共查询到20条相似文献,搜索用时 0 毫秒
1.
In situ formation of a [Pd(OAc)2bipy] (bipy = 2,2′-bipyridyl) complex in water selectively catalyses the hydration of a wide range of organonitriles at 70 °C. Catalyst loadings of 5 mol% afford primary amide products in excellent yields in the absence of hydration-promoting additives such as oximes and hydroxylamines. 相似文献
2.
New homogeneous catalysts for the hydration of nitriles to amides are described. The catalyst precursors are coordination compounds of Pt(II) with secondary phosphine oxides. They contain a hydrogen bridged mono-anionic didentate phosphinito group, together with a third phosphine oxide ligand and a monodentate anionic ligand, either hydride or chloride. Reacting the chloride with silver ion, or the hydride with water gives a cationic species which is the active catalyst. On coordination to the cation the nitrile becomes susceptible to nucleophilic attack. The hydrolysis gives the amide as the sole product, and there is no tendency towards further hydrolysis to the acid. The effects of substituents on phosphorus are investigated, and a reaction mechanism is suggested. The most active catalyst, [PtH(PMe2OH)(PMe2O)2H], 2a, is derived from dimethylphosphine oxide, and this precursor catalyses the hydration of acrylonitrile to acrylamide with a turnover number of 77,000, without addition to the C=C double bond. 相似文献
3.
Baowei Zhao 《Tetrahedron letters》2006,47(38):6765-6768
The addition of arylboronic acid to nitriles catalyzed by palladium(II) species in the presence of bipyridine as the ligand was developed. The use of bipyridine is crucial for changing the properties of arylpalladium species from more electrophilic to more nucleophilic making the reaction possible. 相似文献
4.
《Journal of Coordination Chemistry》2012,65(14):2444-2454
A 3D copper phosphate, [Cu2(PO4)(OH)] n (1), has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction analysis. In [Cu2(PO4)(OH)] n , there are two types of copper centers having distorted trigonal bipyramidal geometry and distorted octahedral geometry that are connected by the μ2-bridging of each phosphate oxygen ultimately forming a η8-PO4 bridged 3D network. The compound exhibited excellent catalytic performance in olefin epoxidation. Epoxidation of styrene and substituted styrenes, as well as bulky olefins like cycloalkenes and long-chain alkenes, is efficiently catalyzed by [Cu2(PO4)(OH)] n using tert-butylhydroperoxide in acetonitrile. The results obtained in the heterogeneous catalytic reactions show that the olefins are converted to the respective epoxides in good yield with high selectivity. [Cu2(PO4)(OH)] n was catalytically more active and selective in comparison to simple copper(II) phosphate salt in heterogeneous medium. The catalyst can be recycled and reused several times without significant loss of activity. 相似文献
5.
A simple and efficient synthesis of amides by selective hydration of aromatic and aliphatic nitriles is described. The catalysts are prepared in situ from easily available Ru-precursors and ligands using water as the solvent. The most active catalyst, is obtained from [RuCl2(dmso)4] and benzylated 1,3,5-triaza-7-phosphaadamantane. Of the 16 substrates examined, 92–99% conversions of 14 nitriles were achieved in one hour at reflux temperature. 相似文献
6.
Narasimha Swamy Thirukovela Ramesh Balaboina Shravankumar Kankala Ravindhar Vadde Chandra Sekhar Vasam 《Tetrahedron》2019,75(18):2637-2641
A first example of silver(I) N-heterocyclic carbene (Ag(I)-NHC) catalyzed on-water synthesis of primary amides by hydration of nitriles under mild reaction conditions is described. This organometallic catalytic system has excellent tolerance for various homo-aromatic, hetero-aromatic and aliphatic nitriles to afford primary amides in good yields in neat water. 相似文献
7.
《Comptes Rendus Chimie》2014,17(4):316-323
Homocoupling of terminal alkynes to 1,3-diynes has been investigated with Cu(II)-modified clay under mild and operationally simple conditions without the use of any ligand or a stabilizing agent. The catalyst is robust, ecofriendly, efficient, furnishes good to excellent yields of the desired products and can be reused several times with negligible loss in catalytic activity. 相似文献
8.
