- REACTION OF NUCLEOBASES WITH α-ACETYLENIC ESTERS, POTENTIALLY USEFULL FOR CHEMICAL MODIFICATION OF NUCLEIC ACIDS
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The NH2 group and the adjacent ring nitrogen of adenosine and cytidine react with α-acetylenic esters by addition across the triple bond and formation of a lactam with the ester group.
- Olomucki, M.,Gall, J. Y., Le,Colinart, S.,Durant, F.,Norberg, B.,Evrard, G.
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Read Online
- Trisannelation of acrylates to 1,3,5-benzenetricarboxylates by a Pd(OAc)2/HPMoV/CeCl3/O2 system
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(Chemical Equation Presented) A new type of trisannelation reaction of acrylates through acetal formation was developed by Pd(OAc)2 combined with molybdovanadophosphoric acid (HPMo8V4) and Lewis acid under atmospheric diox
- Tamaso, Ken-Ichi,Hatamoto, Yuji,Sakaguchi, Satoshi,Obora, Yasushi,Ishii, Yasutaka
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Read Online
- Understanding the Incorporation and Release of Salicylic Acid in Metal-Organic Frameworks for Topical Administration
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Although metal-organic frameworks (MOFs) have been widely demonstrated to be great candidates for drug delivery applications, they have been mainly proposed for the intravenous route. Here, eight highly porous benchmarked MOFs, with different topologies a
- Rojas, Sara,Horcajada, Patricia
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Read Online
- Iron-catalyzed trimerization of terminal alkynes enabled by pyrimidinediimine ligands: A regioselective method for the synthesis of 1,3,5-substituted arenes
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The development of pyrimidine-based analogues of the well-known pyridinediimine (PDI) iron complexes enables access to a functional-group-tolerant methodology for the catalytic trimerization of terminal aliphatic alkynes. Remarkably, in contrast to established alkyne trimerization protocols, the 1,3,5-substituted arenes are the main reaction products. Preliminary mechanistic investigations suggest that the enhanced π-acidity of the pyrimidine ring, combined with the hemilability of the imine groups coordinated to the iron center, facilitates this transformation. The entry point in the catalytic cycle is an isolable iron dinitrogen complex. The catalytic reaction proceeds via a 1,3-substituted metallacycle, which explains the observed 1,3,5-regioselectivity. Such a metallacycle could be isolated and represents a rare 1,3-substituted ferracycle obtained through alkyne cycloaddition.
- Doll, Julianna S.,Eichelmann, Robert,Hertwig, Leif E.,Bender, Thilo,Kohler, Vincenz J.,Bill, Eckhard,Wadepohl, Hubert,Ro?ca, Drago?-Adrian
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p. 5593 - 5600
(2021/05/31)
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- Cyclotrimerization of alkynes catalyzed by a self-supported cyclic tri-nuclear nickel(0) complex with α-diimine ligands
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A cyclic tri-nuclear α-diimine nickel(0) complex [{Ni(μ-LMe-2,4)}3] (2) was synthesized from a “pre-organized”, trimerized trigonal LNiBr2-type precursor [Ni3(μ2-Br)3(μ3-Br)2(LMe-2,4)3]·Br (1; LMe-2,4 = [(2,4-Me2C6H3)NC(Me)]2). In complex 2, the α-diimine ligands not only exhibit the normal N,N′-chelating mode, but they also act as bridges between the Ni atoms through an unusual π-coordination of a C═N bond to Ni. Complex 2 is able to catalyze the cyclotrimerization of alkynes to form substituted benzenes in good yield and regio-selectivity for the 1,3,5-isomers, which is found to vary with the nature of the alkyne employed. This complex represents a convenient self-supported nickel(0) catalyst with no need for additional ligands and reducing agent.
- Shen, Lingyi,Zhao, Yanxia,Luo, Qiong,Li, Qian-Shu,Liu, Bin,Redshaw, Carl,Wu, Biao,Yang, Xiao-Juan
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supporting information
p. 4643 - 4649
(2019/04/05)
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- Enhanced Catalytic Activity of Nickel Complexes of an Adaptive Diphosphine-Benzophenone Ligand in Alkyne Cyclotrimerization
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Adaptive ligands, which can adapt their coordination mode to the electronic structure of various catalytic intermediates, offer the potential to develop improved homogeneous catalysts in terms of activity and selectivity. 2,2′-Diphosphinobenzophenones have previously been shown to act as adaptive ligands, the central ketone moiety preferentially coordinating reduced metal centers. Herein, the utility of this scaffold in nickel-catalyzed alkyne cyclotrimerization is investigated. The complex [(p-tolL1)Ni(BPI)] (p-tolL1 = 2,2′-bis(di(para-tolyl)phosphino)-benzophenone; BPI = benzophenone imine) is an active catalyst in the [2 + 2 + 2] cyclotrimerization of terminal alkynes, selectively affording 1,2,4-substituted benzenes from terminal alkynes. In particular, this catalyst outperforms closely related bi- and tridentate phosphine-based Ni catalysts. This suggests a reaction pathway involving a hemilabile interaction of the C-O unit with the nickel center. This is further borne out by a comparative study of the observed resting states and DFT calculations.
