- Palladium salt and functional reduced graphene oxide complex: in situ preparation of a generally applicable catalyst for C-C coupling reactions
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A novel Pd catalyst was designed by affording Pd2+ salt on the surface of functional reduced graphene oxide (FRGO), providing a new cheap and stable in situ prepared palladium catalyst for C-C coupling reactions, including the Heck reaction, Suzuki reaction, C-H bond functionalization reactions of thiophenes, and terminal alkyne C-H activation and homocoupling.
- Wang, Sheng,Hu, Donghua,Hua, Wenwen,Gu, Jiangjiang,Zhang, Qiuhong,Jia, Xudong,Xi, Kai
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- NiFe2O4@SiO2@ZrO2/SO42-/Cu/Co nanoparticles: A novel, efficient, magnetically recyclable and bimetallic catalyst for Pd-free Suzuki, Heck and C-N cross-coupling reactions in aqueous media
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The novel heterogeneous bimetallic nanoparticles of Cu-Co were synthesized based on magnetic nanoparticles, and the magnetic nanocatalyst was characterized by XRD, FE-SEM, EDX mapping, BET, TEM, HRTEM, FTIR, TGA, and VSM. This catalyst was successfully applied as a recyclable magnetically catalyst in Heck, Suzuki, and C-N cross-coupling reactions with various aryl halides (iodides, bromides, and chlorides as challengeable substrates), with olefins, phenylboronic acid, and amines, respectively. We considered the rise of synergetic effects from the different Lewis acid and Br?nsted acid sites present in the catalyst. The catalyst was synthesized with cheap, available materials and a simple synthesis method. The catalyst can be separated easily using an external magnet. It was recycled for more than ten runs without a sensible loss of its catalytic activity, and no significant leaching of the Cu and Co quantity was observed. The significant benefits of the method are high-level generality, simple operation, and there are no heavy metals and toxic solvents. This is a quick, easy, efficacious and environmentally friendly protocol, and no by-products are formed in the reaction. These features make it an appropriate practical alternative protocol. In comparison with recent works, the other advantage of this catalyst is the synthesis of a wide variety of C-C and C-N bond derivatives (more than 40 derivatives). The other significant advantage is the low temperature of the reaction and the use of the least possible amount of the catalyst (0.003 g). The efficiency was good to excellent and the catalyst selectivity has been high. We aspire that our study inspires more interest to design novel catalysts based on using low-cost metal ions (such as cobalt and copper) in the cross-coupling reactions. This journal is
- Alavi G., Seyyedeh Ameneh,Nasseri, Mohammad Ali,Kazemnejadi, Milad,Allahresani, Ali,Hussainzadeh, Mahdi
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p. 7741 - 7757
(2021/05/13)
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- Structural Effect of Pincer Pd(II)–ONO Complexes Modified with Acylthiourea on Sizes of the In Situ Generated Pd Nanoparticles During Heck Coupling Reaction
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Abstract: The Pd nanoparticles generated in situ from Pd–pincer complexes catalyzed Heck coupling reaction. For this purpose, new Pd(II)–ONO pincer complexes (1–4) containing acylthiourea ancillary ligand were obtained by treating [Pd(ONO)(CH3CN)] with the respective N-substituted carbamothioyl benzamide ligand (L1–L4). Formation of these complexes was confirmed by UV–Visible, FT-IR, NMR and mass spectroscopic techniques. The sizes of in situ formed Pd nanoparticles were greatly affected by the substituent in ancillary ligand, which in turn influenced their catalytic activity towards Heck coupling reaction. The in situ formed Pd nanoparticles during Heck reaction were removed from the reaction medium and analyzed using HR-TEM to estimate the sizes of the Pd nanoparticles. Complex [Pd(ONO)((N-benzylcarbamothioyl)benzamide)] (1) which does not possess any substituent on the benzyl moiety of acylthiourea produced the smallest Pd nanoparticles with the average particle size of 3.7?nm. Hence, complex 1 showed the utmost catalytic activity. With complex 1, 51–99% of conversion was observed during Heck coupling reaction of styrene with various aryl halides. XPS results confirmed that the recovered black particles were Pd(0). A reasonable recyclability results were achieved by these in situ generated Pd nanoparticles. Graphic Abstract: [Figure not available: see fulltext.]
