- Electron attachment and detachment: Electron affinities of isomers of trifluoromethylbenzonitrile
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Rate constants for electron attachment to the three isomers of trifluoromethylbenzonitrile [(CF3)(CN)C6H4, or TFMBN] were measured over the temperature range of 303-463 K in a 133-Pa He buffer gas, using a flowing-afterglow Langmuir-probe apparatus. At 303 K, the measured attachment rate constants are 9.0×10-8 (o-TFMBN), 5.5× 10-8 (m-TFMBN), and 8.9 × 10-8 cm 3 s-1 (p-TFMBN), estimated accurate to ±25%. The attachment process formed only the parent anion in all three cases. Thermal electron detachment was observed for all three anion isomers, and rate constants for this reverse process were also measured. From the attachment and detachment results, the electron affinities of the three isomers of TFMBN were determined to be 0.70(o-TFMBN), 0.67(m-TFMBN), and 0.83 eV (p-TFMBN), all ±0.05 eV. G3(MP2) [Gaussian-3 calculations with reduced Moller-Plesset orders (MP2)] calculations were carried out for the neutrals and anions. Electron affinities derived from these calculations are in good agreement with the experimental values.
- Miller, Thomas M.,Viggiano,Friedman, Jeffrey F.,Van Doren, Jane M.
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Read Online
- Nitrile Synthesis via Desulfonylative-Smiles Rearrangement
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Herein, we designed a simple nitrile synthesis from N-[(2-nitrophenyl)sulfonyl]benzamides via base-promoted intramolecular nucleophilic aromatic substitution. The process features redox-neutral conditions as well as no requirement of toxic cyanide species and transition metals. Our process shows broad scope and various functional group compatibility, affording a variety of (hetero)aromatic nitriles in good to excellent yields.
- Abe, Masahiro,Nitta, Sayasa,Miura, Erina,Kimachi, Tetsutaro,Inamoto, Kiyofumi
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p. 4460 - 4467
(2022/03/15)
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- Recyclable and Reusable Pd(OAc)2/XPhos–SO3Na/PEG-400/H2O System for Cyanation of Aryl Chlorides with Potassium Ferrocyanide
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Pd(OAc)2/XPhos–SO3Na in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be a highly efficient catalyst for the cyanation of aryl chlorides with potassium ferrocyanide. The reaction proceeded smoothly at 100 or 120?oC with K2CO3 or KOAc as base, delivering a variety of aromatic nitriles in good to excellent yields. The isolation of the crude products is facilely performed by extraction with cyclohexane and more importantly, both expensive Pd(OAc)2 and XPhos–SO3Na in PEG-400/H2O system could be easily recycled and reused at least six times without any apparent loss of catalytic efficiency. Graphical Abstract: Palladium-catalyzed cyanation of aryl chlorides with potassium ferrocyanide leading to aryl nitriles by using Pd(OAc)2/XPhos–SO3Na/PEG-400/H2O as a highly efficient and recyclable catalytic system is described.[Figure not available: see fulltext.]
- Cai, Mingzhong,Huang, Bin,Liu, Rong,Xu, Caifeng
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- SO2F2-Mediated one-pot cascade process for transformation of aldehydes (RCHO) to cyanamides (RNHCN)
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A simple, mild and practical cascade process for the direct conversion of aldehydes to cyanamides was developed featuring a wide substrate scope and great functional group tolerability. This method allows for transformations of readily available, inexpensive, and abundant aldehydes to highly valuable cyanamides in a pot, atom, and step-economical manner with a green nitrogen source. This protocol will serve as a robust tool for the installation of the cyanamide moiety in various complicated molecules.
- Ding, Chengrong,Ge, Shuting,Wei, Junjie,Zhang, Guofu,Zhao, Yiyong
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p. 17288 - 17292
(2020/05/18)
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- Acceptorless dehydrogenation of amines to nitriles catalyzed by N-heterocyclic carbene-nitrogen-phosphine chelated bimetallic ruthenium (II) complex
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We have developed a clean, atom-economical and environmentally friendly route for acceptorless dehydrogenation of amines to nitriles by combining a new dual N-heterocyclic carbene-nitrogen-phosphine ligand R(CNP)2 (R = o-xylyl) with a ruthenium precursor [RuCl2(η6-C6H6)]2. In this system, the electronic and steric factors of amines had a negligible influence on the reaction and a broad range of functional groups were well tolerated. All of the investigated amines could be converted to nitriles in good yield of up to 99% with excellent selectivity. The unprecedented catalytic performance of this system is attributed to the synergistic effect of two ruthenium centers chelated by R(CNP)2 and a plausible reaction mechanism is proposed according to the active species found via in situ NMR and HRMS.
- Chen, Hua,Fu, Haiyan,Ji, Li,Li, Ruixiang,Nie, Xufeng,Zheng, Yanling
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p. 378 - 385
(2020/10/02)
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- Method for catalyzing receptor-free dehydrogenation of primary amine to generate nitrile by Ru coordination compound
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The invention discloses a method for catalyzing receptor-free dehydrogenation of primary amine to generate nitrile by a Ru coordination compound. The method comprises: adding a Ru coordination compound, an alkali, a primary amine and an organic solvent into a reaction test tube according to a mol ratio of 1:100:(100-500):1000-3000, and carrying out a stirring reaction under the condition of 80 to120 DEG C; and when gas chromatography monitors that the raw materials completely disappear, stopping the reaction, collecting the reaction solution, centrifuging the reaction solution, taking the supernatant, extracting with dichloromethane, merging the organic phases, drying, filtering, evaporating the organic solvent under reduced pressure to obtain a filtrate, and carrying out column chromatography purification on the filtrate to obtain the target product nitrile. According to the invention, the catalyst is good in activity, single in catalytic system, good in product selectivity, simple in subsequent treatment and good in system universality after the reaction is finished, has a good catalytic effect on various aryl, alkyl and heteroaryl substituted primary amines, and also has a gooddehydrogenation performance on secondary amines.
