- Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
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Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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p. 7652 - 7666
(2021/12/13)
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- Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
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In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
- Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
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p. 3498 - 3506
(2021/04/07)
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- Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
- Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
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supporting information
p. 15396 - 15405
(2021/10/12)
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- Selective oxidation of alkenes to carbonyls under mild conditions
-
Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
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Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
- Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
-
-
- Manganese/Copper Co-catalyzed Electrochemical Wacker-Tsuji-Type Oxidation of Aryl-Substituted Alkenes
-
A manganese/copper co-catalyzed electrochemical Wacker-Tsuji-type oxidation of aryl-substituted alkenes has been developed. The process involves the use of 5 mol % MnBr2 and 7.5 mol % CuCl2, in 4:1 acetonitrile/water in an undivided cell at 60 °C, with 2.8 V constant applied potential. α-Aryl ketones are formed in moderate to excellent yields, with the advantages of avoidance of palladium as a catalyst and any external chemical oxidant in an easily operated, cost-effective procedure.
- Lai, Junshan,Pericàs, Miquel A.
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supporting information
p. 7338 - 7342
(2020/10/02)
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- Towards a practical perfluoroalkylation of (hetero)arenes with perfluoroalkyl bromides using cobalt nanocatalysts
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A convenient methodology for perfluoroalkylation including trifluoromethylation of (hetero)arenes with perfluoroalkyl bromides was developed. Key for the success is the use of a specific cobalt-based nanocatalyst, which can be recycled at least up to 4 times. The scope of this first cobalt-catalyzed perfluoroalkylation is presented and detailed catalyst characterization (e.g. analytical STEM, XPS, and XRD) has been carried out.
- Bartling, Stephan,Beller, Matthias,Ellinger, Stefan,Kreyenschulte, Carsten Robert,Lund, Henrik,Neumann, Helfried,Taeschler, Christoph,Weniger, Florian,Zhang, Shaoke
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p. 1731 - 1738
(2020/04/09)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Iron(III)-Catalyzed Hydration of Unactivated Internal Alkynes in Weak Acidic Medium, under Lewis Acid-Assisted Br?nsted Acid Catalysis
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Alkylarylalkynes are converted with full regioselectivity into the corresponding arylketones by formal hydration of the triple bond under weak acidic conditions, at times and temperatures (≤95 °C) comparable to those used for terminal alkynes. The process catalyzed by Fe2(SO4)3nH2O in glacial acetic acid exhibits good functional group compatibility, including that with bulky triple bond substituents, and can be extended to the one-pot transformation of aryltrimethylsilylacetylenes into acetyl derivatives via a desilylation-hydration sequence. The overall reactivity pattern along with proton affinity data indicate that the triple bond is activated by proton transfer rather than by π-interaction with the metal ion. This mechanistic feature, at variance with that of noble metal catalysts, accounts for the total regioselectivity and the insensitivity to steric hindrance exhibited by the Fe2(SO4)3nH2O/AcOH catalytic system. (Figure presented.).
- Antenucci, Achille,Flamini, Piergiorgio,Fornaiolo, Marco Valerio,Di Silvio, Sergio,Mazzetti, Sara,Mencarelli, Paolo,Salvio, Riccardo,Bassetti, Mauro
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p. 4517 - 4526
(2019/08/26)
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- METHOD FOR PRODUCING A 3'-TRIFLUOROMETHYL GROUP-SUBSTITUTED AROMATIC KETONE
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PROBLEM TO BE SOLVED: To provide a method for producing a 3'-trifluoromethyl group-substituted aromatic ketone that uses an inexpensive and easily available raw material and is industrially excellent with high production efficiency. SOLUTION: A 3-halogen-substituted benzotrifluoride compound is reacted with a magnesium metal in the presence of a lithium chloride of 1.0 mol or more times higher than the 3-halogen-substituted benzotrifluoride compound, to convert it to a Grignard reagent, and the Grignard reagent is reacted with an acid anhydride at a reaction temperature of 0°C or less and then hydrolyzed, thereby producing 3'-trifluoromethyl group-substituted aromatic ketone. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
- -
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Paragraph 0039-0046
(2019/07/18)
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- Nucleophilic Isomerization of Epoxides by Pincer-Rhodium Catalysts: Activity Increase and Mechanistic Insights
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Herein, we present the efficient isomerization of epoxides into methyl ketones with a novel pincer-rhodium complex under very mild conditions. The catalyst system has an excellent functional group tolerance and a wide array of epoxides was tested. The corresponding methyl ketones were obtained in very high yields with excellent chemo- and regioselectivity. In addition, we investigated mechanistic details like the isomerization of the catalyst, and we obtained evidence that the catalytic cycle follows a β-hydride elimination-reductive elimination pathway after the nucleophilic ring opening of the epoxide.