- Jerome,Babu, S. Ganesh,Karvembu
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p. 1633 - 1645
(2020/10/15)
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- Bimetallic Ni–Pd Synergism—Mixed Metal Catalysis of the Mizoroki-Heck Reaction and the Suzuki–Miyaura Coupling of Aryl Bromides
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Abstract: A combination of Pd and Ni complexes activated aryl bromides for the thermal Mizoroki-Heck reaction and Suzuki coupling giving high yields in short reaction times. A thermal redox mechanism probably occurs whereby Ni complex transfers electron and reduces the Pd (II) to Pd (0) which then takes the reactants through the standard protocol of oxidative-addition, migratory insertion and reductive elimination, typical for the Mizoroki-Heck reaction and the Suzuki coupling. Graphic Abstract: [Figure not available: see fulltext.]
- Kashid, Abhijit A.,Patil, Dharmaraj J.,Mali, Ramling D.,Patil, Vijay P.,Neethu,Meroliya, Heena K.,Waghmode, Shobha A.,Iyer, Suresh
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p. 353 - 358
(2020/08/05)
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- Catalytic activity of Pd dithiolate complexes with large-bite-angle diphosphines in Heck coupling reactions
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Palladium(II) complexes of aryl dithiolates and wide-bite-angle diphosphines Xantphos and dppf have been developed as efficient catalysts in Suzuki and Suzuki carbonylation reactions. The catalytic activity of these highly stable, discrete and charged complexes was investigated in Heck coupling reactions of styrene and a variety of aryl bromides. Under optimized reaction conditions these palladium complexes showed excellent activity with high turnover number (6 × 106) and high turnover frequency (4 × 105 h?1). The effect of bite angle of diphosphines on the catalytic activity of the complexes [Pd2(P∩P)2(SC12H8S)]2(OTf)4 followed the trend P∩P = Xantphos > dppf > dppe as the order of their bite angles. The catalyst could be reused, and after three cycles the formation of significant amount of Pd nanoparticles was noticed, which were characterized using powder X-ray diffraction, energy-dispersive X-ray analysis and transmission electron microscopy. The high catalytic activity has been attributed to the Pd nanoparticles.
- Mane, Pravin A.,Neogy, Suman,Dey, Sandip
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- Enantioselective Remote C(sp3)-H Cyanation via Dual Photoredox and Copper Catalysis
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The remote C(sp3)-H cyanation of carboxamides has been described by merging photoredox and copper catalysis in a site-selective and enantiocontrolled manner. The protocol is the integration of photoinduced and nitrogen-centered radical-mediated intermolecular hydrogen atom transfer with chiral copper-complex-catalyzed radical cyanation. This strategy gives enantio-enriched cyanated amides in high yields.
- Chen, Hui,Jin, Weiwei,Yu, Shouyun
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supporting information
p. 5910 - 5914
(2020/08/12)
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- Ligand-Free C–C Coupling Reactions Promoted by Hexagonal Boron Nitride-Supported Palladium(II) Catalyst in Water
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A micron-scale palladium(II) material has been successfully prepared using Schiff base-modified hexagonal boron nitride as a support and used for the first time as an efficient and recyclable catalyst in organic synthesis. The morphology, composition, metal loading and thermal stability of the catalyst were studied using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), inductively coupled plasma (ICP) and thermogravimetric (TG) analyses. Then, the micron material was tested in various C–C cross-coupling reactions and exhibited excellent catalytic activities in the Suzuki and Heck reactions. Moreover, the catalyst could be easily recovered by simple filtration and reused at least ten times without significant loss of its catalytic activity. In general, this work demonstrates the possibility of using Schiff-base@hexagonal boron nitride as an efficient support for heterogeneous catalysts. (Figure presented.).