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Paragraph 0034-0039; 0136-0141
(2020/09/16)
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- Metallaphotoredox Perfluoroalkylation of Organobromides
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Ruppert-Prakash type reagents (TMSCF3, TMSC2F5, and TMSC3F7) are readily available, air-stable, and easy-to-handle fluoroalkyl sources. Herein, we describe a mild, copper-catalyzed cross-coupling of these fluoroalkyl nucleophiles with aryl and alkyl bromides to produce a diverse array of trifluoromethyl, pentafluoroethyl, and heptafluoropropyl adducts. This light-mediated transformation proceeds via a silyl-radical-mediated halogen atom abstraction pathway, which enables perfluoroalkylation of a broad range of organobromides of variable steric and electronic demand. The utility of the method is demonstrated through the late-stage functionalization of several drug analogues.
- Zhao, Xiangbo,MacMillan, David W. C.
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supporting information
p. 19480 - 19486
(2020/12/18)
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- Metal-free dehydrosulfurization of thioamides to nitriles under visible light
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A visible light-mediated, metal-free dehydrosulfurization reaction of thioamides to nitriles is described. This reaction features high yields, mild reaction conditions, and the use of a cheap organic dye as the photoredox catalyst and air as the oxidant.
- Xu, Tianxiao,Cao, Tianpeng,Feng, Qingyuan,Huang, Shenlin,Liao, Saihu
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supporting information
p. 5151 - 5153
(2020/05/26)
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- A Transition-Metal-Free One-Pot Cascade Process for Transformation of Primary Alcohols (RCH2OH) to Nitriles (RCN) Mediated by SO2F2
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A new transition-metal-free one-pot cascade process for the direct conversion of alcohols to nitriles was developed without introducing an “additional carbon atom”. This protocol allows transformations of readily available, inexpensive, and abundant alcohols to highly valuable nitriles.
- Jiang, Ying,Sun, Bing,Fang, Wan-Yin,Qin, Hua-Li
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p. 3190 - 3194
(2019/05/21)
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- Catalytic oxidative conversion of aldehydes into nitriles using NH3·H2O/FeCl2/NaI/Na2S2O8: A practical approach to febuxostat
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A novel approach to convert aldehydes into nitriles using NH3·H2O/FeCl2/NaI/Na2S2O8 has been developed. Both alkyl and aryl nitriles were obtained in good to excellent yields. Electron-withdrawing and electron-donating groups, such as fluoro, chloro, bromo, nitro, ester, cyano, trifluoromethyl and alkoxy were tolerated. Notably, febuxostat and its intermediate, ethyl 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5-thiazolecarboxylate, were obtained in excellent yields.
- Chen, Han,Sun, Sijia,Xi, Haoying,Hu, Kaifang,Zhang, Ning,Qu, Jingping,Zhou, Yuhan
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supporting information
p. 1434 - 1436
(2019/05/01)
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- Visible light-induced direct conversion of aldehydes into nitriles in aqueous medium using Co@g-C3N4 as photocatalyst
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Unprecedented Co@g-C3N4 catalyzed visible light driven efficient conversion of a variety of aldehydes into corresponding nitriles is reported. Operational simplicity, excellent yield of pure products (87–94%), ambient reaction condition, using aqueous methanol as solvent, visible-light photocatalysis are the salient features of envisaged methodology for direct conversion of aldehydes into nitriles. Furthermore, reusability of Co@g-C3N4 was checked up to five runs and it was noticed that there was no substantial change in morphology as well as the catalytic efficiency of catalyst.
- Verma, Fooleswar,Shukla, Prashant,Bhardiya, Smita R.,Singh, Manorama,Rai, Ankita,Rai, Vijai K.
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- Palladium-Catalyzed Late-Stage Direct Arene Cyanation
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Methods for direct benzonitrile synthesis are sparse, despite the versatility of cyano groups in organic synthesis and the importance of benzonitriles for the dye, agrochemical, and pharmaceutical industries. We report the first general late-stage aryl C–H cyanation with broad substrate scope and functional-group tolerance. The reaction is enabled by a dual-ligand combination of quinoxaline and an amino acid-derived ligand. The method is applicable to direct cyanation of several marketed small-molecule drugs, common pharmacophores, and organic dyes. Benzonitriles are some of the most versatile building blocks for organic synthesis, in particular in the pharmaceutical industry, but general methods to make them by direct C–H functionalization are unknown. In this issue of Chem, Ritter and coworkers describe a late-stage aryl C–H cyanation with broad substrate scope and functional-group tolerance, enabled by a palladium-dual-ligand catalyst system. The reaction may serve for the late-stage modification of drug candidates. Aryl nitriles constitute an important class of organic compounds that are widely found in natural products, pharmaceuticals, agricultural chemicals, dyes, and materials. Moreover, nitriles are versatile building blocks to access numerous other important molecular structure groups. However, no general method for direct aromatic C–H cyanation is known. All approaches to date require either an appropriate directing group or reactive electron-rich substrates, such as indoles, which limit their synthetic applications. Here we describe an undirected, palladium-catalyzed late-stage aryl C–H cyanation reaction for the synthesis of complex aryl nitriles that would otherwise be more challenging to produce. The wide substrate scope and good functional-group tolerance of this reaction provide direct and quick access to structural diversity for pharmaceutical and agrochemical development.
