Presence Of Phosphine Ligands Research Articles

Pd/C: An efficient and reusable catalyst for the synthesis of flavones via carbonylation of aryl halides

This work describes an efficient and mild approach for the synthesis of flavones via catalytic carbonylation of aryl halides with 2‐hydroxyacetophenone using the commercial Pd/C as an efficient, heterogeneous and recyclable catalyst. Under balloon pressure of CO, 0.6 mol% Pd/C is sufficient for moderate yields of flavones for the carbonylation of aryl iodides under phosphine‐free conditions and aryl bromides in the presence of phosphine ligand. The catalyst is easily separable and shows significant recyclability. Moreover, the reaction mechanism was discussed, and a possible mechanism that contains two different cyclisation pathways was proposed.

A Heterogeneous Catalyst for the Transformation of Fatty Acids to α-Olefins

Heterogeneous catalysts have so far not been very efficient [turnover frequency (TOF) 95%) for one such deoxygenation, decarbonylative dehydration, by using a heterogeneous Pd/C catalyst in the presence of phosphine ligands. The process is solvent free, allows for catalyst recycling, and does not require in situ distillation of the product to maintain high selectivity.

Carboxylate switch between hydro- and carbopalladation pathways in regiodivergent dimerization of alkynes.

Experimental and theoretical investigation of the regiodivergent palladium-catalyzed dimerization of terminal alkynes is presented. Employment of N-heterocyclic carbene-based palladium catalyst in the presence of phosphine ligand allows for highly regio- and stereoselective head-to-head dimerization reaction. Alternatively, addition of carboxylate anion to the reaction mixture triggers selective head-to-tail coupling. Computational studies suggest that reaction proceeds via the hydropalladation pathway favoring head-to-head dimerization under neutral reaction conditions. The origin of the regioselectivity switch can be explained by the dual role of carboxylate anion. Thus, the removal of hydrogen atom by the carboxylate directs reaction from the hydropalladation to the carbopalladation pathway. Additionally, in the presence of the carboxylate anion intermediate, palladium complexes involved in the head-to-tail dimerization display higher stability compared to their analogues for the head-to-head reaction.

ChemInform Abstract: Diastereoselective Synthesis of Substituted Tetrahydropyrans by Copper(II)—Bisphosphine‐Catalyzed Olefin Migration and Prins Cyclization.

AbstractA mild tandem olefination/Prins cyclization of hex‐5‐en‐1‐ols with a variety of aldehydes in the presence of phosphine ligands (I)‐(III) is developed.

ChemInform Abstract: Ligand‐Promoted Reaction on Silver Nanoparticles: Phosphine‐Promoted, Silver Nanoparticle‐Catalyzed Cyclization of 2‐(1‐Hydroxy‐3‐arylprop‐2‐ynyl)phenols.

ChemInformVolume 42, Issue 13 Heterocyclic Compounds ChemInform Abstract: Ligand-Promoted Reaction on Silver Nanoparticles: Phosphine-Promoted, Silver Nanoparticle-Catalyzed Cyclization of 2-(1-Hydroxy-3-arylprop-2-ynyl)phenols. Min Yu, Min Yu Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorMingdeng Lin, Mingdeng Lin Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorChengyan Han, Chengyan Han Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorLi Zhu, Li Zhu Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorChao-Jun Li, Chao-Jun Li Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorXiaoquan Yao, Xiaoquan Yao Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this author Min Yu, Min Yu Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorMingdeng Lin, Mingdeng Lin Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorChengyan Han, Chengyan Han Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorLi Zhu, Li Zhu Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorChao-Jun Li, Chao-Jun Li Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this authorXiaoquan Yao, Xiaoquan Yao Dep. Appl. Chem., Sch. Mater. Sci. Eng., Nanjing Univ. Aeron. Astron., Nanjing 210016, Peop. Rep. ChinaSearch for more papers by this author First published: 03 March 2011 https://doi.org/10.1002/chin.201113078Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume42, Issue13March 29, 2011 RelatedInformation

Ligand-promoted reaction on silver nanoparticles: phosphine-promoted, silver nanoparticle-catalyzed cyclization of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols

A highly efficient annulation of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols leading to the key intermediates to synthesize aurones was catalyzed by silver nanoparticles/carbon black-supported silver nanoparticles. In the presence of phosphine ligand, both the catalysts show excellent catalytic activities in the reaction and give the products with good yields as well as excellent regio- and stereo-selectivities in a water-toluene mixed solvent. Furthermore, the catalysts can be recovered and recycled effectively several times.