- Tian, Yingying,Jürgens, Eva,Mill, Katharina,Jordan, Ronja,Maulbetsch, Theo,Kunz, Doris
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p. 4028 - 4035
(2019/06/25)
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- Visible-Light photoredox decarboxylation of perfluoroarene iodine(III) Trifluoroacetates for C-H trifluoromethylation of (Hetero)arenes
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A scalable and operationally simple decarboxylative trifluoromethylation of (hetero)arenes with easily accessible C6F5I(OCOCF3)2 under photoredox catalysis has been developed. This method is tolerant of various (hetero)arenes and functional groups. Notably, C6F5I is recycled from the decarboxylation reaction and further used for the preparation of C6F5I(OCOCF3)2. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the application of trifluoroacetic acid in trifluoromethylation reactions.
- Yang, Bin,Yu, Donghai,Xu, Xiu-Hua,Qing, Feng-Ling
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p. 2839 - 2843
(2018/04/14)
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- Regio- and chemoselective rearrangement of terminal epoxides into methyl alkyl and aryl ketones
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The development of the highly active pincer-type rhodium catalyst 2 for the nucleophilic Meinwald rearrangement of functionalised terminal epoxides into methyl ketones under mild conditions is presented. An excellent regio- and chemoselectivity is obtained for the first time for aryl oxiranes.
- Tian, Yingying,Jürgens, Eva,Kunz, Doris
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p. 11340 - 11343
(2018/10/31)
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- Easy Access to Enantiopure (S)- and (R)-Aryl Alkyl Alcohols by a Combination of Gold(III)-Catalyzed Alkyne Hydration and Enzymatic Reduction
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Chemoenzymatic one-pot processes based on the combination of metal catalysis and biocatalysis open up highly attractive perspectives regarding the production of enantiopure compounds. By combining a gold-catalyzed hydration reaction with an enzymatic reduction, we present a straightforward and atom-economical chemoenzymatic method for the synthesis of secondary alcohols with excellent optical purity. Efficient cofactor recycling exploits the solvent of the metal-catalyzed step as an auxiliary substrate for the enzymatic step.
- Schaaf, Patricia,Gojic, Vladimir,Bayer, Thomas,Rudroff, Florian,Schnürch, Michael,Mihovilovic, Marko D.
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p. 920 - 924
(2018/02/23)
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- Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains
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Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents.
- Cvijeti?, Ilija N.,Verbi?, Tatjana ?.,Ernesto de Resende, Pedro,Stapleton, Paul,Gibbons, Simon,Jurani?, Ivan O.,Drakuli?, Branko J.,Zloh, Mire
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p. 1474 - 1488
(2017/11/17)
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- Pd-catalyzed Oxidative Cross-coupling of Alkyl Chromium(0) Fischer Carbene Complexes with Organoboronic Acids
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Alkyl chromium(0) carbene complexes have been explored as the cross-coupling partners in the palladium-catalyzed reaction with aryl or alkenyl boronic acids. This coupling reaction displays the versatile reactivities of alkyl chromium(0) carbenes under palladium catalysis. Mechanistically, this transformation is proposed to involve deprotonation of the alkyl chromium carbene substrate to generate a vinyl chromium anion intermediate that undergoes transmetalation to organopalladium species and reductive elimination.
- Wang, Kang,Yang, Jinghui,Yao, Xingqi,Wang, Jianbo
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supporting information
p. 3165 - 3168
(2018/10/15)
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- Nickel-Catalyzed Addition of Arylboronic Acids to Alkyl Nitriles for Synthesis of Aryl Ketones in Fluorinated Solvent
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A mild and efficient nickel-catalyzed addition of arylboronic acids to alkyl nitriles in a fluorinated solvent for the synthesis of various aryl ketones is described. A broad range of arylboronic acids and alkyl nitriles were investigated, and the desired products were obtained with good to excellent yields under the optimized conditions. This method provides an opportunity for the synthesis of aryl ketones from alkyl nitriles, especially acetonitrile, with a non-noble metal catalyst in one pot.