- Zhao, Da,Xu, Peng,Ritter, Tobias
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supporting information
p. 97 - 107
(2019/01/21)
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- Metal-free HNO3/TEMPO-catalyzed conversion of benzyl alcohols to aromatic nitriles with oxygen molecule as the terminal oxidant
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A non-metal catalytic method for the aerobic conversion of primary alcohols to aromatic nitriles via a single-step operation was developed. A series of primary benzyl alcohols underwent this transformation to give the targeted products in moderate to high yields under the catalysis of TEMPO/ HNO3.
- Zhao, Bo,Ren, Yun-Lai,Ren, Fangping,Tian, Xinzhe,Zhao, Shuang
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supporting information
p. 627 - 632
(2019/05/01)
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- Oxidative cyanide-free cyanation on arylboronic acid derivatives using aryl/heteroaryl thiocyanate using novel IL-PdCl4 catalyst under mild condition
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An efficient and simple method is reported for the cyanation on arylboronic acid using various simple/indole thiocyanates using a new IL-PdCl4 catalyst. The cascade process involves a coupling reaction without any additive to give a wide range of cyanide derivatives. Cyanation on various arylboronic acids underwent smoothly affording the corresponding arylnitriles in good to high yields.
- Vaghasiya, Beena K.,Satasia, Shailesh P.,Thummar, Rahul P.,Kamani, Ronak D.,Avalani, Jemin R.,Sapariya, Nirav H.,Raval, Dipak K.
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p. 507 - 515
(2018/05/15)
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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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- Green method for catalyzing alcohols and ammonia to prepare nitriles by using heterogeneous mesoporous cobalt catalyst
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The invention provides a novel green method for catalyzing alcohols and ammonia to prepare nitriles by using a heterogeneous mesoporous cobalt catalyst. According to the method, cobalt acetate and nitrogen-containing ligands are taken as precursors, the novel heterogeneous mesoporous cobalt catalyst is prepared through high-temperature calcinations by using a hard template agent method, and catalyzed synthesis of various nitriles is realized in non-halogen solvents, particularly synthesis of aromatic and heterocyclic nitriles can be realized. The catalytic system has the characteristics that the novel and high-efficiency mesoporous cobalt catalyst is used; safe and green oxygen serves as an oxidizing agent; extra aids do not need to be added; the reaction is easy to operate; particularly the synthesis of aromatic and heterocyclic nitriles can be efficiently realized, and the nitriles can be repeatedly recycled. The novel heterogeneous mesoporous cobalt catalyst is used in the invention and has excellent research and industrial application prospects.
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Paragraph 0046-0048
(2017/07/20)
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- Decarbonylative Cyanation of Amides by Palladium Catalysis
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Transition-metal-catalyzed cyanation of aryl halides is a process of significant importance in the preparation pharmaceuticals, organic materials and agrochemicals. Here, we demonstrate a palladium-catalyzed decarbonylative cyanation of amides by highly selective carbon-nitrogen bond cleavage for the synthesis of a wide range of aryl nitriles. The utility of this technology is demonstrated by the synthesis of isotopically labeled aryl nitriles and orthogonal cross-coupling reactions of bench-stable amides to establish cross-coupling synthons with opposite polarity.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 3095 - 3098
(2017/06/23)
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- Phosphovanadomolybdic acid catalyzed direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 as the CF3 source and O2 as the terminal oxidant
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A direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 (Langlois' reagent) as the CF3 source and O2 as the terminal oxidant has been developed. In the presence of catalytic amounts of phosphovanadomolybdic acids, such as H6PV3Mo9O40, various kinds of substituted benzenes and heteroaromatic compounds could be converted into the corresponding trifluoromethylated products.
- Li, Chifeng,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 1417 - 1420
(2017/02/23)
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- High catalytic activity of mesoporous Co-N/C catalysts for aerobic oxidative synthesis of nitriles
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A high-efficiency and atom-economic synthetic strategy for nitriles by aerobic ammoxidation of alcohols is developed using a novel mesoporous cobalt-coordinated nitrogen-doped carbon catalyst (meso-Co-N/C) fabricated from a cobalt-coordinating polymer, which manifests superior activity towards the target reaction. The catalytic system features a broad substrate scope for various benzylic, allylic as well as heterocyclic alcohols, providing good to excellent yields of the target products with high selectivities, albeit with 0.5 mol% Co catalyst loading. 11,11′-Bis(dipyrido[3,2-a:2′,3′-c]phenazinyl) (bidppz) with extreme thermostability is selected as a robust ligand bridge between cobalt ions, resulting in the homogeneous distribution of active sites at the atomic or subnanoscale level and high catalyst yield. Silica colloid or ordered mesoporous silica SBA-15 is employed to realize the mesoporous structure. The unprecedented performance of the meso-Co-N/C catalyst is attributed to its high Brunauer-Emmett-Teller (BET) surface area (up to 680 m2 g-1) with a well-controlled mesoporous structure and homogeneous distribution of active sites. Kinetic analysis demonstrates that the catalytic oxidation of benzyl alcohol to benzaldehyde is the turnover-limiting step and that the apparent activation energy for benzonitrile synthesis is 61.5 kJ mol-1 and cationic species are involved in the reaction.