Ruthenium and rhodium nanoparticles as catalytic precursors in supercritical carbon dioxide

Ruthenium and rhodium nanoparticles (MNP) were prepared in the presence of phosphine ligands containing fluorinated groups, starting from well-defined organometallic compounds. The syntheses of these new materials evidenced the crucial tuning between metal precursor and ligand. These nanocatalysts were used in hydrogenation reactions of arene derivatives in organic solvent (THF) and supercritical carbon dioxide (scCO 2). The catalytic behaviour observed (activity and selectivity) showed that both Ru and Rh systems are less active in scCO 2 than in THF, preventing the hydrogenation of the aromatic group when electron-donor groups (like ether moieties) are present on the substrate.

A Ligand Free and Room Temperature Protocol for Pd-Catalyzed Kumada−Corriu Couplings of Unactivated Alkenyl Phosphates

Kumada-Corriu cross-couplings of nonactivated cyclic and acyclic vinyl phosphates with aryl magnesium reagents afforded a series of 1,1-disubtituted alkenes in good yields for most cases when the reactions were performed at room temperature with the simple palladium salt, PdCl(2), without the presence of phosphine ligands.

Oxidative Addition Step in Reactions Involving Palladium Activation of Carbon-Halogen and Carbon-Oxygen Bonds

Different modifications of the Heck reaction involving the activation of carbon-halogen and carbon-oxygen bonds by palladium (styrene phenylation with iodobenzene or benzoic anhydride and iodobenzene carbonylation, reductive coupling, and reduction) are studied by in situ31P NMR spectroscopy. The catalytic cycles of the reactions include oxidative addition to Pd(0) formed in situ. The product composition in this step depends strongly on the composition of the reaction mixture, which is related to PhX conversion in the main catalytic process and with the nature of the catalyst precursor. A new hypothesis as to the mechanism of the catalytic cycle in alkene arylation in the presence of phosphine ligands is suggested. This hypothesis is consistent with NMR monitoring data and with the value of the kinetic isotope effect.

Novel nickel(II) and cobalt(II) catalysts based on poly-salen type ligands for the dimerization of propylene

A series of poly-salen type Ni(II) and Co(II) complexes were prepared, and the catalytic behavior in the dimerization of propylene has been studied in combination with aluminum co-catalysts and phosphine ligands. The effects of various reaction factors, such as the type of phosphine ligand and the P/Ni ratio, the type of aluminum co-catalyst and its quantity, particularly the nature of the nickel and cobalt complexes, were also examined. The results indicated that the productivity of the catalytic system was strongly dependent on the steric character of poly-salen ligand in the Ni(H) and Co(II) complexes. It was also found that reaction temperature deeply affected the performance of the catalytic system in the presence of phosphine ligand and alkyl aluminum promoter, and higher regioselectivities to 2,3-dimethylbutenes (2,3DMB) in the dimers were observed with incorporation of bulky and basic PCy3 into the nickel and cobalt catalysts. An extremely high activity in the propylene dimerization (TOF up to 221,000 h(-1)) was obtained with the 2b system under suitable conditions, which was much higher than that obtained with the corresponding monomeric salen system. However, it seemed difficult to realize recycling of the catalysts owing to the restrict dependence of catalytic activity with its solubility, at least under the adopted conditions. (C) 2002 Elsevier Science B.V. All rights reserved.

Propylene dimerization using bis(salicylaldehyde)nickel(II) complexes in the presence of organoaluminum and phosphine ligands

Abstract Dimerization of propylene was studied with several bis(salicylaldehyde)nickel(II) complexes in combination with aluminum co-catalysts, eventually in the presence of ancillary phosphine ligands. The effects of the type and relative amount of aluminum co-catalyst as well as the nature of nickel precursors were examined. The results clearly indicated that the nickel precursors characterized by the presence of either bulky substituents or electron-withdrawing groups on the salicylaldehyde ligands displayed high activity. The catalytic performance was also remarkably modified in the presence of phosphine ligand, and the regioselectivity in the dimers was directed to 2,3DMB with incorporation of basic and bulky PCy3 into the nickel catalysts, especially at the temperature below 0 °C. A preliminary UV-Vis study was performed in order to detect the variation of nickel species involved in the dimerization process. The bis(2-hydroxy-1-naphthaldehyde)nickel (1d) system exhibited an extremely high productivity (TOF up to 262,000 h−1) as well as a moderate regioselectivity to 2,3DMB (65.6%) in the dimerization of propylene under appropriate reaction parameters.

