- Fe(II) complexes that mimic the active site structure of acetylacetone dioxygenase: O2 and NO reactivity
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Acetylacetone dioxygenase (Dke1) is a bacterial enzyme that catalyzes the dioxygen-dependent degradation of β-dicarbonyl compounds. The Dke1 active site contains a nonheme monoiron(II) center facially ligated by three histidine residues (the 3His triad); coordination of the substrate in a bidentate manner provides a five-coordinate site for O2 binding. Recently, we published the synthesis and characterization of a series of ferrous β-diketonato complexes that faithfully mimic the enzyme-substrate intermediate of Dke1 (Park, H.; Baus, J.S.; Lindeman, S.V.; Fiedler, A.T. Inorg. Chem. 2011, 50, 11978-11989). The 3His triad was modeled with three different facially coordinating N3 supporting ligands, and substituted β-diketonates (acacX) with varying steric and electronic properties were employed. Here, we describe the reactivity of our Dke1 models toward O2 and its surrogate nitric oxide (NO), and report the synthesis of three new Fe(II) complexes featuring the anions of dialkyl malonates. Exposure of [Fe( Me2Tp) (acacX)] complexes (where R2Tp = hydrotris(pyrazol-1-yl)borate with R-groups at the 3- and 5-positions of the pyrazole rings) to O2 at -70 °C in toluene results in irreversible formation of green chromophores (λmax ~750 nm) that decay at temperatures above -60 °C. Spectroscopic and computational analyses suggest that these intermediates contain a diiron(III) unit bridged by a trans μ-1,2-peroxo ligand. The green chromophore is not observed with analogous complexes featuring Ph2Tp and PhTIP ligands (where PhTIP = tris(2-phenylimidazoly-4-yl)phosphine), since the steric bulk of the phenyl substituents prevents formation of dinuclear species. While these complexes are largely inert toward O2, Ph2Tp-based complexes with dialkyl malonate anions exhibit dioxygenase activity and thus serve as functional Dke1 models. The Fe/acac X complexes all react readily with NO to yield highspin (S = 3/2) {FeNO}7 adducts that were characterized with crystallographic, spectroscopic, and computational methods. Collectively, the results presented here enhance our understanding of the chemical factors involved in the oxidation of aliphatic substrates by nonheme iron dioxygenases.
- Park, Heaweon,Bittner, Michael M.,Baus, Jacob S.,Lindeman, Sergey V.,Fiedler, Adam T.
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- A trispyrazolylborato iron malonato complex as a functional model for the acetylacetone dioxygenase
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(Chemical Equation Presented) Position available: A pentacoordinate iron(II) complex that binds and activates dioxygen shows dioxygenase activity and cleaves diethyl phenylmalonate, in analogy to acetylacetone dioxygenase (see scheme). The mechanism for the model compound allows interesting hypotheses to be made about the enzyme function.
- Siewert, Inke,Limberg, Christian
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- Green synthesis of zinc oxide particles with apple-derived compounds and their application as catalysts in the transesterification of methyl benzoates
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ZnO nanoparticles (ZnONPs) were successfully synthesized using bravo-de-esmolfe apple extract in aqueous medium at room temperature. ZnO microparticles, prepared with a pure apple phytochemical, quercetin (ZnOq), or without phytochemicals (ZnO) were studied for comparative purposes. The re-use of apple waste for highly efficient catalyst production, based on green synthetic routes, can be added to the concept of a circular economy. The synthesized ZnO particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2adsorption/desorption Brunauer-Emmett-Teller (BET) theory. The XRD patterns indicated the formation of a hexagonal wurtzite phase with high purity and SEM and TEM analyses revealed the morphology of the particles. The apple extract produced spherical ZnONPs composed of round lamina-like structures, similar to the micro sized lamina-like shape of ZnOq and dissimilar to the flower-like shape of ZnO. The green synthesized ZnO nanoparticles (ZnONPs) led to a high product yield ofca. 96% within 24 h of reaction time in the transesterification reaction of different carboxylic esters.
- Alegria, Elisabete C. B. A.,Alves, Marta M.,Fátima Montemor, M.,Pombeiro, Armando J. L.,Ribeiro, Ana P. C.,Saraiva, Marta S.,Soliman, Mohamed M. A.
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- Copper-catalysed Oxidation of Hydroxy Compounds by tert-Butyl Hydroperoxide Under Phase-transfer Conditions
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In the presence of quaternary ammonium phase-transfer agents copper salts catalyse the selective oxidative dehydrogenation of alcohols and hydroxy acids by tert-butyl hydroperoxide in aqueous-organic two-phase systems.
- Feldberg, Liron,Sasson, Yoel
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- A Facially Coordinating Tris-Benzimidazole Ligand for Nonheme Iron Enzyme Models
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Herein, we report a new tripodal tris-benzimidazole ligand (Tbim) that structurally mimics the 3-His coordination environment of certain nonheme mononuclear iron oxygenases. The coordination chemistry of Tbim was explored with iron(II) revealing a diverse set of coordination modes. The aerobic oxidation of biomimetic model substrate diethyl-2-phenylmalonate was studied using the Tbim?Fe and Fe(OTf)2.
- Gunasekera, Parami S.,Abhyankar, Preshit C.,MacMillan, Samantha N.,Lacy, David C.
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- VO(OEt)Cl2-induced oxidative deamination
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VO(OEt)Cl2 oxidized 2-phenylglycine derivatives via oxidative deamination and/or decarboxylation giving ethyl benzoate and ethyl phenylglyoxylate.