- Tu, Dong-Huai,Li, Yang,Zhao, Bo,Gu, Yu-Jie,Wang, Bo,Lu, Ju-You,Lu, Jian
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supporting information
p. 593 - 596
(2017/12/06)
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- METHOD OF PRODUCING 2'-TRIFLUOROMETHYL GROUP-SUBSTITUTED AROMATIC KETONE
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A method produces a 2′-trifluoromethyl-substituted aromatic ketone and includes reacting a 2-halogen-substituted benzotrifluoride compound with magnesium metal to convert the compound to a Grignard reagent; and reacting the Grignard reagent with an acid anhydride; and then hydrolyzing the resultant to produce a 2′-trifluoromethyl-substituted aromatic ketone. The method of producing a 2′-trifluoromethyl-substituted aromatic ketone enables 2′-trifluoromethyl-substituted aromatic ketone to be produced without using expensive raw materials by generating a Grignard reagent as an intermediate and reacting this Grignard reagent with an acid anhydride in an efficient productivity. The 2′-trifluoromethyl-substituted aromatic ketone that is produced by the method of producing a 2′-trifluoromethyl-substituted aromatic ketone can be used as fine chemicals, raw materials for pharmaceuticals and agrochemicals, raw materials for resins and plastics, electronics and information related materials, optical materials, and the like.
- -
-
Paragraph 0042; 0043; 0044; 0045; 0046; 0047; 0053
(2017/04/18)
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- A novel modified MIL-101-NH2 ligand for CuI-catalyzed and air promoted oxidation of secondary alcohols
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An efficient Cu(i)-catalyzed aerobic alcohol oxidation system was developed utilizing a novel metal-organic framework (MOF) ligand at room temperature. Several relatively inert secondary alcohols were converted to their corresponding ketones in high yields and selectivities in the presence of a Cu(i) catalyst and air as the oxidant. This newly developed Cu(i)/MOF ligand system can also be easily extended to the aerobic oxidation of primary alcohols including aliphatic ones. Furthermore, the MIL-101-N-2-pyc ligand can be recycled several times without compromising reaction activity.
- Liu, Hui,Ramella, Daniele,Yu, Peng,Luan, Yi
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p. 22353 - 22359
(2017/07/10)
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- Stereoselective amination of racemic sec-alcohols through sequential application of laccases and transaminases
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A one-pot/two-step bienzymatic asymmetric amination of secondary alcohols is disclosed. The approach is based on a sequential strategy involving the use of a laccase/TEMPO catalytic system for the oxidation of alcohols into ketone intermediates, and their following transformation into optically enriched amines by using transaminases. Individual optimizations of the oxidation and biotransamination reactions have been carried out, studying later their applicability in a concurrent process. Therefore, 17 racemic (hetero) aromatic sec-alcohols with different substitutions in the aromatic ring have been converted into enantioenriched amines with good to excellent selectivities (90-99% ee) and conversion values (67-99%). The scalability of the process was also demonstrated when two different amine donors were used in the transamination step, such as isopropylamine and cis-2-buten-1,4-diamine. Satisfyingly, both sacrificial amine donors can shift the equilibrium toward the amine formation, leading to the corresponding isolated enantioenriched amines with good to excellent results.
- Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
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supporting information
p. 474 - 480
(2017/06/23)
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- Picolinoyl functionalized MOF ligands for an air-promoted secondary alcohol oxidation with CuBr
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A novel Zr-derived metal-organic framework (MOF) ligand was designed and synthesized, and found to effect efficient Cu(i)-catalyzed oxidations of secondary alcohols. The UiO-66-NH-PC solid ligand was utilized as an efficient oxidation reaction ligand. Several secondary alcohols were selectively transformed to ketones in good yields, using air as the oxidant, and under mild reaction conditions. In order to broaden the applicability of the method, various primary alcohols and benzylic compounds were also tested in the oxidation reaction, and afforded the corresponding aldehydes and ketones in very high yields. Finally, the recyclability of the synthesized UiO-66-NH-PC ligand was confirmed by reusing the same batch of catalyst up to five times without observing any decrease in reactivity.
- Du, Xin,Luan, Yi,Yang, Fengxia,Ramella, Daniele,Shu, Xin
-
supporting information
p. 4400 - 4405
(2017/07/10)
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- Preparation method for m-trifluoromethyl acetophenone and intermediate thereof
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The invention discloses a preparation method for m-trifluoromethyl acetophenone and an intermediate thereof. The preparation method comprises the steps of (a) Grignard reaction, wherein a compound A reacts with a Grignard reagent in a non-protonic solvent at the reaction temperature of 0-200 DEG C to obtain a compound B, the Grignard reagent is one or more of isopropylmagnesium chloride, isopropylmagnesium bromide, cyclohexylmagnesium chloride, cyclohexylmagnesium bromide, tert-butylmagnesium chloride and tert-butylmagnesium bromide, and the molar ratio of the Grignard reagent to the non-protonic solvent to the compound A is (0.9-2) to (2-20) to 1; (b) acetylization, wherein the compound B obtained in the step (a) reacts with an acetylization reagent in a non-protonic solvent at the reaction temperature between -40 DEG C and 200 DEG C to obtain the m-trifluoromethyl acetophenone. The reaction process is mild, and the preparation method is suitable for industrial mass production.
