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1.
Tsang DS Yang S Alphonse FA Yudin AK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(3):886-894
In the presence of rhodium(I) hydride catalysts, tertiary N-allylamines are known to isomerise into E enamines. In contrast, we have recently found that N-allylaziridines isomerise to form Z enamines. On the basis of literature data, the most likely mechanism of isomerisation would involve a rhodium hydride addition/beta-hydride elimination sequence. We show that the observed selectivity cannot be adequately explained by this pathway and is more consistent with initial CH-activation followed by rearrangement to form a five-membered cyclometallated rhodium intermediate. This intermediate subsequently undergoes reductive elimination to form a C--H bond. The resulting geometrically stable Z enamines are useful building blocks for stereoselective synthesis. 相似文献
2.
Facile Synthesis and Versatile Reactivity of an Unusual Cyclometalated Rhodium(I) Pincer Complex 下载免费PDF全文
Linda S. Jongbloed Prof. Dr. Bas de Bruin Prof. Dr. Joost N. H. Reek Dr. Martin Lutz Dr. Ir. Jarl Ivar van der Vlugt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7297-7305
The synthesis of the reactive PN(CH) ligand 2‐di(tert‐butylphosphanomethyl)‐6‐phenylpyridine ( 1H ) and its versatile coordination to a RhI center is described. Facile C?H activation occurs in the presence of a (internal) base, thus resulting in the new cyclometalated complex [RhI(CO)(κ3‐P,N,C‐ 1 )] ( 3 ), which has been structurally characterized. The resulting tridentate ligand framework was experimentally and computationally shown to display dual‐site proton‐responsive reactivity, including reversible cyclometalation. This feature was probed by selective H/D exchange with [D1]formic acid. The addition of HBF4 to 3 leads to rapid net protonolysis of the Rh?C bond to produce [RhI(CO)(κ3‐P,N,(C?H)‐ 1 )] ( 4 ). This species features a rare aryl C?H agostic interaction in the solid state, as shown by X‐ray diffraction studies. The nature of this interaction was also studied computationally. Reaction of 3 with methyl iodide results in rapid and selective ortho‐methylation of the phenyl ring, thus generating [RhI(CO)(κ2‐P,N‐ 1Me )] ( 5 ). Variable‐temperature NMR spectroscopy indicates the involvement of a RhIII intermediate through formal oxidative addition to give trans‐[RhIII(CH3)(CO)(I)(κ3‐P,N,C‐ 1 )] prior to C?C reductive elimination. The RhIII–trans‐diiodide complex [RhI(CO)(I)2(κ3‐P,N,C‐ 1 )] ( 6 ) has been structurally characterized as a model compound for this elusive intermediate. 相似文献
3.
Chiral 1,5‐cyclooctadiene rhodium(I) cationic complexes with C2‐symmetric chelate diphosphoramidite ligands containing (R,R)‐1,2‐diaminocyclohexane as the backbone and two atropoisomeric biaryl units were easily synthesized and fully characterized by multinuclear one‐ and two‐dimensional NMR spectroscopy and elemental analysis. These complexes were used as catalysts in the asymmetric hydrogenation of dimethyl itaconate, methyl 2‐acetamidoacrylate and (Z)‐methyl‐2‐acetamido‐3‐phenylacrylate. The rhodium complexes derived from diphosphoramidite ligands that contain two (R) or (S) BINOL (2,2′‐dihydroxy‐1,1′‐binaphthyl) units proved to be efficient catalysts, giving complete conversion and very good enantioselectivity (up to 88% ee). An uncommon positive H2 pressure effect on the enantioselectivity was observed in the hydrogenation of dimethyl itaconate catalyzed by Rh‐complex with diphosphoramidite ligand that contains two (S)‐binaphthol moieties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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M. Costa G. P. Chiusoli R. Gaetti B. Gabriele G. Salerno 《Russian Chemical Bulletin》1998,47(5):936-940
New rhodium-catalyzed amination reactions of arylacetylenes and cyclohexen-1-ylacetylene in the presence of strong bases with
the use of carbon dioxide as an auxiliary are described. Secondary amines attack the terminal carbon atom of the triple bond
followed by protonation of the adjacent carbon atom. Alternatively, the reaction can proceed further with the addition of
the second alkyne molecule. The conditions for the selective synthesis of enamines (up to 87% yield) or α-substituted propynylamines
(up to 86% yield) are reported.
Dipartimento di Chimica Organica e Industriale dell'Università, Viale delle Scienze, I-43100 Parma, Italia.
Dipartimento di Chimica, Università della Calabria, Arcavacata di Rende, I-80036 Cosenza, Italia.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 966–970, May, 1998. 相似文献
6.