- Cheng, Xu,Li, Weijian,Nie, Ruifang,Ma, Xiaojun,Sang, Rui,Guo, Li,Wu, Yong
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supporting information
p. 454 - 466
(2017/02/10)
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- Novel cyclodextrin-modified h-BN@Pd(II) nanomaterial: An efficient and recoverable catalyst for ligand-free C-C cross-coupling reactions in water
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An environmentally friendly palladium(II) catalyst supported on cyclodextrin-modified h-BN was successfully prepared. The catalyst was characterized by FT-IR, SEM, TG, XRD and XPS, and the loading level of Pd in h-BN@β-CD@Pd(II) was measured to be 0.088?mmol g?1 by ICP. It exhibits excellent catalytic activity for the Suzuki and Heck reactions in water, and can be easily separated and consecutively reused for at least nine times. In addition, a series of pharmacologically interesting products were successfully synthesized using this catalyst to demonstrate its potential applications in pharmaceutical industries. Above all, this work opens up an interesting and attractive avenue for the use of cyclodextrin-functionalized h-BN as an efficient support for hydrophilic heterogeneous catalysts.
- Ma, Xiaojun,Lv, Guanghui,Cheng, Xu,Li, Weijian,Sang, Rui,Zhang, Yong,Wang, Qiantao,Hai, Li,Wu, Yong
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- Palladium(II)-Schiff base complex immobilized covalently on h-BN: An efficient and recyclable catalyst for aqueous organic transformations
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A moisture- and air-stable palladium(II)-Schiff base complex supported on h-BN was simply prepared by using commercially available reagents. This nanomaterial was applied as an excellent and recyclable heterogeneous catalyst for the Suzuki and Heck cross-coupling reactions. And it has been characterized by FT-IR, XRD, SEM, XPS, TG and ICP-AES techniques. High yields, ligand-free, low reaction time, water as solvent, non-toxicity and recyclability of the catalyst are the main merits of these protocols. In addition, a series of pharmacologically relevant products were successfully synthesized using this catalyst. Above all, this work opens up an interesting and attractive avenue for the use of h-BN as an efficient support for heterogeneous catalysts.
- Li, Weijian,Lv, Guanghui,Cheng, Xu,Sang, Rui,Ma, Xiaojun,Zhang, Yong,Nie, Ruifang,Li, Jie,Guan, Mei,Wu, Yong
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supporting information
p. 8557 - 8564
(2016/12/07)
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- Ordered mesoporous SBA-15/PrSO3Pd and SBA-15/PrSO3PdNP as active, reusable and selective phosphine-free catalysts in C-X activation Heck coupling process
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The incorporation of sulfonate into mesoporous SBA-15 molecular sieves as ligands for palladium ions was used. Then SBA-15/PrSO3Pd and SBA-15/PrSO3PdNP were prepared and applied for the Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding cross-coupling products under phosphine-free aerobic conditions with good to excellent yields. These supported palladium pre-catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications.
- Rostamnia, Sadegh,Rahmani, Turaj
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p. 471 - 474
(2015/06/30)
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- In site preparation of Pd(II)-MoS2 complex: A new high-efficiency catalyst for alkenylation of heteroaromatics by direct C-H bond activation
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Pd(II)-MoS2 catalyst was designed by affording Pd2+ salt on the surface of single-layered molybdenum disulfide nanosheets.. Based on the dispersible template, this metal salt and molybdenum disulfide complex offered several advantages, including easy preparation, low cost, and capability to prepare excellent dispersible metal ion cluster nanostructures. The application of this complex in alkenylation of heteroaromatics was reported. Direct C-H activation of indoles, furans and thiophenes was carried out to combine with several kinds of terminal olefins. This catalyst also performed high efficiency in several other kinds of coupling reactions. Thus, a universal suitable catalyst for C-H activation and CC bond formation was invented by a convenient in situ preparation.