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-
Paragraph 0064-0066
(2017/03/17)
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- Method for preparing aldehyde/ketone by catalyzing alcohol oxidation with ferric salt
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The invention provides a method for preparing aldehyde/ketone by catalyzing alcohol oxidation with a ferric salt. The method comprises the following steps: mixing a compound shown in a formula (I) of a substrate, a ferric salt catalyst, a cocatalyst TEMPO (tetramethylpiperidinooxy), an amino acid ligand and a solvent; carrying out return flow agitation in an oxygen or air atmosphere for 1 to 60 h; then post-processing a reaction solution to obtain a product, namely a compound shown in a formula (II). According to the method provided by the invention, the ferric acid which is low in cost, easily available and environment-friendly is used as the catalyst; amino acids which are rich in resource, low in cost, easily available and easy to modify in a natural field are used as the ligand; the reaction substrate is high in applicability; first-grade benzyl alcohol, second-grade benzyl alcohol, allyl alcohol, heterocyclic aromatic alcohols and the like can be converted into corresponding aldehyde/ketone at high yield by adopting an oxidation system of the invention.
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-
Paragraph 0037; 0038; 0039; 0040; 0106; 0107; 0108-0110
(2016/10/07)
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- Metal-free oxidation of secondary benzylic alcohols using aqueous TBHP
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We report a simple, yet efficient metal-free oxidation of secondary benzylic alcohols in the presence of t-butyl hydroperoxide (70% TBHP) with high yields of up to 98%. This type of reaction can be carried out using a wide variety of substrates, requires no other organic solvent, and proves to be tolerant toward a variety of different functional groups.
- Wu, Jianglong,Liu, Yan,Ma, Xiaowei,Liu, Ping,Gu, Chengzhi,Dai, Bin
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supporting information
p. 1747 - 1758
(2016/10/30)
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- Ligand-dependent formation of ion-pair CuI/CuIII trifluoromethyl complexes containing bisphosphines
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We report novel ion-pair bisphosphine CuI/CuIII trifluoromethyl complexes [(P2)2CuI]+[CuIII(CF3)4]- (P2 = DPPE, BINAP or Xantphos) fea
- Zhang, Song-Lin,Bie, Wen-Feng
-
supporting information
p. 17588 - 17592
(2016/11/18)
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- Preparation of Trifluoromethylphenyl Magnesium Halides in the Presence of LiCl and Synthesis of 2′-Trifluoromethyl-Aromatic Ketones
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The effect of LiCl-promoted insertion of magnesium turnings into halogenated-trifluoromethylbenzenes for Grignard reagent synthesis was investigated. In the presence of less than 1.0 equiv of LiCl, chloro(trifluoromethyl)benzene Grignard reagents were easily generated. The 2-trifluoromethylphenyl magnesium chloride Grignard reagent was obtained in high yield and 2′-trifluoromethyl-substituted aromatic ketone was synthesized through reaction of the obtained Grignard reagent with a carboxylic anhydride in an 83% yield.
- Nakatani, Jiro,Nozoe, Tatsuhiro
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p. 1633 - 1636
(2016/09/23)
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- Isolation and characterization of copper(III) trifluoromethyl complexes and reactivity studies of aerobic trifluoromethylation of arylboronic acids
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The isolation, characterization and reactivity of transition metal trifluoromethyl complexes are fundamental and challenging topics in trifluoromethylation chemistry. We report herein the synthesis and isolation of two new complexes [(phen)CuI(PPh3)2]+[CuIII(CF3)4]- (2) and (phen)CuIII(CF3)3 (3) as well as a known complex (bpy)CuIII(CF3)3 (4) at room temperature. 2 and 3 have been fully characterized using 1H, 19F, 31P NMR, elemental analyses and X-ray crystallography. Reactivity studies indicate that 2 is unreactive toward arylboronic acids. In contrast, 3 and 4 can react with various aryl and heteroaryl boronic acids to deliver trifluoromethylated arenes in good to quantitative yields under mild conditions. The presence of a fluoride additive in DMF under aerobic conditions is crucial to these reactions. This study provides fundamental information about the structure and reactivity of elusive Cu(iii) trifluoromethyl complexes that have been proposed as relevant reactive intermediates in many trifluoromethylation reactions.
