- Molecular iodine/DMSO mediated oxidation of internal alkynes and primary alcohols using a one-pot, two step approach towards 2,4,5-trisubstituted imidazoles: Substrate scope and mechanistic studies
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An efficient, eco-friendly and practical oxidation of internal alkynes and primary alcohols as key steps towards the synthesis of 2,4,5-trisubstituted imidazoles is reported. This green synthetic methodology employed an acid and metal-free molecular iodine/DMSO system, to afford a variety of substituted imidazoles in moderate to good yields, with a range of functionalities tolerated. Mechanistic studies revealed two distinct oxidation pathways, which ultimately form the diketone and aldehyde that serve as key intermediates in the multicomponent domino synthesis.
- Jeena, Vineet,Naidoo, Shivani
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- Reductive homo-coupling of 2-aryl-2-oxazolinium salts
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The reductive homo-coupling of 2-aryl-2-oxazolinium salts was achieved by reduction with Zn-CTMS, electroreduction with zinc anode, or direct electroreduction. The homo-coupled products were converted to α-diketones.
- Shono,Kise,Nomura,Yamanami
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- Synthesis of a new class of cationic Pd(II) complexes with 1,2,3-triazol-5-ylidene ligand and their catalytic application in the conversion of internal alkynes to 1,2-diketones
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A new class of cationic Pd(II) complexes of the type [Pd(Tz)(Cl)(bipy)]+Cl? and [Pd (Tz)(Cl)(phen)]+Cl? (Tz = 1,4-diaryl-3-methyl-1,2,3-triazol-5-ylidene, bipy = 2,2′-bipyridine and phen = 1,10-phenanthroline) with various wing tip groups were synthesized from the corresponding 1,2,3-triazolium iodide via the corresponding chloro bridged dinuclear complexes [(Tz)(Cl)Pd(μ-Cl)2Pd(Cl)(Tz)]. The synthesized cationic complexes were screened for their catalytic activity of hydration of alkynes and found to be excellent towards the selective conversion of internal alkynes to the corresponding 1,2-diketones in good yields. A plausible mechanism was proposed for this conversion.
- Shaik, Jeelani Basha,Ramkumar, Venkatachalam,Sankararaman, Sethuraman
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- A Time-resolved EPR Study of One- and Two-Photon Processes in the Photochemical Reactions of Benzil
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A time-resolved EPR study of the photochemical reactions of benzil in isopropyl alcohol and a benzene-triethylamine (TEA) mixed solvent is reported.Emissive and absorptive chemically induced dynamic electron polarization signals of the intermediate radicals were observed in these two systems.The observed radicals are assigned as the benzoyl and benzil ketyl radicals in the former case and the benzil anion in the latter case.It is found that these photochemical reactions occur from the higher excited triplet state through a two-photon process in isopropyl alcohol and from the lowest excited triplet state through a one-photon process in the benzene-TEA mixed solvent, respectively.
- Mukai, Masahiro,Yamauchi, Seigo,Hirota, Noboru
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- A new hydrazone-based colorimetric chemosensor for naked-eye detection of copper ion in aqueous medium
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A new hydrazone-based colorimetric Cu2+ chemosensor is synthesized. Its structure was confirmed by single-crystal X-ray diffraction. Its binding properties towards various metal ions are examined through absorption spectroscopy. In aqueous THF solution, the chemosensor exhibits selective recognition towards Cu2+ over other metal ions with a colour change from colourless to pink. The complex formed between the chemosensor and Cu2+ ions forms a 2:1 stoichiometry with an association constant of 2.46 × 108M?2. The analytical detection limit for Cu2+ by the naked eye is as low as 10.0 μM.
- Shi, Shao-Min,Li, Qiao,Hu, Sheng-Li
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- Formic acid oxidatively cleaves 1,2,3,4-tetraaryl-2-butene-1,4-diones to 1,2-diaryl-1,2-ethanediones under microwave irradiation
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Formic acid oxidatively cleaves 1,2,3,4-tetraaryl-2-butene-1,4-diones (1,2-aroylstilbenes) to 1,2-diaryl-1,2-ethanediones (benzils) under microwave irradiation. Mechanistic probing revealed that formic acid incorporates one of its oxygen atoms into benzil.
- Rao, H. Surya Prakash,Jothilingam,Vasantham,Scheeren, Hans W.
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- Gold-Catalyzed Intermolecular Alkyne Oxyarylation for C3 Functionalization of Benzothiophenes
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C3-selective C-C bond formation on benzothiophenes is challenging, and few direct functionalization methods are available. A gold-catalyzed reaction of alkynes with benzothiophene S-oxides provides regioselective entry into C3-alkylated benzothiophenes with the C7-alkylated isomer as the minor product. This oxyarylation reaction works with alkyl and aryl alkynes and substituted and unsubstituted benzothiophenes. Mechanistic studies identify that sulfoxide inhibits the catalyst [DTBPAu(PhCN)]SbF6, which also degrades and forms the unreactive complex [(DTBP)2Au]SbF6.
- Rist, Paige A.,Grainger, Richard S.,Davies, Paul W.
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- Oxidation of Organic Molecules with a Redox-Active Guanidine Catalyst
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Herein, we report the first examples of the use of redox-active guanidines as catalysts in the green oxidation of organic molecules with dioxygen. In one half-reaction, the oxidized form of the redox-active guanidine is converted into the reduced, protonated state, thereby enabling dehydrogenative oxidation of the substrate (3,5-di-tert-butylcatechol→ortho-benzoquinone, benzoin→benzil, and 2,4-di-tert-butylphenol→biphenol). In the other half-reaction, efficient re-oxidation of the guanidine to the oxidized state is achieved with dioxygen in the presence of a copper catalyst. These results pave the way for the broader use of redox-active guanidines as oxidation catalysts.
- Wild, Ute,Sch?n, Florian,Himmel, Hans-J?rg
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- Cathodic coupling of aliphatic esters. Useful reaction for the synthesis of 1,2-diketone and acyloin
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It has been found in this study that electroreduction of aliphatic ester (1) with Mg electrode leads to the formation of the corresponding 1,2-diketone under aprotic conditions, whereas bis(trimethylsilyloxy)alkene is afforded through acyloin condensation when the reduction is carried out in the presence of chlorotrimethylsilane.
- Kashimura, Shigenori
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- Recyclable Pd-contained perovskite catalyst synthesized by a low temperature hydrothermal method for aerobic alcohol oxidation
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We successfully prepared Pd-containing perovskite strontium titanate (Pd-STO) by a relatively low-temperature hydrothermal method (i.e., 373 K) without posterior calcination. The particle size and porosity of the STO perovskite could be tuned by changing the molar ratio of H2O/NH3 (e.g., 5.0, 12.5 and 25.0) during the preparation of the amorphous titania sources. The mesoporous contained Pd-STO(12.5) showed superior catalytic performance compared to that of the other Pd-STO(x) (x = H2O/NH3) perovskites for alcohol oxidation with molecular oxygen. Both the refluxing of the non-polar solvents and addition of molecular sieves enhanced the reaction yield significantly. The Pd-incorporated perovskite (Pd-STO) showed better recyclability compared with that of the impregnated perovskite (imp-Pd/STO).