Mechanistic Studies on Pd-Catalyzed Telomerization and Co-Cyclization of Butadiene: Amphiphilicity of Bis-π-allylpalladium Intermediate in the Presence of Phosphine Ligand

Abstract Pd-catalyzed reactions of butadiene, which proceed through a bis-π-allylpalladium intermediate, (η3,η3-C8H12)Pd (2), were performed in the presence of both a pronucleophile (aceto- or cyanoacetate) and an electrophile (benzaldehyde). Methyl aceto- or cyanoacetate and benzaldehyde reacted independently with 2 to give telomers 8 and the divinyl-substituted pyranes 9, respectively. In the case of methyl cyanoacetate, the co-cyclization of 2 with 2-cyano-3-phenylpropenoate (11) formed in situ also took place to afford the cyclohexane derivative 10. Namely, three kinds of amphiphilic additions of the C8-chain of 2 occurred to δ+H–Nuδ−, δ+C=Cδ−, and δ+C=Oδ− simultaneously in a one-pot reaction. The Pd-catalyzed reaction of allyl chloride, allyltributylstannane, methyl cyanoacetate, and benzaldehyde was undertaken under neutral conditions, expecting the amphiphilic reactions by the intermediacy of (η3-C3H5)2Pd (6) formed in situ. Allylation of both benzaldehyde and methyl cyanoacetate took place. Competitively amphiphilic bis-allylation of the polar double bond of 11 also occurred to form the 1,7-octadiene derivative 18. The mechanisms of both reactions can be explainable in terms of the amphiphilicity of the intermediates (2 and 6) in the presence of a phosphine ligand.

Novel nickel catalysts based on perfluoroalkyl-β-diketone ligands for the selective dimerization of propylene to 2,3-dimethylbutenes

The propylene dimerization to 2,3-dimethylbutenes (DMB) by novel homogeneous catalysts prepared in situ by two alternative routes was described. The former synthetic procedure was based on the oxidative addition of hexafluoro-2,4-pentandione (hfacac) to bis(1,5-cyclooctadiene)nickel(0) [Ni(cod) 2] in the presence of an ancillary phosphine ligand and an organoaluminium compound. The latter route consisted in the reaction of bis(perfluoroalkyl-β-diketonato)nickel(II) complexes with the organoaluminium compound in the presence of the phosphine ligand. In this context the novel bis(tetradecafluoro-4,6-nonandionato)nickel(II)·2 dimethylformamide complex [Ni(tdfnd) 2(dmf) 2] was synthesized and its crystal and molecular structures were determined. The catalytic systems obtained with both procedures resulted highly active in the oligomerization of propylene (TOF>20000 h −1). In particular, when Ni(hfacac) 2 was combined with the bulky and basic tricyclohexylphosphine (PCy 3) and MAO was adopted as co-catalyst a very high regioselectivity to DMB within the C 6 cut was achieved (ca. 90%). The use of Ni(tdfnd) 2(dmf) 2 in the place of Ni(hfacac) 2 gave similar results under the same reaction conditions. Changing the type of phosphine ligand and the nature of the organoaluminium co-catalyst it was possible to deeply modify both regio- and chemo-selectivity of the process, thus allowing to orientate the reaction towards specific target oligomeric products.

Selective propylene dimerization to 2,3-dimethylbutenes by homogeneous catalysts prepared by oxidative addition of α-nitroketones to nickel(0) complexes in the presence of phosphine ligands and organoaluminium co-catalysts

Novel nickel catalysts, prepared in situ by oxidative addition of α-nitroketones to nickel(0) complexes, in the presence of a phophine ancillary ligand and activated by organoaluminium co-catalysts were investigated in propylene oligomerization with the aim to selectively obtain 2,3-dimethylbutenes (DMB). In particular, the effect of the nature of the α-nitroketonate ligand as well as of the basicity and bulkiness of the phosphine on catalyst performances were studied. Finally, the influence of the type of organoaluminium co-catalyst and reaction temperature were examined. In particular, when the Ni(cod) 2/tricyclohexylphosphine (PCy 3)/α-nitroacetophenone (naph)/methylalumoxane (MAO) catalytic system was employed, the highest up to now reported regioselectivity within C 6 cut (>90%) was achieved. Moreover, the use of balanced mixtures of MAO and Et 2AlCl allowed to optimize the catalyst performances up to an overall yield to DMB of almost 70%, a significant productivity being also achieved (TOF=4500 h −1).

Novel Cu–Te Clusters Synthesised from tBuTeSiMe3: [Cu18Te6(TetBu)6(PPh2Et)7], [Cu19Te6(TetBu)7(PEt3)8], [Cu27Te15(PiPr2Me)12] and [Cu58Te32(PtBu2nBu)14

The reactions of CuCl and tBuTeSiMe3 in the presence of phosphine ligands result in the formation of four new Cu/Te cluster complexes, [Cu18Te6(TetBu)6(PPh2Et)7], [Cu19Te6(TetBu)7(PEt3)8], [Cu27Te15(PiPr2Me)12] and [Cu58Te32(PtBu2 nBu)14], which have been structurally characterized by single crystal structural analysis. The former two clusters show a layer-type tellurium frameworks in which the copper atoms are asymmetrically spread. The latter two clusters possess a tellurium framework in a body-centered Te14-Frank-Kasper polyhedron or a Te28 polyhedron with four interstitial tellurium atoms and belong to mixed-valence Cu/Te compounds.