- Zhang, Song-Lin,Bie, Wen-Feng
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p. 70902 - 70906
(2016/08/05)
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- Copper-mediated trifluoromethylation of diaryliodonium salts with difluoromethyltriflate
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The reaction of diaryliodonium salts with difluoromethyltriflate in the presence of TBAT and CuTC gave the corresponding trifluoromethylated arenes in moderate yields. Compared to other difluorocarbene-derived trifluoromethylation reactions, the current one proceeded at mild reaction conditions (room temperature) within short reaction time (5 min).
- Yang, Jing-Yun,Xu, Xiu-Hua,Qing, Feng-Ling
-
-
- Exploring the Catalytic Reactivity of Nickel Phosphine-Phosphite Complexes
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In this study, we present an investigation into various nickel phosphite and phosphite-phosphine complexes for use in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions and the ammonia arylation reaction. In these coupling reactions, it was discovered that the Ni[P(OEt)3]4, (dppf)Ni[P(OPh)3]2, and (binap)Ni[P(OPh)3]2 catalysts were the most effective. In addition, an optimisation process for these catalytic systems as well as functional group compatibility are discussed.
- Kampmann, Sven S.,Man, Nikki Y. T.,McKinley, Allan J.,Koutsantonis, George A.,Stewart, Scott G.
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p. 1842 - 1853
(2015/12/26)
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- Palladium catalyzed decarboxylative acylation of arylboronic acid with ethyl cyanoacetate as a new acylating agent: Synthesis of alkyl aryl ketones
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Palladium catalyzed acylation of arylboronic acid containing various functional groups was performed efficiently by ethyl cyanoacetate/substituted ethyl cyanoacetate as the acylating agent in aqueous triflic acid medium. The alkyl aryl ketones were obtained in good to excellent yields, first by addition of arylboronic acid to the nitrile group of ethyl cyanoacetate and their derivatives, followed by in situ decarboxylation of the resulting β-ketoester.
- Yousuf, Md,Das, Tuluma,Adhikari, Susanta
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p. 8763 - 8770
(2015/11/10)
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- N-Functionalized Amino Acids Promoted Aerobic Copper-Catalyzed Oxidation of Benzylic Alcohols in Water
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Instead of traditional N,N-bidentate ligands, N-functionlized amino acids were used as powerful N,O-bidentate ligands in aerobic copper/TEMPO-catalyzed system for promoting oxidation of benzylic alcohols. Under the optimized reaction conditions, a wide range of primary and secondary benzylic alcohols have been efficiently converted into aldehydes and ketones with good to excellent yields in water.
- Zhang, Guofu,Lei, Jie,Han, Xingwang,Luan, Yuxin,Ding, Chengrong,Shan, Shang
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p. 779 - 784
(2015/03/30)
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- Catalytic trifluoromethylation of aryl- and vinylboronic acids by 2-cyclopropyl-1-(trifluoromethyl)benzo[ b ]thiophenium triflate
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Catalytic trifluoromethylation of aryl- and vinylboronic acids by 2-cyclopropyl-1-(trifluoromethyl)benzo[b]thiophenium triflate is described. In the presence of a catalytic amount of CuOAc and 2,4,6-collidine in ethyl acetate, the reaction proceeded in good to high yields for various substrates under mild reaction conditions at room temperature.
- Arimori, Sadayuki,Shibata, Norio
-
supporting information
p. 1632 - 1635
(2015/04/14)
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- One-pot sandmeyer trifluoromethylation and trifluoromethylthiolation
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Practical one-pot procedures were developed for both Sandmeyer-type trifluoromethylations and trifluoromethylthiolations. Starting from broadly available (hetero)aromatic amines, various benzotrifluorides were synthesized in high yields via in situ diazotization and copper-mediated trifluoromethylation using the inexpensive Ruppert-Prakash trifluoromethylating reagent. In the presence of sodium thiocyanate as a sulfur source, aryl trifluoromethyl thioethers are exclusively formed.
- Bayarmagnai, Bilguun,Matheis, Christian,Risto, Eugen,Goossen, Lukas J.