- Saputra, Leo,Kojima, Takashi,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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- Synthetic Approach to Some New Annulated 1,2,4-Triazine Skeletons with Antimicrobial and Cytotoxic Activities
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The synthesis of some triazolotriazine, tetrazolotriazine, triazinotetrazine, and triazinotetrazepino-indole by the reaction of 4-amino-6-benzyl-3-hydrazinyl-1,2,4-triazin-5(4H)-one (2) with different reagents is described. The synthesized compounds were
- Hamama, Wafaa S.,El-Bana, Ghada G.,Shaaban, Saad,Zoorob, Hanafi H.
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- Synthesis of Carbamates from Alkyl Bromides and Secondary Amines Using Silver Carbonate
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Synthesis of alkyl carbamates from alkyl bromides and secondary amines using silver carbonate as a carbonate source under mild condition is described. Various secondary amines and bromo derivatives were converted into alkyl carbamate derivatives in 33 to 62 % yield.
- Acharya, Vanitha,Mal, Sanjib,Kilaru, Jagadeesh P.,Montgomery, Mark G.,Deshpande, Sudhindra H.,Sonawane, Ravindra P.,Manjunath, Bhanu N.,Pal, Sitaram
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- The thermolysis and photochemistry of hybrid initiators for 'living' free radical polymerization
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A new initiator potentially capable of both thermal and photochemical initiation of 'living' free radical polymerization (LFRP) has been prepared. Both of these reaction pathways have been examined and identified in terms of their products. The thermal reaction is highly dependent on the reaction conditions and displays competitive radical and ionic reactivity. In the presence of a proton source, the ionic pathway is highly favored. Photochemical activation leads predominantly to Norrish type I cleavage where the photoproducts further react by α-cleavage resulting in the formation of benzaldehyde.
- Skene,Connolly, Terrence J.,Scaiano
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- Synthesis ofN-alkoxyphthalimide derivativesviaPIDA-promoted cross dehydrogenative coupling reaction
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A PIDA-promoted cross-dehydrogenative coupling reaction betweenN-hydroxyphthalimide (NHPI) and aryl ketones for efficient synthesis ofN-alkoxyphthalimide products in moderate to good yields has been described. This methodology is distinguished by catalyst-free conditions, readily available starting materials, wide substrate scope and operational simplicity. In addition, a gram-scale reaction and synthetic transformation of the product into synthetically useful intermediates has been demonstrated.
- Chen, Rongxiang,Liu, Bing,Li, Wenbo,Wang, Kai-Kai,Miao, Changqing,Li, Zhizhuang,Lv, Yingjie,Liu, Lantao
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- Metal-Free Oxidative Thioesterification of Methyl Ketones with Thiols/Disulfides for the Synthesis of α-Ketothioesters
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A direct Csp3-H bond oxidative thioesterification of methyl ketones with aromatic thiols/disulfides promoted by TBAI/K2S2O8 has been developed. The reaction provides successfully a simple and efficient method for the synthesis of functionalized α-ketothioesters of aromatic thiols. This practical methodology exhibits readily available starting materials, large-scale applicability, synthetic application, and broad functional group tolerance. A possible mechanism for the transformation is proposed.
- Hu, Biao,Zhou, Pan,Zhang, Qiaohe,Wang, Yanqin,Zhao, Siyun,Lu, Lingling,Yan, Shengjiao,Yu, Fuchao
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- A novel synthesis of aromatic α-diketones from electron transfer reactions of aromatic acids with either lithium 4,4'-di-t-butylbiphenyl radical anion or lithium metal
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Some aromatic α-diketones were directly synthesized in high yields from ultrasound-promoted reactions of the corresponding acids with excess lithium in dry THF. Use of a catalytic amount of 4,4'-di-t-butylphenyl (DBB) enhanced the coupling reaction rate.
- Karaman,Fry
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- Conversion of alkynes into 1,2-diketones using HFIP as sacrificial hydrogen donor and DMSO as dihydroxylating agent
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A metal-free and hypervalent iodine free conversion of internal alkynes into 1,2-diketo compounds has been described. The efficacy of the present protocol rely on the use of HFIP (1,1,1,3,3,3-Hexafluoro-2-propanol) as reducing agent of alkynes and DMSO as dihydroxylating agent of olefins to acquire the desired chemical transformations. The obtained 1,2-diketones were further transformed into useful derivatives.
- Gujjarappa, Raghuram,Vodnala, Nagaraju,Putta,Ganga Reddy, Velma,Malakar, Chandi C.
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- Benzoin oxidation at extreme temperature by bis(1,2-benzenedithiolato)dioxotungstate(VI) complex: A model study for hyperthermostable tungsten oxidoreductases
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The oxidation of benzoin by (NEt4)2[MVIO2(S2C 6H4)2] (M = W (1) and Mo (2)) (S2C6H4 = 1,2-benzenedithiolate) was studied to clarify the role of tungsten ions in hyperthermostable enzymes. The reaction was analyzed by saturation kinetics, primary isotope effects of kH/kD, and the high temperture reaction at 100°C. The rate constants were also compared with those of the selenolato analogs.
- Oku, Hiroyuki,Ueyama, Norikazu,Nakamura, Akira
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- Isoquinolinium fluorochromate: A new and efficient oxidant for organic substrates
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Isoquinolinium fluorochromate is a versatile reagent for the effective and selective oxidation of organic substrates, in particular for alcohols, under mild conditions.
- Srinivasan,Stanley, Preethi,Balasubramanian
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- An efficient one-step thiamine catalyzed synthesis of furil and its analogues
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By employing thiamine (vitamin B1) as the catalyst, a new 'one-step' method for the synthesis of furil from furfuraldehyde has been developed. The method proved to be very promising in preliminary studies thus indicating that several other diketones such as 2,2'-pyridyl-, 2,2'-thenyl- and benzyldiketones can be obtained efficiently by the same approach. Additionally, it avoids the use of sodium cyanide, and shows much higher yields when compared to conventional methods.
- Pimpim,Rubega,De Bravo,Kascheres
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- SYNTHESIS OF (Z)-STILBENDIOL DIBENZOATE BY SENSITIZED PHOTOOXYGENATION OF 2,3,5,6-TETRAPHENYL-p-DIOXIN
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Sensitized photooxygenation of 2,3,5,6-tetraphenyl-p-dioxin with singlet and triplet excitable sensitizers yields (Z)-stilbendiol dibenzoate together with benzil.Experimental proofs show that unconnected mechanisms could operate accounting for the 1,2-diketone and the endiol diester formation.
