- Copper-promoted cyanation of aryl iodides with N,N-dimethyl aminomalononitrile
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A copper-promoted cyanation of aryl iodides has been successfully developed by using N,N-dimethyl aminomalononitrile as the cyanide source with moderate toxicity and better stability. This reaction features broad substrate scope, excellent reaction yields, readily available catalyst, and simple reaction conditions.
- Liu, Si-Zhan,Li, Jing,Xue, Cao-Gen,Xu, Xue-Tao,Lei, Lin-Sheng,Huo, Chen-Yu,Wang, Zhen,Wang, Shao-Hua
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supporting information
(2021/02/01)
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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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- 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; 0184-0189
(2020/09/16)
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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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- On-Demand Generation and Use in Continuous Synthesis of the Ambiphilic Nitrogen Source Chloramine
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Herein, we demonstrate the on-demand synthesis of chloramine from aqueous ammonia and sodium hypochlorite solutions, and its subsequent utilization as an ambiphilic nitrogen source in continuous-flow synthesis. Despite its advantages in cost and atom economy, chloramine has not seen widespread use in batch synthesis due to its unstable and hazardous nature. Continuous-flow chemistry, however, provides an excellent platform for generating and handling chloramine in a safe, reliable, and inexpensive manner. Unsaturated aldehydes are converted to valuable aziridines and nitriles, and thioethers are converted to sulfoxides, in moderate to good yields and exceedingly short reaction times. In this telescoped process, chloramine is generated in situ and immediately used, providing safe and efficient conditions for reaction scale-up while mitigating the issue of its decomposition over time.
- Danahy, Kelley E.,Styduhar, Evan D.,Fodness, Aria M.,Heckman, Laurel M.,Jamison, Timothy F.
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supporting information
p. 8392 - 8395
(2020/11/18)
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- Cascade Process for Direct Transformation of Aldehydes (RCHO) to Nitriles (RCN) Using Inorganic Reagents NH2OH/Na2CO3/SO2F2 in DMSO
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A simple, mild, and practical process for direct conversion of aldehydes to nitriles was developed feathering a wide substrate scope and great functional group tolerability (52 examples, over 90% yield in most cases) using inorganic reagents (NH2OH/Na2CO3/SO2F2) in DMSO. This method allows for transformations of readily available, inexpensive, and abundant aldehydes to highly valuable nitriles in a pot, atom, and step-economical manner without transition metals. This protocol will serve as a robust tool for the installation of cyano-moieties to complicated molecules.
- Fang, Wan-Yin,Qin, Hua-Li
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p. 5803 - 5812
(2019/05/14)
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- Ligand-Promoted Non-Directed C?H Cyanation of Arenes
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This article reports the first example of a 2-pyridone accelerated non-directed C?H cyanation with an arene as the limiting reagent. This protocol is compatible with a broad scope of arenes, including advanced intermediates, drug molecules, and natural products. A kinetic isotope experiment (kH/kD=4.40) indicates that the C?H bond cleavage is the rate-limiting step. Also, the reaction is readily scalable, further showcasing the synthetic utility of this method.
- Liu, Luo-Yan,Yeung, Kap-Sun,Yu, Jin-Quan
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supporting information
p. 2199 - 2202
(2019/01/24)
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- Pd-Catalyzed Cyanation of (Hetero)Aryl Halides by Using Biphosphine Ligands
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Tetraadamantylbiphosphine (TABP; L1), which showed superior activity in the palladium-catalyzed cyanation of 4-chloroanisole compared to standard phosphines, was synthesized as a new ligand. The generality of the new catalytic system was shown by the cyanation reaction of approximately 30 (hetero)aryl halides including hindered, electron-rich, and electron-poor aryl chlorides. These reactions constitute the first examples of using biphosphine ligands in Pd-catalyzed coupling reactions.