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supporting information
p. 2343 - 2348
(2014/07/21)
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- Ruthenium(II)-NNN complex catalyzed Oppenauer-type oxidation of secondary alcohols
-
Highly efficient Oppenauer-type oxidation of secondary alcohols to the corresponding ketones has been realized by means of the ruthenium(II) complex catalysts bearing a 2-(benzoimidazol-2-yl)-6-(3,5-dimethylpyrazol-1-yl)pyridine ligand. The oxidation reaction underwent in the presence of acetone as oxidant under mild conditions, reaching final TOF values up to 3960 h-1. The hemilability of the ligand is attributed to the high catalytic activity of these Ru(II) complexes.
- Wang, Qingfu,Du, Wangming,Liu, Tingting,Chai, Huining,Yu, Zhengkun
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p. 1585 - 1588
(2014/03/21)
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- L-Proline: An efficient N,O-bidentate ligand for copper-catalyzed aerobic oxidation of primary and secondary benzylic alcohols at room temperature
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A novel and highly practical copper-catalyzed aerobic alcohol oxidation system with l-proline as the ligand at room temperature has been developed. A wide range of primary and secondary benzylic alcohols tested have been smoothly transformed into corresponding aldehydes and ketones with high yields and selectivities.
- Zhang, Guofu,Han, Xingwang,Luan, Yuxin,Wang, Yong,Wen, Xin,Ding, Chengrong
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supporting information
p. 7908 - 7910
(2013/09/02)
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- Sandmeyer trifluoromethylation of arenediazonium tetrafluoroborates
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Copper capabilities: Diazonium salts are converted into the corresponding trifluoromethyl derivatives in the presence of a trifluoromethyl-copper complex generated in situ from CuSCN and the inexpensive, easy-to-use trifluoromethylating reagent Me3Si-CF3 (see scheme). This Sandmeyer-type reaction allows the straightforward synthesis of trifluoromethylated arenes and heteroarenes from the corresponding amines. Copyright
- Danoun, Grégory,Bayarmagnai, Bilguun,Grünberg, Matthias F.,Goo?en, Lukas J.
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supporting information
p. 7972 - 7975
(2013/08/23)
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- Mild and efficient nickel-catalyzed heck reactions with electron-rich olefins
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A new efficient protocol for the nickel-catalyzed Heck reaction of aryl triflates with vinyl ethers is presented. Mild reaction conditions that equal those of the corresponding palladium-catalyzed Heck reaction are applied, representing a practical and more sustainable alternative to the conventional regioselective arylation of vinyl ethers. A catalytic system comprised of Ni(COD)2 and 1,1″-bis(diphenylphosphino)ferrocene (DPPF) in combination with the tertiary amine Cy2NMe proved effective in the olefination of a wide range of aryl triflates. Both electron-deficient and electron-rich arenes proved compatible, and the corresponding aryl methyl ketone could be secured after hydrolysis in yields approaching quantitative. Good functional group tolerance was observed matching the characteristics of the analogous Pd-catalyzed Heck reaction. The high levels of catalytic activity were explained by the intermediacy of a cationic nickel(II) complex potentially responsible for the successive β-hydride elimination and base promoted catalyst regeneration. Although these elementary reactions are normally considered challenging, DFT calculations suggested this pathway to be favorable under the applied reaction conditions.
- Gogsig, Thomas M.,Kleimark, Jonatan,Nilsson Lill, Sten O.,Korsager, Signe,Lindhardt, Anders T.,Norrby, Per-Ola,Skrydstrup, Troels
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supporting information; experimental part
p. 443 - 452
(2012/03/07)
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- Room temperature aryl trifluoromethylation via copper-mediated oxidative cross-coupling
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A method for the room temperature copper-mediated trifluoromethylation of aryl and heteroaryl boronic acids has been developed. This protocol is amenable to normal benchtop setup and reactions typically require only 1-4 h. Proceeding under mild conditions, the method tolerates a range of functional groups, allowing access to a variety of trifluoromethylarenes.
- Senecal, Todd D.,Parsons, Andrew T.,Buchwald, Stephen L.
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supporting information; experimental part
p. 1174 - 1176
(2011/05/02)
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- Copper-catalyzed trifluoromethylation of aryl boronic acids using a CF 3+ reagent
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A copper-catalyzed process for trifluoromethylation of aryl, heteroaryl, and vinyl boronic acids has been developed. The reaction is conducted under mild conditions and shows tolerance to moisture and a variety of functional groups.