- Orsino, Alessio F.,Gutiérrez Del Campo, Manuel,Lutz, Martin,Moret, Marc-Etienne
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p. 2458 - 2481
(2019/03/08)
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- Silica Gel as a Promoter of Sequential Aza-Michael/Michael Reactions of Amines and Propiolic Esters: Solvent- and Metal-Free Synthesis of Polyfunctionalized Conjugated Dienes
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We present an efficient, simple, metal- and solvent-free silica-gel-promoted synthesis of functionalized conjugated dienes by sequential aza-Michael/Michael reactions by starting from commercially available primary amines and propiolic esters. The scope a
- Aleksi?, Jovana,Stojanovi?, Milovan,Baranac-Stojanovi?, Marija
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p. 1811 - 1835
(2018/07/29)
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- Cyclotrimerization of phenylacetylene catalyzed by a cobalt half-sandwich complex embedded in an engineered variant of transmembrane protein FhuA
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An (η5-cyclopentadienyl)cobalt(i) complex was covalently incorporated into an engineered variant of the transmembrane protein ferric hydroxamate uptake protein component: A, FhuA ΔCVFtev, using a thiol-ene reaction. A CD spectrum shows the structural integrity of the biohybrid catalyst. MALDI-TOF of the segment containing the anchoring site for the cobalt complex Cys545 confirmed successful conjugation. This biohybrid catalyst catalyzed the cyclotrimerization of phenylacetylene to give a mixture of regioisomeric 1,2,4- and 1,3,5-triphenylbenzene in aqueous medium.
- Thiel,Sauer,Mertens,Polen,Chen,Schwaneberg,Okuda
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supporting information
p. 5452 - 5456
(2018/08/12)
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- Reactions of dicobalt octacarbonyl with dinucleating and mononucleating bis(imino)pyridine ligands
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This work focuses on the application of dicobalt octacarbonyl (Co2(CO)8) as a metal precursor in the chemistry of formally low-valent cobalt with redox-active bis(imino)pyridine [NNN] ligands. The reactions of both mononucleating mes
- Hollingsworth, Ryan L.,Beattie, Jeffrey W.,Grass, Amanda,Martin, Philip D.,Groysman, Stanislav,Lord, Richard L.
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p. 15353 - 15363
(2018/11/20)
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- Graphene Oxide: An Efficient Acid Catalyst for the Construction of Esters from Acids and Alcohols
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Graphene oxide was found to be an efficient and reusable acid catalyst for the esterification reaction. A wide range of aliphatic and aromatic acids and alcohols were compatible with the standard conditions and afforded the corresponding products in good yields. The heterogeneous catalyst can be easily recovered and recycled in dichloro-ethane solvent with good catalytic activity.
- Chen, Zhengwang,Wen, Yuelu,Fu, Yejuan,Chen, Hai,Ye, Min,Luo, Guotian
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supporting information
p. 981 - 985
(2017/05/05)
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- Divergent reactivity of a new dinuclear xanthene-bridged bis(iminopyridine) di-nickel complex with alkynes
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The reaction of a dinucleating bis(iminopyridine) ligand L bearing a xanthene linker (L = N,N′-(2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene-4,5-diyl)bis(1-(pyridin-2-yl)methanimine)) with Ni2(COD)2(DPA) (COD = cyclooctadiene, DPA = diphenylacetylene) leads to the formation of a new dinuclear complex Ni2(L)(DPA). Ni2(L)(DPA) can also be obtained in a one-pot reaction involving Ni(COD)2, DPA and L. The X-ray structure of Ni2(L)(DPA) reveals two square-planar Ni centers bridged by a DPA ligand. DFT calculations suggest that this species features NiI centers antiferromagnetically coupled to each other and their iminopyridine ligand radicals. Treatment of Ni2(L)(DPA) with one equivalent of ethyl propiolate (HCCCO2Et) forms the Ni2(L)(HCCCO2Et) complex. Addition of the second equivalent of ethyl propiolate leads to the observation of cyclotrimerised products by 1H NMR spectroscopy. Carrying out the reaction under catalytic conditions (1 mol% of Ni2(L)(DPA), 24 h, room temperature) transforms 89% of the substrate, forming primarily benzene products (triethyl benzene-1,2,4-tricarboxylate and triethyl benzene-1,3,5-tricarboxylate) in 68% yield, in a ca. 5:1 relative ratio. Increasing catalyst loading to 5 mol% leads to the full conversion of ethyl propiolate to benzene products; no cyclotetramerisation products were observed. In contrast, the reaction is significantly more sluggish with methyl propargyl ether. Using 1 mol% of the catalyst, only 25% conversion of methyl propargyl ether was observed within 24 h at room temperature. Furthermore, methyl propargyl ether demonstrates the formation of cyclooctatetraenes in significant amounts at a low catalyst concentration, whereas a higher catalyst concentration (5 mol%) leads to benzene products exclusively. Density functional theory was used to provide insight into the reaction mechanism, including structures of putative dinuclear metallocyclopentadiene and metallocycloheptatriene intermediates.