- Wang, Sheng,Deng, Guoqing,Gu, Jiangjiang,Hua, Wenwen,Jia, Xudong,Xi, Kai
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- Rh(III)-catalyzed olefination of N-sulfonyl imines: Synthesis of ortho -olefinated benzaldehydes
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Rh(III)-catalyzed olefination of N-sulfonyl imines using acrylates and styrenes has been achieved for the synthesis of ortho-olefinated benaldehydes. This reaction proceeds via a chelation assisted C-H olefination/in situ hydrolysis process.
- Zhang, Tao,Wu, Lamei,Li, Xingwei
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p. 6294 - 6297
(2014/01/17)
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- Application of a dimeric P,C-palladacycle complex as a catalyst in Suzuki and Heck cross-coupling reactions
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In this Letter the dimeric palladacycle [Pd(μ-C1)(P (OPh) 2(OC6H4)]2 containing a phosphorus donor atom is prepared and its catalytic activity was tested in the Suzuki reaction of phenylboronic acid at room temperature, and the Heck reaction of styrene at 130 °C with aryl halides of varying electron density. All reactions were monitored by GC and generally gave high yields of coupled products. Copyright
- Karami, Kazem,Ghasemi, Mahdiyeh,Naeini, Nasrin Haghighat
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p. 1352 - 1355
(2013/04/10)
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- A robust first-pass protocol for the heck-mizoroki reaction
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The Heck-Mizoroki (HM) reaction is one of the most widely used C-C bond-forming methods of contemporary synthesis. Notwithstanding this, these reactions frequently require significant optimization before efficient transformations can be obtained. We describe here the results of a study that aimed to establish a generic experimental protocol for HM reactions which enables acceptable yields from first-pass experiments. The methodology utilizes readily available stable catalysts and can be applied to a broad range of coupling partners.
- Murray, Paul M.,Bower, John F,Cox, David K,Galbraith, Ewan K,Parker, Jeremy S,Sweeney, Joseph B.
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p. 397 - 405
(2013/04/24)
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- Copper(ii) oxide on aluminosilicate mediated Heck coupling of styrene with aryl halides in water
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CuO/aluminosilicate has been found to be an efficient catalyst for the aqueous Heck coupling of styrene with aryl halides under ligand free conditions. The catalyst (CuO/aluminosilicate) was prepared from CuCl2· 6H2O, aluminium nitrate and tetraethyl orthosilicate (TEOS) and characterized by XRD, HR-TEM, SEM-EDX and XPS. The reaction conditions were optimized with different solvents, bases, catalyst amounts and temperatures using sytrene and 4-chlorobenzonitrile as a model system. The scope of the reaction was subsequently extended to include various substituted aryl halides. Regioselectivity, heterogeneity and reusability were performed.