- Zhang, Shaoke,Neumann, Helfried,Beller, Matthias
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supporting information
p. 67 - 70
(2017/11/27)
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- Catalytic Cyanation Using CO2 and NH3
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Li and co-workers describe the catalytic cyanation of organic halides with CO2 and NH3. In the presence of Cu2O/DABCO as the catalyst, a variety of aromatic bromides and iodides were transformed to the desired nitrile products with broad functional-group tolerance. Both 13C- and/or 15N-labeled nitriles were obtained conveniently with appropriately isotope-labeled CO2 and NH3. Construction of functionalized chemical compounds from small molecules in a highly selective and efficient manner is crucial for sustainable development. The chemical-based manufacturing sector of the future should aim to produce chemicals from very simple and abundant resources, just as nature uses CO2 and N2 to generate sugars, amino acids, and so forth. In practice, however, the utilization of CO2 for the generation of industrial products, such as drugs and related intermediates, still remains a major challenge. Here, we describe the facile cyanide-free production of high-value nitriles with CO2 and NH3 as the sole sources of carbon and nitrogen, respectively. This practical and catalytic methodology provides a unique strategy for the utilization of small molecules for sustainable and cost-effective applications. Selective cyanation of aryl halides was achieved with CO2 and NH3 as the only sources of carbon and nitrogen, respectively. In the presence of Cu catalysts under low pressure (3 atm), a variety of aromatic iodides and bromides were transformed to the desired nitrile products without the use of toxic metal cyanides. Notably, olefins, esters, amides, alcohols, and amino groups were tolerated. Mechanistic studies suggest that Cu(III)-aryl insertion by isocyanate intermediates is involved. [13C,15N]-labeled nitriles were conveniently accessible from the respective isotope-labeled CO2 and NH3 via this methodology.
- Wang, Hua,Dong, Yanan,Zheng, Chaonan,Sandoval, Christian A.,Wang, Xue,Makha, Mohamed,Li, Yuehui
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supporting information
p. 2883 - 2893
(2019/01/05)
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- Selective aerobic oxidation of benzylic amines to aryl nitriles catalyzed by CuBr2/N-methyl imidazole
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A convenient and efficient copper-catalyzed aerobic oxidation of primary amines to aryl nitriles was described. Various benzylic and allylic amines were selectively oxidized to the corresponding nitriles in high yields using CuBr2/NMI as the catalyst and O2 as the oxidant. The oxidation reaction profiles monitored by 1H NMR disclosed the scenario of the reaction path as well as the role of the additives. The addition of NMI increased the rate of reaction and suppressed the hydrolysis and the deamination.
- Shen, Yifan,Zhou, Yu,Jiang, Lili,Ding, Guangni,Luo, Luo,Zhang, Zhaoguo,Xie, Xiaomin
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p. 4266 - 4271
(2018/07/06)
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- Ex situ generation of stoichiometric HCN and its application in the Pd-catalysed cyanation of aryl bromides: Evidence for a transmetallation step between two oxidative addition Pd-complexes
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A protocol for the Pd-catalysed cyanation of aryl bromides using near stoichiometric and gaseous hydrogen cyanide is reported for the first time. A two-chamber reactor was adopted for the safe liberation of ex situ generated HCN in a closed environment, which proved highly efficient in the Ni-catalysed hydrocyanation as the test reaction. Subsequently, this setup was exploited for converting a range of aryl and heteroaryl bromides (28 examples) directly into the corresponding benzonitriles in high yields, without the need for cyanide salts. Cyanation was achieved employing the Pd(0) precatalyst, P(tBu)3-Pd-G3 and a weak base, potassium acetate, in a dioxane-water solvent mixture. The methodology was also suitable for the synthesis of 13C-labelled benzonitriles with ex situ generated 13C-hydrogen cyanide. Stoichiometric studies with the metal complexes were undertaken to delineate the mechanism for this catalytic transformation. Treatment of Pd(P(tBu)3)2 with H13CN in THF provided two Pd-hydride complexes, (P(tBu)3)2Pd(H)(13CN), and [(P(tBu)3)Pd(H)]2Pd(13CN)4, both of which were isolated and characterised by NMR spectroscopy and X-ray crystal structure analysis. When the same reaction was performed in a THF : water mixture in the presence of KOAc, only (P(tBu)3)2Pd(H)(13CN) was formed. Subjection of this cyano hydride metal complex with the oxidative addition complex (P(tBu)3)Pd(Ph)(Br) in a 1 : 1 ratio in THF led to a transmetallation step with the formation of (P(tBu)3)2Pd(H)(Br) and 13C-benzonitrile from a reductive elimination step. These experiments suggest the possibility of a catalytic cycle involving initially the formation of two Pd(ii)-species from the oxidative addition of LnPd(0) into HCN and an aryl bromide followed by a transmetallation step to LnPd(Ar)(CN) and LnPd(H)(Br), which both reductively eliminate, the latter in the presence of KOAc, to generate the benzonitrile and LnPd(0).