- Hollingsworth, Ryan L.,Bheemaraju, Amarnath,Lenca, Nicole,Lord, Richard L.,Groysman, Stanislav
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p. 5605 - 5616
(2017/07/10)
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- Pd and Ni complexes of a novel vinylidene β-diketimine ligand: Their application as catalysts in Heck coupling and alkyne trimerization
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A β-diketimine ligand with vinylidene substitution at γ-carbon, CH2C(CH3CNAr)2 (Ar?=?2,6-diisopropylphenyl) (L2), was synthesized by treating β-diketimine H2C(CH3CNAr)2 with n-BuLi followed by paraformaldehyde. L2 formed the homobimetallic ether-bridged β-diketiminate complex [O{(CH2-β-diketiminate)Pd(OAc)}2] (1) with (PdOAc)2. It also gave complexes [L2PdCl2] (2) and [L2NiBr2] (3) when treated with PdCl2(CH3CN)2 and NiBr2(dimethoxyethane), respectively. All the compounds were characterized using 1H/13C NMR spectroscopy and single-crystal X-ray diffraction studies. The catalytic activity of Pd and Ni complexes 1, 2 and 3 was explored in Heck coupling and alkyne trimerization reactions and it was found that they are very good catalysts. The results are reported in detail.
- Beesam, Raghavendra,Nareddula, Dastagiri Reddy
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- Anionic hexadeca-carboxylate tetrapyrazinoporphyrazine: Synthesis and in vitro photodynamic studies of a water-soluble, non-aggregating photosensitizer
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A sodium salt of zinc tetrapyrazinoporphyrazine bearing eight 3,5-dicarboxylatophenyl substituents (1) was synthesized. The presence of sixteen negative charges in a rigid arrangement on the periphery of the macrocycle inhibited its aggregation in water or buffers at pH > 5.8. Strong aggregation was, however, observed in buffers at pH 50 = 5.7 ± 1.1 μM) was found to be influenced by both pH and interactions with serum proteins. This was demonstrated with a detailed in vitro study based on the inhibition of vacuolar H+-ATPase using bafilomycin A1, which increased the intracellular fluorescence of 1. Compound 1 also formed interactions with serum proteins that partially quenched its excited states; however, they also protected the compound from self-aggregation at low pH.
- MacHacek, Miloslav,Kollár, Jan,Miletin, Miroslav,Ku?era, Radim,Kubát, Pavel,Simunek, Tomas,Novakova, Veronika,Zimcik, Petr
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p. 10064 - 10077
(2016/02/05)
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- Production Of Terephthalic Acid Via Reductive Coupling Of Propiolic Acid Or Propiolic Acid Derivatives
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A method of making terephthalic acid via reductive coupling of two molecules of propiolic acid or propiolic acid derivatives is presented. The reductive coupling can be catalyzed by compounds comprising metals, and propiolic acid or propiolic acid derivatives can be produced from acetylene and carbon dioxide. At least 4 of the 8 carbons in the terephthalic acid are non-fossil-derived.
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Paragraph 0036
(2016/10/04)
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- Evaluating the Effect of Catalyst Nuclearity in Ni-Catalyzed Alkyne Cyclotrimerizations
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An evaluation of catalyst nuclearity effects in Ni-catalyzed alkyne oligomerization reactions is presented. A dinuclear complex, featuring a Ni-Ni bond supported by a naphthyridine-diimine (NDI) ligand, promotes rapid and selective cyclotrimerization to form 1,2,4-substituted arene products. Mononickel congeners bearing related N-donor chelates (2-iminopyridines, 2,2′-bipyridines, or 1,4,-diazadienes) are significantly less active and yield complex product mixtures. Stoichiometric reactions of the dinickel catalyst with hindered silyl acetylenes enable characterization of the alkyne complex and the metallacycle that are implicated as catalytic intermediates. Based on these experiments and supporting DFT calculations, the role of the dinuclear active site in promoting regioselective alkyne coupling is discussed. Together, these results demonstrate the utility of exploring nuclearity as a parameter for catalyst optimization.
- Pal, Sudipta,Uyeda, Christopher
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supporting information
p. 8042 - 8045
(2015/07/15)
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- Synthesis and analysis of in vitro anti-arthritic activity of dendrimers with methyl, ethyl and isopropyl salicylates as surface groups
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Frchet type dendrimers with salicylates as surface groups have been synthesized using the divergent approach and their in vitro anti-arthritic activity was analyzed by inhibition of protein denaturation.
- Jayanthi, Mani,Rajakumar, Perumal
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p. 63208 - 63215
(2015/02/19)
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- Synthesis and properties of poly(p-phenylene vinylene) derivatives with hyperbranched structure and containing a nitro substituent
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In order to improve efficiency, processability, and stability, two groups of novel poly(p-phenylene vinylene) (PPV) derivatives (P1-P 3 and P4-P6) with hyperbranched structure and containing a nitro substituent were synthesized via a Gilch reaction in different monomer ratios. The properties of the polymers were investigated by using UV-Vis absorption, fluorescence spectroscopy, cyclic voltammetry, and thermogravimetric analysis. The result shows that the band gaps of the PPV derivatives with a nitro substituent were decreased and the polymers had higher molecular weights (106), excellent solubility in common organic solvents, good film-forming ability, and better thermal stability. The polymers can be used as an efficient acceptor material in polymeric solar cells. Graphical abstract: [Figure not available: see fulltext.]