Highly active supported palladium catalyst for the regioselective synthesis of 2-arylpropionic acids by carbonylation

A catalyst system consisting of supported palladium in the presence of phosphine ligands, TsOH and LiCl catalyses the carbonylation of 1-arylethanols to 2-arylpropionic acids with significantly improved activity and regioselectivity; the catalyst can be recycled with no loss in activity and selecivity.

Novel Cu–Se clusters with Se–layer structures: [Cu32Se7(SenBu)18(PiPr3)6], [Cu50Se20(SetBu)10(PiPr3)10], [Cu73Se35(SePh)3(PiPr3)21], [Cu140Se70(PEt3)34] and [Cu140Se70(PEt3)36

The clusters [Cu32Se7(SenBu)18(PiPr3)6], [Cu50Se20(SetBu)10(PiPr3)10], [Cu73Se35(SePh)3(PiPr3)21], [Cu140Se70(PEt3)34] and [Cu140Se70(PEt3)36] were prepared from the reactions of CuCl, RSeSiMe3 and Se(SiMe3)2 (R = Ph, nBu or tBu) in the presence of phosphine ligands and their molecular structures were determined. The Se–Bu bond was cleaved more easily than the Se–Ph bond under the reaction conditions studied.

Synthesis, Structure, and Electrochemical Studies of μ3-η2,η2,η2-C60 Triosmium Complexes

Two μ3-η2,η2,η2-C60 complexes, Os3(CO)8(PPh3)(μ3-η2,η2,η2-C60) (8) and Os3(CO)7(PMe3)2(μ3-η2,η2,η2-C60) (9), have been prepared by decarbonylation of Os3(CO)9(μ3-η2,η2,η2-C60) (6) with Me3NO/MeCN in the presence of phosphine ligands. The molecular structure of 8 has been determined by a single-crystal X-ray diffraction study. The structure of 8 is derived from that of Os3(CO)11(PPh3) by replacing three axial carbonyl ligands with a μ3-face-capping C6 ring of C60. The 13C NMR spectra (C60 region) of 6 and Os3(CO)8(PMe3)(μ3-η2,η2,η2-C60) (7) show 11 sp2 and 1 sp3 carbon resonances and 29 sp2 and 3 sp3 carbon resonances, respectively, which are consistent with C3v and Cs symmetric nature of the two complexes in solution. Electrochemical properties of 6, 7, and 9 have been studied by cyclic voltammetry (CV) in 1,2-dichlorobenzene (DCB) solutions. The general features of CV curves have revealed four reversible redox couples for 6 and 7 and three for 9 in the DCB potential window. The μ3-η2,η2,η2-C60 complexes,...

Conversion of arene groups to η 2-cyclohexene rings at tungsten metal centers

The sodium amalgam (4Na per W) reduction of hydrocarbon solutions of [W(OC 6HPh 4-2,3,5,6) 2Cl 4] ( 1) (OC 6HPh 4-2,3,5,6 = 2,3,5,6 tetraphenylphenoxide) in the presence of phosphine ligands (L) leads to the deep-green complexes [W(OC 6HPh 3-η 6-C 6H 5)(OC 6PHh 4-2,3,5,6)(L)] ( 2a, L = PMe 2Ph; 2b, L = PMePh 2). The solid state structure of 2a shows one of the ortho-phenyl groups of an aryloxide ligand bound to the tungsten metal center. The η 6-arene complex 2a reacts very slowly with H 2 (1 atm, 25°C) in C 6D 6 solution to produce a dark-brown complex [W(OC 6HPh 3-η 2-C 6H 9)(OC 6HPh 3-η 6-C 6H 5)(PMe 2Ph)] ( 3a), the solid-state structure of which shows that one of the ortho-phenyl rings has undergone reaction with two equivalents of H 2 to produce a cyclohex-1-ene ring which is η 2-bound to the metal center. The remaining aryloxide ligand in 3a is chelated through an η 6-interaction, leading to a formal 18-electron configuration at the metal.

Crystal and molecular structure of [Ta(H)2(OC6H3Pri 2-2,6)3(PMe2Ph)]: a distorted six-coordinate tantalum dihydride

Reaction of [Ta(OC6H3Pri2-2,6)3R2](R = CH2C6H4-4-Me) with H2 in the presence of phosphine ligands (L) leads to the dihydride compounds [Ta(H)2(OC6H3Pri2-2,6)3(L)], the solid-state structure of the PMe2Ph derivative shows a geometry about the metal centre that is severely distorted from octahedral; hydrogenation of aryl-phosphines and other aromatic substrates is catalysed by these dihydride compounds.