- Lopez, Luigi
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- Water-soluble diruthenium complexes bearing acetate and carbonate bridges: Highly efficient catalysts for aerobic oxidation of alcohols in water
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The aerobic oxidation of alcohols in water can be performed efficiently in the presence of a catalytic amount of the water-soluble diruthenium complex Ru2(μ-OAc)3(μ-CO3) under an atmospheric pressure (1 atm) of O2. The Royal Society of Chemistry 2006.
- Komiya, Naruyoshi,Nakae, Takahiro,Sato, Hideomi,Naota, Takeshi
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- Laser-driven heterogeneous catalysis: Efficient amide formation catalysed by Au/SiO2 systems
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A proof of concept of laser-assisted heterogeneously catalysed processes at room temperature using silica supported gold nanoparticles is reported. Au/SiO2 nanoparticles were laser-irradiated at 532 nm (SPR maximum absorbance) to catalyse the selected reaction, namely the production of 4-benzoylmorpholine from benzaldehyde and morpholine via amide formation, for which quantitative yields to the target amide were obtained after 3-5 h of reaction. The protocol could also be extended to a tandem oxidation/amidation process which shows the potential of the proposed approach for the promotion of liquid-phase organic reactions at room temperature.
- Pineda, Antonio,Gomez, Leyre,Balu, Alina M.,Sebastian, Victor,Ojeda, Manuel,Arruebo, Manuel,Romero, Antonio A.,Santamaria, Jesus,Luque, Rafael
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- A rapid and convenient oxidation of secondary alcohols
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A rapid (normally 20?min to 2?h) and selective oxidation of secondary alcohols to ketones can be achieved using 0.4?equivalents trichloroisocyanuric acid and 1.2?equivalents pyridine at room temperature in ethyl acetate. A likely mechanism for the reaction is proposed.
- Dip, Irene,Gethers, Christina,Rice, Tonya,Straub, Thomas S.
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- Anion Effects in Oxidative Aliphatic Carbon-Carbon Bond Cleavage Reactions of Cu(II) Chlorodiketonate Complexes
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Aliphatic oxidative carbon-carbon bond cleavage reactions involving Cu(II) catalysts and O2 as the terminal oxidant are of significant current interest. However, little is currently known regarding how the nature of the Cu(II) catalyst, including the anions present, influence the reaction with O2. In previous work, we found that exposure of the Cu(II) chlorodiketonate complex [(6-Ph2TPA)Cu(PhC(O)CClC(O)Ph)]ClO4 (1) to O2 results in oxidative aliphatic carbon-carbon bond cleavage within the diketonate unit, leading to the formation of benzoic acid, benzoic anhydride, benzil, and 1,3-diphenylpropanedione as organic products. Kinetic studies of this reaction revealed a slow induction phase followed by a rapid decay of the absorption features of 1. Notably, the induction phase is not present when the reaction is performed in the presence of a catalytic amount of chloride anion. In the studies presented herein, a combination of spectroscopic (UV-vis, EPR) and density functional theory (DFT) methods have been used to examine the chloride and benzoate ion binding properties of 1 under anaerobic conditions. These studies provide evidence that each anion coordinates in an axial position of the Cu(II) center. DFT studies reveal that the presence of the anion in the Cu(II) coordination sphere decreases the barrier for O2 activation and the formation of a Cu(II)-peroxo species. Notably, the chloride anion more effectively lowers the barrier associated with O-O bond cleavage. Thus, the nature of the anion plays an important role in determining the rate of reaction of the diketonate complex with O2. The same type of anion effects were observed in the O2 reactivity of the simple Cu(II)-bipyridine complex [(bpy)Cu(PhC(O)C(Cl)C(O)Ph)ClO4] (3).
- Saraf, Sushma L.,Mi?aczewska, Anna,Borowski, Tomasz,James, Christopher D.,Tierney, David L.,Popova, Marina,Arif, Atta M.,Berreau, Lisa M.
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- Stereoselective intermolecular nitroaminoxylation of terminal aromatic alkynes: Trapping alkenyl radicals by TEMPO
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The vinyl radical is one of the most unstable organic radicals. It is demonstrated that a nitro radical attacks phenylacetylene and makes the phenyl ring deconjugated with a double bond so that the resulting vinyl radical may be stabilized by delocalization to the phenyl rings π orbital and easily trapped by TEMPO. It is noteworthy that all desired products were obtained in moderate to good yields in an (E)-configuration.
- Yan, Hong,Rong, Guangwei,Liu, Defu,Zheng, Yang,Chen, Jie,Mao, Jincheng
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- A novel application of the Dess-Martin reagent to the synthesis of an FK506 analogue and other tricarbonyl compounds
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The use of the Dess-Martin reagent for the oxidation of β-hydroxy and β-ketoamides, esters and ketones to the corresponding tricarbonyl compounds is reported. The method is shown to be applicable to the synthesis of analogues of the immunosuppressant FK506.
- Batchelor,Gillespie,Golec,Hedgecock
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- Synthesis and Catalytic Reactivity of a Dicopper(II) μ-η2:η2-Peroxo Species Supported by 1,4,7-Tri-tert-butyl-1,4,7-triazacyclononane
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O2-derived CunO2 adducts are attractive targets for aerobic oxidation catalysis because of their remarkable reactivity, but oxidation of the supporting ligand limits catalytic turnover. We report that tBu3tacn (1,4,7-tri-tert-butyl-1,4,7-triazacyclononane) supports a dicopper(II) μ-η2:η2-peroxo species with the highest solution stability outside of an enzyme. Decomposition of this species proceeds without oxidation of the tBu3tacn ligand. Additive-free catalytic aerobic oxidation reactions at or above room temperature are described, highlighting the potential of oxidatively robust ligands in aerobic copper catalysis.
- Karahalis, Gregory J.,Thangavel, Arumugam,Chica, Bryant,Bacsa, John,Dyer, R. Brian,Scarborough, Christopher C.
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- Radical anions of acyclic vicinal oligoketones: An electron spin resonance study
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Radical anions of acyclic vicinal oligoketones with up to five CO units, 1a-d(·-) and 2a-c(·-), were generated by reduction of the parent compounds with potassium in presence of kryptofix 222 and studied by ESR measurements. The inverse correlation between g-values and the amount of spin populations on the terminal substituents prove that these radical anions are extended π-systems.
- Doerner, Thomas,Gleiter, Rolf,Neugebauer, Franz A.