- Babu, S. Ganesh,Neelakandeswari,Dharmaraj,Jackson, S. David,Karvembu
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p. 7774 - 7781
(2013/06/27)
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- Rhodium(III)-catalyzed oxidative C-H functionalization of azomethine ylides
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Put it on a ring: A rhodium(III) complex can catalyze the oxidative coupling of azomethine imines with olefins, leading to the synthesis of 1,2-dihydrophthalazines, olefinated aldehydes, or fused pyridines, depending on the conditions used. Copyright
- Zhen, Wencui,Wang, Fen,Zhao, Miao,Du, Zhengyin,Li, Xingwei
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supporting information
p. 11819 - 11823
(2013/01/15)
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- Ring-closure reactions of 1,2-diaza-4,5-benzoheptatrienyl metal compounds: Experiment and theory
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2-Alkenylbenzylidene hydrazones 5a-m, which are accessible in good to excellent yields in a four-step synthesis, are converted into 1,2-diaza-4,5-benzoheptatrienyl metal compounds 1a-m by treatment with KO-t-Bu as base. These metal compounds undergo the various types of reactions in good yields and exclusively depending on the nature of substituents R1 and R3. Thus, metal compounds 1a-c carrying alkyl substituents R 1 and R3 form 3H-benzodiazepines 6a-c after electrophilic quench of the intermediate cyclic anion 7 in a 7-endo-trig electrocyclic reaction with a moebius aromatic transition structure 1--TS. Similarly, a benzothienyl derivative 5n is converted into diazepine 6d. Potassium compounds 1d-h, which are N-methyl and aryl substituted at R 3, form 1,2-dihydrophthalazines 8a-e in a predominantly charge-controlled 6-exo-trig cyclization reaction. In contrast, aryl-aryl-substituted systems 5i-m did not lead to cyclic products upon deprotonation, but the intermediate open-chain metal compounds 1i-m were trapped by acid chlorides at N1 to yield the hydrazides 10a-e. We interpret thermodynamics and kinetics of these reactions in the context of the Baldwin rules on the basis of quantum chemical calculations and discuss the transition structures considering the results of NICS and NBO-charge calculations. Examples of the products 6, 8, and 10 could be characterized by X-ray diffraction.
- Kleine, Tillmann,Bergander, Klaus,Froehlich, Roland,Wibbeling, Birgit,Wuerthwein, Ernst-Ulrich
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scheme or table
p. 1979 - 1991
(2011/05/07)
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- Organostannoxane-supported Pd(0) nanoparticles as efficient catalysts for Heck-coupling reactions
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A new functional organostannoxane cage, SnP, that contains phosphine ligands in its periphery has been structurally utilized as support palladium(0) nanoparticles SnPPd. The latter was shown to catalyze the Heck coupling reactions of wide variety of functionalities efficiently.
- Chandrasekhar, Vadapalli,Narayanan, Ramakirushnan Suriya
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supporting information; experimental part
p. 3527 - 3531
(2011/06/27)
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- Substituent-dependent structures and catalysis of benzimidazole-tethered N-heterocyclic carbene complexes of Ag(i), Ni(ii) and Pd(ii)
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Homoleptic cationic benzimidazole-imidazolin-2-ylidene N-heterocyclic carbene (NHC = L) complexes of NiII and PdII have been prepared directly from the ligand precursor in salt form [H.L]Cl and from the transmetallation route via AgI. The N-tether of the imidazolinylidene ring imposes a significant influence on the nuclearity of the intermediate Ag(i)-NHC complexes and the geometric isomer outcome of the d8 products. Use of a benzyl-substituted NHC gives [Ag4(L Bn)2Cl4], 2a (from [HLBn]Cl, 1a, and Ag2O) (Bn = benzyl), which shows an alignment of four silver atoms bridged by the difunctional C-N ligands and chlorides. Its transmetallation with NiCl2(PPh3)4 and PdCl2(MeCN) 2 results in double-metal salts 2[M(LBn)2] 2+[Ag4Cl8]4- (M = Ni (3a) and Pd (4a)). The nuclearity of the Ag4 aggregate is maintained in the transmetallation process. Their Ag-free forms [M(LBn) 2]Cl2 (M = Ni (5) and Pd (6)) were prepared by direct deprotonation of 1a with M(OAc)2. The two carbenic carbon donor are cis- to each other in both 3a and 4a, thus imposing the weaker σ-benzimidazole nitrogen donor to be trans to them. A sterically demanding mesityl pendant however gives the dinuclear dissymmetic [Ag2(L Mes)2Cl2], 2b (Mes = mesityl) that shows a 12-membered metallomacrocyclic ring with a 2-coordinated [AgI(NHC) 2] and 4-coordinated [AgI(Imd)2Cl2] (Imd = imidazole). Transmetallation of the latter, or direct metallation from [HLMes]Cl, 1b, gives [M(LMes)2]Cl2 (M = Ni (3b) and Pd (4b)) with the two carbonic carbon trans to each other. The catalytic potential of 3b and 4b, which are more effective than 5 and 6, has been demonstrated by their high activities in Ni-catalyzed Kumada at room temperature and Pd-catalyzed Heck couplings of aryl and/or heteroaryl halides, respectively.