- Hirao, Toshikazu,Ohshiro, Yoshiki
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- O2 activation at a trispyrazolylborato nickel(II) malonato complex
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To support mechanistic inferences made for an iron-based dioxygenase model, a nickel analogue, i.e. a TpNi-malonate (1) was prepared. 1 proved to represent a rare case of a nickel complex reacting with O2 in a controlled manner-mechanistically different from the iron case-and leads to hydroxylation of the malonate.
- Hoof,Sallmann,Herwig,Braun-Cula,Limberg
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- Metal-free oxidative esterification of acetophenones with alcohols: A facile one-pot approach to α-ketoesters
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A novel and efficient oxidative esterification method for the synthesis of α-ketoesters has been developed under mild and environmentally benign conditions, which is a facile one-pot approach to α-ketoesters from commercially available acetophenones with alcohols, especially under metal-free conditions, with broad substrate scope. A possible mechanism is proposed on the basis of a series of control experiments and DMSO18 isotopic labelling experiments.
- Guo, Shiyu,Dai, Zhongxue,Yang, Zhao,Zhu, Ning,Wan, Li,Li, Xin,Liu, Chengkou,Fang, Zheng,Guo, Kai
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- A remarkable effect of quaternary ammonium bromide for the N- hydroxyphthalimide-catalyzed aerobic oxidation of hydrocarbons
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A methodology for the aerobic oxidation of organic substrates in the absence of any metal catalyst has been established using combined catalytic system consisting of N-hydroxyphthalimide and quaternary ammonium bromide. Thus, various hydrocarbons were successfully oxidized under dioxygen atmosphere to the corresponding oxygenated compounds in good selectivities.
- Matsunaka, Katsuhisa,Iwahama, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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- Chemo- And diastereoselective synthesis of pyrrolidines from aroylformates and δ-tosylamino enones via P(NMe2)3-mediated reductive amination/base-catalyzed michael addition cascade
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A novel P(NMe2)3-mediated tandem (1 + 4) annulation between aroylformates and δ-tosylamino enones has been developed that affords a facile synthesis of functionalized pyrrolidines in moderate to excellent yields with exclusive chemoselectivity and high diastereoselectivity. Mechanistic investigation reveals that the reaction proceeds through an unprecedented P(NMe2)3-mediated reductive amination/base-catalyzed Michael addition cascade. The reaction herein also represents the first study of the reactivity patterns of the Kukhtin-Ramirez adducts toward ambiphilic nucleophile-electrophiles.
- Liu, Rongfang,Liu, Jialin,Cao, Jilei,Li, Ruifeng,Zhou, Rong,Qiao, Yan,Gao, Wen-Chao
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- FACTORS AFFECTING DYE SENSITISED PHOTO-OXIDATION REACTIONS; THE EFFECT OF OXYGEN CONCENTRATION AND ITS USE TO PROBE THE MECHANISM OF DECARBOXYLATION OF α-OXO-CARBOXYLIC ACIDS AND ESTERS
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The dye sensitised photo-oxidation of α-oxo-carboxylic acids and esters leads to the production of carbon dioxide.The yield of carbon dioxide is dependent upon the oxygen concentration.This, together with the fact that carbon dioxide evolution can be observed in the absence of oxygen, is in accord with the view that the decarboxylation reactions involve an initial dye-substrate interaction rather than a singlet oxygen mediated reaction.
- Davidson, R. Stephen,Goodwin, Dean,Pratt, Julie E.
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- Unraveling two pathways for NHPI-mediated electrocatalytic oxidation reaction
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Two pathways for N-hydroxyphthalimide (NHPI)-mediated electrocatalytic oxidation using phenylacetate derivatives as template substrates were first reported for benzylic C[sbnd]H oxidation to oxygenated and non-oxygenated products. DFT calculation indicates that the hydrogen-atom transfer (HAT) process between phthalimido-N-oxyl (PINO) and substrate is a rate-determined step. Aromatic α-keto esters and 2-((1,3-dioxoisoindolin-2-yl)oxy)-2-aryl acetate obtained by cross-coupling between benzylic radical and PINO can be selectively synthesized through controlling the concentration of PINO radical. This method provides a deep understanding for selective weak C[sbnd]H oxidation using NHPI as redox mediator.
- Xu, Leitao,Yi, Yangjie,Hu, Sideng,Ye, Jiao,Hu, Aixi
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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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- Copper on charcoal: Cu0nanoparticle catalysed aerobic oxidation of α-diazo esters
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By using a charcoal supported nano Cu0catalyst (Cu/C), a highly efficient oxidation of α-diazo esters to α-ketoesters with molecular oxygen as the sole oxidant has been developed. In the presence of the Cu/C catalyst, 2-aryl-α-diazo esters with both electron-donating and electron-withdrawing groups can be oxidized to the corresponding α-ketoesters efficiently. Furthermore, this Cu/C catalyst can catalyse the reaction of aryl α-diazo ester with water to form aryl ketoester, 2-aryl-2-hydroxyl acetate ester and 2-aryl acetate ester. In this case, water is split by α-diazo ester, and the diazo group is displaced by the oxygen or hydrogen atom in water. Mechanistic investigation showed that the reaction of α-diazo ester with oxygen proceeds through a radical pathway. In the presence of 2,2,6,6-tetramethyl piperidine nitrogen oxide, the reaction of α-diazo ester with oxygen is dramatically inhibited. Furthermore, the reaction of α-diazo ester with water is investigated by an isotopic tracer method, and GCMS detection showed that a disproportionation reaction occurred between α-diazo ester and water.