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- Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
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Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
- Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
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- Oxidation of: O -dioxime by (diacetoxyiodo)benzene: Green and mild access to furoxans
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Furoxan has been widely used in the field of high energy density materials because of its excellent properties such as high density, high standard enthalpy of formation and high nitrogen content. However, its existing synthesis methods are still restricted by the problems of difficult substrate preparation and manual handling of hazardous reagents. Herein, we disclosed a mild oxidation strategy to efficiently obtain furoxan derivatives starting from readily available o-dioxime substrates. This reaction features high functional group tolerance and easy scale-up, and has excellent regioselectivity for specific nonsymmetric o-dioximes. This method greatly reduces the safety risk and simplifies the operation process, and means that diversified furoxan derivatives can be easily accessed, thus paving the way for the wide application of furoxan derivatives. This journal is
- He, Chunlin,Pang, Siping,Zhang, Qi,Zhang, Xun,Zhao, Cheng
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supporting information
p. 1489 - 1493
(2022/01/31)
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- Generation of Oxyphosphonium Ions by Photoredox/Cobaloxime Catalysis for Scalable Amide and Peptide Synthesis in Batch and Continuous-Flow
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Phosphine-mediated deoxygenative nucleophilic substitutions, such as the Mitsunobu reaction, are of great importance in organic synthesis. However, the conventional protocols require stoichiometric oxidants to trigger the formation of the oxyphosphonium i
- Chen, Xiangyang,Houk, Kendall N.,Mo, Jia-Nan,Su, Junqi,Umanzor, Alexander,Zhang, Zheng,Zhao, Jiannan
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supporting information
(2022/01/06)
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- Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis
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Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (?COCN2?) attached to p
- Belov, Vladimir N.,Bossi, Mariano L.,Hell, Stefan W.,Shojaei, Heydar
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- Photocatalytic synthesis of tetra-substituted furans promoted by carbon dioxide
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We report a simple protocol for the transition metal-free, visible-light-driven conversion of 1,3-diketones to tetra-substituted furan skeleton compounds in carbon dioxide (CO2) atmosphere under mild conditions. It was found that CO2could be incorporated at the diketone enolic OH position, which was key to enabling the cleavage of a C-O bond during the rearrangement of a cyclopropane intermediate. This method allows for the same-pot construction of two isomers of the high-value tetra-substituted furan scaffold. The synthetic scope and preliminary mechanistic investigations are presented.
- K?nig, Burkhard,Ritu,Tian, Ya-Ming,Wang, Huaiju
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p. 241 - 246
(2022/01/06)
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- Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
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Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
- Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
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p. 2955 - 2961
(2021/07/22)
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- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
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Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
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supporting information
p. 7832 - 7837
(2021/09/28)
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- Aerobic oxygenation of α-methylene ketones under visible-light catalysed by a CeNi3complex with a macrocyclic tris(salen)-ligand
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A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce-O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.
- Fujiwara, Sakiko,Kon, Yoshihiro,Mashima, Kazushi,Nagae, Haruki,Okuda, Jun,Sakamoto, Kazutaka,Sato, Kazuhiko,Schindler, Tobias
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supporting information
p. 11169 - 11172
(2021/11/04)
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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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- Mn(III) active site in hydrotalcite efficiently catalyzes the oxidation of alkylarenes with molecular oxygen
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Developing efficient heterogeneous catalytic systems based on easily available materials and molecular oxygen for the selective oxidation of alkylarenes is highly desirable. In the present research, NiMn hydrotalcite (Ni2Mn-LDH) has been found as an efficient catalyst in the oxidation of alkylarenes using molecular oxygen as the sole oxidant without any additive. Impressive catalytic performance, excellent stability and recyclability, broad applicable scope and practical potential for the catalytic system have been observed. Mn3+ species was proposed to be the efficient active site, and Ni2+ played an important role in stabilizing the Mn3+ species in the hydrotalcite structure. The kinetic study showed that the aerobic oxidation of diphenylmethane is a first-order reaction over Ni2Mn-LDH with the activation energy (Ea) and pre-exponential factor (A0) being 85.7 kJ mol?1 and 1.8 × 109 min?1, respectively. The Gibbs free energy (ΔG≠) was determined to be -10.4 kJ mol-1 K-1 for the oxidation based on Eyring-Polanyi equation, indicating the reaction is exergonic. The mechanism study indicated that the reaction proceeded through both radical and carbocation intermediates. The two species were then trapped by molecular oxygen and H2O or hydroxyl species, respectively, to yield the corresponding products. The present research might provide information for constructing highly efficient and stable active site for the catalytic aerobic oxidation based on available and economic material.
- Wang, Anwei,Zhou, WeiYou,Sun, Zhonghua,Zhang, Zhong,Zhang, Zhihui,He, MingYang,Chen, Qun
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- Gold-Catalyzed [3+2]-Annulations of α-Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
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This work reports gold-catalyzed [3+2]-annulations of α-diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3-dihydrofurans with high regio- and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]-annulations with α-diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral forms of gold and phosphoric acid. Our mechanistic analysis supports that cyclopentadienes serve as nucleophiles to attack gold carbenes at the more substituted alkenes, yielding gold enolates that complex with chiral phosphoric acid to enhance the enantioselectivity.
- Chen, Ching-Nung,Cheng, Wei-Min,Wang, Jian-Kai,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
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p. 4479 - 4484
(2021/01/21)
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- A modular, low footprint and scalable flow platform for the expedient α-aminohydroxylation of enolizable ketones
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The unique reactivity profile of α-chloronitroso derivatives is expressed to its fullest potential through the development of an integrated, modular and scalable continuous flow process for the electrophilic α-aminohydroxylation of various enolizable ketones. Flow conditions contribute to mitigating the high reactivity and toxicity of α-chloronitroso derivatives and provide an efficient, versatile and safe protocol for the α-aminohydroxylation of ketones with a minimal footprint. Fundamental aspects of the α-aminohydroxylation process were computed by DFT and further supported the experimental observations, hence leading to the unprecedented α-chloronitroso-based α-aminohydroxylation of primary, secondary and tertiary substrates. Recycling of the carbon backbone of the α-chloronitroso derivatives provides a high atom economy for the preparation of value-added molecules. This work showcases α-chloronitroso derivatives as economic and efficient vehicles for transferring electrophilic synthons of hydroxylamine toward nucleophilic enolates. A representative range of precursors and analogs of pharmaceutical active ingredients, including WHO essentials and drugs in shortage (such as epinephrine and ketamine), are prepared within minutes according to a fully concatenated process. The process features sequential modules with distinct unit operations including chemical transformations and multiple in-line extractions. The process relies on an upstream chemical Generator that manages the preparation of α-chloronitroso derivatives and that feeds downstream a series of α-aminohydroxylation modules. The setup is amenable to the addition of libraries of compounds for feeding upstream the process of discovery in medicinal chemistry and is transposable to pilot scale. Several layers of in-line analytical procedures are featured to improve process control and safety.
- Kassin, Victor-Emmanuel H.,Morodo, Romain,Toupy, Thomas,Jacquemin, Isaline,Van Hecke, Kristof,Robiette, Rapha?l,Monbaliu, Jean-Christophe M.