- Shang, Sensen,Wang, Lianyue,Dai, Wen,Chen, Bo,Lv, Ying,Gao, Shuang
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p. 5746 - 5753
(2016/07/21)
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- Transition-Metal-Free Deacylative Cleavage of Unstrained C(sp3)-C(sp2) Bonds: Cyanide-Free Access to Aryl and Aliphatic Nitriles from Ketones and Aldehydes
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A transition-metal-free deacylative C(sp3)-C(sp2) bond cleavage for the synthetically practical oxidative amination of ketones and aldehydes to nitriles is first described, using cheap and commercially abundant NaNO2 as the oxidant and the nitrogen source. Various nitriles bearing aryl, heteroaryl, alkyl, and alkenyl groups could be smoothly obtained from ketones and aldehydes in high yields, avoiding highly toxic cyanides or transition metals.
- Ge, Jing-Jie,Yao, Chuan-Zhi,Wang, Mei-Mei,Zheng, Hong-Xing,Kang, Yan-Biao,Li, Yadong
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supporting information
p. 228 - 231
(2016/02/03)
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- Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion
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We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations.
- Xu, Boran,Hartigan, Elizabeth M.,Feula, Giancarlo,Huang, Zheng,Lumb, Jean-Philip,Arndtsen, Bruce A.
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supporting information
p. 15802 - 15806
(2016/12/16)
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- Meta-trifluoromethyl benzyl cyanide process for the preparation of
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The invention relates to a preparation method of 3-trifluoromethyl phenylacetonitrile. According to the preparation method, aminobenzyl cyanide is taken as a raw material and has a trifluoromethylation reaction, a diazotization reaction and a reduction reaction sequentially to prepare 3-trifluoromethyl phenylacetonitrile. The preparation method has a reasonable process, high yield and few side effects and is applicable to industrial production.
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Paragraph 0011; 0031-0033
(2017/02/09)
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- Trifluoromethylation of (hetero)aryl iodides and bromides with copper(i) chlorodifluoroacetate complexes
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A new copper-mediated trifluoromethylation reaction using copper(i) chlorodifluoroacetate complexes as reagents is reported. The complex [L2Cu][O2CCF2Cl] (L = bpy, dmbpy, phen) reacted with (hetero)aryl iodides and bromides in the presence of CsF in DMF at 75 °C to afford the trifluoromethylarenes in good to excellent yields. High compatibility with various chemical functions or (hetero)cycles was also observed in the reaction. A reaction mechanism involving a difluorocarbene intermediate, along with a subsequent formation of a -CF3 anion was proposed.
- Lin, Xiaoxi,Li, Zhengyu,Han, Xiaoyan,Weng, Zhiqiang
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p. 75465 - 75469
(2016/08/24)
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- Decarboxylative Trifluoromethylating Reagent [Cu(O2CCF3)(phen)] and Difluorocarbene Precursor [Cu(phen)2][O2CCF2Cl]
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This article describes the new economic decarboxylative trifluoromethylating reagent [Cu(phen)(O2CCF3)] (1; phen=1,10-phenanthroline) and the efficient difluorocarbene precursor [Cu(phen)2][O2CCF2Cl] (2). Treatment of copper tert-butoxide with phen and subsequent addition of trifluoroacetic acid or chlorodifluoroacetic acid afforded air-stable complexes 1 and 2, respectively, which were characterized by X-ray crystallography. The copper(I) ion in 1 is coordinated by a bidentate phen ligand, a monodentate trifluoroacetate group, and a molecule of CH3CN in a distorted tetrahedral coordination geometry. The molecular structure of 2 adopts an ionic form that consists of a [Cu(phen)2]+ cation and a chlorodifluoroacetate anion. Complex 1 reacted with a variety of aryl and heteroaryl halides to form trifluoromethyl (hetero)arenes in good yields. The corresponding Hammett plot exhibited a linear relationship and a reaction parameter (ρ)=+0.56±0.02, which indicated that the trifluoromethylation reaction proceeded via a nucleophilic reactive species. Complex 2 reacts with phenols to produce aryl difluoromethyl ethers in modest-to-excellent yields. Mechanistic investigations revealed that the difluoromethylation reaction proceeds by initial copper-mediated formation of difluorocarbene and subsequent concerted addition of difluorocarbene to the phenol to form a three-center transition state.
- Lin, Xiaoxi,Hou, Chuanqi,Li, Haohong,Weng, Zhiqiang
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supporting information
p. 2075 - 2084
(2016/02/12)
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- Transnitrilation from Dimethylmalononitrile to Aryl Grignard and Lithium Reagents: A Practical Method for Aryl Nitrile Synthesis
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An electrophilic cyanation of aryl Grignard or lithium reagents, generated in situ from the corresponding aryl bromides or iodides, by a transnitrilation with dimethylmalononitrile (DMMN) was developed. DMMN is a commercially available, bench-stable solid. The transnitrilation with DMMN avoids the use of toxic reagents and transition metals and occurs under mild reaction conditions, even for extremely sterically hindered substrates. The transnitrilation of aryllithium species generated by directed ortho-lithiation enabled a net C-H cyanation. The intermediacy of a Thorpe-type imine adduct in the reaction was supported by isolation of the corresponding ketone from the quenched reaction. Computational studies supported the energetic favorability of retro-Thorpe fragmentation of the imine adduct. (Chemical Equation Presented).