- Chu, Changhu,Dong, Wenwen,Lin, Jia,Teng, Jiangge,Wang, Zhiwei,Zhao, Rong
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p. 6120 - 6126
(2021/07/21)
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- Photoinduced Diverse Reactivity of Diazo Compounds with Nitrosoarenes
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A diverse reactivity of diazo compounds with nitrosoarene in an oxygen-transfer process and a formal [2 + 2] cycloaddition is reported. Nitosoarene has been exploited as a mild oxygen source to oxidize an in situ generated carbene intermediate under visible-light irradiation. UV-light-mediated in situ generated ketenes react with nitosoarenes to deliver oxazetidine derivatives. These operationally simple processes exemplify a transition-metal-free and catalyst-free protocol to give structurally diverse α-ketoesters or oxazetidines.
- Roy, Sourav,Kumar, Gourav,Chatterjee, Indranil
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p. 6709 - 6713
(2021/09/08)
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- DABCO mediated one pot synthesis of sulfoxonium ylides under blue LED
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DABCO mediated practical and convenient one pot method has been developed to access sulfoxonium ylides under photoredox and metal free conditions at room temperature. The protocol explored the reactivity of DMSO and α-aryl-α-diazo esters in presence of DABCO under blue LED condition. We demonstrated the generality of this protocol by synthesizing a variety of sulfoxonium ylides in very good yields. The practicality of the protocol has been demonstrated by the gram scale synthesis as well as by the extension of this protocol to synthesize precursors of biologically active compounds. This straightforward and practical method offers an alternative route to access very useful sulfoxonium ylides from α-aryl-α-diazoacetates.
- Khade, Vikas V.,Thube, Archana S.,Warghude, Prakash K.,Bhat, Ramakrishna G.
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supporting information
(2021/07/25)
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- Asymmetric Aldol Reaction of Alkenyl Esters with α-Keto Esters Catalyzed by Chiral Tin Alkoxides
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A catalytic enantioselective aldol reaction of alkenyl esters with α-keto esters was achieved by using an (R)-BINOL-derived chiral tin dibromide possessing 4-t-butylphenyl groups at the 3- and 3′-positions as a chiral precatalyst in the presence of sodium methoxide and methanol. Optically active aldol products possessing a chiral tertiary carbon were diastereoselectively obtained with up to 92% ee and moderate to high yields, not only from cyclic alkenyl esters, but also from acyclic ones under the influence of the chiral tin methoxide generated in situ.
- Takagi, Kotaro,Uchiyama, Chika,Yanagisawa, Akira
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supporting information
p. 2085 - 2089
(2021/12/01)
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- Carbene-Catalyzed Enantioselective Aromatic N-Nucleophilic Addition of Heteroarenes to Ketones
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The aromatic nitrogen atoms of heteroarylaldehydes are activated by carbene catalysts to react with ketone electrophiles. Multi-functionalized cyclic N,O-acetal products are afforded in good to excellent yields and optical purities. Our reaction involves the formation of an unprecedented aza-fulvene-type acylazolium intermediate. A broad range of N-heteroaromatic aldehydes and electron-deficient ketone substrates works effectively in this transformation. Several of the chiral N,O-acetal products afforded through this protocol exhibit excellent antibacterial activities against Ralstonia solanacearum (Rs) and are valuable in the development of novel agrichemicals for plant protection.
- Liu, Yonggui,Luo, Guoyong,Yang, Xing,Jiang, Shichun,Xue, Wei,Chi, Yonggui Robin,Jin, Zhichao
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supporting information
p. 442 - 448
(2019/11/25)
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- Palladium-Catalyzed Oxidative C≡C Triple Bond Cleavage of 2-Alkynyl Carbonyl Compounds Toward 1,2-Dicarbonyl Compounds?
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A new, general palladium-catalyzed oxidative strategy for the cleavage of the C≡C triple bond is presented. By employing PdCl2, CuBr2, TEMPO and air as the catalytic system and H2O as the carbonyl oxygen atom source, a wide range of 2-alkynyl carbonyl compounds, including 1,3-disubstituted prop-2-yn-1-ones, propiolamides and propiolates, lost an alkynyl carbon to access various 1,2-dicarbonyl compounds, e.g., 1,2-diones, 2-keto amides and 2-keto esters, through Wacker oxidation, intramolecular cyclization and C—C bond cleavage cascades.
- Hu, Ming,Li, Jin-Heng,Luo, Mu-Jia,Zhou, Ming-Bo
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p. 553 - 558
(2020/04/20)
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- Metal-Free Oxidative Esterification of Ketones and Potassium Xanthates: Selective Synthesis of α-Ketoesters and Esters
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A novel and efficient oxidative esterification for the selective synthesis of α-ketoesters and esters has been developed under metal-free conditions. In the protocol, various α-ketoesters and esters are available in high yields from commercially available ketones and potassium xanthates. Mechanistic studies have proven that potassium xanthate not only promotes oxidative esterification but also provides an alkoxy moiety for the reaction, which involves the cleavage and reconstruction of C-O bonds.
- Luo, Xianglin,He, Runfa,Liu, Qiang,Gao, Yanping,Li, Jingqing,Chen, Xiuwen,Zhu, Zhongzhi,Huang, Yubing,Li, Yibiao
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p. 5220 - 5230
(2020/05/18)
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- Copper(I)-catalyzed aerobic oxidation of α-diazoesters
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A practical Cu-catalyzed oxidation of α-diazoesters to α-ketoesters using molecular oxygen as an oxidant has been developed. Both electron-poor and electron-rich aryl α-diazoesters are suitable substrates and provide the α-ketoesters in good yields. In this oxidative system, α-diazo-β-ketoesters are also compatible as substrates but unexpectedly furnish α-ketoesters via C-C bond cleavage, rather than the vicinal tricarbonyl products.