- Xu, Jun,Luo, Dong-Fen,Xiao, Bin,Liu, Zhao-Jing,Gong, Tian-Jun,Fu, Yao,Liu, Lei
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supporting information; experimental part
p. 4300 - 4302
(2011/06/21)
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- Synthesis and discovery of 2,3-dihydro-3,8-diphenylbenzo[1,4]oxazines as a novel class of potent cholesteryl ester transfer protein inhibitors
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2,3-Dihydro-3,8-diphenylbenzo[1,4]oxazines were identified as a new class of potent cholesteryl ester transfer protein inhibitors. The most potent compound 6a (IC50 = 26 nM) possessed a favorable pharmacokinetic profile with good oral bioavailability in rat (F = 53%) and long human liver microsome stability (t1/2 = 62 min). It increased HDL-C in human CETP transgenic mice and high-fat fed hamsters. The structure and activity relationship of this series will be described in this Letter.
- Wang, Aihua,Prouty, Catherine P.,Pelton, Patricia D.,Yong, Maria,Demarest, Keith T.,Murray, William V.,Kuo, Gee-Hong
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scheme or table
p. 1432 - 1435
(2010/07/06)
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- Oxidation of alcohols by transfer hydrogenation: driving the equilibrium with an intramolecular trap
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Levulinic acid and its esters participate in transfer hydrogenation with a range of secondary alcohols. Reduction of the levulinate leads to cyclisation into a γ-lactone, thereby acting as an oxidant for alcohols without the need for a large excess of reagents.
- Wise, Nicola J.,Williams, Jonathan M.J.
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p. 3639 - 3641
(2008/02/03)
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- Synthesis of functionalised acetophenone
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Nickel catalysed Heck arylation of the electron-rich olefin n-butyl vinyl ether with a wide variety of aryl bromides has been accomplished in the ionic liquid [bmim][BF4], affording an efficient green chemistry synthetic procedure for preparing functionalised acetophenone. The reaction gave a high regioselectivity and high yield without the need for the costely or toxic halide scavengers, leading predominantly to a branch-arylated α-product.
- Sun, Li,Pei, Wen,Shen, Chen
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p. 388 - 389
(2007/10/03)
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- Removal of the acyl donor residue allows the use of simple alkyl esters as acyl donors for the dynamic kinetic resolution of secondary alcohols
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The dynamic kinetic resolution of secondary alcohols using a lipase and a ruthenium catalyst as developed by Baeckvall required some improvements to make it suitable for its use in an industrial process. The use of p-chlorophenyl acetate as acyl donor is not desirable in view of the toxicity of the side product. We herein report that simple alkyl esters can be used as acyl donors if the alcohol or ketone residue formed during the enzymatic acylation is continuously removed during the reaction. The addition of a ketone speeds up the racemisation process and allowed us to reduce the amounts of enzyme and ruthenium catalyst. The scope of this method was explored and a suitable range of acyl donors found. Various benzylic and aliphatic alcohols were reacted using isopropyl butyrate or methyl phenylacetate as acyl donor and in most cases the ester was isolated in >95% yield and 99% ee. Furthermore, it was demonstrated that the alcohol by-products of the enzymatic resolution could be used as the hydrogen source in the asymmetric reductive transesterification of ketones.
- Verzijl, Gerard K.M.,De Vries, Johannes G.,Broxterman, Quirinus B.
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p. 1603 - 1610
(2007/10/03)
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- Method for producing, via organometallic compounds, organic intermediate products
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The present invention provides a process for preparing aryllithium compounds by reacting haloaliphatics with lithium metal to form a lithium alkyl and reacting the lithium alkyl with aromatic halogen compounds of formula (III) in a halogen-metal exchange reaction to form the corresponding lithium aromatics of formula (IV).
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Page/Page column 4
(2008/06/13)
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- Development and comparison of the substrate scope of Pd-catalysts for the aerobic oxidation of alcohols
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(Chemical Equation Presented) Three catalysts for aerobic oxidation of alcohols are discussed and the effectiveness of each is evaluated for allylic, benzylic, aliphatic, and functionalized alcohols. Additionally, chiral nonracemic substrates as well as chemoselective and diastereoselective oxidations are investigated. In this study, the most convenient system for the Pd-catalyzed aerobic oxidation of alcohols is Pd(OAc)2 in combination with triethylamine. This system functions effectively for the majority of alcohols tested and uses mild conditions (3 to 5 mol % of catalyst, room temperature). Pd(IiPr)(OAc)2(H2O) (1) also successfully oxidizes the majority of alcohols evaluated. This system has the advantage of significantly lowering catalyst loadings but requires higher temperatures (0.1 to 1 mol % of catalyst, 60°C). A new catalyst is also disclosed, Pd(IiPr)(OPiv)2 (2). This catalyst operates under very mild conditions (1 mol %, room temperature, and air as the O2 source) but with a more limited substrate scope.