- Reeves, Jonathan T.,Malapit, Christian A.,Buono, Frederic G.,Sidhu, Kanwar P.,Marsini, Maurice A.,Sader, C. Avery,Fandrick, Keith R.,Busacca, Carl A.,Senanayake, Chris H.
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supporting information
p. 9481 - 9488
(2015/08/11)
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- Silver-Catalyzed C-H Trifluoromethylation of Arenes Using Trifluoroacetic Acid as the Trifluoromethylating Reagent
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Direct trifluoromethylation of arenes using TFA as the trifluoromethylating reagent was achieved with Ag as the catalyst. This reaction not only provides a new protocol for aryl C-H trifluoromethylation, but the generation of CF3· from TFA may prove useful in other contexts and could potentially be extended to other trifluoromethylation reactions. (Chemical Equation Presented).
- Shi, Guangfa,Shao, Changdong,Pan, Shulei,Yu, Jingxun,Zhang, Yanghui
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supporting information
p. 38 - 41
(2015/07/28)
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- Mechanism of trifluoromethylation of aryl halides with CuCF3and the ortho effect
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A combined experimental (radical clock, kinetic, Hammett) and computational (DFT, MM) study of the trifluoromethylation reaction of aryl halides with CuCF3 reveals a nonradical mechanism involving Ar-X oxidative addition to the Cu(I) center as the rate determining step. The reaction is second order, first order in each reactant with ΔG? ≈ 24 kcal/mol for PhI (computed ΔG? = 21.9 kcal/ mol). An abrupt change in the gradient on the Hammett plot of log(kR/ kH) versus σp for 11 p-RC6H4I substrates produces two correlations (ρ = +0.69 and +1.83), which is temptingly suggestive of two different reaction pathways. Only one mechanism is operational, however, as advocated by a single linear correlation with σp- (ρ = +0.91), analysis of the experimental ρ values, close similarity of the transition states varying in R and displaying clear signs of -M interactions, and excellent reproduction of the plot by DFT. The long-known yet previously uncomprehended ortho effect has been quantified, for the first time, using the reaction of CuCF3 with a series of o-RC6H4Br: R(kR/kH) = H (1) 2Me (850) 2 (4300) 2H (150 000). With minor contributions from electronic factors, the ortho effect is largely determined by (i) the stabilizing coordination of the o-substituent to Cu in the transition state with the Cu?O distance varying directly with the barrier and (ii) the steric bulk of the o-substituent that raises the ground state free energy of the haloarene (Go ortho - Go H or Go ortho - Go para) by inflicting molecular strain and consequently weakening the Ar-X bond.
- Konovalov, Andrey I.,Lishchynskyi, Anton,Grushin, Vladimir V.
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supporting information
p. 13410 - 13425
(2015/03/30)
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- Efficient copper-catalyzed trifluoromethylation of aromatic and heteroaromatic iodides: The beneficial anchoring effect of borates
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Efficient copper-catalyzed trifluoromethylation of aromatic iodides was achieved with TMSCF3 in the presence of trimethylborate. The Lewis acid was used to anchor the in situ generated trifluoromethyl anion and suppress its rapid decomposition. Broad applicability of the new trifluoromethylating reaction was demonstrated in the functionalization of different aromatic and heteroaromatic iodides.
- Gonda, Zsombor,Kovacs, Szabolcs,Weber, Csaba,Gati, Tamas,Meszaros, Attila,Kotschy, Andras,Novak, Zoltan
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supporting information
p. 4268 - 4271
(2014/09/30)
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- Efficient palladium-catalyzed cyanation of aryl/heteroaryl bromides with K4[Fe(CN)6] in t-BuOH-H2O using tris(2-morpholinophenyl)phosphine as a ligand
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A practical method for the synthesis of various aryl/heteroaryl nitriles using non-toxic K4[Fe(CN)6] as the cyanide source is described. The cyanation of aryl/heteroaryl bromides with K4[Fe(CN) 6] proceeded smoothly in the presence of a Pd/tris(2- morpholinophenyl)phosphine (L5) catalyst under mild conditions. The corresponding aryl/heteroaryl nitriles were produced in good to excellent yields. The Royal Society of Chemistry 2013.
- Zou, Tao,Feng, Xiujuan,Liu, Hesong,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
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p. 20379 - 20384
(2013/11/06)
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- Replacing conventional carbon nucleophiles with electrophiles: Nickel-catalyzed reductive alkylation of aryl bromides and chlorides
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A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (-OH, -NHTs, -OAc, -OTs, -OTf, -COMe, -NHBoc, -NHCbz, -CN, -SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki-Miyaura, Stille, and Hiyama-Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R-X) and no reaction at the nucleophilic carbon (R-[M]) for organoboron (-Bpin), organotin (-SnMe3), and organosilicon (-SiMe2OH) containing organic halides (X-R-[M]). A Hammett study showed a linear correlation of σ and σ(-) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2-1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents.
- Everson, Daniel A.,Jones, Brittany A.,Weix, Daniel J.
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supporting information; experimental part
p. 6146 - 6159
(2012/05/07)
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- Oxidative trifluoromethylation of arylboronates with shelf-stable potassium (trifluoromethyl)trimethoxyborate
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Introducing CF3: Arylboronic acid pinacol esters are converted into the corresponding benzotrifluorides with the easy-to-use one-component trifluoromethylating reagent potassium (trifluoromethyl)trimethoxyborate, mediated by copper acetate under an oxygen atmosphere (see scheme). Copyright
- Khan, Bilal A.,Buba, Annette E.,Goossen, Lukas J.