- Xu, Changming,Bai, Lei,Wang, Yongchang
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supporting information
p. 12579 - 12584
(2020/11/09)
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- Green preparation method of aryl [alpha]-keto ester compound
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The invention discloses a green preparation method of an aryl [alpha]-keto ester compound. The method comprises the specific steps that an [alpha]-diazo compound serves as a reaction raw material, copper sulfate serves as a catalyst, water serves as a solvent, a target product aryl [alpha]-keto ester compound is prepared through a reaction at the temperature of 60 DEG C, the structural general formula of the [alpha]-diazo compound is shown in the specification, and the structural general formula of the correspondingly prepared target product aryl [alpha]-keto ester compound is shown in the specification. The method for synthesizing the target product aryl [alpha]-keto ester compound by catalyzing the [alpha]-diazo compound derivative with copper sulfate has the advantages that the reactioncondition is green and mild, the catalyst is cheap and easy to obtain, the operation is simple and convenient, the yield is relatively high, the universality of a reaction substrate is wide, and thelike.
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Paragraph 0015-0036
(2020/05/30)
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- Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
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Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
- Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
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supporting information
p. 14499 - 14503
(2019/09/17)
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- Novel synthesis method for oxophenylacetate
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The invention discloses a novel synthesis method for oxophenylacetate and belongs to the technical field of synthesis. The novel synthesis method comprises the steps: firstly, reacting benzonitrile and a halogenation reagent at 20-35 DEG C to obtain dihalogenated phenylacetonitrile; then, adding a mixed solution of acid and water into dihalogenated phenylacetonitrile at 35-55 DEG C, and carrying out a reaction at 50-60 DEG C for 2-8 h, wherein the molar ratio of a product I to the water to the acid is 1:(1-10):(1-10); and finally, adding alcohol into the reaction solution in the former step at50-60 DEG C, then, carrying out stirring, controlling the temperature at 60-70 DEG C, carrying out a constant-temperature reaction for 1-4 h, and carrying out cooling and extraction to obtain a target product. The reaction raw materials adopted in the method are wide in source and low in price, the operation process is simple, and the yield of the product is high.
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Paragraph 0031; 0034; 0035
(2019/04/06)
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- Template-Directed Synthesis of Photocatalyst-Encapsulating Metal-Organic Frameworks with Boosted Photocatalytic Activity
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In the past decade, the use of visible light to promote organic transformations has gained intense attention. In this study, we developed a template-directed synthesis method to use homogeneous Ru and Ir photocatalysts as structure-directing templates and succeeded to prepare a series of photocatalyst-encapsulating metal-organic frameworks (photocatalyst@MOFs) with zeolite-like structures. The open channels and polyhedral cages of MOFs effectively dispersed the encapsulated photocatalysts and facilitated the transport of reactants and products, leading to boosted catalytic activity and good reusability toward important organic reactions such as aerobic oxidation reaction of benzyl halides and the cyclization of tertiary anilines and maleimides under visible light. Moreover, we also demonstrate the versatility and universality of our templating strategy. It not only can form MOFs which cannot be accessed by other synthesis methods, but also can encapsulate various commercially available homogeneous photocatalysts into MOFs. This work explores an avenue to prepare heterogeneous photocatalysts to catalyze value-added reactions.
- Yang, Xiaojie,Liang, Tao,Sun, Jiaxing,Zaworotko, Michael J.,Chen, Yao,Cheng, Peng,Zhang, Zhenjie
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p. 7486 - 7493
(2019/08/26)
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- Cobalt-Catalyzed Transfer Hydrogenation of α-Ketoesters and N-Cyclicsulfonylimides Using H2O as Hydrogen Source
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A Co-catalyzed effective transfer hydrogenation of various α-ketoesters and N-cyclicsulfonylimides by safe and environmentally benign H2O as hydrogen source is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N-cyclicsulfonylimides. (Figure presented.).
- Gao, Yang,Zhang, Xuexin,Laishram, Ronibala Devi,Chen, Jingchao,Li, Kangkui,Zhang, Keyang,Zeng, Guangzhi,Fan, Baomin
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supporting information
p. 3991 - 3997
(2019/08/02)
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- CuO-catalyzed oxidation of aryl acetates with aqueous tert-butyl hydroperoxide for the synthesis of α-ketoesters
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A practical method to access α-ketoesters from readily available aryl acetates is developed. In this approach, aqueous tert-butyl hydroperoxide and CuO are employed. No additional solvents are required and it was found that the peroxide side products in the reaction can be decomposed by pyridine.
- Jiang, Jin
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p. 235 - 240
(2019/07/16)
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- Preparation of Organic Nitrates from Aryldiazoacetates and Fe(NO3)3·9H2O
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A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
- Thurow, Samuel,Fernandes, Alessandra A. G.,Quevedo-Acosta, Yovanny,De Oliveira, Matheus F.,De Oliveira, Marcelo G.,Jurberg, Igor D.
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p. 6909 - 6913
(2019/09/12)
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- Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: Synthesis of propargyl alcohols and α-ketoesters
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The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere (N2 or O2). A N2 atmosphere favours propargyl alcohols via a direct C-C coupling process, whereas an O2 atmosphere results in the generation of α-ketoesters through the oxidative CC/C-O coupling pathway.