- Kristensen, Steffan K.,Eikeland, Espen Z.,Taarning, Esben,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 8094 - 8105
(2017/11/27)
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- Copper-free Sandmeyer cyanation of arenediazonium o-benzenedisulfonimides
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Arene and heteroarenediazonium o-benzenedisulfonimides can be used as efficient reagents in Sandmeyer cyanation. This work reports such reactions carried out by us under very mild conditions using tetrabutyl ammonium cyanide as a safe cyanide source and, interestingly, without the need for a Cu catalyst. The reactions have given rise to aryl nitriles in good yields (25 examples, average yield 75%). A good amount of o-benzenedisulfonimide was recovered from each reaction and then reused to prepare other salts. Mechanistic insights have allowed us to highlight the fundamental role of the o-benzenedisulfonimide anion as an electron transfer agent.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 1437 - 1441
(2016/02/03)
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- Rhodium-Catalyzed Transnitrilation of Aryl Boronic Acids with Dimethylmalononitrile
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An efficient transnitrilation of aryl boronic acids with dimethylmalononitrile (DMMN) is described. This rhodium-catalyzed electrophilic cyanation presents a novel approach to prepare aryl nitriles by using a carbon-bound cyanating reagent which undergoes cross-coupling with the aryl boronic acid. The reaction expands the degree of functional-group compatibility exhibited by the transnitrilation of aryl Grignard and aryllithium reagents. A variety of aryl boronic acid derivatives and dialkylmalononitriles were amenable to the transnitrilation.
- Malapit, Christian A.,Reeves, Jonathan T.,Busacca, Carl A.,Howell, Amy R.,Senanayake, Chris H.
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supporting information
p. 326 - 330
(2016/01/25)
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- Acetonitrile as a cyanating reagent: Cu-catalyzed cyanation of arenes
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A novel approach to the Cu-catalyzed cyanation of simple arenes using acetonitrile as an attractive cyano source has been documented. The C-H functionalization of arenes without directing groups involves a sequential iodination/cyanation to give the desired aromatic nitriles in good yields. A highly efficient Cu/TEMPO system for acetonitrile C-CN bond cleavage has been discovered. TEMPO is used as a cheap oxidant and enables the reaction to be catalytic in copper. Moreover, TEMPOCH2CN 6 has been identified as the active cyanating agent and shows high reactivity for forming the -CN moiety.
- Zhu, Yamin,Zhao, Mengdi,Lu, Wenkui,Li, Linyi,Shen, Zengming
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supporting information
p. 2602 - 2605
(2015/06/16)
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- Electroorganic synthesis of nitriles via a halogen-free domino oxidation-reduction sequence
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A direct electroorganic sequence yielding nitriles from oximes in undivided cells is reported. Despite the fact that intermediate nitrile oxides might be formed, the method is viable to prepare benzonitriles without substituents ortho to the aldoxime moiety. This constant current method is easy to perform for a broad scope of substrates and employs common electrodes, such as graphite and lead.
- Hartmer, Marius F.,Waldvogel, Siegfried R.
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supporting information
p. 16346 - 16348
(2015/11/16)
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- Efficient cyanation of aryl halide with K4[Fe(CN) 6]·3H2O catalyzed by a P-O bidentate chelate palladium complex under air
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Cyanation of aryl halide with K4[Fe(CN)6] ·3H2O has been carried out in the presence of a high-activity catalyst: an air-stable P-O bidentate chelate palladium complex. This method is applicable to both activated and deactivated aryl halides, and even a variety of aromatic nitriles are obtained in good yields under aerobic conditions. Copyright
- Fu, Leiqing,Li, Xiaogang,Zhu, Qiming,Chen, Sanbao,Kang, Yanping,Guo, Mengping
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p. 699 - 701
(2014/10/15)
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- A general, practical palladium-catalyzed cyanation of (hetero)aryl chlorides and bromides
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Playing it safe: The nontoxic cyanide source K4[Fe(CN) 6]×3 H2O can be used for the cyanation of (hetero)aryl halides. The application of palladacycle catalysts prevents poisoning during catalyst formation, thereby allowing for low catalyst loadings, fast reaction times, and wide heterocyclic substrate scope.
- Senecal, Todd D.,Shu, Wei,Buchwald, Stephen L.