Pd/Al2O3 catalysts modified by cerium or lanthanum promoters are tested for hydrocarbon conversion: methylcyclopentane (MCP) hydrogenolysis, 2-methylpentane (2MP) isomerization and 3-methylhexane (3MH) hydrocracking, deshydrocyclization and aromatization. The following parameters are reviewed: (i) precursor salt of palladium (chloride or nitrate), (ii) rare earth nature (La or Ce), (iii) rare earth content within the range 0–100% and (iv) impregnation mode (coimpregnation or successive impregnations). The influence of chloride coming from the precursor salt of palladium on the catalytic behaviour is strongly underlined. Chlorine anions are trapped by rare earth cations at the interface, as evidenced in a subsequent paper dealing with characterization studies of these same catalysts (K. Kili, L. Hilaire, F. Le Normand, submitted). Although the reactions readily occur on metallic sites, as evidenced by 13C labelled experiments, the addition of rare earth increases the activity and modifies the selectivity, especially for 2MP isomerization. These changes are rationalized in terms of significant modification of the kinetic surface parameters (competitive hydrogen and hydrocarbon coverages). This is explained by (i) lowering of the hydrogen coverage of the palladium sites accompanying surface diffusion on the interface with the support and (ii) creation of new selective sites at the transition metal–rare earth interface. The other parameters investigated yield only minor changes of the catalytic behaviour. 相似文献
9.
Daiki Monguchi Daisuke Hashizume Mikiko Sodeoka 《Journal of organometallic chemistry》2008,693(5):867-873
We describe herein the catalytic asymmetric conjugate reduction of α,β-unsaturated carbonyl compounds using a novel cationic Pd-iPr-DUPHOS complex. In this reaction, EtOH worked well as a solvent and a reducing agent, and the reaction was completed within several hours in most cases to afford the reduced compounds almost quantitatively with modest to good enantioselectivity (up to 72% ee). It was found that the Pd-iPr-DUPHOS complex was more reactive than the previously reported Pd-BINAP complex when molecular sieves 4A was added as an additive. Based on an X-ray structural analysis of [Pd{(S,S)-iPr-duphos}](OTf)2 complex, a working hypothesis of the reaction mechanism is also described. 相似文献
10.
Biswanath Das Parigi Raghavendar ReddyChithaluri Sudhakar Maram Lingaiah 《Tetrahedron letters》2011,52(27):3521-3522
Silica supported perchloric acid has been utilized as an efficient heterogeneous recyclable catalyst for N-alkylation of amides (sulfonamides and carboxamides) using alcohols (primary and secondary aliphatic as well as benzylic). The products are formed in high yields within 2-3 h. 相似文献
11.
Mohammad Navid Soltani Rad Ali Khalafi-Nezhad Mohammad Ali Faghihi 《Tetrahedron letters》2007,48(38):6779-6784
A convenient and efficient one-pot preparation of nitriles from alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, treatment of alcohols with a mixture of NaCN, TsIm and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in refluxing DMF furnishes the corresponding alkyl nitriles in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°. 相似文献
12.
Patrik Nilsson 《Journal of organometallic chemistry》2005,690(18):4197-4202
An investigation of the kinetics of the Heck reaction between 4-iodoanisole and styrene catalysed by {cis-1,3-bis[(di-tert-butylphosphino)methyl]-cyclohexane} palladium (II) iodide (1) has been performed in DMF-d7 solution. Based on mercury poisoning experiments a heterogeneous palladium catalyst formed from the pre-catalyst is proposed. Saturation behaviour with respect to the olefin concentration suggests a mechanism consisting of a pre-equilibrium association of the olefin followed by a rate determining reaction with aryl halide. The equilibrium constant for the olefin association, K1, and the rate constant for the subsequent oxidative addition step, k2, were determined to (5.7 ± 2.5) × 10−3 and 18.4 ± 2.7 M−1 s−1, respectively. 相似文献
13.
Convenient and efficient methods for the preparation of novel 6-amido and 6-phenylsulfanylimidazo[1,2-a]pyridine derivatives that utilize copper-catalyzed methodologies are reported. These methods are particularly noteworthy because of their experimental simplicity and the low cost of the catalyst system. 相似文献
14.
Sandra S. Pröckl 《Tetrahedron》2005,61(41):9855-9859
In situ generation of highly active palladium species by intermediate dissolution of Pd from solid supported catalysts has been demonstrated to be a very successful approach for the activation of aryl chlorides in Heck reactions. The new ‘heterogeneous’ Pd catalysts act as reservoir for molecular Pd species with unsaturated coordination sphere in solution. Crucial Pd leaching and re-deposition onto the support can be controlled by optimization of reaction conditions and by the properties of the catalysts. Pd is re-deposited onto the support at the end of the reaction. The catalysts, palladium supported on activated carbon, on various metal oxides or fluorides and Pd complexes in zeolites, are easy to prepare, though the preparation conditions are crucial. The catalysts convert all aryl bromides completely within minutes (TON 100,000). Aryl chlorides (even deactivated ones) are converted with high yields, within 2-6 h. The catalysts belong to the most active ones in Heck reactions at all (including best homogeneous systems) and fulfill all relevant requirements for practical applications in laboratory and industry. 相似文献
15.