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supporting information
p. 2336 - 2351
(2021/04/07)
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Efficient Synthesis of Cu(II)-N-Heterocyclic Carbene Complexes in Water and Their Activity Towards Aerobic Alcohol Oxidation
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The majority of the copper N-heterocyclic carbene (NHC) complexes contain Cu in a +1 oxidation state. The Cu(II)-NHC complexes reported so far usually require strict inert atmosphere conditions. In this work, we report a very facile and quantitative preparation of a series of new Cu(II)-NHC complexes (2 a–c) starting from the inexpensive and readily available Cu(II) salts like Cu(OAc)2 and CuCl2 ? 2H2O with imidazolium salts (1 a–c), wherein 2 b and 2 c were exclusively synthesized in water under aerobic condition. It should be emphasized that this is the first example where Cu(II)-NHC complexes have been prepared in the aqueous medium. All the complexes have manifested with a heterobidentate C, O chelate type of coordination to Cu(II) centers forming trans-[Cu(IRpyO)2] (where R=Me, Mes, Dipp) type of complexes where 2 b forms a perfect square planar Cu(II)-NHC complex. Complexes 2 a–c were evaluated as catalysts for the aerobic oxidation of alcohols.
- Ahmad Bhat, Irshad,Avinash, Iruthayaraj,Kumar Sachan, Sharad,Singh, Sadhana,Anantharaman, Ganapathi
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p. 4560 - 4565
(2021/11/13)
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- One-pot synthesis, structural analysis, and oxidation applications of a series of diaryltellurium dicarboxylates
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This paper presents a concise and efficient one-pot synthesis of a variety of functionalized diaryltellurium dicarboxylates. The method is based on a mild photosensitized oxygenation of cheap and readily available carboxylic acids. The molecular structures of the diaryltellurium dicarboxylates were determined unambiguously using single-crystal X-ray diffraction analysis. The thus obtained diaryltellurium dicarboxylates were used to study the oxidation of benzoin derivatives.
- Higashikawa, Go,Koguchi, Shinichi,Ohmura, Shiori,Shibuya, Yuga,Toyoda, Anna
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p. 32837 - 32840
(2021/12/07)
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- Visible-Light-Induced Photocatalytic Oxidative Decarboxylation of Cinnamic Acids to 1,2-Diketones
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A concerted metallophotoredox catalysis has been realized for the efficient decarboxylative functionalization of α,β-unsaturated carboxylic acids with aryl iodides in the presence of perylene bisimide dye to afford 1,2-diketones.
- Chand, Shiv,Pandey, Anand Kumar,Singh, Rahul,Singh, Krishna Nand
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p. 6486 - 6493
(2021/05/06)
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- [Fe(bpy)3]2+-based porous organic polymers with boosted photocatalytic activity for recyclable organic transformations
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Three rigid metal porous organic polymers (POPs) based on an iron(ii) complex are prepared from the condensation reactions of an octahedral [Fe(bpy)3]2+-cored hexaaldehyde and three rod-like aromatic diamines. The POPs have been studied as the first series of earth-abundant metal complex-connected photocatalysts for heterogeneous visible light-driven oxidation of benzyl halides and enantioselective α-alkylation of aldehydes. Both yields and enantioselectivities of the reactions catalyzed by one of the POPs, which possesses the largest porosity, rival or even surpass those of the reactions homogeneously catalyzed by control [Fe(bpy)3]2+complexes. Moreover, POP catalysts are highly stable and exhibit a considerable activity after recycling 10 times.
- Liu, Hong-Kun,Lei, Yi-Fei,Tian, Peng-Ju,Wang, Hui,Zhao, Xin,Li, Zhan-Ting,Zhang, Dan-Wei
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supporting information
p. 6361 - 6367
(2021/03/22)
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- Synthesis of 1,2-diketones by mercury-catalyzed alkyne oxidation
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The first mercury-catalyzed synthesis of 1,2-diketones by alkyne oxidation has been developed. This inexpensive method extends the potential of mercury catalysis and allows the rapid construction of various 1,2-diketones and α-carbonyl amides in good yields with high functional group tolerance.
- Mei, Xiaochuan,Hu, Weican,Gao, Kexin,Gao, Haotian,Wang, Chaoyang,Qian, Guoying,Rong, Zhouting
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supporting information
p. 2661 - 2667
(2021/07/09)
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- Oxidation of Diphenylacetylene in the Presence of Heterogeneous Carbon-Containing Catalysts Based on Palladium, Graphene, and Graphene Oxide
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Abstract: Efficient methods have been developed for the oxidation of diphenylacetylene to 1,2-diphenyldiketone (benzyl) in DMSO both on commercially available heterogeneous carbon-containing palladium catalysts and on composite materials Pd-graphene and P
- Ioni, Yu. V.,Popova, A. S.,Shapovalov, S. S.
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p. 1621 - 1623
(2021/11/24)
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- Synthesis of Diarylethynes from Aryldiazonium Salts by Using Calcium Carbide as an Alkyne Source in a Deep Eutectic Solvent
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An efficient method for the synthesis of diarylethynes from aryldiazonium salts by using calcium carbide as an alkyne source at room temperature in a deep eutectic solvent is described. The salient features of this protocol are an inexpensive and easy-to-handle alkyne source, a nonvolatile and recyclable solvent, mild conditions, and a simple workup procedure.
- Ma, Xiaolong,Li, Zheng
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supporting information
p. 631 - 635
(2020/12/28)
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- Catalyst-Free and Transition-Metal-Free Approach to 1,2-Diketones via Aerobic Alkyne Oxidation
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A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.
- Shen, Duyi,Wang, Hongyan,Zheng, Yanan,Zhu, Xinjing,Gong, Peiwei,Wang, Bin,You, Jinmao,Zhao, Yulei,Chao, Mianran
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supporting information
p. 5354 - 5361
(2021/05/05)
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- Lanthanide complexes based on an anthraquinone derivative ligand and applications as photocatalysts for visible-light driving photooxidation reactions
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Four isostructural lanthanide coordination complexes based on 3,7-diamino-9,10-anthraquinone-2,6-disulfonate (dianionic, L) have been synthesized by hydrothermal method, namely [Er(L)(H2O)6]?[Er(H2O)8]?2L?8H2O (Er-L), [Tm(L)(H2O)6]?[Tm(H2O)8]?2L?8.5H2O (Tm-L), [Yb(L)(H2O)6]?[Yb(H2O)8]?2L?9H2O (Yb-L), [Lu(L)(H2O)6]?[Lu(H2O)8]?2L?9H2O (Lu-L). Single-crystal X-ray analysis reveals the existence of both coordinated and free ligand L in the crystal structure. Versatile sulfonate groups on these distinct L ligands, together with very rich coordinated and lattice water molecules, form a lot of hydrogen-bonding motifs that contribute to the stabilization of the crystal packing. It is interesting that the ligands stack into columns through strong π-π interactions and the centroid-centroid distances are between 3.281 and 3.331 ?. These ligands are stacked in an alternate off-set mode to avoid the steric hindrance between the bulky sulfonate groups, generating a repeated structural unit involving six stacked ligands. These lanthanide complexes proved to be good heterogeneous photocatalyst for promoting the visible-light driving photooxidation reactions of diarylacetylenes and thioethers. The Er-L complex exhibited the best catalytic activity and showed good catalytic efficiency over a wide range of substrates for both reaction systems. The Er-L photocatalyst can be easily isolated by simple filtration as crystalline material upon completion of the photooxidation reaction without structure change, and can be recycled for at least five catalytic cycles with persistent catalytic efficiency without any need of activation or regeneration. This family of lanthanide complexes represent a category of promising heterogeneous photocatalysts in terms of green chemistry, with the potential of promoting organic transformations highly efficiently under the irradiation of visible light.