- Ni, Ke,Meng, Ling-Guo,Ruan, Hongjie,Wang, Lei
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supporting information
p. 8438 - 8441
(2019/07/22)
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- Ambient and aerobic carbon-carbon bond cleavage toward α-ketoester synthesis by transition-metal-free photocatalysis
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The α-oxoesterification of the CC double bond in readily available enaminones enabling efficient synthesis of α-ketoesters is developed. The reactions showing general tolerance to the reactions of primary and secondary alcohols proceed well under air via Rose Bengal (RB)-based photocatalysis. Particularly, this mild synthetic method has been discovered to tolerate various polyhydroxylated substrates such as phenolic alcohol, diols and triols with an excellent selectivity of mono-oxoesterification. What is more noteworthy is that α-ketoester functionalized 16-dehydropregnenolone acetate resulting from the elaboration on a natural product has been obtained practically.
- Yu, Qing,Zhang, Yating,Wan, Jie-Ping
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supporting information
p. 3436 - 3441
(2019/06/24)
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- Highly adequate oxidative esterification of α-carbonyl aldehydes with alkyl halides in TBAI/TBHP mediated system
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An efficient and viable synthesis of α-ketoesters from alkyl halides and α-carbonyl aldehydes has been reported under metal-free conditions. The present method involves oxidative esterification of α-carbonyl aldehydes with alkyl halide using TBAI as a promoter and TBHP as an oxidant to form α-ketoesters in good to excellent yields with versatile structural diversity. Use of commercially accessible and inexpensive substrates, broad substrate scope and good functional group tolerance are the key features of this protocol.
- Bhargude, Pooja L.,Lade, Jatin J.,Patil, Bhausaheb N.,Vadagaonkar, Kamlesh S.,Chaskar, Atul C.
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supporting information
p. 1325 - 1333
(2019/04/30)
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- Tandem N, N-Dialkylation Reaction of N-Trimethylsilyl α-Iminoesters Utilizing an Umpolung Reaction and Characteristics of the Silyl Substituent: Synthesis of Pyrrolidine, Piperidine, and Iminodiacetate
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Umpolung reactions of N-trimethylsilyl α-iminoester with organometallics gave directly N-alkylaminoesters in high yields without the need for removing a protecting group at the nitrogen atom. Efficient syntheses of pyrrolidines, piperidines, and iminodiacetate derivatives were also developed via tandem N,N- or N,C-dialkylation reactions utilizing characteristics of the silyl substituent. Furthermore, under the influence of silica gel, the addition of an enolate to the imino nitrogen proceeded to give an iminodiacetate derivative.
- Mizota, Isao,Tadano, Yurie,Nakamura, Yusuke,Haramiishi, Tomoki,Hotta, Miyuki,Shimizu, Makoto
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supporting information
p. 2663 - 2667
(2019/04/30)
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- ZnO nanoparticles: An efficient catalyst for transesterification reaction of α-keto carboxylic esters
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Pure ZnO nanoparticles were synthesized by a sustainable precipitation method using zinc nitrate and sodium hydroxide in aqueous medium at room temperature. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV–vis) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The XRD patterns indicate the formation of the hexagonal wurtzite phase with high purity and SEM-EDS analysis confirm the purity and a homogenous distribution of the nanostructures. The ZnO nanostructures present plate-like agglomerates, resulting in a quasi-spherical morphology. The catalytic activity of the formed ZnO nanoparticles was evaluated towards the transesterification reaction of different carboxylic esters in the presence of various alcohols. This catalyst is highly selective for the transesterification of α-keto carboxylic ester (methyl benzoylformate) and leads to ca. 97percent of product yield within 24 h of reaction time.
- Alegria, Elisabete C. B. A.,Karmakar, Anirban,Pombeiro, Armando J. L.,Rúbio, Guilherme M. D. M.,Ribeir, Ana P. C.,Saraiva, Marta S.,Soliman, Mohamed M. A.,da Silva, M. Fátima C. Guedes
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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supporting information
p. 6584 - 6592
(2018/10/05)
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- Organocatalytic Nitroaldol Reaction Associated with Deuterium-Labeling
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A deuterium-labeling reaction of nitroalkanes in deuterium oxide and the subsequent nitroaldol reaction have been accomplished under basic and organocatalytic conditions to provide the deuterium-labeled β-nitroalcohols in high yields and high deuterium contents. β-Deuterated β-nitroalcohols could be smoothly obtained from the reaction of nitroalkanes and various electrophiles using the easily-removal basic resin WA30. Furthermore, the asymmetric nitroaldol reaction using nitromethane and α-keto esters as electrophiles in the presence of a quinine-derived organocatalyst in deuterium oxide could provide the desired β-deuterated nitroalcohol derivatives with high enantioselectivities. (Figure presented.).
- Yamada, Tsuyoshi,Kuwata, Marina,Takakura, Ryoya,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 637 - 641
(2017/12/13)
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- Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers
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The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.
- Ponra, Sudipta,Rabten, Wangchuk,Yang, Jianping,Wu, Haibo,Kerdphon, Sutthichat,Andersson, Pher G.
