Triphenylphosphine Palladium Research Articles

Synthesis of Substituted Terphenyl Derivatives

Several substituted terphenyl derivatives were prepared following two synthetic routes with five steps. Condensation of 4‐amino‐3‐bromo‐benzotrifluoride with 4‐(methylthio) phenyl boronic acid in the presence of sodium carbonate and palladium triphenylphosphine in toluene gave 4‐amino‐3‐(4‐methylthiophenyl)‐benzotrifluoride. Treatment of this compound with osmium tetroxide in the presence of 4‐methyl morpholine‐N‐oxide yielded the corresponding sulfone, which was converted into the iodo derivative using sodium nitrite. The iodo derivative thus obtained was treated first with propylmagnesium chloride and triethylborane and subsequently with hydroxylamine‐O‐sulfonic acid to furnish the target compounds.

Synthesis of Novel Biarenes of 3‐Biaryl‐1‐ferrocenyl‐2‐propene‐1‐one

The novel structures of organometallic compounds, 3‐(4′‐aryl)phenyl‐1‐ferrocenyl‐2‐propene‐1‐ones (5) were synthesized by Pd(0) [tetrakis(triphenylphosphine)palladium] catalyzed of Suzuki cross‐coupling reaction. Their structures were determined with elemental analyses, IR spectra and 1H NMR spectra.

Synthesis of New Aromatic Perfluorovinyl Ether Monomers Containing Phosphonic Acid Functionality.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of new aromatic perfluorovinyl ether monomers containing phosphonic acid functionality

The synthesis of a new perfluorovinyl ether monomer containing phosphonic acid functionality is reported. It started from 4-[(α,β,β-trifluorovinyl)oxy]bromo benzene prepared in two steps from the nucleophilic substitution of 4-bromophenate to 1,2-dibromotetrafluoroethane. The [(α,β,β-trifluorovinyl)oxy]benzene dialkyl phosphonate was prepared according to various methods of phosphonation like a Michaelis–Arbuzov or a Michaelis–Becker or a palladium catalysed arylation in the presence of various reactants. The influence of the nature of the method and of the reactants onto the yields is discussed. It was shown that reaction involving a palladium triphenyl phosphine catalyst led to the best yield. All different aromatic intermediates and fluoromonomers were characterised by 1 H , 31 P and 19 F NMR, mass spectrometry (EI), and by FTIR.

Progress in the Palladium‐Catalyzed Cyanation of Aryl Chlorides.

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Progress in the palladium-catalyzed cyanation of aryl chlorides.

The development of new palladium catalysts for the cyanation of various aryl and heteroaryl chlorides is described. The combination of amine co-catalysts with chelating phosphine ligands, for example, 1,4-bis(diphenylphosphino)butane (dppb) or 1,5-bis(diphenylphosphino)pentane (dpppe), allows an efficient cyanation of chloroarenes with simple potassium cyanide. General palladium-catalyzed cyanation of nonactivated and deactivated chloroarenes is possible for the first time. Studies of the oxidative addition of aryl halides to palladium triphenylphosphine complexes in the presence and absence of amines suggest that the co-catalyst is capable of preventing catalyst deactivation caused by the presence of excess cyanide ions in solution.

Synthesis, characterization and properties of a novel silicon-substituted soluble polymer with a PPV structure

Soluble poly(2,5-di-t-butyldimethylsilyloxy-1,4-phenylenevinylene) was prepared via a Stille coupling reaction between 2,5-diiodo-1,4-bis-(t-butyldimethylsilyloxy)benzene and E-1,2-bis(tri- n-butylstannyl)ethylene in the presence of tetrakis-(triphenylphosphine)palladium(0) as the catalyst. The characterization of this material by 1 H- and 13 C- NMR, UV-Vis., and IR spectroscopies is described. The molecular weights, determined by GPC analysis and referred to standard polystyrene, were Mn= 2027 and Mw = 2621. Photoluminescence measurements were performed in solution and on thin films of pure material or of a blend with polystyrene.

Preparation of novel palladium(II) complexes with dithiocarbimates from sulfonamides

Potassium N-R-sulfonyldithiocarbimates, K2(RSO2N=CS2) (R = Me, Ph, 2-MeC6H4), react with Pd(OAc)2 to yield complex anions bis(N-R-sulfonyldithiocarbimato)palladate(II), [Pd(RSO2N=CS2)2]2−, which were isolated as their n-Bu4N+ salts. When the reaction was performed in the presence of Ph3P in a 2:1 ratio with respect to Pd(OAc)2, the N-R-sulfonyldithiocarbimatobis(triphenylphosphine)palladium(II) complexes were obtained. Elemental analyses, i.r. spectra and electronic spectra data were consistent with the formation of palladium–sulfur diamagnetic square planar complexes in the first case and mixed square planar complexes of palladium with Ph3P and dithiocarbimates in the second case. The 1H-n.m.r., 13C-n.m.r. and 31P-n.m.r. spectra showed the expected signals for the Bu4N+ cation, Ph3P and the dithiocarbimate moieties.

