes the steps of: (A) providing a compound (I) with an unsaturated double bond, a trifluoromethyl-containing reagent, and a catalyst; wherein, the catalyst is represented by Formula (II): M(O)mL1yL2z??(II);wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and(B) mixing the compound with an unsaturated double bond and the trifluoromethyl-containing reagent to perform an oxidative cleavage of the compound with the unsaturated double bond by using the catalyst in air or under oxygen atmosphere condition to obtain a compound represented by Formula (III):
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-
Paragraph 0068; 0069
(2021/07/10)
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- Method for oxidative cracking of compound containing unsaturated double bonds
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The invention relates to a method for oxidative cracking of a compound containing unsaturated double bonds. The method comprises the following steps: (A) providing a compound (I) containing unsaturated double bonds, a trifluoromethyl-containing reagent and a catalyst, wherein the catalyst is shown as a formula (II): M(O)mL1yL2z (II), M, L1, L2, m, y, z, R1, R2 and R3 being defined in the specification; and (B) mixing the compound containing the unsaturated double bonds and the trifluoromethyl-containing reagent, and performing an oxidative cracking reaction on the compound containing the unsaturated double bonds in the presence of air or oxygen by using the catalyst to obtain a compound represented by formula (III),.
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Paragraph 0102-0107
(2021/07/09)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method comprises the following step: (A) providing a compound (I) with an unsaturated double bond, a reagent with trifluoromethyl, and a catalyst; wherein the catalyst is represented by the following formula (II): M(O)mL1yL2z (II); wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and (B) mixing the compound with an unsaturated double bond and the reagent with a trifluoromethyl to perform an oxidation of the compound with the unsaturated double bond by using the catalyst at air or an oxygen condition to get a compound presented as formula (III):
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Paragraph 0050-0052
(2021/03/19)
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- Heterogeneous vanadium-catalyzed oxidative cleavage of olefins for sustainable synthesis of carboxylic acids
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The development of green and sustainable processes to synthesize active pharmaceutical ingredients and key starting materials is a priority for the pharmaceutical industry. A green and sustainable protocol for the oxidative cleavage of olefins to produce pharmaceutically and biologically valuable carboxylic acids is achieved. The developed protocol involves 70% aq. TBHP as an oxidant over a heterogeneous vanadium catalyst system. Notably, the synthesis of industrially important azelaic acid from various renewable vegetable oils is accomplished. The catalyst could be recycled for up to 5 cycles without significant loss in yield and the protocol was successfully demonstrated at the gram-scale.
- Upadhyay, Rahul,Rana, Rohit,Sood, Aakriti,Singh, Vikash,Kumar, Rahul,Srivastava, Vimal Chandra,Maurya, Sushil K.
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supporting information
p. 5430 - 5433
(2021/06/09)
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- Electrochemical Difunctionalization of Styrenes via Chemoselective Oxo-Azidation or Oxo-Hydroxyphthalimidation
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Atom- and step-economic oxo-azidation and oxo-hydroxyphthalimidation of styrenes have been developed under mild electrolytic conditions, respectively. Various valuable alpha-azido or hydroxyphthalimide aromatic ketones were synthesized efficiently from readily available styrenes, azides, and N-hydroxyphthalimides. Mechanism studies show that two different pathways involved in these two transformations.
- Jiang, Haobin,Wang, Feng,Ye, Zenghui,Zhang, Fengzhi,Zhu, Rongjin
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supporting information
p. 8240 - 8245
(2021/11/17)
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- Photo-induced oxidative cleavage of C-C double bonds of olefins in water
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The carbonyl compounds, synthesized by the oxidative cleavage of their corresponding olefins, are of great significance in organic synthesis, especially aryl ketones. We have developed a gentle and effective protocol, using acid red 94 as the organic metal-free photocatalyst, O2 as the oxidant, and water as the solvent. Under visible light irradiation, aryl ketone derivatives were obtained in moderate to excellent yields, showing good economic and environmental advantages.