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supporting information
p. 13878 - 13883
(2018/10/24)
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- A benzo b furyl ketone dye synthesis method (by machine translation)
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The invention relates to a of benzodifaradone dye synthesis method, first to the manufacture of chlorine list alkyl esters, aromatic hydrocarbon as the raw material for Friedel-crafts reaction intermediates 1 or 1 ', then the intermediate 1, intermediate 1' hydrogenation reduction for preparing intermediate 2 and intermediate 2 ', intermediate 2 with condensation product of [...] intermediate 3 with the intermediate 2' condensation reaction to produce intermediate 4, intermediate 4 is oxidized to obtain the benzo b butenolides. The present invention provides a process for synthesis of low cost, low risk, low pollution, the process route is simple without a separate purification process; production and cheap, the cost is far lower than the existing technology, and the product higher total yield can be up to 69%, content is greater than 98.5%, has extremely high economic efficiency, and is suitable for large-scale production, it has good industrial application prospect. (by machine translation)
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Paragraph 0035-0036
(2018/09/11)
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- Ball-milling synthesized hydrotalcite supported Cu-Mn mixed oxide under solvent-free conditions: An active catalyst for aerobic oxidative synthesis of 2-acylbenzothiazoles and quinoxalines
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A rapid solvent-free ball-milling method was developed to prepare a hydrophobic hydrotalcite supported Cu-Mn mixed oxide catalyst (Cu-Mn/HT). The mechanochemically prepared catalyst exhibited high catalytic activity and recyclability towards the aerobic synthesis of 2-acylbenzothiazoles and quinoxalines in green medium ethanol compared with the ones synthesized via grinding and wet-impregnation. Moreover, control experiments showed that the catalyst was successfully used in green oxidative esterification and coupling as well. Cu-Mn/HT was characterized by BET, ICP, XRD, XPS, SEM and TEM, which indicated that more surface oxygen vacancies and formed CuMn2O4 species on HT might contribute to the catalytic activity.
- Meng, Xu,Bi, Xiuru,Yu, Chaoying,Chen, Gexin,Chen, Baohua,Jing, Zhenqiang,Zhao, Peiqing
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supporting information
p. 4638 - 4644
(2018/10/23)
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- Heterogeneous Esterification from α-Hydroxy Ketone and Alcohols through a Tandem Oxidation Process over a Hydrotalcite-Supported Bimetallic Catalyst
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Heterogeneous aerobic oxidative esterification between α-hydroxy ketone and alcohols catalyzed by a hydrotalcite-supported bimetallic catalyst (CuMn/HT) using O2 as a green oxidant was achieved. Recyclable CuMn/HT exhibits high catalytic activity due to increased content of oxygen vacancies and a newly generated CuMn2O4 crystal phase. This clean esterification proceeds through a tandem oxidation process in the absence of any additives and ligands and affords α-keto esters in good to excellent yields. Moreover, the catalytic system tolerates complicated bioactive molecules as raw materials and can be performed on a multigram scale.
- Meng, Xu,Bi, Xiuru,Chen, Gexin,Chen, Baohua,Zhao, Peiqing
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p. 1716 - 1722
(2018/10/25)
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- Copper catalyzed photoredox synthesis of α-keto esters, quinoxaline, and naphthoquinone: Controlled oxidation of terminal alkynes to glyoxals
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Herein, we report a facile visible light induced copper catalyzed controlled oxidation of terminal CC alkynes to α-keto esters and quinoxalines via formation of phenylglyoxals as stable intermediates, under mild conditions by using molecular O2 as a sustainable oxidant. The current copper catalysed photoredox method is simple, highly functional group compatible with a broad range of electron rich and electron poor aromatic alkynes as well as aliphatic alcohols (1°, 2° and 3° alcohols), providing an efficient route for the preparation of α-keto esters (43 examples), quinoxaline and naphthoquinone with higher yields than those in the literature reported thermal processes. Furthermore, the synthetic utility of the products has been demonstrated in the synthesis of two biologically active molecules, an E. coli DHPS inhibitor and CFTR activator, using the current photoredox process. In addition, we applied this methodology to the one-pot synthesis of a heterocyclic compound (quinoxaline, an FLT3 inhibitor) by trapping the intermediate phenylglyoxal with O-phenylenediamine. The intermediate phenylglyoxal can also be isolated and further reacted with an internal alkyne to form naphthoquinone. This process can be readily scaled up to the gram scale.
- Das, Deb Kumar,Kumar Pampana, V. Kishore,Hwang, Kuo Chu
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p. 7318 - 7326
(2018/10/15)
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- CuCl/TMEDA/nor-AZADO-catalyzed aerobic oxidative acylation of amides with alcohols to produce imides
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Although aerobic oxidative acylation of amides with alcohols would be a good complement to classical synthetic methods for imides (e.g., acylation of amides with activated forms of carboxylic acids), to date, there have been no reports on oxidative acylation to produce imides. In this study, we successfully developed, for the first time, an efficient method for the synthesis of imides through aerobic oxidative acylation of amides with alcohols by employing a CuCl/TMEDA/nor-AZADO catalyst system (TMEDA = teramethylethylendiamine; nor-AZADO = 9-azanoradamantane N-oxyl). The proposed acylation proceeds through the following sequential reactions: aerobic oxidation of alcohols to aldehydes, nucleophilic addition of amides to the aldehydes to form hemiamidal intermediates, and aerobic oxidation of the hemiamidal intermediates to give the corresponding imides. This catalytic system utilizes O2 as the terminal oxidant and produces water as the sole by-product. An important point for realizing this efficient acylation system is the utilization of a TMEDA ligand, which, to the best of our knowledge, has not been employed in previously reported Cu/ligand/N-oxyl systems. Based on experimental evidence, we consider that plausible roles of TMEDA involve the promotion of both hemiamidal oxidation and regeneration of an active CuII-OH species from a CuI species. Here promotion of hemiamidal oxidation is particularly important. Employing the proposed system, various types of structurally diverse imides could be synthesized from various combinations of alcohols and amides, and gram-scale acylation was also successful. In addition, the proposed system was further applicable to the synthesis of α-ketocarbonyl compounds (i.e., α-ketoimides, α-ketoamides, and α-ketoesters) from 1,2-diols and nucleophiles (i.e., amides, amines, and alcohols).