Stereoselective Synthesis of 1,3-enynylselenides via Palladium-Catalysed Cross Coupling Reactions

( E)-α-Bromovinylselenides undergo a cross coupling reaction with alkynyl Grignard reagents in the presence of tetrakis(triphenylphosphine)palladium(0) in THF at room temperature to afford 1,3-enynylselenides in good yields.

Synthesis and Characterization of 2,5-Bis(2-pyridyl)thiophene

2-[2-(Trimethylsilyl)ethynyl] pyridine ( 6 ) was prepared in 95% yield by reaction of 2-bromopyridine with trimethylsilylacetylene in triethylamine in the presence of bis(triphenylphosphine)Palladium(II) chloride and Copper(I) iodide. Desilylation of ( 6 ) by refluxing with sodium hydroxide in methanol (yield 95%) of 2-ethynylpyridine ( 5 ). Oxidative coupling of ( 5 ) in pyridine by oxygen in the presence of Copper(I) chloride gives 70% yield of 1,4-bis(2-pyridyl)1,3-butadiyne ( 4 ). Reaction of 4 with sodium sulfide affords 100% of 2,5-bis(2-pyridyl) thiophene ( 1 ).

New methods for high-throughput synthesis

New methodologies for library synthesis have been developed. They are based on new carbon­carbon bond-formation reactions in the solid-phase and organic synthesis using polymer-supported catalysts. We have immobilized alkyl glyoxylate equivalents onto resins and prepared novel polymer-supported imines. We have also developed unprecedented polymer-supported catalysts such as microencapsulated scandium trifluoromethanesulfonate [MC Sc(OTf)3], osmium tetroxide (MC OsO4), and palladium triphenylphosphine [MC Pd(PPh3)] for high-throughput synthesis.

A general and highly regio and stereoselective method for the synthesis of (E)-2-(2-arylvinyl)-3,1-benzoxathiin-4-ones through palladium–copper catalysis

A palladium–copper-catalysed procedure for the synthesis of (E)-2-(2-arylvinyl)-3,1-benzoxathiin-4-ones 5a–5h is developed. 3-[2-(Methoxycarbonyl)phenylthio]propyne 2 reacts with aryl iodides 3a–3h in the presence of bis(triphenylphosphine)palladium(II) dichloride, copper(I) iodide and triethylamine in acetonitrile to furnish the disubstituted alkynes 4a–4h in good yields (70–84%). These on alkaline hydrolysis and subsequent cyclisation of the carboxylic acids formed with copper(I) iodide (20 mol%) and triethylamine in tetrahydrofuran under reflux afford (E)-2-(2-arylvinyl)-3,1-benzoxathiin-4-ones 5a–5h in 61–70% yield rather than the expected benzoxathiepinones 6. The reactions of (E)-2-(2-arylvinyl)-3,1-benzoxathiin-4-ones 5a and 5g with nucleophiles and the hydrogenation of compounds 5a, 5b and 5d are also studied.

Synthesis of pentenoic acid analogs as potential anti-influenza agents

The synthesis of (2Z,4RS)-5-acetamido-4-guanidino-2-benzamidopent-2-enoic acid (sodium salt) 5 is reported. Wittig–Horner olefination of diamino protected propionaldehyde 8 with phosphonoglycine trimethyl ester 11 provided (Z)-olefin methyl ester 12. The methyl ester was converted to allyl ester 15 by initial hydrolysis with lithium hydroxide followed by reaction with allyl bromide. Target compound 5 was prepared from allyl ester 15 by initial formation of bis(Boc)guanidino ester 16 followed by treatment with tetrakis(triphenylphosphine)palladium(0). The product was evaluated for activity against influenza neuraminidase and was found to be weakly active.

ChemInform Abstract: Synthesis of (8E,10Z)-Tetradeca-8,10-dienal, Sex Pheromone of Horse Chestnut Leafminer (Cameraria ohridella), and All Its Geometrical Isomers.

(8 E ,10 Z )-Tetradeca-8,10-dienal ( 1a ), sex pheromone of the horse chestnut leafminer ( Cameraria ohridella ; Lepidoptera, Gracillariidae), and its geometrical isomers ( 1b - 1d ) were efficiently synthesized using tetrakis(triphenylphosphine)palladium catalyzed cross-coupling reactions of alk-1-ynes or alkenyl alanes with corresponding vinyl iodides. The stereoisomeric purity of obtained tetradecadienals 1a - 1d was higher than 95% (GC). Relative electroantennographic (EAG) activities of the prepared compounds 1a - 1d elicited on male antennae supported the previously published identification of the C. ohridella sex pheromone.