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supporting information
p. 10035 - 10039
(2013/10/01)
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- Cu2O-mediated room temperature cyanation of aryl boronic acids/esters and TMSCN
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A method for the efficient and reliable synthesis of aryl nitriles via the Cu2O-catalyed cross-coupling of aryl boronic acids or esters and TMSCN is presented. A broad range of substrates decorated by electron-rich and deficient, sterically very congested, and labile functionalities were tolerated. Moreover, the reaction can proceed under mild conditions at room temperature. These advantages paired with the use of cheap, readily available, and halogen-free Cu2O as catalysts make the protocol an appealing option for aryl cyanations. A method for the efficient and reliable synthesis of aryl nitriles via the Cu2O-catalyed cross-coupling of aryl boronic acids or esters and TMSCN is presented. The room temperature operation paired with the use of cheap, readily available, and halogen-free Cu2O as catalysts makes the protocol an appealing option for aryl cyanations. Copyright
- Ye, Yong,Wang, Yanhua,Liu, Pengtang,Han, Fushe
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supporting information
p. 27 - 30
(2013/08/24)
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- Ethyl cyanoacetate: A new cyanating agent for the palladium-catalyzed cyanation of aryl halides
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A new Pd-catalyzed cyanation reaction has been discovered using ethyl cyanoacetate as the cyanating reagent. A variety of electron-rich and electron-deficient aryl halides were efficiently converted into their corresponding nitriles in good to excellent yields.
- Zheng, Shuyan,Yu, Chunhui,Shen, Zhengwu
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supporting information; experimental part
p. 3644 - 3647
(2012/08/28)
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- A mild and efficient palladium-catalyzed cyanation of aryl chlorides with K4[Fe(CN)6]
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An efficient palladium-catalyzed cyanation of aryl chlorides is established. In the presence of a highly effective Pd/CM-phos catalyst, cyanation of aryl chlorides proceeds at 70 °C in general, which is the mildest reaction temperature achieved so far for this process. Common functional groups such as keto, aldehyde, ester, nitrile and-NH2, and heterocyclic coupling partners including N-H indoles are well tolerated. Moreover, a sterically hindered nonactivated ortho,ortho-disubstituted electrophile is shown to be a feasible coupling partner in cyanation.
- Yeung, Pui Yee,So, Chau Ming,Lau, Chak Po,Kwong, Fuk Yee
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supporting information; experimental part
p. 648 - 651
(2011/04/15)
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- One-pot conversion of aromatic bromides and aromatics into aromatic nitriles via aryllithiums and their DMF adduct
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Various aromatic bromides and iodides were smoothly converted into the corresponding aromatic nitriles in good to moderate yields by the treatment with n-butyllithium and subsequently DMF, followed by treatment with molecular iodine in aq NH3. The same treatment of typical aromatics and heteroaromatics with n-butyllithium and subsequently DMF, followed by treatment with molecular iodine in aq NH3 also provided the corresponding aromatic nitriles in good yields. Moreover, the same treatment of aromatic bromides and aromatics with half amount of DIH (1,3-diiodo-5,5- dimethylhydantoin) instead of molecular iodine worked effectively to give the corresponding aromatic nitriles, respectively, in good yields. These reactions are novel and environmentally benign one-pot methods for the preparation of aromatic nitriles from aromatic bromides and aromatics, respectively, through the formation of aryllithiums and their DMF adducts.
- Ushijima, Sousuke,Moriyama, Katsuhiko,Togo, Hideo
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experimental part
p. 958 - 964
(2011/03/19)
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- Copper-catalyzed benzylic C-H oxygenation under an oxygen atmosphere via N-H imines as an intramolecular directing group
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Copper-catalyzed benzylic C-H oxygenation under an oxygen atmosphere was developed starting from carbonitriles and Grignard reagents via N-H imine intermediates. The present process is characterized by the following two-step sequence in a one-pot manner: (1) addition of Grignard reagents to carbonitriles to form N-H imines and (2) benzylic C-H oxygenation (C=O bond formation) triggered by 1,5-hydrogen atom transfer with transient iminyl copper species.