- Li, Fuwei,Hu, Jian Jin,Koh, Lip Lin,Hor, T. S. Andy
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experimental part
p. 5231 - 5241
(2010/08/04)
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- 1,7-electrocyclization reactions of 2-Aza-4,5-benzoheptatrienyl- and 4-Aza-6,7-benzononatetraenyllithium compounds: Synthesis of novel 2-benzazepines and (benzocyclooctenyl) amines
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Deprotonation reactions of N-benzyl- and N-allylimines 1 and 4 led to benzo-annulated 2-azaheptatrienyl- and 4- azanonatetraenyllithium compounds, which underwent 1,7- electrocyclization reactions to yield the novel 2,3-dihydro- 1/f-benzo[c]azepines 3, 5,
- Sajitz, Melanie,Froehlich, Roland,Wurthwein, Ernst-Ulrich
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experimental part
p. 2342 - 2353
(2009/09/05)
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- Size controlled synthesis of Pd nanoparticles in water and their catalytic application in C-C coupling reactions
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Catalytically active Pd nanoparticles have been synthesized in water by a novel reduction of Pd(II) with a Fischer carbene complex where polyethylene glycol (PEG) was used as stabilizer. PEG molecules wrap around the nanoparticles to impart stability and prevent agglomeration, yet leave enough surface area available on the nanoparticle for catalytic activity. Our method is superior to others in terms of rapid generation and stabilization of Pd nanoparticles in water with a cheap, readily available PEG stabilizer. The size of the nanoparticles generated can be controlled by the concentration of PEG in water medium. The size decreased with the increase in the PEG: Pd ratio. This aqueous nano-sized Pd is a highly efficient catalyst for Suzuki, Heck, Sonogashira, and Stille reaction. Water is used as the only solvent for the coupling reactions.
- Sawoo, Sudeshna,Srimani, Dipankar,Dutta, Piyali,Lahiri, Rima,Sarkar, Amitabha
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experimental part
p. 4367 - 4374
(2009/09/30)
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- Easy-separable magnetic nanoparticle-supported Pd catalysts: Kinetics, stability and catalyst re-use
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A series of novel palladium-based catalysts supported on magnetic nanoparticles with diameters of 7- 17 nm have been prepared and evaluated in C-C coupling, hydrogenation and amination reactions. One type of catalyst used palladium complexes containing phosphine and/or acetate ligands for applications in Suzuki and Heck reactions. The second type consisted of Pd(0)-functionalised magnetic cores for use in hydrogenation and C-C coupling. Each type was effective for a range of reactions and was easily recoverable from the reaction mixture due to the superparamagnetic behaviour of the support. Detailed rate studies, found to correspond to pseudo-first-order kinetics, were conducted to assist in determining the mechanism of the reactions and showed that, during Heck reactions, Pd leaching is critically dependent on the presence of the aryl halide. The catalysts were found to retain their activity for several cycles although the rate of reaction was markedly reduced on re-use. Crown Copyright
- Laska, Urszula,Frost, Christopher G.,Price, Gareth J.,Plucinski, Pawel K.
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experimental part
p. 318 - 328
(2011/05/07)
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- Photochemistry of chloro-2-vinylstilbenes
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Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds.Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol.At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclohex-2-ene (39) is formed formed from 20.The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41).The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38).However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo-hex-2-ene (40).This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule.It is shown that both isomers of 22 can photocyclize into 40.
- Brouw, P. M. op den,Laarhoven, W. H.
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