- Zhang, Yilan,Yue, Xiaoguang,Liang, Chenfeng,Zhao, Jianming,Yu, Wenbo,Zhang, Pengfei
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supporting information
(2021/08/27)
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- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
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The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
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supporting information
p. 10005 - 10013
(2021/07/19)
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- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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supporting information
p. 5936 - 5943
(2021/08/23)
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- Selective oxidation of alkenes to carbonyls under mild conditions
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Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
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A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
- Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
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p. 6591 - 6597
(2021/09/10)
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- Aerobic oxidative C?C bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst
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High valency iron-containing perovskite catalyst BaFeO3-dcould efficiently promote the additive-free oxidative C?C bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O2as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.
- Shibata, Satomi,Kamata, Keigo,Hara, Michikazu
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p. 2369 - 2373
(2021/04/22)
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- A simple synthesis of [RuCl2(NHC)(p-cymene)] complexes and their use in olefin oxidation catalysis
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A simple and efficient synthetic route to [RuCl2(NHC)(p-cymene)] and [Ru(CO3)(NHC)(p-cymene)] complexes making use of a weak base, under aerobic conditions, is reported. This method enables access to a series of NHC-ruthenium compounds with moderate to good yields under mild conditions. The Ru pre-catalysts were successfully used in olefin oxidation catalysis at low catalyst loading and reach complete conversion in short times.
- Ma, Xinyuan,Guillet, Sébastien G.,Peng, Min,Van Hecke, Kristof,Nolan, Steven P.
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supporting information
p. 3959 - 3965
(2021/03/29)
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- Radical-mediated aerobic oxidation of substituted styrenes and stilbenes
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A 2,2-azobis(isobutyronitrile)-catalyzed oxidative cleavage of alkenes with molecular oxygen as the oxidant was described. Carbonyl compounds and oxiranes were obtained in moderate yield under mild conditions. This study provided useful insights into the mechanism of aerobic oxidative cleavage of alkenes.
- Aman, Hasil,Chiu, Wei-Hua,Chuang, Gary Jing,Liu, Pin-Heng
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p. 20103 - 20106
(2021/12/02)
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- Fe-S Catalyst Generated in Situ from Fe(III)- And S3?--Promoted Aerobic Oxidation of Terminal Alkenes
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An iron-sulfur complex formed by the simple mixture of FeCl3 with S3?- generated in situ from K2S is developed and applied to selective aerobic oxidation of terminal alkenes. The reaction was carried out under an atmosphere of O2 (balloon) and could proceed on a gram scale, expanding the application of S3?- in organic synthesis. This study also encourages us to explore the application of an Fe-S catalyst in organic reactions.
- Ai, Jing-Jing,Huang, Cheng-Mi,Li, Jian,Liu, Bei-Bei,Rao, Weidong,Wang, Fei,Wang, Shun-Yi
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supporting information
p. 4705 - 4709
(2021/06/28)
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- Catalytic C(β)-O Bond Cleavage of Lignin in a One-Step Reaction Enabled by a Spin-Center Shift
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A challenge to the utilization of lignin as a feedstock for aromatic fine chemicals lies in selective cleavage of copious β-O-4 linkages. A photocatalytic strategy for the selective cleavage of the C(β)-O bonds of model substrates and natural lignin extracts is achieved by a redox-neutral, catalytic cycle that does not require stoichiometric reagents. Mechanistic studies reveal the generation of a thiyl radical, which is derived from a cystine-derived H-atom transfer catalyst, initiates a spin-center shift (SCS) that leads to C(β)-O bond cleavage. The SCS reactivity is reminiscent of the C(β)-O bond cleavage chemistry that occurs in the active site of ribonucleotide reductase.
- Zhu, Qilei,Nocera, Daniel G.
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p. 14181 - 14187
(2021/11/27)
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- Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate-based Cobalt Catalyst
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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C≡C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH4)3[CoMo6O18(OH)6], which is supported by a central cobalt (III) mononucleus and a ring-shaped pure inorganic ligand composed of six MoVIO6 octahedrons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.
- Xie, Ya,Wang, Jingjing,Wang, Yunyun,Han, Sheng,Yu, Han
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p. 4985 - 4989
(2021/10/12)
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- Synthesis and Catalytic Applications of Multinuclear Gold(I)-1,2,3-Triazolylidene Complexes
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A series of mono- to trinuclear gold(I) complexes (1–3) supported by oxo-functionalized 1,2,3-triazolylidenes have been prepared. All new compounds were fully characterized by means of 1H and 13C NMR spectroscopy, elemental analyses, and in the case of complexes 1 and 2 by x-ray diffraction. The catalytic performance of the new triazolylidene gold complexes was tested in several hydroelementation and cyclization processes employing a variety of alkynes as starting materials. According to the overall results, the trinuclear complex 3 displayed the highest catalytic activity in all processes, providing good to excellent yields under mild reaction conditions.