Rhodium catalysts supported on six different aluminosilicate structures were prepared by hydrogen reduction of a cationic organometallic rhodium complex anchored to the support. The precursor active phase was incorporated in acetone medium through ion exchange using [Rh(Me2CO)x(NBD)]ClO4 as the metal precursor species, in which NBD is 2,5‐norbornadiene and (Me2CO)x is acetone. The effect of the structure and characteristics of the support on metal load and dispersion was studied in the heterogeneous catalysts thus prepared. The supports were characterized by X‐ray diffraction, energy‐dispersive X‐ray analysis, volumetric adsorption and surface acidity. For the precursors and catalysts, the metal load was determined by UV–VIS spectra, the reduction temperature was determined by differential scanning calorimetry, and rhodium dispersion was measured by chemisorption. The structure of the materials used as supports had a great influence on the catalyst prepared. A higher metal content was achieved in the supports with laminar structures, whereas better dispersion was shown by the catalysts supported on zeolitic structures. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Radhey S. Srivastava 《应用有机金属化学》2001,15(9):769-771
A rhodium–dimethylsulfoxide‐promoted catalytic oxidation of a thioether to sulfoxide is studied. Screening of different rhodium complexes reveals moderate to excellent catalytic properties for the oxidation of thioethers using molecular oxygen as an oxidant. The scope of this reaction is discussed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
9.
Thermal decomposition of rhodium(III) chloride under inert, oxidative and reductive gas atmospheres was investigated in order
to determine its thermal properties. Stoichiometries of the reactions occurring during heating are described. it is suggested
that the chemical formula of soluble rhodium(III) chloride should be presented as RhCl3·HCL·xH2O. Cold crystallisation of anhydrous rhodium(III) chloride at a temperature of about 500°C was established. The procedure
for quantitative determination of volatile matter (water and hydrochloric acid) content and rhodium content by thermogravimetry
is given and discussed. The repeatability and reproducibility of the method are estimated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Stabilization of a Chiral Dirhodium Carbene by Encapsulation and a Discussion of the Stereochemical Implications 下载免费PDF全文
Dr. Christophe Werlé Dr. Richard Goddard Petra Philipps Dr. Christophe Farès Prof. Alois Fürstner 《Angewandte Chemie (International ed. in English)》2016,55(36):10760-10765
For the first time, the stereochemical course of an asymmetric cyclopropanation can be discussed on the basis of experimental structural information on a pertinent chiral dirhodium carbene intermediate. Key to success was the formation of racemic single crystals of a heterochiral [Rh2{(S*)‐PTTL}4{=C(Ar)COOMe}][Rh2{(R*)‐PTTL}4] (Ar=MeOC6H4; PTTL=N‐phthaloyl‐tert‐leucinate) capsule, which has been characterized by X‐ray diffraction. NMR spectroscopic data confirm that the obtained structural portrait is also relevant in solution and provide additional information about the dynamics of this species. The chiral binding pocket is primarily defined by the conformational preferences of the N‐phthaloyl‐protected amino acid ligands and reinforced by a network of weak interligand interactions that get stronger when chlorinated phthalimide residues are used. 相似文献
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Edyta Stochmal Magdalena Hasik Wincenty Turek Andrzej Bernasik Anna Adamczyk Agnieszka Plis Lidia Litynska‐Dobrzynska 《先进技术聚合物》2011,22(6):1067-1077
Polypyrrole (PPy) with dispersed metallic Rh particles has been prepared by all‐chemical route, i.e. reduction of Rh3+ ions existing in RhCl3 aqueous solutions with sodium borohydride (NaBH4) carried out in the presence of the previously obtained PPy doped with chloride ions (PPyCl). PPy–Rh composites thus formed have been characterized using X‐ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM) combined with energy dispersive X‐ray (EDX) microanalysis, Rh3d X‐ray photoelectron (XPS), and IR spectroscopies. This has made it possible to find out that metallic Rh nanoparticles, mainly of sizes below 10 nm, have been present in the composites. Agglomerates, with sizes up to 0.7 µm, have been formed in the systems containing higher amounts of Rh. PPy serving as the matrix in the composites has been doped. However, its doping level has been lower than that of the starting PPyCl. This has been explained by partial reduction of the polymer occurring during preparation of the composites. Catalytic properties of the PPy–Rh systems have been investigated using isopropyl alcohol conversion as a test reaction. It has been established that the composites are active redox catalysts. This makes them promising materials for applications as catalysts of various redox processes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
13.