- Li, Ruyu,Mo, Yanjiao,Shi, Rong,Li, Peng,Li, Chengyu,Wang, Zhenjiang,Wang, Xun,Li, Shengbiao
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- Metal-free synthesis of 1,3,5-trisubstituted benzenes by the cyclotrimerization of enaminones or alkynes in water
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The cyclotrimerization reactions of enaminones and electron deficient terminal alkynes have been efficiently performed in water in the presence of only a small amount of lactic acid. The reactions led to the green synthesis of a variety of 1,3,5-triacylbenzenes without using any metal as catalyst. Brief investigation on different elaboration of the triacylbenzene product demonstrated the versatile synthetic application of these 1,3,5-triacylbenzenes. This journal is the Partner Organisations 2014.
- Wan, Jie-Ping,Lin, Yunfang,Hu, Kaikai,Liu, Yunyun
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p. 20499 - 20505
(2014/06/09)
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- Supported gold nanoparticle-catalyzed cis -selective disilylation of terminal alkynes by σ disilanes
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Supported gold nanoparticles on metal oxides (1 mol %) catalyze for the first time the cis-selective disilylation of terminal alkynes by 1,2-disilanes in isolated yields up to 94%. It is likely that the reaction proceeds through oxidative insertion of the
- Gryparis, Charis,Kidonakis, Marios,Stratakis, Manolis
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p. 6038 - 6041
(2014/01/06)
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- Reactivity of electron-deficient alkynes on gold nanoparticles
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Propiolates cyclotrimerize in the presence of catalytic amounts of gold nanoparticles to give aryl benzoates in high yields and with turnover frequencies of thousands per hour. Types of alkynes other than propiolates do not react, and, if molecular oxygen
- Leyva-Perez, Antonio,Oliver-Meseguer, Judit,Cabrero-Antonino, Jose R.,Rubio-Marques, Paula,Serna, Pedro,Al-Resayes, Saud I.,Corma, Avelino
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p. 1865 - 1873
(2013/09/02)
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- Cyclotrimerization of terminal alkynes catalyzed by the system of NiCl 2/Zn and (benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines
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An effective regioselective cyclotrimerization of terminal alkynes is achieved by the direct utilization of NiCl2·6H2O, Zn, and 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine in one step under ambient temperature.
- Xi, Chanjuan,Sun, Zelin,Liu, Yongbing
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supporting information
p. 13327 - 13330
(2013/09/23)
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- Catalyst-free transformations of diethyl 2-ethoxymethylenemalonate and diethyl polyfluorobenzoylmalonates in water
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The unusual transformation of diethyl 2-ethoxymethylenemalonate into triethyl 1,3,5-benzenetricarboxylate is described. This one-pot reaction proceeds in water without any catalyst in a good yield. One of the proposed intermediates of this process is also used under similar conditions to give the desired trisubstituted benzene. A catalyst-free, efficient, practical, and convenient process in water based on deethoxycarbonylation has been developed to form ethyl polyfluorobenzoylacetates in a high yield from diethyl polyfluorobenzoylmalonates.
- Bazhin, Denis N.,Kudyakova, Yulia S.,Burgart, Yanina V.,Saloutin, Victor I.
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supporting information; experimental part
p. 1961 - 1963
(2012/05/19)
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- A mechanistic study of the utilization of arachno-diruthenaborane [(Cp*RuCO)2B2H6] as an active alkyne-cyclotrimerization catalyst
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The reaction of nido-[1,2-(Cp*RuH)2B3H 7] (1 a, Cp=I·5-C5Me 5) with [Mo(CO)3(CH3CN)3] under mild conditions yields the new metallaborane arachno-[(Cp*RuCO) 2B2H6] (2). Compound 2 catalyzes the cyclotrimerization of a variety of internal- and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivities of nido-1 a and arachno-2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne-insertion to catalytic cyclotrimerization, respectively. Density functional calculations have been used to evaluate the reaction pathways of the cyclotrimerization of alkynes catalyzed by compound 2. The reaction involves the formation of a ruthenacyclic intermediate and the subsequent alkyne-insertion step is initiated by a [2+2] cycloaddition between this intermediate and an alkyne. The experimental and quantum-chemical results also show that the stability of the metallacyclic intermediate is strongly dependent on the nature of the substituents that are present on the alkyne. Everything changes but Ru: The reactivities of nido-[1,2-(Cp*RuH)2B3H7] and arachno-[(Cp*RuCO)2B2H6] with alkynes show that a change in geometry (nido to arachno) drives a change from alkyne-insertion to catalytic cyclotrimerization, respectively. Copyright
- Geetharani,Tussupbayev, Samat,Borowka, Julia,Holthausen, Max C.,Ghosh, Sundargopal