- Rendón-Nava, David,álvarez-Hernández, Alejandro,Mendoza-Espinosa, Daniel
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supporting information
p. 840 - 847
(2021/02/26)
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- Catalyst- and acid-free Markovnikov hydration of alkynes in a sustainable H2O/ethyl lactate system
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An efficient and sustainable protocol for the hydration of alkynes has been developed under metal/acid/catalyst/ligand-free conditions in a water/ethyl lactate mixture. The hydrogen-bond network in the ethyl lactate and water mixture plays a crucial and decisive role in activating the alkynes for hydration to afford the corresponding methyl ketones. This strategy gives the Markovnikov (ketone) addition product selectively over other possible products. The essential role of hydrogen bonding has been confirmed by experimental and theoretical techniques. A probable mechanism has been suggested by various control tests. The efficacy of the method has been further explored for the competent production of value-added α,β-unsaturated carbonyl compounds through the reaction of aldehydes with alkynes as ketonic surrogates. The environmentally benign hydration method takes place under mild conditions, has broad functional-group compatibility, and uses the ethyl lactate/water (1:3) medium as a “green alternative” in the absence of any hazardous, harmful, or expensive substances.
- Dandia, Anshu,Saini, Pratibha,Chithra,Vennapusa, Sivaranjana Reddy,Parewa, Vijay
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- Ring size and nothing else matters: unusual regioselectivity of alkyne hydration by NHC gold(i) complexes
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We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(i) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(i) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.
- Ageshina, Alexandra A.,Asachenko, Andrey F.,Chesnokov, Gleb A.,Minaeva, Lidiya I.,Nechaev, Mikhail S.,Philippova, Anna N.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.
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supporting information
p. 5686 - 5689
(2021/06/16)
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- Green oxidation of amines by a novel cold-adapted monoamine oxidase mao p3 from psychrophilic fungi pseudogymnoascus sp. p3
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The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30? C, retains 75% of activity at 20? C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.
- Bia?kowska, Aneta M.,Jod?owska, Iga,Szymczak, Kamil,Twarda-Clapa, Aleksandra
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supporting information
(2021/10/25)
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- Electrochemical reactivity of S-phenacyl-O-ethyl-xanthates in hydroalcoholic (MeOH/H2O 4:1) and anhydrous acetonitrile media
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The electrochemical behavior of a series of S-phenacyl-O-ethyl-xanthates (O-ethyl-dithiocarbonate acetophenone derivatives) in hydroalcoholic (MeOH/H2O 4:1) and anhydrous media (ACN/TBAPF6) using carbon electrodes was studied. Cyclic voltammetry showed in hydroalcoholic media only two cathodic waves, whereas in ACN one anodic and two cathodic waves were present. The first cathodic wave corresponded to the reduction of the phenylketone group, whereas the first anodic was attributed to the xanthate unit. Macroelectrolysis on graphite and vitreous carbon at anodic and cathodic potentials, let us to explore the synthetic potential of this electrochemical reactions. With some compounds in hydroalcoholic media and using carbon electrodes, polymeric material was deposited on the electrode impeding the reaction; this deposit was characterized by AFM and SEM-EDS. The electroreduction on Ti electrode overcome this problem and gave the corresponding acetophenones (>95%). On the other hand, in ACN, small quantities of the dimeric 1,4-dicarbonyl compounds X-PhCOCH2CH2COPh-X (7–15%), as well as the corresponding acetophenones (ca. 50%) were isolated. Oxidation macroelectrolysis showed a very complicated transformation without synthetic value. The reaction mechanism for the reduction and the homolytic dissociation into the phenacyl radical was supported by DFT calculations.
- López-López, Ernesto Emmanuel,López-Jiménez, Sergio J.,Barroso-Flores, Joaquín,Rodríguez-Cárdenas, Esdrey,Tapia-Tapia, Melina,López-Téllez, Gustavo,Miranda, Luis D.,Frontana-Uribe, Bernardo A.