Polymeric reagents prepared by exchanging silver(I) for H+ on a macroreticular polystyrene sulfonate ion exchange resin are shown to be capable of selectively absorbing triphenylphosphine from solutions of triphenylphosphine complexes of rhodium(I) and ruthenium(II). Absorption of triphenylphosphine during alkene hydrogenations catalyzed by RhCl(PPh3)3, RuCl2(PPh3)3 and RuHCl(PPh3)3 led to increased hydrogenation rates in hydrogenation of 1-hexene and other alkenes. Addition of this silver(I) polystyrene sulfonate to alkene hydrogenations catalyzed by HRh(CO) (PPh3)3, RuH2(PPh3)3 and RuH(OCOCH3) (PPh3)3 also led to modest rate accelerations. Catalyst activations seen in these alkene hydrogenations were shown to be due in some cases to triphenylphosphine absorption. In other cases, HCl or HCl plus triphenylphosphine absorption was responsible for the formation of a more active catalyst solution. 相似文献
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Tseng CK Lee CR Han CC Shyu SG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(9):2716-2723
Complex [Na(phen)3][Cu(NPh2)2] ( 2 ), containing a linear bis(N‐phenylanilide)copper(I) anion and a distorted octahedral tris(1,10‐phenanthroline)sodium counter cation, has been isolated from the catalytic C? N cross‐coupling reaction with the CuI/phen/tBuONa (phen=1,10‐phenanthroline) catalytic system. Complex 2 can react with 4‐iodotoluene to produce 4‐methyl‐N,N‐diphenylaniline ( 3 a ) with 70.6 % yield. In addition, 2 can work as an effective catalyst for C? N coupling under the same reaction conditions, thus indicating that 2 is the intermediate of the catalytic system. Both [Cu(NPh2)2]? and [Cu(NPh2)I]? have been observed by in situ electron ionization mass spectrometry (ESI‐MS) under catalytic reaction conditions, thus confirming that they are intermediates in the reaction. A catalytic cycle has been proposed based on these observations. The molecular structure of 2 has been determined by single‐crystal X‐ray diffraction analysis. 相似文献
16.
A series of square planar cis-dicarbonyl polymer coordinated rhodium complexes with uncoordinated donors near the central
rhodium atoms for carbonylation of methanol to acetic acid are reported. Data of IR, XPS and thermal analysis show that these
complexes are very stable. The intramolecular substitution reaction is proposed for their high stability. These complexes
show excellent catalytic activity, selectivity and less erosion to the equipment for the methanol carbonylation to acetic
acid. The distillation process may be used instead of flash vaporization in the manufacture of acetic acid, which reduces
the investment on the equipment.
Project supported by the National Natural Science Foundation of China (Grant No. 29574186). 相似文献
17.
On the Use of Metal Purine Derivatives (M=Ir,Rh) for the Selective Labeling of Nucleosides and Nucleotides 下载免费PDF全文
Marta Valencia Mamen Martín‐Ortiz Prof. Dr. Mar Gómez‐Gallego Prof. Dr. Carmen Ramírez de Arellano Prof. Dr. Miguel A. Sierra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3831-3838
The reactions of neutral or cationic IrIII and RhIII derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides. 相似文献
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Two Rhodium(III) Ions Confined in a [18]Porphyrin Frame: 5,10,15,20-Tetraaryl-21,23-Dirhodaporphyrin
Grzegorz Vetter Dr. Agata Białońska Paulina Krzyszowska Sebastian Koniarz Prof. Ewa Pacholska-Dudziak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(46):e202201513
Tetraaryl-21,23-dirhodaporphyrin and a series of related monorhodaporphyrins have been obtained by tellurium-to-rhodium exchange in a reaction of tetraaryl-21,23-ditelluraporphyrin with [RhCl(CO)2]2. These organometallic metallaporphyrins contain rhodium(III) centers embedded in rhodacyclopentadiene rings, incorporated within the porphyrin frames. The skeletons of 21,23-dirhodaporphyrin and 21-rhoda-23-telluraporphyrin are strongly deformed in-plane from the rectangular shape typical for porphyrins, due to rhodium(III) coordination preferences, the large size of the two core atoms, and the porphyrin skeleton constrains. These two metallaporphyrins exhibit fluxional behavior, as studied by 1H NMR and DFT, involving the in-plane motion and the switch of the rhodium center(s) between two nitrogen donors. A side product detected in the reaction mixture, 21-oxa-23-rhodaporphyrin, results from tellurium-to-oxygen exchange, occurring in parallel to the tellurium-to-rhodium exchange. The reaction paths and mechanisms have been analyzed. The title 21,23-dirhodaporphyrin contains a bridged bimetallic unit, Rh2Cl2, in the center of the macrocycle, with two rhodium(III) ions lying approximately in the plane of the porphyrinoid skeleton. The geometry of the implanted Rh2Cl2 unit is affected by macrocyclic constrains. 相似文献