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supporting information; experimental part
p. 1577 - 1581
(2012/03/10)
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- The first example for cyanation of arylboronic acids with nontoxic and inexpensive K4[Fe(CN)6]
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Nontoxic and inexpensive K4[Fe(CN)6] is first introduced as a cyanating agent to cyanation of arylboronic acids. The present method is simple, practical, and allowed a wide range of substrates including functionalized phenylboronic acids, 1-naphthylboronic acid as well as heterocyclic boronic acids to be smoothly converted into the corresponding products in moderate to high yields.
- Tian, Xinzhe,Sun, Yanpei,Dong, Chuanhua,Zhang, Kaixuan,Liang, Tengfei,Zhang, Yu,Hou, Chaodong
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supporting information; experimental part
p. 719 - 721
(2012/09/22)
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- A general strategy for the perfluoroalkylation of arenes and arylbromides by using arylboronate esters and [(phen)CuRF]
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A versatile method for the synthesis of aryl perfluoroalkanes from arenes and aryl bromides is described. Substituted arenes or aryl bromides are converted in situ to an aryl boronate ester that readily undergoes perfluoroalkylation in air with [(phen)CuRF]. A broad range of aryl bromide substrates were perfluoroalkylated in good yield for the first time. [(phen)CuCF3] is now commercially available and has been prepared on 20g scale. Copyright
- Litvinas, Nichole D.,Fier, Patrick S.,Hartwig, John F.
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p. 536 - 539
(2012/02/16)
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- Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes
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Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium [(P{(NC 5H10)(C6H11)2}) 2PdCl2] (1) is a highly active and generally applicable C-C cross-coupling catalyst. Apart from its high catalytic activity in Suzuki, Heck, and Negishi reactions, compound 1 also efficiently converted various electronically activated, nonactivated, and deactivated aryl bromides, which may contain fluoride atoms, trifluoromethane groups, nitriles, acetals, ketones, aldehydes, ethers, esters, amides, as well as heterocyclic aryl bromides, such as pyridines and their derivatives, or thiophenes into their respective aromatic nitriles with K4[Fe(CN)6] as a cyanating agent within 24 h in NMP at 140 °C in the presence of only 0.05 mol % catalyst. Catalyst-deactivation processes showed that excess cyanide efficiently affected the molecular mechanisms as well as inhibited the catalysis when nanoparticles were involved, owing to the formation of inactive cyanide complexes, such as [Pd(CN)4]2-, [(CN)3Pd(H)]2-, and [(CN)3Pd(Ar)]2-. Thus, the choice of cyanating agent is crucial for the success of the reaction because there is a sharp balance between the rate of cyanide production, efficient product formation, and catalyst poisoning. For example, whereas no product formation was obtained when cyanation reactions were examined with Zn(CN)2 as the cyanating agent, aromatic nitriles were smoothly formed when hexacyanoferrate(II) was used instead. The reason for this striking difference in reactivity was due to the higher stability of hexacyanoferrate(II), which led to a lower rate of cyanide production, and hence, prevented catalyst-deactivation processes. This pathway was confirmed by the colorimetric detection of cyanides: whereas the conversion of β-solvato-α-cyanocobyrinic acid heptamethyl ester into dicyanocobyrinic acid heptamethyl ester indicated that the cyanide production of Zn(CN)2 proceeded at 25 °C in NMP, reaction temperatures of >100 °C were required for cyanide production with K4[Fe(CN) 6]. Mechanistic investigations demonstrate that palladium nanoparticles were the catalytically active form of compound 1. A balancing act: Compound 1 (see scheme) is a highly active cyanation catalyst. Furthermore, a sharp balance between the rates of cyanide generation, efficient product formation, and catalyst deactivation owing to excess cyanide was observed in deactivation processes. Copyright
- Gerber, Roman,Oberholzer, Miriam,Frech, Christian M.
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supporting information; experimental part
p. 2978 - 2986
(2012/04/04)
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- Reaction of triflyl-imidazole with aldoximes: Facile synthesis of nitriles and formation of novel aldoxime-bis(N-triflyl)-imidazole adducts
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The synthetic utility of N-triflylimidazole as an in situ reagent for facile, high yielding, synthesis of various aliphatic, aromatic, and heteroaromatic nitriles from the corresponding aldoximes has been demonstrated. With benzaldoximes, in the presence of certain substitutents (2-F; 2-OMe; 3-CF3; 2-Me-5-F) a different course of reaction was observed, leading instead to novel 1:1 aldoxime-bis(N-triflyl)imidazole covalent adducts, in which the aldoxime oxygen atom is bonded to the imidazole C-2 ring carbon. For these aldoximes, conversion to nitrile could be effected by reaction with Tf2O in the absence of imidazole. The molecular structure of the adduct formed from 2-methyl-5-fluoro-benzaldoxime was confirmed by X-ray analysis. Plausible mechanisms for the formation of 1:1 covalent adducts have been considered. Various attempts to isolate such adducts via the reaction of an authentic sample of bis(N-triflyl)imidazolium trifate with aldoxime were unsuccessful. Remarkably, whereas isolated benzaldoxime adducts undergo deprotonation/methylation with NaH/MeI, an authentic sample of bis(N-triflyl)imidazolium triflate did not undergo H/Me exchange under these conditions. These transformations are discussed.
- Kalkhambkar, Rajesh G.,Bunge, Scott D.,Laali, Kenneth K.