Comparison of the LMCT resonance Raman spectra of PdCl2(PCy3)2 and PdCl2(PPh3)2: effect of the phenyl versus cyclohexyl substituents on the LMCT excited state

Resonance Raman spectra have been obtained at four excitation wavelengths within the A-band ligand to metal charge transfer (LMCT) absorption of trans-dichloro-bis(tricyclo-hexylphosphine) palladium(II) and a resonance Raman intensity analysis was done to elucidate the excited state structure relative to the ground state. Comparison of the present results for trans-dichlorobis(tricyclohexylphosphine) palladium(II) with those previously reported for trans-dichlorobis(triphenylphosphine) palladium(II) shows that the phenyl ligand appears to primarily affect the adjacent P-C vibrational reorganizational energy and does not significantly perturb the Pd-Cl or Pd-P vibrational reorganizational energies.

Evidence for the hydride mechanism in the methoxycarbonylation of ethene catalysed by palladium–triphenylphosphine complexes

Analysis of the phosphorus containing by-products from the catalytic methoxycarbonylation of ethene using a palladium triphenylphosphine complex with a combination of High Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) indicated increasing levels of phosphonium salts through the course of the reaction, major ones being methyltriphenylphosphonium, ethyltriphenylphosphonium and 3-oxopentyltriphenylphosphonium (CH3CH2C(O)CH2CH2PPh3) cations, isolated as the sulfonate salts. The latter are shown to be produced by metal mediated pathways and believed to be indicative of the operation of the hydride mechanism.

Low symmetry metal complexes: chloro cysteine ethyl ester-N,S triphenylphosphine palladium(II), a new regioselective hydrocarboxylation catalyst for 2-phenylpropanoic acid, and its crystal structure

The hydrochlorides of cysteamine, cysteine ethyl ester and penicillamine methyl ester, react with Pd(PPh3)4 to yield low symmetry complexes of palladium(II) that incorporate the N,S-aminothiolato ligand and triphenylphosphine; the complex with cysteine ethyl ester, structurally characterized by X-ray diffraction, proved to be an effective catalyst for the hydrocarboxylation of styrene with high selectivity (98%) towards 2-phenylpropanoic acid.

Optimisation of Palladium-Based Supported Liquid-Phase Catalysts in the Heck Reaction

Heck reactions using sulphonated triphenylphosphine palladium complexes have been carried out using a supported liquid-phase catalysis system in a batch reactor. The catalyst complex is held in solution in a polar, hydrophilic film supported upon porous glass beads whilst reactants and products are restricted to a nonmiscible solvent phase. Several factors in the preparation of the supported catalyst were investigated with the aim of ensuring good assembly, distribution, and immobilisation of the catalyst complex across the surface of the beads. The thickness of the hydrophilic film upon the porous glass beads was varied. The hydrophilic nature of the ligand complex was studied using mono- and trisulphonated sodium and lithium salts of triphenylphosphine. The effects of level of catalyst loading and ligand/catalyst ratio upon leaching and activity were also examined. These factors have been examined to develop a better understanding of the catalysis occurring in supported liquid-phase systems.

Vibrational reorganizational energies of the A-band LMCT absorption in trans-dichlorobis (triphenylphosphine) palladium (II) determined from resonance Raman intensity analysis

Resonance Raman spectra including absolute resonance Raman cross section measurements have been recorded for four excitation wavelengths within the A-band ligand to metal charge transfer (LMCT) absorption at ˜ 340 nm of trans-dichlorobis(triphenylphosphine) palladium (II). A relatively simple model together with time-dependent wavepacket calculations were used to simulate simultaneously the absolute absorption and resonance Raman intensities in order to get an estimate of the vibrational reorganizational energies associated with the Aband absorption plus the homogeneous and inhomogeneous broadening to the absorption bandwidth. It seems that there is significant interaction of the triphenylphosphine ligands with the Cl/Pd chromophore of the LMCT absorption band. The results for transdichlorobis(triphenylphosphine) palladium(II) are compared with those of other inorganic compounds.

Kinetic Study of Cycloolefin Oxidation with a Pd(0) Complex

A new chemical process is proposed for the oxidation of cyclic olefins, such as cyclooctene and cyclododecene, to cyclic ketones in the presence of hydrogen peroxide and a catalytic system based on tetrakis(triphenylphosphine)palladium(0) (Pd(PPh 3 ) 4 ). The kinetic equation of the cyclooctene oxidation can be expressed by r olefin =k[olefin]([catalyst]-k'[H + ] 1.7 ). Note that the reaction rate increases linearly with catalyst and olefin concentration and depends on the H + concentration. The catalyst retains its activity when bound to a polymer. This allows catalyst recycling and better control of the reaction medium. Unlike most common processes for cyclic ketone production, the proposed novel method occurs in a single step and does not require any cocatalyst.