- Kataoka, Kengo,Wachi, Keiju,Jin, Xiongjie,Suzuki, Kosuke,Sasano, Yusuke,Iwabuchi, Yoshiharu,Hasegawa, Jun-Ya,Mizuno, Noritaka,Yamaguchi, Kazuya
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p. 4756 - 4768
(2018/06/07)
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- Displacement of Dinitrogen by Oxygen: A Methodology for the Catalytic Conversion of Diazocarbonyl Compounds to Ketocarbonyl Compounds by 2,6-Dichloropyridine-N-oxide
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Dirhodium(II) catalyzed dinitrogen extrusion from diazocarbonyl compounds by 2,6-dichloropyridine-N-oxide forms ketocarbonyl compounds in near-quantitative yields. Reactions occur at room temperature, and the pyridine product does not coordinate with dirhodium(II) to inhibit catalysis. Anhydrous tricarbonyl compounds, as well as dicarbonyl compounds, are conveniently prepared by this methodology, and they have been used in situ for catalytic ene and aldol transformations.
- Yu, Yang,Sha, Qiang,Cui, Hui,Chandler, Kory S.,Doyle, Michael P.
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supporting information
p. 776 - 779
(2018/02/09)
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- Visible Light Promotes Decyanation Esterification Reaction of β - Ketonitriles with Dioxygen and Alcohols to α-Ketoesters
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A green and mild method has been developed for the conversion of β-ketonitriles into α-ketoesters under catalyst-free conditions. A plausible mechanism is that visible light promotes singlet oxygen generation to form the products through oxidative C-H bond functionalization and C-C σ -bond cleavage.
- Xu, Chen,Zhang, Nan-Nan,Li, Xiao-Ji,Ge, Yan-Qin,Diao, Pin-Hui,Guo, Cheng
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supporting information
p. 1065 - 1070
(2018/05/01)
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- Switchable C-H Functionalization of N-Tosyl Acrylamides with Acryloylsilanes
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A controllable Rh-catalyzed protocol to access alkylation and alkenylation-annulation of N-tosyl acrylamide with acryloyl silane is reported. In contrast to the directing group or catalyst-dependent divergent sp2 C-H alkylation/alkenylation, the intrinsic property of acryloylsilane allows the switchable reaction manifold, thereby affording either alkylation or annulation products with slight modification of the reaction conditions.
- Song, Shengjin,Lu, Ping,Liu, Huan,Cai, Sai-Hu,Feng, Chao,Loh, Teck-Peng
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supporting information
p. 2869 - 2872
(2017/06/13)
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- A method for synthesis of α - keto ester
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A synthetic method of [alpha]-keto ester. The invention relates to the technical field of chemical synthesis. The synthetic method comprises a step of in a solvent, with benzene seleninic acid as a catalyst and air as an oxidizing agent, oxidizing [alpha]-hydroxy acid ester to obtain an oxidized product [alpha]-keto ester. In the method, air is employed as the oxidizing agent, which is clean, is easy to obtain, and is harmless to environment. The method employs the benzene seleninic acid as the catalyst instead of a metal catalyst, so that the [alpha]-keto ester is metabolizable in human body and is ecological friendly since selenium is required microelement of living bodies. The synthetic method is carried out under mild conditions and is less in damage on devices. A system for the method is durable, so that the method is suitable for industrial production.
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Paragraph 0036-0038
(2017/08/25)
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- Copper-catalyzed TEMPO oxidative cleavage of 1,3-diketones and β-keto esters for the synthesis of 1,2-diketones and α-keto esters
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A copper-catalyzed efficient and practical method has been developed for the synthesis of 1,2-diketones and α-keto esters. TEMPO was used as a radical initiator and scavenger, oxidizing the cleavage of α-methylene of 1,3-diketones and β-keto esters to form 1,2-diketones and α-keto esters. This method provided a general way for the formation of 1,2-dicarbonyl compounds.
- Zhou, Peng-Jun,Li, Cheng-Kun,Zhou, Shao-Fang,Shoberu, Adedamola,Zou, Jian-Ping
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p. 2629 - 2637
(2017/04/03)
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- α-Alkoxycarbonyl-α-hydroxy secondary amides from a carbamoylsilane and α-ketoesters
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The addition of N-methoxymethyl-N-organylcarbamoyl(trimethyl)silane to α-ketoesters in anhydrous toluene at 60 °C afforded α-alkoxycarbonyl-α-siloxy amides in high yields (75–96%). The methoxymethyl was used as an amino protecting group and could be easily converted into hydrogen atom by simple acid hydrolysis leading to α-alkoxycarbonyl-α- hydroxy secondary amides.
- Li, Weidong,Han, Yuling,Chen, Jianxin
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p. 5813 - 5819
(2017/09/05)
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- A Mechanochemical-Assisted Oxidation of Amines to Carbonyl Compounds and Nitriles
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A mild, efficient, metal- and solvent-free oxidation of primary amines to aldehydes, ketones, and nitriles under ball-milling conditions is presented. This method has proved to be compatible with various functional groups and only requires easily accessible starting materials. Simple purification of the reaction mixtures by short-column chromatography afforded pure aldehydes, ketones, and nitriles as products.
- Gaspa, Silvia,Porcheddu, Andrea,Valentoni, Antonio,Garroni, Sebastiano,Enzo, Stefano,De Luca, Lidia
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supporting information
p. 5519 - 5526
(2017/09/06)
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- I 2 /TBHP-Promoted Approach to α-Keto Esters from Trifluoromethyl β-Diketones and Alcohols via C-C Bond Cleavage
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A metal-free oxidative coupling reaction of trifluoromethyl β-diketones with alcohols for the synthesis of α-keto esters in good to excellent yields has been developed. Preliminary mechanistic studies suggest that an I 2 /TBHP promoted sequential iodination, C-C bond cleavage, C-O bond formation and oxidation pathway is involved in this reaction.