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supporting information; experimental part
p. 5184 - 5187
(2011/10/13)
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- Rational catalysis design on the basis of mechanistic understanding: Highly efficient Pd-catalyzed cyanation of aryl bromides with NaCN in recyclable solvents
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Rational catalysis design on the basis of a detailed mechanistic understanding has been used to successfully develop the first efficient general Pd-catalyzed aromatic cyanation reaction under the highly sought after practicable conditions: (i) MCN (M = Na or K) as a cyanide source; (ii) low-boiling recyclable solvents; and (iii) minimal quantities of inexpensive, nontoxic promoters. The developed catalytic reaction converts aromatic bromides to the corresponding nitriles in 88-99% isolated yield with NaCN and 0.5-1.0 mol % of a t-Bu3P-monoligated Pd catalyst in MeCN-THF within 2 h at 70 °C. The process exhibits high functional group tolerance.
- Ushkov, Alexander V.,Grushin, Vladimir V.
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experimental part
p. 10999 - 11005
(2011/09/16)
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- Cooperative effect of silver in copper-catalyzed trifluoromethylation of aryl iodides using Me3SiCF3
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An effective model of cooperative effect of silver for the coppercatalyzed trifluoromethylation of activated and unactivated aryl iodides to trifluoromethylated arenes using Me3SiCF3 was achieved with a broad substrate scope.
- Weng, Zhiqiang,Lee, Richmond,Jia, Weiguo,Yuan, Yaofeng,Wang, Wenfeng,Feng, Xue,Huang, Kuo-Wei
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experimental part
p. 3229 - 3232
(2011/07/31)
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- A general rhodium-catalyzed cyanation of aryl and alkenyl boronic acids
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Give me a cyanide: N-cyano-N-phenyl-p-methylbenzenesulfonamide as a cyanation reagent allows the synthesis of aryl(alkenyl) nitriles in good yield under mild conditions (see scheme; cod=cycloocta-1,5-diene). Combination of the procedure with the direct borylation of arenes and hydroboration of alkynes leads to the straightforward synthesis of various nitriles.
- Anbarasan, Pazhamalai,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 519 - 522
(2011/03/16)
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- Highly efficient Pd-catalyzed cyanation of aryl chlorides and arenesulfonates with potassium ferrocyanide in aqueous media
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A highly improved Pd-catalyzed cyanation of aryl chlorides to corresponding benzonitriles was demonstrated in aqueous media. Moreover, Pd-catalyzed cyanation of aryl tosylates and benzenesulfonates with K4[Fe(CN) 6] was developed under the similar conditions, which extended application scope of the cyanation. Graphical Abstract: [Figure not available: see fulltext.]
- Zhang, Junli,Chen, Xiaorong,Hu, Tongjie,Zhang, Yuan,Xu, Kunling,Yu, Yanpeng,Huang, Jun
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experimental part
p. 56 - 60
(2011/01/12)
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- Palladium nanoparticles stabilized by a copolymer of N-vinylimidazole with N-vinylcaprolactam as efficient recyclable catalyst of aromatic cyanation
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A new recyclable catalytic system was developed based on palladium nanoparticles and a copolymer of N-vinylimidazole and N-vinylcaprolactam for cyanation of aromatic bromides. The source of the cyanide ion was a nontoxic potassium hexacyanoferrate.
- Beletskaya,Selivanova,Tyurin,Matveev,Khokhlov
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experimental part
p. 157 - 161
(2010/07/06)
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- Ligand-free Cu-catalyzed cyanation of aryl halides with K 4[Fe(Cn)6] in water
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A simple methodology for Cu-catalyzed cyanation of aryl halides with K 4[Fe(CN)6] was developed with water as the solvent in conjunction with ligand-free Cu(OAc)2·H2O as the catalyst. The suggested methodology i
- Ren, Yunlai,Zhao, Shuang,Tian, Xinzhe,Liu, Zhifei,Wang, Jianji,Yin, Weiping
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scheme or table
p. 564 - 567
(2010/04/23)
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- Cul/1,10-phenanthroline: An efficient catalyst system for the cyanation of aryl halides
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Aryl nitriles have been prepared in good yields from the corresponding aryl halides with potassium hexacyanoferrate(II) using Cul/1,10-phenanthroline as the catalyst system. Furthermore, the reaction is compatible with a wide range of functional groups including nitro and carbonyl substituents.
- Zhu, Yi-Zhong,Cai, Chun
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p. 484 - 485
(2008/09/20)
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- Pd/C: A recyclable catalyst for cyanation of aryl halides with K4[Fe(CN)6]
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Aryl nitriles have been prepared from the corresponding aryl halides with potassium hexacyanoferrate(II) using Pd/C as a catalyst. No ligand or cocatalyst is required. This protocol also avoids the use of highly toxic alkali cyanides. Furthermore, the catalyst can be recycled via simple filtration and washing sequences. Copyright Taylor & Francis Group, LLC.