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- Selective Degradation of Styrene-Related Plastics Catalyzed by Iron under Visible Light**
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Efficient degradation of plastics, the vital challenge for a sustainable future, stands in need of better chemical recycling procedures that help produce commercially valuable small molecules and redefine plastic waste as a rich source of chemical feedstock. However, the corresponding chemical recycling methods, while being generally restricted to polar polymers, need improvement. Particularly, degradation of chemically inert nonpolar polymers, the major constitutes of plastics, suffers from low selectivity and very harsh transformation conditions. Herein, an efficient method was developed for selective degradation of styrene-related plastics under gentle conditions through multiple oxidation of sp3 C?H bonds and sp3 C?C bonds. The procedure was catalyzed with inexpensive iron salts under visible light, using oxygen as green oxidant. Furthermore, simple iron salts could be used to degrade plastics in the absence of solvent under natural conditions, highlighting the potential application of iron salts as additives for degradable plastics.
- Wang, Miao,Wen, Jinglan,Huang, Yahao,Hu, Peng
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p. 5049 - 5056
(2021/10/12)
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- Copper(II)-Ethanolamine Triazine Complex on Chitosan-Functionalized Nanomaghemite for Catalytic Aerobic Oxidation of Benzylic Alcohols
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Abstract: In this study a novel, effective and recoverable Cu(II)-catalyst was synthesized by incorporating of Cu(OAc)2 within ethanolamine-triazine derivative (TAETA) attached to chitosan (Chs)-functionalized γ-Fe2O3 nanoparticles [MNP@Chs/TAETA-Cu(II)]. It was characterized by different techniques such as FT-IR, EDS, ICP, TEM, TGA and VSM. The as-prepared nanocomposite demonstrated high oxidation activity and desired selectivity in the aerobic oxidation of structurally diverse set of benzyl alcohols. Spectral results and leaching experiments revealed that this magnetically recoverable heterogeneous catalyst preserved its structure after it was reused several?times. This protocol offers some beneficial features such as the use of oxygen as an ideal oxidant, stability of nanocomplex, easily catalyst separation by using an external magnetic field and efficient recycling as well as the lack of by-products. Graphic Abstract: [Figure not available: see fulltext.]
- Hasanpour, Benyamin,Jafarpour, Maasoumeh,Feizpour, Fahimeh,Rezaeifard, Abdolreza
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- Catalytic alcohol oxidation using cationic Schiff base manganeseIII complexes with flexible diamino bridge
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Four Schiff base manganese(III) complexes with derivatives of [(R,R)-N,N’-bis(salicy1idene)-1,2-cyclohexanediaminato)] including substituents on salicylaldehyde such as 3-methoxy, 3,5-di-tert-butyl and 3,5-chloro were synthesized and characterized using a combination of IR, UV–Vis, and HR ESI-MS techniques. The catalytic activity of these complexes was tested in the oxidation of 1-phenylethanol to acetophenone, revealing very good performances for all of the four manganese complexes. The catalytic reactions were carried out in the presence of tert-butyl hydroperoxide (TBHP) as oxidant and imidazole as co-catalyst. Complex Mn-4, bearing electron withdrawing [(R,R)-N,N’-bis(3,5-di-chloro-salicylidene)-1,2-cyclohexanediaminato)] ligand was found to be the most stable of the tested Mn(III) complexes and was selected for the oxidation of several primary and secondary alcohols.
- Kakavand, Meysam,Mastrorilli, Piero,Mesto, Ernesto,Neshat, Abdollah,Osanlou, Farzane,Schingaro, Emanuela,Todisco, Stefano
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- Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
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Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.
- Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
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p. 4429 - 4438
(2021/07/12)
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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Visible-Spectrum Solar-Light-Mediated Benzylic C-H Oxygenation Using 9,10-Dibromoanthracene As an Initiator
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We report a visible-light-mediated benzylic C-H oxygenation reaction. The reaction is initiated by solar light or the blue LED activation of 9,10-dibromoanthracene in a reaction with oxygen and takes place at ambient temperature and air pressure. Secondary benzylic positions are oxygenated to ketones, while tertiary benzylic carbons are oxygenated to give hydroperoxides. Notably, cumene hydroperoxide is produced in a higher yield and at milder conditions than the currently employed industrial conditions.