- Shao, Tongle,Fang, Xiang,Zhou, Jun,Jin, Chen,Yang, Xueyan,Wu, Fanhong
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supporting information
p. 2018 - 2023
(2017/09/13)
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- Reductive carboxylation of aromatic esters by electron transfer from magnesium metal
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Magnesium-promoted reductive carboxylation of ethyl benzoate in the presence of chlorotrimethylsilane in N,N-dimethylformamide brought about a new carbon-carbon bond formation between the carbonyl carbon atom and carbon dioxide to give the corresponding benzoylformic acid in good yield. It is noteworthy that only ethyl benzoates with substituents at the meta-position were converted into benzoylformic acid derivatives. Moreover, no mandelic acid was detected even under the reductive conditions. This result indicates that benzoylformic acid was obtained after hydrolysis of a carboxylated intermediate, which would be alive as a stabilized structure in the reaction media.
- Maekawa, Hirofumi,Okawara, Hikaru,Murakami, Taro
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supporting information
p. 206 - 209
(2016/12/28)
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of 1,2-Dicarbonyl Compounds
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A highly enantioselective hydrosilylation of 1,2-dicarbonyl compounds was successfully realized for the first time utilizing the combination of tricyclohexylphosphine and chiral alkenylborane derived in situ from diyne as a frustrated Lewis pair catalyst. A variety of optically active α-hydroxy ketones and esters were obtained in 52-98% yields with 86-99% ee's.
- Ren, Xiaoyu,Du, Haifeng
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supporting information
p. 810 - 813
(2016/02/09)
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- Copper(II)-Mediated Aerobic Oxidation of Benzylimidates: Synthesis of Primary α-Ketoamides
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A simple and straightforward method for the synthesis of primary α-ketoamides has been discovered. The reaction represents the first example of benzylimidates directly converting to primary α-ketoamides by using sustainable molecular oxygen as an oxidant. This reaction proceeds in the presence of copper(II) salt via cleavage of benzylic C-H and C-O bonds of the benzylimidates with liberation of alcohols as the only byproduct. A wide substrate scope, operationally mild conditions, the use of single substrates, and a reaction scaled up to grams make this strategy very attractive and practical. Furthermore, mechanistic studies illustrate that the imidate group adjacent to the benzylic position plays crucial role in facilitating this chemical process.
- Kumar, Yogesh,Shaw, Mukta,Thakur, Rima,Kumar, Amit
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p. 6617 - 6625
(2016/08/16)
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- Cu(ii)-catalyzed esterification reaction via aerobic oxidative cleavage of C(CO)-C(alkyl) bonds
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A novel Cu(ii)-catalyzed aerobic oxidative esterification of simple ketones for the synthesis of esters has been developed with wide functional group tolerance. This process is assumed to go through a tandem sequence consisting of α-oxygenation/esterification/nucleophilic addition/C-C bond cleavage and carbon dioxide is released as the only byproduct.
- Ma, Ran,He, Liang-Nian,Liu, An-Hua,Song, Qing-Wen
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supporting information
p. 2145 - 2148
(2016/02/09)
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- Copper(II)-Catalyzed Benzylic C(sp3)-H Aerobic Oxidation of (Hetero)Aryl Acetimidates: Synthesis of Aryl-α-ketoesters
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A straightforward method is developed in this paper for the synthesis of α-ketoesters through copper-catalyzed aerobic oxidation of (hetero)aryl acetimidates using molecular oxygen as a sustainable oxidant. The reaction represents the first example of the direct synthesis of aryl-α-ketoesters from arylacetimidates through the aerobic oxidation of a benzylic C(sp3)-H (CO) bond in moderate to good yield. This transformation occurs under mild reaction conditions with a wide range of substrates and utilizes a readily available oxidant and catalyst. The synthetic utility of this transformation is demonstrated through scaled-up synthesis. A plausible reaction mechanism is also proposed.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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p. 12247 - 12257
(2016/12/23)
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- Novel Synthesis of α-Keto Esters and Amides by an sp3 C-H Oxidation of Nitromethyl Aryl Ketones Promoted by Ion-Supported (Diacetoxyiodo)benzene
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A simple and efficient method is described for the preparation of α-keto esters or amides from nitromethyl aryl ketones. In the presence of nucleophiles (alcohols or amines), the ion-supported (di-acetoxyiodo)benzene-promoted sp3 C-H oxidation of nitromethyl aryl ketones proceeded efficiently under mild conditions to give the corresponding α-keto esters and amides in moderate to good yields. This is the first reported use of (diacetoxyiodo)benzene in the synthesis of α-keto esters and amides. The reaction is ecofriendly and has the -advantages of mild conditions, short reaction times, and a recyclable reagent.
- Jiang, Xiaoying,Gan, Bing,Liu, Jiwei,Xie, Yuanyuan
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supporting information
p. 2737 - 2741
(2016/11/25)
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- Rhodium(iii)-catalyzed C-H allylation of electron-deficient alkenes with allyl acetates
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Rhodium-catalyzed C-H allylation of acrylamides with allyl acetates is reported. The use of weakly coordinating directing group resulted in high reaction efficiency, broad functionality tolerance and excellent γ-selectivity, which opens a new synthetic pathway for the access of 1,4-diene skeletons.
- Feng, Chao,Feng, Daming,Loh, Teck-Peng
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supporting information
p. 342 - 345
(2015/01/09)
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