- Zhu, Yi-Zhong,Cai, Chun
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p. 3359 - 3366
(2008/02/12)
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- Pd/C: A recyclable catalyst for cyanation of aryl bromides
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Aryl cyanides have been prepared from the corresponding aryl bromides with potassium hexacyanoferrate(II) using Pd/C as a catalyst. It is shown that the addition of Bu3N is the key factor in obtaining the corresponding aryl cyanides. Furthermore, the catalyst can be recycled by filtration and washing sequences, making the method also attractive for industrial applications. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Zhu, Yi-Zhong,Cai, Chun
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p. 2401 - 2404
(2008/03/12)
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- Effect of structure in benzaldehyde oximes on the formation of aldehydes and nitriles under photoinduced electron-transfer conditions
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(Chemical Equation Presented) The mechanistic aspects of the photosensitized reactions of a series of benzaldehyde oximes (1a-o) were studied by steady-state (product studies) and laser flash photolysis methods. Nanosecond laser flash photolysis studies have shown that the reaction of the oxime with triplet chloranil (3CA) proceeds via an electron-transfer mechanism provided the free energy for electron transfer (ΔGET) is favorable; typically, the oxidation potential of the oxime should be below 2.0 V. Substituted benzaldehyde oximes with oxidation potentials greater than 2.0 V quench 3CA at rates that are independent of the substituent and the oxidation potential. The most likely mechanism under these conditions is a hydrogen atom transfer mechanism as this reaction should be dependent on the O-H bond strength only, which is virtually the same for all oximes. Product studies have shown that aldoximes feact to give both the corresponding aldehyde and the nitrile. The important intermediate in the aldehyde pathway is the iminoxyl radical, which is formed via an electron transfer-proton transfer (ET-PT) sequence (for oximes with low oxidation potentials) or via a hydrogen atom transfer (HAT) pathway (for oximes with larger oxidation potentials). The nitriles are proposed to result from intermediate iminoyl radicals, which can be formed via direct hydrogen atom abstraction or via an electron-transfer-proton- transfer sequence. The experimental data seems to support the direct hydrogen atom abstraction as evidenced by the break in linearity in the plot of the quenching rates against the oxidation potential, which suggests a change in mechanism. The nitrile product is favored when electron-accepting substituents are present on the benzene ring of the benzaldehyde oximes or when the hydroxyl hydrogen atom is unavailable for abstraction. The latter is the case in pyridine-2-carboxaldoxime (2), where a strong intramolecular hydrogen bond is formed. Other molecules that form weaker intramolecular hydrogen bonds such as 2-furaldehyde oxime (3) and thiophene-2-carboxaldoxime (4) tend to yield increasing amounts of aldehyde.
- De Lijser, H.J. Peter,Hsu, Susan,Marquez, Bernadette V.,Park, Adriana,Sanguantrakun, Nawaporn,Sawyer, Jody R.
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p. 7785 - 7792
(2007/10/03)
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- Synthesis of imides, N-acyl vinylogous carbamates and ureas, and nitriles by oxidation of amides and amines with dess-martin periodinane
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Expanding our synthetic tool repertoire: The DMP-mediated oxidation of a range of amide substrates has been demonstrated, affording the corresponding imides and N-acyl vinylogous carbamates and ureas. Likewise, an array of benzylic and related amines have also been successfully converted into their nitrile counterparts (see scheme; DMP = Dess-Martin periodinane). (Chemical Equation Presented)
- Nicolaou,Mathison, Casey J. N.
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p. 5992 - 5997
(2007/10/03)
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- COPPER-CATALYZED FORMATION OF CARBON-HETEROATOM AND CARBON-CARBON BONDS
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One aspect of the present invention relates to copper-catalyzed carbon-heteroatom and carbon-carbon bond-forming methods. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-sulfur bond between the sulfur atom of a thiol moiety and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In other embodiments, the present invention relates to copper(II)-catalyzed methods of forming a carbon-nitrogen bond between the nitrogen atom of an amide and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-carbon bond between the carbon atom of cyanide ion and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In another embodiment, the present invention relates to a copper-catalyzed method of transforming and aryl, heteroaryl, or vinyl iodide. Yet another embodiment of the present invention relates to a tandem method, which may be practiced in a single reaction vessel, wherein the first step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl iodide from the corresponding aryl, heteroaryl, or vinyl chloride or bromide; and the second step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl nitrile, amide or sulfide from the aryl, heteroaryl, or vinyl iodide formed in the first step.
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- Process for the preparation of aromatic nitriles
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The invention relates to a process for the preparation of aromatic nitrites from halogenoaromatics or aryl perfluorosulfonates and alkali metal cyanides in the presence of palladium catalysts, zinc, and polyethers.
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- Nucleophilic aromatic substitution for heteroatoms: An oxidative electrochemical approach
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The nucleophilic aromatic substitution for heteroatom through electrochemical oxidation of the intermediate σ-complexes (Meisenheimer complexes) in simple nitroaromatic compounds is reported for the first time (NASX process). The studies have been carried out with hydride, cyanide, fluoride, methoxy, and ethanethiolate anions and n-butylamine as a nucleophile, at the cyclic voltammetry (CV) and preparative electrolysis level. The cyclic voltammetry experiments allow for detection and characterization of the σ-complexes and they have led us to a proposal for the mechanism of the oxidation step. Furthermore, the power of the CV technique in the analysis of the reaction mixture throughout the whole chemical and electrochemical process is described.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 2548 - 2555
(2007/10/03)
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- Process for producing trifluoromethylbenzylamines
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The invention relates to a process for producing a trifluoromethylbenzylamine represented by the following general formula (1). This process includes hydrogenating a trifliuoromethylbenzonitrile represented by the following general formula (2) by hydrogen in an organic solvent in the presence of ammonia, using a Raney catalyst, where each R independently represents a halogen selected from the group consisting of fluorine, chlorine, bromine and iodine, an alkyl group having a carbon atom number of 1-4, an alkoxy group having a carbon atom number of 1-4, an amino group, a hydroxyl group or a trifluoromethyl group, and n represents an integer from 0 to 4, where R and n are defined as above. With this process, it is possible to obtain the trifluoromethylbenzylamine easily and inexpensively at an extremely high yield.
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