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supporting information; experimental part
p. 8482 - 8489
(2012/07/28)
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- Potentiometric and spectrophotometric studies on the binding ability of a flexible tripodal catecholamine ligand toward iron(III)
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The tripodal catecholamine ligand N1,N3,N 5-tris(2-(2,3-dihydroxybenzylamino)ethyl)cyclohexane-1,3, 5-tricarboxamide (CYCOENCAT, L) has been synthesized and characterized. The ligand was investigated as a chelator for Fe(I
- Sahoo, Suban K.,Baral, Minati,Kanungo
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scheme or table
p. 2849 - 2855
(2012/01/13)
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- Potentiometric study of a benzene-based tripodal triamine as chelator for Zn(II) ion
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The complexation of a C3-symmetrical tripodal triamine ligand, N1,N3,N5-tris(2-aminoethyl)benzene-1,3,5- tricarboxamide (TAT, L) with Zn(II) ion was investigated at an ionic strength of 0.1 M NaClO4 a
- Bera, Rati Kanta,Sharma, Darshna,Sahoo, Suban K.,Kanungo
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experimental part
p. 590 - 595
(2012/05/05)
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- Palladium nanoparticles-decorated graphene nanosheets as highly regioselective catalyst for cyclotrimerization reaction
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Novel palladium nanoparticles/graphene-based composites were prepared by a method involving palladium nanoparticles in situ growth on chitosan- functionalized graphene. The resulted composites showed uniform palladium nanoparticles distribution, which were characterized by Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD) and electron diffraction pattern (ED), etc. Moreover, such graphene-based nanocomposites were successfully applied to catalyze the cyclotrimerization of acetylene with high regioselectivity (=99.5%) and superior recycling performance without the assistance of any ligands. Copyright
- Cheng, Jinsheng,Tang, Longhua,Li, Jinghong
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experimental part
p. 5159 - 5168
(2012/07/28)
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- Viologen-based benzylic dendrimers: selective synthesis of 3,5-bis(hydroxymethyl)benzylbromide and conformational analysis of the corresponding viologen dendrimer subunit
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Convergent and divergent strategies for the synthesis of viologen dendrimers with 1,3,5-tri-methylene-branching units are discussed. The title compound is easily transformed into 1-[3,5-bis(hydroxymethyl)benzyl]-4-(pyridin-4-yl)pyridinium hexafluorophosphate, which is used in sequential growth and activation steps as a CB2 compound in the cascade-type dendrimer synthesis (B = -OH, activation = -OH → Br). Analysis of the dendrimer structure reveals that three torsional angles, that is, τ1 between the two pyridinium units, τ2 between the methylene and pyridinium and τ3 between the methylene and phenyl, determine the conformational space of the dendrimers. We report here the crystal structure of 1-[3,5-bis(hydroxymethyl)benzyl]-4-(pyridin-4-yl)pyridinium as PF6- salt which represents the smallest subunit of the dendrimer that shows the same three torsional angles. The crystal structure together with the results from PM3 calculations opens an avenue to judge the structure of benzylic viologen-based dendrimers.
- Kathiresan, Murugavel,Walder, Lorenz,Ye, Fei,Reuter, Hans
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supporting information; experimental part
p. 2188 - 2192
(2010/06/19)
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- Reactions of alkynes with [RuCl(cyclopentadienyl)] complexes: The important first steps
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Cyclopentadienyl-ruthenium half-sandwich complexes with η2-bound alkyne ligands have been suggested as catalytic intermediates in the early stages of Ru-catalyzed reactions with alkynes. We show that electronically unsaturated complexes of the formula [RuCl(Cp)(η2-RC=CR')] can be stabilized and crystallized by using the sterically demanding cyclopentadienyl ligand Cp (Cp = η5-l-methoxy-2,4tert-butyl-3-neopentyl-cyclopentadienyl). Furthermore we demonstrate that [RuCl2(Cp)]2 is an active and regioselective catalyst for the [2+2+2] cyclotrimerization of alkynes. The first elementary steps of the reaction of mono(η2- alkyne) complexes containing {RuCl(Cp*)} (Cp* = η5- C5Me5) and (RuCl(Cp)} fragments with alkynes were investigated by DFT calculations at the M06/6-31G* level in combination with a continuum solvent model. Theoretical results are able to rationalize and complement the experimental findings. The presence of the sterically demanding Cp ligand increases the activation energy required for the formation of the corresponding di(η2alkyne) complexes, enhancing the initial regioselectivity, but avoiding the evolution of the system towards the expected cyclotrimerization product when bulky substituents are present. Theoretical results also show that the electronic structure and stability of a metallacyclic intermediate is strongly dependent on the nature of the substituents present in the alkyne.