- Zhu, Ting-Ting,Tao, Yu-Tong,Sun, Yue,Wang, Xue,Zhang, Xiao-Wen,Chai, Jia-Lu,Han, Jie,Zhao, Xiao-Li,Chen, Xu-Dong
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- Rhodium-Catalyzed Aerobic Decomposition of 1,3-Diaryl-2-diazo-1,3-diketones: Mechanistic Investigation and Application to the Synthesis of Benzils
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The conversion of 1,3-diaryl-2-diazo-1,3-diketones to 1,2-daryl-1,2-diketones (benzils) is reported based on a rhodium(II)-catalyzed aerobic decomposition process. The reaction occurs at ambient temperatures and can be catalyzed by a few dirhodium carboxylates (5 mol %) under a balloon pressure of oxygen. Moreover, an oxygen atom from the O2 reagent is shown to be incorporated into the product, and this is accompanied by the extrusion of a carbonyl unit from the starting materials. Mechanistically, it is proposed that the decomposition may proceed via the interaction of a ketene intermediate resulting from a Wolff rearrangement of the carbenoid, with a rhodium peroxide or peroxy radical species generated upon the activation of molecular oxygen. The proposed mechanism has been supported by the results from a set of controlled experiments. By using this newly developed strategy, a large array of benzil derivatives as well as 9,10-phenanthrenequinone were synthesized from the corresponding diazo substrates in varying yields. On the other hand, the method did not allow the generation of benzocyclobutene-1,2-dione from 2-diazo-1,3-indandione because of the difficulty of inducing the initial rearrangement.
- Zhu, Jia-Liang,Tsai, Yi-Ting
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p. 813 - 828
(2020/12/22)
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- Spectroscopic evidence of chirality in tetranuclear Cu(II)-Schiff base complexes, catalytic potential for oxidative kinetic resolution of racemic benzoin
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Two chiral Schiff base ligands 2-((1-hydroxy-3-phenylpropan-2-ylimino)methyl)-6-methoxyphenol (L1H2) and 2-(4-hydroxy-3-isopropylbut-1-enyl)-6-methoxyphenol (L2H2) have been synthesized by the condensation of l-phenylalaninol/l-valinol and o-vanillin (2-hydroxy-3-methoxy benzaldehyde). A tetranuclear homometallic Cu(II) complex [Cu4(L1H)2(L1)2] (ClO4)2 (C1) and a hexanuclear heterometallic complex [Cu4(L2)4Na2(DMF)2(H2O)] (ClO4)2 (C2) have been synthesized with the ligands. Both the complexes possess cubane like Cu4O4 core with interesting structural variations and inherit the chirality of their corresponding ligands. The catalytic potential of the complexes has been explored for the oxidative kinetic resolution of racemic benzoin. The electronic, optical and chiroptical properties of the ligands and the complexes have been studied by DFT and TD-DFT calculations.
- Sadhukhan, Dipali,Ghosh, Prithwi,Ghanta, Susanta
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p. 1714 - 1724
(2020/12/17)
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- Electrochemical Oxidative Difunctionalization of Alkenes to Access α-Oxygenated Ketones
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Dioxygenation of alkenes was developed by the combination of electrochemical synthesis and aerobic oxidation, leading to easy accessibility of α-oxygenated ketones in an eco-friendly fashion. Using air as the oxygen source and the absence of transition metals were the critical features of this protocol. A wide range of alkenes and N-hydroxyimides were found to be compatible and provided α-oxygenated ketones in moderate to high yields.
- Dai, Changhui,Shen, Yijie,Wei, Yifan,Liu, Ping,Sun, Peipei
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p. 13711 - 13719
(2021/10/01)
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- A copper-promoted synthesis of epoxy-bridged [60]fullerene-fused lactones and further derivatization
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A facile copper-promoted decarboxylative annulation of [60]fullerene (C60) with two identical α-oxocarboxylic acidsviaan unprecedented cascade addition pathway has been exploited to synthesize the unique epoxy-bridged C60-fused lactones for the first time. Further transformations into the rare epoxy-bridged C60-fused hemiacetals and bicyclic-fused 1,2,3,4-adducts as well as application in a perovskite solar cell device of the obtained products have also been demonstrated. The structures of the epoxy-bridged C60-fused lactones and derived reductive products have been unequivocally established by single-crystal X-ray crystallography. Plausible reaction mechanisms leading to the observed products are proposed.
- Lu, Wen-Qiang,Zhou, Dian-Bing,Yin, Zheng-Chun,Liu, Qing-Song,Wang, Guan-Wu
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supporting information
p. 7043 - 7046
(2021/07/21)
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- Sol-gel synthesis of ceria-zirconia-based high-entropy oxides as high-promotion catalysts for the synthesis of 1,2-diketones from aldehyde
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Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions.
- Dinjar, Kristijan,Djerdj, Igor,Koj?inovi?, Jelena,Kukovecz, ákos,Markovi?, Berislav,Mileti?, Aleksandar,Nagy, Sándor Balázs,Sapi, Andras,Stenzel, David,Széchenyi, Aleksandar,Szenti, Imre,Tang, Yushu,Tatar, Dalibor,Varga, Gábor,Ziegenheim, Szilveszter
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supporting information
(2021/10/20)
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- One-pot cascade synthesis of α-diketones from aldehydes and ketones in water by using a bifunctional iron nanocomposite catalyst
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A new methodology for the synthesis of α-diketones was reportedviaa one-pot cascade process from aldehydes and ketones catalyzed by a bifunctional iron nanocomposite using H2O2as a green oxidant in water. The one-pot strategy showed excellent catalytic stability, comprehensive suitability of substrates and important practical utility for directly synthesizing biologically active and medicinally valuable N-heterocyclesviaan intermittent process.
- Song, Tao,Zhou, Xin,Wang, Xiaoxue,Xiao, Jianliang,Yang, Yong
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supporting information
p. 1955 - 1959
(2021/03/26)
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- Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts
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A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.
- Guo, Pengfei,Liao, Shengyun,Wang, Shun,Shi, Jing,Tong, Xinli
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p. 399 - 403
(2021/02/27)
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- 1-butyl-3-methylimidazol-2-ylidene as an efficient catalyst for cross-coupling between aromatic aldehydes and N-aroylbenzotriazoles
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Cross-coupling of aromatic aldehydes with N-aroylbenzotriazoles in [Bmim]Br in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) provided an efficient procedure for the synthesis of 1,2-diarylethane-1,2-diones.