- Santra, Sourav K.,Szpilman, Alex M.
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p. 1164 - 1171
(2020/12/23)
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- LIGHT INDUCED CATALYTIC C-H OXYGENATION OF ALKANES
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A method of oxygenating a benzylic C-H bond is provided. The method comprises light induced activation of an initiator and subsequent reaction with oxygen, resulting in the formation of free radicals. Subsequently, free radicals catalyze the reaction of the benzylic C-H bond with oxygen, thereby forming an oxygenated compound.
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Paragraph 00219-00220 00223; 00225
(2021/04/02)
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- Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
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A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
- Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
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- An efficient and practical aerobic oxidation of benzylic methylenes by recyclable: N -hydroxyimide
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An efficient and practical benzylic aerobic oxidation catalyzed by cheap and simple N-hydroxyimide organocatalyst has been achieved with high yields and broad substrate scope. The organocatalyst used can be recycled and reused by simple workup and only minute amount (1 mol% in most cases) of simple iron salt is used as promoter. Phenyl substrates with mild and strong electron-withdrawing group could also be oxygenated in high yields as well as other benzylic methylenes. Influence of substituents, gram-scale application, catalysts decay and general mechanism of this methodology has also been discussed. This journal is
- Wang, Jian,Zhang, Cheng,Ye, Xiao-Qing,Du, Wenting,Zeng, Shenxin,Xu, Jian-Hong,Yin, Hong
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p. 3003 - 3011
(2021/01/28)
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- Gold complexes of bis-indazole-derived N-Heterocyclic carbene: Synthesis, structural characterizations, and catalysis
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A novel series of bis Indy-NHC gold complexes have been developed and investigated via a mild Ag-carbene transfer route. The obtained complexes were characterized by NMR spectroscopy and X-ray diffraction analysis. The catalytic property of these gold complexes was further evaluated in the oxidation of benzylic. The gold complex E1 showed a high catalytic activity in the oxidation of various benzylic substrates, resulting in the corresponding carbonyl compounds with excellent yields using TBHP as oxidant.
- Zhang, Hua,Xu, Ting,Li, Dongdong,Cheng, Tao,Chen, Jing,Zhou, Yang
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- Visible-Light-Driven Selective Air-Oxygenation of C?H Bond via CeCl3 Catalysis in Water
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Visible-light-induced C?H aerobic oxidation is an important chemical transformation that can be applied for the synthesis of aromatic ketones. High-cost catalysts and toxic solvents were generally needed in the present methodologies. Here, an efficient aqueous C?H aerobic oxidation protocol was reported. Through CeCl3-mediated photocatalysis, a series of aromatic ketones were produced in moderate to excellent yields. With air as the oxidant, this reaction could be performed under mild conditions in water and demonstrated high activity and functional group tolerance. This method is economical, highly efficient, and environmentally friendly, and it will provide inspiration for the development of aqueous photochemical synthesis reactions.
- Xie, Pan,Xue, Cheng,Shi, Sanshan,Du, Dongdong
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p. 2689 - 2693
(2021/05/07)
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- Study of ethylbenzene oxidation over polymer-silica hybrid supported Co (II) and Cu (II) complexes
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Polymer-silica hybrid support (SA-2-AMPS-SiO2) was synthesized and Co (II), Cu (II) metals were loaded over hybrid support by incipient impregnation technique. Oxidation of ethylbenzene was carried out for testing catalytic activity of catalyst
- Chaudhary, Vasu,Sharma, Sweta
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p. 601 - 613
(2020/03/10)
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- Preparation and characterization of a copper oxide nanoparticle-supported red-mud catalyst for liquid phase oxidation of ethyl benzene to acetophenone
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In this study, liquid phase oxidation of ethyl benzene to acetophenone was widely investigated using a new recyclable supported catalyst of CuO nanoparticles impregnated over activated red-mud (CuO_AARM). The catalyst was prepared using a hydrothermal rea
- Bal, Rajaram,Dey, Ratan Kumar,Mishra, Subhashree,Sangma, Simon Watre
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supporting information
p. 13070 - 13079
(2021/08/03)
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