Linda Axelsson Jean-Baptiste VeronJonas Sävmarker Jonas LindhLuke R. Odell Mats Larhed 《Tetrahedron letters》2014
A palladium(II)-catalyzed decarboxylative protocol for the synthesis of aryl ketones has been developed. The addition of TFA was shown to improve the reaction yield and employing THF as solvent enabled the use of solid nitriles and in only a small excess. Using this method, five different benzoic acids reacted with a wide range of nitriles to produce 29 diverse (hetero)aryl ketone derivatives in up to 94% yield. 相似文献
16.
Tertiary, secondary, and benzylic alcohols react efficiently with nitriles in the presence of the catalyst calcium hydrogen sulfate, Ca(HSO4)2, to produce amides in high yields. In this study, a modified Ritter reaction using this solid acid catalyst is found to be an environmentally safe method for converting 2,6-bis(hydroxymethyl)-4-halo anisole into the corresponding diamides in CH3CN. 相似文献
17.
Kalicharan Chattopadhyay 《Tetrahedron letters》2009,50(26):3164-957
Palladium nanoparticles supported on different shapes of nanocrystalline CuO are prepared by the treatment of Cu(NO3)2 and Pd(OAc)2 in polyethylene glycol (PEG-6000). The shapes of the CuO/Pd composite are dependent on the amount of PEG used. Suzuki coupling was catalyzed efficiently by the oval-shaped material, whereas the rod shape facilitates the cyanation reaction. The CuO/Pd catalyst is recovered and reused for subsequent Suzuki reactions; however, cyanation poisons the catalyst for further use. Both these reactions are very clean and high yielding. 相似文献
18.
2-Aminobenzyl alcohol reacts with an array of ketones in dioxane at 100 °C in the presence of a catalytic amount of CuCl2 along with KOH under O2 atmosphere to afford the corresponding quinolines in good yields. 2-Aminobenzyl alcohol is also oxidatively coupled and cyclized with various aldehydes by step-by-step procedure, an initial treatment of 2-aminobenzyl alcohol in the presence of CuCl2 and KOH in dioxane under O2 atmosphere and subsequent addition of aldehyde to the mixture followed by stirring under argon atmosphere, to give 3-substituted quinolines in moderate to good yields. 相似文献
19.
20.
Bianca Antonioli David J. Bray Jack K. Clegg Kerstin Gloe Karsten Gloe Anne Jäger Katrina A. Jolliffe Olga Kataeva Leonard F. Lindoy Peter J. Steel Christopher J. Sumby Marco Wenzel 《Polyhedron》2008
Interaction of copper(II) salts with 2,2′-dipyridylamine (1), N-cyclohexylmethyl-2,2′-dipyridylamine (2), di-2-pyridylaminomethylbenzene (3), 1,2-bis(di-2-pyridylaminomethyl)-benzene (4), 1,3-bis(di-2-pyridylaminomethyl)benzene (5), 1,4-bis(di-2-pyridylaminomethyl)benzene (6), 1,3,5-tris(di-2-pyridylaminomethyl)benzene (7) and 1,2,4,5-tetrakis(di-2-pyridylaminomethyl)benzene (8) has yielded the following complexes: [Cu(2)(μ-Cl)Cl]2, [Cu(3)(μ-Cl)Cl]2 · H2O, [Cu2(4)(NO3)4], [Cu2(5)(NO3)4] · 2CH3OH, [Cu2(6)(CH3OH)2(NO3)4], [Cu4(8)](NO3)4] · 4H2O while complexation of palladium(II) with 1, 4, 5 and 6 gave [Pd(1)2](PF6)2 · 2CH3OH, [Pd2(4)Cl4], [Pd2(4)(OAc)4], [Pd2(5)Cl4], [Pd2(6)Cl4] and [Pd2(6)(OAc)4] · CH2Cl2, respectively. X-ray structures of [Cu(2)(μ-Cl)Cl]2, [Cu(3)(μ-Cl)Cl]2 · 2C2H5OH, [Cu2(6)(CH3OH)2(NO3)4], [Pd(1)2](PF6)2 · 2CH3OH, [Pd2(4)(OAc)4] · 4H2O and [Pd2(6)(OAc)4] · 2CH2Cl2 are reported. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a diverse range of coordination geometries and lattice arrangements, with the structures of [Pd2(4)(OAc)4] · 4H2O and [Pd2(6)(OAc)4] · 2CH2Cl2, incorporating the isomeric ligands 4 and 6, showing some common features. Liquid–liquid (H2O/CHCl3) extraction experiments involving copper(II) and 1–3, 5, 7and 8 show that the degree of extraction depends markedly on the number of dpa-subunits (and concomitant lipophilicity) of the ligand employed with the tetrakis-dpa derivative 8 acting as the most efficient extractant of the six ligand systems investigated. 相似文献