- Dutta, Barnali,Curchod, Basile F. E.,Campomanes, Pablo,Solari, Euro,Scopelliti, Rosario,Rothlisberger, Ursula,Severin, Kay
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experimental part
p. 8400 - 8409
(2010/09/05)
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- Selective cyclodimerization and cyclotrimerization of acetals bearing electron-withdrawing groups catalyzed by lewis acids
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Acetais like 3,3-dlethoxyproplonate bearing electron-withdrawing groups were found to undergo cyclodimerization and cyclotrimerization in the presence of Lewis acids to give coumalates and 1,3,5-trisubstituted benzenes. The selectivity of these products depended on the Lewis acids employed. For instance, ethyl coumalate was obtained from, ethyl 3,3diethoxypropionate in high selectivity under the influence of d-block Lewis acids like FeCl3, whereas triethyl 1,3,5-benzenetricarboxylate was obtained in preference to ethyl coumalate under the influence of lanthanoid Lewis acids like GdCl3, Various coumalates were synthesized by the FeCl3catalyzed cross-cyclodimerization of acetals with active methylene compounds, From 4,4-diniethoxy-2-butanone, however, 1,3,5-triacetylbenzene, which is difficult to prepare regioselectively by conventional methods, was formed in quantitative yield under the influence of AlCl3, This reaction would provide a very convenient route to 1,3,5-triacetylbenzene,
- Maeda, Sayuki,Obora, Yasushi,Ishii, Yasutaka
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experimental part
p. 4067 - 4072
(2009/12/24)
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- Copper(0)-induced deselenative insertion of N,N-disubstituted selenoamides into acetylenic C-H bond leading to propargylamines
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Upon heating at 110 °C in the presence of copper(0) powder, terminal acetylenes undergo a novel deselenative C-H bond insertion reaction of N,N-disubstituted selenoamides, affording the corresponding propargylamines in good to excellent yields, selectivel
- Mitamura, Takenori,Ogawa, Akiya
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supporting information; experimental part
p. 2045 - 2048
(2009/10/24)
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- Palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups in scCO2
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Product control of palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups can be achieved through modifying reaction conditions. When the oxidant, such as CuCl2/O2, benzoquinone/O2 or O2, was present in scCO2, aerobic oxidation of terminal olefins goes smoothly. With enough MeOH and sufficient oxygen, acetalization preponderated over cyclotrimerization, while with little MeOH as co-solvent in scCO2 or no MeOH in DMF and an appropriate pressure of O2, cyclotrimerization of terminal olefins became the dominated reaction. When oxygen is absent and triethylamine was added into the reaction system, palladium-catalyzed C-N bond formation occurs to produce β-amino acid derivatives as the sole product.
- Jiang, Huan-Feng,Shen, Yan-Xia,Wang, Zhao-Yang
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p. 508 - 514
(2008/03/28)
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- RhCl3/amine-catalyzed [2+2+2] cyclization of alkynes
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The RhCl3·3H2O/i-Pr2NEt-catalyzed [2+2+2] cyclotrimerization of alkynes has been achieved. The reaction can be widely used for various alkynes and provides tri- or hexa-substituted benzenes regioselectively in high yields. The [2+2+2] cycloaddition of diynes and alkynes is also developed, and it affords benzene derivatives in moderate to high yields.
- Yoshida, Kenta,Morimoto, Ichiro,Mitsudo, Koichi,Tanaka, Hideo
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p. 5800 - 5807
(2008/09/21)
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- Tricarbamate of 1,3,5-triaminobenzene via Curtius rearrangement of trimesic acid and subsequent nitration
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The triethyl tricarbamate of 1,3,5-triaminobenzene was prepared from trimesic acid in five steps with 70% overall yield. The tricarbamate underwent nitration to give the mono-, di-, or trinitro analogs in excellent yield. Copyright Taylor & Francis Group, LLC.
- Davis, Matthew C.
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p. 1457 - 1462
(2008/02/02)
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- A simple PdCl2/O2/DMF catalytic system for highly regioselective cyclotrimerization of olefins with electron-withdrawing groups
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A highly regioselective cyclotrimerization of olefins with electron-withdrawing groups in a PdCl2/O2/DMF catalytic system is disclosed, and a possible mechanism has also been proposed, which reveals the PdCl2-catalyzed cyclotrimerization of olefins with electron-withdrawing groups goes through a quite different pathway from that of alkynes.
- Jiang, Huan-Feng,Shen, Yan-Xia,Wang, Zhao-Yang
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p. 7542 - 7545
(2008/03/14)
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- RhCl3/amine-catalyzed cyclotrimerization of alkynes
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RhCl3/amine was found to be an efficient catalyst for the cyclotrimerization of alkynes. The [2 + 2 + 2] cyclotrimerization of internal alkynes proceeded smoothly to afford hexa-substituted benzenes regioselectively in moderate to high yields. Copyright
- Yoshida, Kenta,Morimoto, Ichiro,Mitsudo, Koichi,Tanaka, Hideo
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p. 998 - 999
(2008/02/10)
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- Skeletal change in the PNP pincer ligand leads to a highly regioselective alkyne dimerization catalyst
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A Rh complex of a bulky diarylamino-based PNP pincer ligand is a robust catalyst for the dimerization of terminal alkynes and highly selective for the trans-enyne product. The Royal Society of Chemistry 2006.
- Weng, Wei,Guo, Chengyun,Celenligil-Cetin, Remle,Foxman, Bruce M.,Ozerov, Oleg V.
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p. 197 - 199
(2008/02/07)
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- Studies with functionally substituted enamines: The reactivity of enaminals and enamino esters toward naphthoquinone, hydrazonoyl halides, aminoazoles and hippuric acid
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Whereas enamines 1a,b react with naphthoquinone (2) to yield the naphthofuranals 5a,b, enamine ester 1c react with 2 to yield benzoindole derivatives 7. Enamine 1b reacts with hydrazonoyl halides 8 to yield 3,4-disubstituted pyrazoles 12. On the other hand, the enaminal 1a failed to react with 8, while enamine ester 1c afforded hydrazone 16 on treatment with 8. The enamino ester 1b afforded triethyl 1,3,5-benzenetricarboxylates on refluxing in acetic acid. Georg Thieme Verlag Stuttgart.