- Zhang, Line,Ang, Gim Yean,Chiba, Shunsuke
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supporting information; experimental part
p. 1622 - 1625
(2011/05/05)
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- One-pot conversion of aromatic bromides and aromatics into aromatic nitriles
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Various aromatic bromides and iodides were smoothly converted into the corresponding aromatic nitriles in good to moderate yields by the treatment with butyllithium and subsequently DMF, followed by treatment with molecular iodine in aqueous ammonia. The
- Ushijima, Sousuke,Togo, Hideo
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experimental part
p. 1562 - 1566
(2010/09/05)
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- Process for catalytically preparing aromatic or heteroaromatic nitriles
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The present invention relates to a process for preparing optionally substituted aromatic or heteroaromatic nitriles starting from haloaromatics. These are reacted in a copper-catalysed reaction with potassium hexacyanoferrate(II) or potassium hexacyanoferrate(III) in the presence of heteroaromatic amines.
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Page/Page column 3
(2009/04/24)
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- Increasing the scope of palladium-catalyzed cyanations of aryl chlorides
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An improved protocol for the palladium-catalyzed cyanation of electron-rich aryl chlorides with potassium ferrocyanide [K4[Fe(CN)6]] is presented. Compared to previous procedures the substrate scope is significantly broadened.
- Schareina, Thomas,Jackstell, Ralf,Schulz, Thomas,Zapf, Alexander,Cotte, Alain,Gotta, Matthias,Beller, Matthias
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experimental part
p. 643 - 648
(2009/11/30)
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- A bio-inspired copper catalyst system for practical catalytic cyanation of aryl bromides
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A general and environmentally improved protocol for the cyanation of aryl halides with the nontoxic cyanide source potassium hexacyanoferrate(II) {K 4[Fe(CN)6]} using copper catalysis and a ligand system based on 1-alkyl-1H-imidazoles is presented. The advantages of this system are a wide substrate range, high selectivity, easy handling, and inexpensive reagents.
- Schareina, Thomas,Zapf, Alexander,Cotte, Alain,Mueller, Nikolaus,Beller, Matthias
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experimental part
p. 3351 - 3355
(2009/06/06)
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- Process for catalytically preparing aromatic or heteroaromatic nitriles
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A process is described for catalytically preparing optionally substituted aromatic or heteroaromatic nitrites of the general formula (I) [in-line-formulae]Ar—CN ??(I)[/in-line-formulae] by reacting the corresponding aryl halides of the general formula (II) [in-line-formulae]Ar—X ??(II)[/in-line-formulae] in which X is chlorine, bromine, iodine, triflate, nonaflate, mesylate or tosylate andAr is an optionally substituted aromatic or heteroaromatic radical, characterized in that the reaction is performed in the presence of a palladium compound, a phosphine of the general formula (III) or (IV) where R is an alkyl radical andR′, R″ and R′″ are each an alkyl radical or an aryl radical or heteroaryl radical andA is an alkylene or arylene radical, and potassium hexacyanoferrate(II) or potassium hexacyanoferrate(III), optionally in a solvent and optionally with addition of a base.
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Page/Page column 3-4
(2008/12/07)
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- A state-of-the-art cyanation of aryl bromides: A novel and versatile copper catalyst system inspired by nature
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A general protocol for the cyanation of aryl halides with the nontoxic cyanide source K4[Fe(CN)6] using copper catalysis and a ligand system based on 1-alkylimidazoles is presented. The advantages of this system are the high selectivity, a unique substrate range, easy handling, and inexpensive reagents.
- Schareina, Thomas,Zapf, Alexander,Maegerlein, Wolfgang,Mueller, Nikolaus,Beller, Matthias
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p. 6249 - 6254
(2008/02/13)
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- A new palladium catalyst system for the cyanation of aryl chlorides with K4[Fe(CN)6]
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The development of a novel Pd-catalyzed synthesis of (hetero)aromatic nitriles from the corresponding aryl chlorides and potassium hexacyanoferrate(II) is described. This novel protocol avoids the use of highly toxic alkali cyanides and proceeds in the presence of small amounts of palladium catalysts. High yields and selectivities of the corresponding aryl nitriles were achieved applying di(1-adamantyl)-1-butylphosphine (cataCXium A) as the ligand.