- Phungpis, Baramee,Hahnvajanawong, Viwat
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p. 651 - 657
(2021/02/27)
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- Chromium-catalyzed ligand-free amidation of esters with anilines
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Amides are important structural motifs in pharmaceutical and agrochemical chemistry because of the intriguing biological active properties. We report here the amidation of commercially available esters with anilines that was promoted by low-cost and air-stable chromium(III) pre-catalyst combined with magnesium, providing access to amides. This reaction occurs without the use of external ligands in a simple operation. Mechanistic studies indicate that a reactive aminated Cr species responsible for the amidation can be considered, which may be formed by reaction of low-valent Cr with aniline followed by reduction with hydrogen evolution.
- Chen, Changpeng,Ling, Liang,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 762 - 766
(2021/04/14)
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- Microbial synthesis of (S)- And (R)-benzoin in enantioselective desymmetrization and deracemization catalyzed by aureobasidium pullulans included in the blossom protect agent
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In this study, we examined the Aureobasidium pullulans strains DSM 14940 and DSM 14941 included in the Blossom Protect agent to be used in the bioreduction reaction of a symmetrical dicarbonyl compound. Both chiral 2-hydroxy-1,2-diphenylethanone antipodes were obtained with a high enantiomeric purity. Mild conditions (phosphate buffer [pH 7.0, 7.2], 30 ?C) were successfully employed in the synthesis of (S)-benzoin using two different methodologies: benzyl desymmetrization and rac-benzoin deracemization. Bioreduction carried out with higher reagent concentrations, lower pH values and prolonged reaction time, and in the presence of additives, enabled enrichment of the reaction mixture with (R)-benzoin. The described procedure is a potentially useful tool in the synthesis of chiral building blocks with a defined configuration in a simple and economical process with a lower environmental impact, enabling one-pot biotransformation.
- Ko?odziejska, Renata,Studzinska, Renata,Tafelska-Kaczmarek, Agnieszka,Pawluk, Hanna,Mlicka, Dominika,Wozniak, Alina
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- Heterogeneous Cobalt-Catalyzed C?C Bond Cleavage in Alcohols to Carbonyl Compounds
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Cobalt oxide hydrate (Co(OH)x) supported on metal oxides were prepared. The oxidative cleavage of C(OH)?C bond in alcohol was catalyzed by Co(OH)x/metal oxides using molecular oxygen as the oxidant, and the corresponding product was obtained with high selectivity. The composition and characteristics of the catalysts were analyzed by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), high-angle ring dark-field scanning TEM (HAADF-STEM), N2 physico-adsorption characterization, inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS) and NH3-temperature-programmed desorption (NH3-TPD). Additionally, a reasonable reaction mechanism was proposed based on the characterization results and a series of controlled experiments. Notably, this heterogeneous catalytic system did not require any additives and had good recycling performance.
- Teng, Jia-nan,Zhu, Rui,Li, Xinglong,Fu, Yao
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p. 4355 - 4363
(2021/09/14)
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- Visible-Light-Induced in Situ Generation of Fischer-Type Copper Carbene Complexes from Acylsilanes and Its Application to Catalytic [4 + 1] Cycloaddition with Siloxydienes
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A novel methodology for in situ generation of Fischer-type metal–carbene complexes was developed. Photoirradiation to a mixture of an acylsilane and a cationic copper complex cleanly gave a Fischer-type copper–siloxycarbene complex, which was detected by spectroscopic methods. This carbene complex reacted with siloxydienes in a [4 + 1] cycloaddition manner to give cyclopentene derivatives. It is noteworthy that this reaction proceeds with a catalytic amount of copper through in situ generation of a Fischer-type copper–siloxycarbene complex intermediate.
- Takeuchi, Taiichi,Aoyama, Tsukasa,Orihara, Kurumi,Ishida, Kento,Kusama, Hiroyuki
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p. 9490 - 9494
(2021/12/14)
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- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
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The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
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supporting information
p. 9140 - 9146
(2021/11/23)
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- NaOH-Mediated Direct Synthesis of Quinoxalines from o-Nitroanilines and Alcohols via a Hydrogen-Transfer Strategy
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A NaOH-mediated sustainable synthesis of functionalized quinoxalines is disclosed via redox condensation of o-nitroamines with diols and α-hydroxy ketones. Under optimized conditions, various o-nitroamines and alcohols are well tolerated to generate the desired products in 44-99% yields without transition metals and external redox additives.
- Wang, Yan-Bing,Shi, Linlin,Zhang, Xiaojie,Fu, Lian-Rong,Hu, Weinan,Zhang, Wenjing,Zhu, Xinju,Hao, Xin-Qi,Song, Mao-Ping
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supporting information
p. 947 - 958
(2021/01/14)
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- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
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Different benzylic compounds were efficiently oxidized to the corresponding ketones with aqueous 70% tert-butyl hydroperoxide (TBHP) and the catalytic system composed of CuCl2.2H2O and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC). The catalytic system CuCl2/BQC/TBHP allows obtaining high yields at room temperature under organic solvent-free conditions. The interest of this system lies in its cost effectiveness and its benign nature towards the environment. Benzylic tertbutylperoxy ethers and benzylic alcohols were observed and suggested as the reaction intermediates. Analysis of organic products by atomic absorption did not show any contamination with copper metal. In terms of efficiency, CuCl2/BQC system is comparable or superior to the most of the catalytic systems described in the literature and which are based on toxic organic solvent.
- Ajjou, Abdelaziz Nait,Rahman, Ateeq
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p. 165 - 174
(2020/04/15)
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- Selective Oxidation of Benzylic C-H Bonds Catalyzed by Cu(II)/{PMo12}
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Precise catalytic regulation of carbon radical generation by a highly active oxygen radical to abstract the H atom in a C-H bond is an effective method for the selective activation of C-H synthetic chemistry. Herein, we report a facile catalyst system with commercially available copper(II)/{PMo12} to form a tert-butanol radical intermediate for the selective oxidation of benzylic C-H bonds. The reaction shows a broad range of substrates (benzyl methylene, benzyl alcohols) with good functional group tolerance and chemical selectivity. The corresponding carbonyl compounds were synthesized with good yields under mild conditions. DFT calculations and experimental analysis further demonstrated a reasonable carbon radical mechanism for this type of organic transformation reaction.