- Al-Saleh, Balkis,Makhseed, Saad,Hassaneen, Huwaida M. E.,Elnagdi, Mohamed Hilmy
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- Efficient intermolecular [2 + 2 + 2] alkyne cyclotrimerization in aqueous medium using a ruthenium(IV) precatalyst
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The dimeric bis(allyl)-ruthenium(IV) complex [{Ru(η3:η3-C10H16)(μ-Cl)Cl}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) was found to catalyze efficiently the [2 + 2 + 2] cyclization of terminal and internal alkynes in aqueous medium. Copyright
- Cadierno, Victorio,Garcia-Garrido, Sergio E.,Gimeno, Jose
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p. 15094 - 15095
(2007/10/03)
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- Stereodivergent formation of alkenylsilanes: syn or anti Hydrosilylation of alkynes catalyzed by a cyclopentadienylcobalt(I) chelate bearing a pendant phosphane tether
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The hydrosilylation of alkynes is catalyzed by the di-tert- butylphosphanylethylcyclopentadienyl-cobalt chelate 1. While the reaction of internal alkynes exclusively affords syn hydrosilylation products with triethylsilane, the reaction with triethoxysila
- Yong, Li,Kirleis, Karin,Butenschoen, Holger
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p. 833 - 836
(2007/10/03)
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- Alkyne oligomerization mediated by rhodium complexes with a phosphinosulfonamido ligand and isolation and characterization of a rhodacyclopentadiene complex
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Treatment of N-tosyl aziridine with KPPh2 in THF produces Ph2PCH2CH2NTsK (Ts = p-CH3C 6H4SO2). Reaction of Ph2PCH 2CH2NTsK with [Rh2(μ2-Cl) 2(NBD)2] (NBD = norbornadiene) and [Rh2(μ 2-Cl)2(COD)2] (COD = 1,5-cyclooctadiene) produces [Rh(NBD)(Ph2PCH2CH2NTs)] and [Rh(COD)(Ph2PCH2CH2NTs)] (4), respectively. Reaction of Ph2PCH2CH2NTsK with [Ir 2(μ2-Cl)2(COD)2] gives [Ir(COD)(Ph2PCH2CH2NTs)]. Complex 4 is catalytically active for polymerization of arylalkynes and for cyclotrimerization of HCCCOR (R = OEt, Me). The novel metallacycle [Rh(C(CO 2Et)CHC(CO2Et)CH)(CH(CO2Et)CCCCO 2Et)(Ph2PCH2CH2NHTs)2] was isolated from the reaction of 4 with ethyl propiolate. The metallacycle is catalytically active for cyclotrimerization of ethyl propiolate.
- Xue, Peng,Sung, Herman S.Y.,Williams, Ian D.,Jia, Guochen
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p. 1945 - 1953
(2007/10/03)
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- Synthesis of cis, cis-1,3,5-trisubstituted cyclohexane based chelators with polyfunctional pendant arms
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Some novel organic compounds of the type: cis,cis-1,3,5-tris(X)cyclohexane, where X= -CONH(CH2)2NH2, -CONH(CH 2)3NH2, -CONH(CH2)2NCH -C6H4OH, CON
- Baral, Minati,Kanungo,Moore, Peter
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- Chemo- and regioselective intermolecular cyclotrimerization of terminal alkynes catalyzed by cationic rhodium(I)/modified BINAP complexes: Application to one-step synthesis of paracyclophanes
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A highly regioselective intermolecular cyclotrimerization of terminal alkynes has been developed based on the use of the cationic rhodium(I)/DTBM- Segphos complex. This method can be applied to a variety of terminal alkynes to provide 1,2,4-trisubstituted benzenes in high yield and with high regioselectivity. A chemo- and regioselective intermolecular crossed-cyclotrimerization of dialkyl acetylenedicarboxylates with a variety of terminal alkynes has also been developed based on the use of the cationic rhodium(I)/H8-BINAP complex, furnishing 3,6-disubstituted phthalates in high yields. It constitutes a highly efficient new method for intermolecular crossed-cyclotrimerization of two different monoynes in terms of catalytic activity, chemo- and regioselectivity, scope of substrates, and ease of operation. The versatility of this new crossed-alkyne cyclotrimerization procedure is demonstrated through its application to one-step synthesis of a [6]metacyclophane and [7]-[12]paracyclophanes from the corresponding terminal α,ω-diynes. Mechanistic studies have revealed that the chemo- and regioselectivity of this crossed-alkyne cyclotrimerization are determined by the preferential formation of a specific rhodium metallacycle derived from a terminal alkyne and a dialkyl acetylenedicarboxylate.