- Schareina, Thomas,Zapf, Alexander,M?gerlein, Wolfgang,Müller, Nikolaus,Beller, Matthias
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p. 1087 - 1090
(2008/01/27)
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- Cyanation of aryl chlorides with potassium hexacyanoferrate(II) catalyzed by cyclopalladated ferrocenylimine tricyclohexylphosphine complexes
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Cyanation of aryl chlorides with potassium hexacyanoferrate(II) catalyzed by cyclopalladated ferrocenylimine tricyclohexylphosphine complex has been described. This method is applicable to both activated and deactivated aryl chlorides. The corresponding aryl nitriles were isolated in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Cheng, Yi-Nan,Duan, Zheng,Li, Ting,Wu, Yangjie
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p. 543 - 546
(2007/10/03)
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- An environmentally benign procedure for the Cu-catalyzed cyanation of aryl bromides
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The development of a general Cu-catalyzed synthesis of (hetero)aromatic nitriles from the corresponding aryl bromides and potassium hexacyanoferrate(II) is described. This novel protocol avoids the use of highly toxic alkali cyanides and precious palladium catalysts. Best results were achieved applying Cu(BF4)2?6H2O (0.1 equiv) and N,N′-dimethyl ethylenediamine (DMEDA; 1.0 equiv) in N,N-dimethyl acetamide (DMAc).
- Schareina, Thomas,Zapf, Alexander,Beller, Matthias
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p. 2585 - 2588
(2007/10/03)
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- Potassium hexacyanoferrate(II) - A new cyanating agent for the palladium-catalyzed cyanation of aryl halides
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A new advantageous cyanating agent, potassium hexacyanoferrate(II), is described for the palladium-catalyzed cyanation of aryl halides. All cyanide ions on the iron(II) center can be transferred to the aryl halide using palladium(II) acetate and dppf as the catalyst. Under optimized reaction conditions good yields of benzonitriles and unprecedented catalyst productivities are observed.
- Schareina, Thomas,Zapf, Alexander,Beller, Matthias
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p. 1388 - 1389
(2007/10/03)
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- Rapid, Easy Cyanation of Aryl Bromides and Chlorides Using Nickel Salts in Conjunction with Microwave Promotion
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We report here a fast, easy, and efficient method for the preparation of aryl nitriles from aryl bromides and chlorides. The methodology for aryl bromides involves the use of either Ni(CN)2 or NaCN and NiBr 2. With aryl chlorides, a mix of NaCN and NiBr2 is used and the reaction proceeds via the in situ formation of the corresponding aryl bromide. The reaction can be performed in air and is complete within 10 min.
- Arvela, Riina K.,Leadbeater, Nicholas E.
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p. 9122 - 9125
(2007/10/03)
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- The Phototransposition in Acetonitrile and the Photoaddition of 2,2,2-Trifluoroethanol to the Six Isomers of Dimethylbenzonitrile
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The six dimethylbenzonitriles can be divided into two independent triads in their photochemical reactivity. The first triad is comprised of the 2,3-dimethyl, 3,4-dimethyl, and 2,6-dimethyl isomers (11-2,3, 11-3,4, and 11-2,6, respectively); the second triad is comprised of the 2,4-dimethyl, 2,5-dimethyl, and 3,5-dimethyl isomers (11-2,4, 11-2,5, and 11-3,5, respectively). In acetonitrile, phototransposition converts the members of one triad to other members of the same triad, although only 11-3,4 was reactive enough to have significant conversion approaching a steady-state composition. Irradiation in 2,2,2-trifluoroethanol (TFE) resulted in the formation of addition products, 6-cyano-X,Y-dimethylbicyclo[3.1.0]hex-3-en-2-yl 2,2,2,-trifluoroethyl ethers, but in significant yield only from 11-3,4 of the first triad and 11-2,4 of the second triad. The 11-3,4 isomer gave seven major regio- and stereoisomers; the 11-2,4 isomer gave three different regio- and stereoisomers. These addition products were all explained by formation of bicyclo[3.1.0]hex-3-en-1-yl cations resulting from protonation by TFE at C6 followed by nucleophilic trapping by TFE. From these and previous results on aromatic nitriles, a consistent mechanistic picture is obtained where the critical carbon in determining the products of the phototransposition and photoaddition reactions is the cyano substituted one.
- Howell, Nisa,Pincock, James A.,Stefanova, Roumiana
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p. 6173 - 6178
(2007/10/03)
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- Methyl Group Effect on the Proton Affinity of Methylated Acetophenones Studied by Two Mass Spectrometric Techniques
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The proton affinities (PA) of all isomeric dimethylacetophenones were determined using the "kinetic method" with a tandem mass spectrometer and by measurements of the proton transfer equilibrium in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry.For both methods acetophenone and p-methylacetophenone, with well known PA values, were used as reference bases.Both methods yielded identical PA values for all dimethylacetophenones.The PA of the dimethylacetophenones were in a narrow range between 872 and 880 kJ mol-1 except for 2,6-dimethylacetophenone, for which a PA of 856 kJ mol-1 was found.The results are discussed in terms of possible mesomeric structures stabilizing the positive charge with regard to the substitution pattern in the phenyl ring.Obviously, the significant smaller PA of 2,6-dimethylacetophenone compared with the other isomers is due to the distortion of the conjugation of the C-O double bond with the aromatic ? system.