- Li, Peihe,Wang, Yingying,Wang, Xia,Wang, Yin,Liu, Ying,Huang, Keke,Hu, Jing,Duan, Limei,Hu, Changwen,Liu, Jinghai
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p. 3101 - 3109
(2020/03/23)
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- AIR OXIDATION METHOD OF BENZYLIC POSITION OF ORGANIC COMPOUND AND AIR OXIDATION CATALYST
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PROBLEM TO BE SOLVED: To provide an air oxidation method by which a hydroxy group or oxo group can be introduced by efficient air oxidation of a benzylic position under relatively mild reaction conditions by using a metal complex as a catalyst without a joint use of an additive agent. SOLUTION: An air oxidation method is a method for carrying out air oxidation of a benzylic position of an organic compound having the benzylic position includes bringing the organic compound into contact with molecular oxygen in the presence of a catalyst that is a polynuclear metal complex including two or more kinds of metals. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
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Paragraph 0066-0067
(2020/12/01)
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- High Recovery of Selenium from Kesterite-Based Photovoltaic Cells
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The use of photovoltaic cells is constantly increasing and, in particular, a new generation of thin-film photovoltaic (PV) cells is under development. The absorber of these new cells, kesterite (CZT(S)Se), is composed of abundant chemical elements. Nonetheless, the development of the recycling process for these elements is indispensable for circular economy. This research is focused on the recovery of selenium by thermal oxidation and subsequent reduction. Thus, recycling of selenium has been firstly studied on synthetic kesterite and then validated in a real sample of kesterite extracted from glass-based PV cells. The best results were obtained in a vertical tubular furnace at 750 °C with an input of 20 mL/min of air. The posterior reduction process of selenium oxide was achieved by ascorbic acid, a common and economic reagent. Real kesterite was extracted from PV cells by thermal treatment at 90 °C for 1 hour to remove the encapsulant and ulterior treatment with HCl for the release of kesterite absorber. Optimal conditions from synthetic kesterite were applied to a real sample, recovering more than 90 % of selenium with a purity of 99.4 %.
- Abás, Elisa,Asensio, Maria Pilar,Laguna, Mariano,Pinilla, Jose Luis
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- Design and synthesis of a versatile cooperative catalytic aerobic oxidation system with co-immobilization of palladium nanoparticles and laccase into the cavities of MCF
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We have designed a versatile reusable cooperative catalyst oxidation system, consisting of palladium nanoparticles and laccase with unprecedented reactivity. This biohybrid catalyst was synthesized by the stepwise immobilization of laccase as an enzyme and Pd as a nanometallic component into the same cavity of siliceous mesocellular foams (MCF). MCF and nanobiohybrid catalyst were characterized by BET, SAXS, SEM, EDX elemental mapping, ICP-OES, TEM, TGA, FT-IR, and XPS techniques and the stepwise immobilization of laccase enzyme and Pd onto MCF was evaluated through several compelling electrochemical studies. The present catalytic system exhibits high activity toward (i) aerobic oxidation of alcohols to the corresponding carbonyl compounds, (ii) aerobic oxidation of cyclohexanol and cyclohexanone to phenol and (iii) aerobic dehydrogenation of important N-heteocyclic compounds (tetrahydro quinazolines, quinazolonones, pyrazolines and 1,4-diydropyridines) in the presence of catalytic amount of hydroquinone (HQ) as mediator in phosphate buffer (0.1 M, pH 4.5, 4 mL)/THF (4%, 1 mL) as solvent under mild conditions. The immobilization of both oxygen-activating catalyst (laccase) and oxidizing catalyst (Pd) onto the same support makes the present catalyst system superior to other currently available heterogeneous palladium based catalytic aerobic oxidation systems.
- Moradi, Sirvan,Shokri, Zahra,Ghorashi, Nadya,Navaee, Aso,Rostami, Amin
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p. 305 - 319
(2020/01/21)
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- Catalytic Selective Oxidation of Primary and Secondary Alcohols Using Nonheme [Iron(III)(Pyridine-Containing Ligand)] Complexes
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The selective oxidation of different primary and secondary alcohols to carbonyl compounds by hydrogen peroxide was found to be catalyzed in conversion ranging from good to excellent by an iron(III) complex of a pyridine-containing macrocyclic ligand (Pc-L), without the need of any additive. The choice of the counteranion (Cl, Br, OTf) appeared to be of fundamental importance and the best results in terms of selectivity (up to 99 %) and conversion (up to 98 %) were obtained using the well-characterized [Fe(III)(Br)2(Pc-L)]Br complex, 4c. Magnetic moments in solid-state, also confirmed in solution ([D6]DMSO) by Evans NMR method, were calculated and point out to an iron metal center in the high spin state of 5/2. The crystal structure shows that the iron(III) center is coordinated by the four nitrogen atoms of the macrocycle and two bromide anions to form a distorted octahedral coordination environment. The catalytic oxidation of benzyl alcohol in acetonitrile was found occurring with better conversions and selectivities than in other solvents. The reaction proved to be quite general, tolerating aromatic and aliphatic alcohols, although very low yields were obtained for terminal aliphatic alcohols. Preliminary mechanistic studies are in agreement with a catalytic cycle promoted by a high-spin iron complex.
- Caselli, Alessandro,Gallo, Emma,Panza, Nicola,Rizzato, Silvia,Tseberlidis, Giorgio,di Biase, Armando
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supporting information
p. 6635 - 6644
(2020/10/30)
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- Method for preparing phenytoin sodium
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The invention relates to the field of biological medicines, and discloses a method for preparing phenytoin sodium. The method is characterized by comprising the following steps: (1) carrying out an oxidation reaction on benzoin in a first solvent to obtain diphenyl ethanedione, wherein the first solvent is a mixed solution of an alcohol and water, and the alcohol is at least one selected from C1-C3 monohydric alcohols; (2) carrying out a rearrangement reaction on diphenyl ethanedione to obtain phenytoin; and (3) carrying out salt forming reaction on the phenytoin in water, and performing purifying to obtain the phenytoin sodium. According to the method provided by the invention, few solvent systems are introduced, acetic acid is prevented from being used, subsequent treatment is relativelysimple, and the prepared phenytoin sodium is relatively high in yield and purity and is convenient to large-scale production.
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Paragraph 0079; 0083-0084; 0088-0089; 0093-0094; 0098-0119
(2020/12/08)
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- Ruthenium/dendrimer complex immobilized on silica-functionalized magnetite nanoparticles catalyzed oxidation of stilbenes to benzil derivatives at room temperature
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A new ruthenium/dendrimer complex stabilized on the surface of silica-functionalized nano-magnetite was fabricated and well characterized. The nano-catalyst showed good activity in the synthesis of benzil derivatives via the oxidation of stilbenes with high turnover frequency (TOF) at room temperature. Moreover, the catalyst could also be reused up to fifteen times without any loss of its activity.
- Ghanaatzadeh, Niloofar,Hashemi, Hajar,Moghadam, Majid,Niknam, Khodabakhsh,Saberi, Dariush
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- Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls
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2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.
- Dubovtsev, Alexey Yu.,Shcherbakov, Nikolay V.,Dar'in, Dmitry V.,Kukushkin, Vadim Yu.
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p. 745 - 757
(2020/02/04)
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