- Tanaka, Ken,Toyoda, Kazuki,Wada, Azosa,Shirasaka, Kaori,Hirano, Masao
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p. 1145 - 1156
(2007/10/03)
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- Ruthenium-mediated cyclotrimerization of alkynes utilizing the cationic complex [RuCp(CH3CN)3]PF6
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The substitutionally labile cationic complex [RuCp(CH3CN) 3]+ (as the PF6- salt) was tested with respect to its ability to catalyze the cyclotrimerization of terminal alkynes and diynes to afford benz
- Rüba, Eva,Schmid, Roland,Kirchner, Karl,Calhorda, Maria José
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p. 204 - 211
(2007/10/03)
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- Phosphonium ylide-catalyzed cyclotrimerization of ethyl propynoate
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The cyclotrimerization of ethyl propynoate (2) to yield aromatic triesters is shown to proceed via consecutive [2 + 2] cycloadditions of ethoxycarbonylmethylenetriphenylphosphonium ylide (1) to three moles of (2), followed by cyclization and elimination o
- Labuschagne, A. Johan H.,Malherbe, Johan S.,Meyer, Cornelius J.,Schneider, David F.
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p. 297 - 304
(2007/10/03)
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- Alkyne oligomerization catalyzed by molybdenum(0) complexes
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Three new molybdenum(0) complexes, [Mo(CO)3(Hpz)3] (1), [Mo(CO)2(Hpz)2(DMAD)2] (2), (DMAD = dimethyl acetylenedicarboxylate) and [Mo(CO)3(1-Me-imidazole)3] (3) were synthesized and characterized. Their activity and selectivity in alkyne cyclotrimerization and co-trimerization reactions was investigated. The molecular structures of 1 and 2 have been determined by unconventional powder and standard single-crystal diffraction methods, respectively. 1 consists of a pseudo-octahedral complex of C3 symmetry, with the ligands in fac disposition; complex 2, of idealized C2 symmetry, is obtained by substitution of one CO and one pyrazole in 1 by two DMAD ligands, and shows the rare trans configuration of π-bound acetylenic moieties.
- Ardizzoia, G.Attilio,Brenna,LaMonica,Maspero,Masciocchi
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p. 173 - 180
(2007/10/03)
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- The first cobalt catalyzed [2 + 2 + 2] alkyne cyclotrimerization in aqueous medium at room temperature
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Chelate complex 1 (5 mol%) was found to catalyze the [2 + 2 + 2] cyclization of terminal alkynes in good yields in a 80/20 mixture of water and ethanol at room temperature without further activation.
- Yong, Li,Butenschoen, Holger
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p. 2852 - 2853
(2007/10/03)
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- Benzopyrans. Part 41.1 Reactions of 2-(2-dimethylaminovinyl)-lbenzopyran-4-ones with various dienophiles
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Dienamine 1 with W-phenylmaleimide and chromenone 14 as well as 15 produces, through initial [4 + 2]cycloaddition, xanthenones 10 and 18, respectively. Initial Michael addition of 1 to chromenones 14 and 16, and dimethyl acetylenedicarboxylate (DMAD), triggers the formation of xanthenone 19, 4-azaxanthenone 26 and substituted fumarate 49, respectively. Initial [2 + 2]cycloadducts of dienamines 1-3 with electrophilic acetylenes always undergo further transformations. Thus, 1 with DMAD, dibenzoylacetylene and ethyl propiolate (EP) ultimately gives xanthenones 33, 34 and 37, respectively, the latter being admixed with flavone 43. Enamine 2, cyclisable to xanthenone 11, gives 33 and 35 with DMAD, and 37 and 44 with EP. Reaction of 3 with DMAD affords 36 exclusively. The Royal Society of Chemistry 1999.
- Ghosh, Chandra Kanta,Bhattacharyya, Samita,Ghosh, Chandreyi,Patra, Amarendra
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p. 3005 - 3013
(2007/10/03)
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- The dimerization and cyclotrimerization of acetylenes mediated by phosphine complexes of cobalt(I), rhodium(I), and iridium(I)
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The catalytic dimerization and cyclotrimerization of phenylacetylene, ethyl propiolate, and dimethyl acetylenedicarboxylate were studied by using the metal complexes [Co(PPh3)3Cl] (1), [Co(PPh3)2(CO)2
- Field, Leslie D.,Ward, Antony J.,Turner, Peter
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p. 1085 - 1092
(2007/10/03)
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- Reductive dimerization of dialkyl acetylenedicarboxylate catalyzed by [Rh(binap)(MeOH)2]ClO4 in methanol
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Cationic Rh(I) complex [Rh(binap)(MeOH)2]ClO4 catalyzes reductive dimerization of dialkyl acetylenedicarboxylates 1 to give 1,2,3,4-tetrakis(alkoxycarbonyl)-1,3-butadienes 2 in methanol selectively.
- Tani, Kazuhide,Ueda, Kazuya,Arimitsu, Kenji,Yamagata, Tsuneaki,Kataoka, Yasutaka
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p. 253 - 255
(2007/10/03)
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- Ruthenium catalyzed homocoupling of terminal alkynes
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Several complexes of the type RuTp(L)(L′)Cl (L, L′ = P, N, O donors) were tested with respect to their ability of promoting catalytic C-C-coupling reactions of terminal acetylenes. When L = tertiary phosphine, predominantly dimerization occurs, RuTp(PPhs
- Slugovc, Christian,Doberer, Daniel,Gemel, Christian,Schmid, Roland,Kirchner, Karl,Winkler, Berthold,Stelzer, Franz
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p. 221 - 233
(2007/10/03)
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