- Kukol, A.,Strehle, F.,Thielking, G.,Gruetzmacher, H.-Fr.
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p. 1107 - 1110
(2007/10/02)
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- Nickel(0) or Palladium(0)-catalyzed Cyanation of Aryl Triflates
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Aryl triflates readily participated in a nickel(0) or palladium(0)-catalyzed nucleophilic displacement with cyanide anion, thereby providing a new convenient method for the preparation of aryl cyanides.
- Takagi, Kentaro,Sakakibara, Yasumasa
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p. 1957 - 1958
(2007/10/02)
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- Aqeous and Nonaqueous Polarographic Studies of Substituted 2,6-Dimethylbenzonitrile N-Oxides1)
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Aqueous and nonaqueous polarographic properties of 4-substituted 2,6-dimethylbenzonitrile N-oxides (stable nitrile N-oxides) have been studied and compared with those of the substituted pyridine N-oxides and benzylidenemethylamine N-oxides (nitrones) investigated previously by us.The first reduction wave in both the aqueous and N,N-dimethylformamide (DMF) solvent systems is due to the deoxygenation reaction of the nitrile N-oxide group except when certain substituents are present (see text).This conclusion has also been verified by controlled potential electrolysis in aqueous solution and by cyclic voltammetry in DMF solvent.A plot of the Hammett ? constants of the substituents against E1/2 values was linear with a positive slope for both the aqueous and DMF solvent systems.The slope is smaller than in the case of pyridine N-oxides and nitrones, this being reasonably attributable to the triple bond nature of the CNO group.Half-wave reduction potentials of the nitrile N-oxides are positively shifted compared with those of pyridine N-oxides, particularly in an aqueous solvent.Molecular orbital calculations were applied to interpret the substituent effect on the reduction potentials of the N-oxides. Keywords --- aqueous polarography; nonaqueous polarography; substituent effect on half-wave potential; cyclic voltammetry; controlled potential electrolysis; PPP-SCFMO; CNDO/2; LUMO energy; 4-substituted 2,6-dimethylbenzonitrile N-oxide
- Kubota, Tanekazu,Hiramatsu, Sadaaki,Kano, Kenji,Uno, Bunji,Miyazaki, Hiroshi
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p. 3830 - 3839
(2007/10/02)
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- Unconjugated Arylcyclopropanes. Acid-Catalyzed Addition of Acetic Acid to Highly Hindered Arylcyclopropanes
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The adduct of 1-naphthylcarbene and norbornene, endo-3-(1-naphthyl)-exo-tricyclo2,4>octane (9) has been prepared. 1H and 13C NMR spectra of this system indicate that the unconjugated arylcyclopropane conformation is favored.Rotation about the naphthyl-cyclopropane bond is restricted.The temperature-dependent NMR indicates a 16.9 kcal/mol barrier to attainment of the conjugated conformation.Acetic acid adds readily under acid catalysis to the phenyl analogue exo-3-phenyl-exo-tricyclo2,4>octane (3) and more slowly to the more strained endo-3-phenyl-exo-tricyclo2,4>octane (4).Kinetic data suggest the involvement of a cationic intermediate with little transition-state charge development at the benzylic carbon.The rates of addition to substituted analogues of 3 and 4 correlate with Hammett ? values, giving ρ values of 2.53 and 2.35, respectively.Product-analysis data support the involvement of a benzylic cation, 23.The slower rate of reaction of the more strained endo isomers has been interpreted in terms of a barrier to attainment of the conjugated conformation which appears to be the favorable conformation for protonation of arylcyclopropanes.This suggestion is supported by the observation that the unconjugated systems, exo- and endo-3-(2,6-dimethylphenyl)-exo-tricyclo-2,4>octanes (27 and 28), add acetic acid 480 and 6.2 x 104 times, respectively, more slowly than 3.
- Creary, Xavier
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p. 4653 - 4659
(2007/10/02)
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