- Schultz, Mitchell J.,Hamilton, Steven S.,Jensen, David R.,Sigman, Matthew S.
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p. 3343 - 3352
(2007/10/03)
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- Convenient Processes for the Synthesis of Aromatic Ketones from Aryl Bromides and Carboxylic Anhydrides Using a Cobalt Catalysis
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The cross-coupling of various para- and meta-substituted aromatic bromides, mostly bearing sensitive moieties, with several carboxylic acid anhydrides is reported. This reaction can be carried out in two steps, by forming an aromatic organozinc reagent via cobalt catalysis in the first step, or even more interestingly in a single step, also by using a cobalt-based catalyst. The aromatic ketones are obtained by these new, mild, and convenient methods in 30-79% yields versus starting aryl bromide. Results are also disclosed that suggest the role played by cobalt species in the coupling of organozinc reagents with electrophiles could be similar to those of more commonplace transition metal complexes.
- Kazmierski, Igor,Bastienne, Mylene,Gosmini, Corinne,Paris, Jean-Marc,Perichon, Jacques
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p. 936 - 942
(2007/10/03)
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- Preparation of fluorinated acetophenones
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Fluorine-containing substituted acetophenones are obtained by reaction of corresponding isopropyl-, propenyl-, 2-hydroxy-2-propyl-, 2-hydroperoxy-2-propyl-, 1-methyloxiranyl- or O,O-bis-(2-oxydi-isopropyl)-benzene derivatives with an N-hydroxyphthalimide in presence of an oxidising agent. A method for the production of compounds of formula (I) involves the reaction of compounds of formula (IIa) or (IIb) in presence of 0.1-30 mol% of a N-hydroxyphthalimide and in presence of an oxidising agent. [Image] R 1>1-12C perfluoroalkyl or perfluoroalkoxy; R 2>H, F, Cl, Br, 1-4C alkyl, 1-4C alkoxy, nitro, cyano or COOR 4>; R 3>H, F or Cl; R 4>H or 1-4C alkyl; or two of the groups R 1>-R 3>may be combined as difluoromethylenedioxy, tetrafluoroethylene-1,2-dioxy, 2-oxytetrafluoroethyl or (oxydifluoromethoxy)-difluoromethyl; Z 1>= isopropyl, propenyl, 2-hydroxy-2-propyl, 2-hydroperoxy-2-propyl or 1-methyloxiranyl; Z 2>= O,O-bis-(2-oxydi-isopropyl).
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- 1,4-Diazabicyclo[3.2.2]nonane-phenylisoxazole derivatives, preparation and therapeutic use thereof
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Compounds corresponding to general formula (I) in which R1, R2, R3, R4 and R5 each represent, independently of one another, a hydrogen or halogen atom or a nitro, amino, trifluoromethyl, trifluoromethoxy, cyano, hydroxy, (C1-C6)alkyl, (C1-C6)alkoxy or phenyl group, it also being possible for two of these substituents in adjacent positions together to represent a methylenedioxy group, and R6 represents a hydrogen atom or a (C1-C6)alkyl group. Application in therapeutics.
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- Palladium-catalyzed reaction of aryl iodides with acetic anhydride. A carbon monoxide-free synthesis of acetophenones
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(Matrix presented) The palladium-catalyzed reaction of aryl iodides with acetic anhydride provides a straightforward and experimentally simple carbon monoxide-free route to acetophenones. The reaction tolerates a wide range of funcfionalized aryl iodides. Acetophenones are isolated in excellent yield with a variety of neutral, slightly electron-rich, and slightly electron-poor aryl iodides, whereas moderate yields are obtained with aryl iodides containing strongly electron-withdrawing substituents.
- Cacchi, Sandro,Fabrizi, Giancarlo,Gavazza, Federica,Goggiamani, Antonella
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p. 289 - 291
(2007/10/03)
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- A convenient method for the preparation of aromatic ketones from acyl chlorides and arylzinc bromides using a cobalt catalysis
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Aromatic ketones are synthesized efficiently via cobalt catalyzed cross-coupling reaction between arylzinc bromides and acid chlorides. Arylzinc bromides prepared chemically via a cobalt catalysis undergo coupling without additional catalyst unlike their electrochemical analogs.
- Fillon, Hyacinthe,Gosmini, Corinne,Périchon, Jacques
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p. 8199 - 8202
(2007/10/03)
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