- Diphosphine-palladium and -platinum complexes as catalysts for the Baeyer-Villiger oxidation of ketones: Effect of the diphosphine, oxidation of acyclic ketones, and mechanistic studies
-
A variety of Pd and Pt complexes of the type [(P-P)M(μ-OH)]22+ (M = Pd, Pt; P-P = a series of tetraphenyldiphosphines) were tested in the Baeyer-Villiger oxidation of ketones with hydrogen peroxide. The effect of the diphosphine-metal ring size on the catalytic activity indicates that the larger the ring, the better the catalyst and that, in general, Pt complexes are superior. The complex modified with P-P = dppb is the most active catalyst and allows for the first time the oxidation of a series of acyclic ketones. The corresponding migratory aptitude series is in full agreement with the one known for the stoichiometric organic reaction employing peracids as oxidants. A test of the reactivity of different peroxidic oxidants (H2O2, t-BuOOH, KHSO5, carbamide peroxide) shows that hydrogen peroxide is the most effective. A kinetic study of the oxidation of 2-methylcyclohexanone with [(dppb)-Pt(μ-OH)]22+ as the catalyst shows typical half-order dependence on the catalyst concentration, suggesting that the hydroxy dimer opens up to form the catalytically active species. The reaction is first order in ketone and hydrogen peroxide and is independent of the acidity of the system. The reaction is suggested to proceed via a quasi-peroxymetallacyclic intermediate and bears strong similarities to the stoichiometric organic reaction.
- Gavagnin, Roberta,Cataldo, Maurizio,Pinna, Francesco,Strukul, Giorgio
-
-
Read Online
- Carbon monoxide-ethene copolymerization catalyzed by [PdCl2(dppb)] in H2O-H(CH2)nCOOH (dppb = 1,4-bis(diphenyphosphino)butane; N = 0, 1, 2)
-
[PdCl2(dppb)] is highly active in the catalytic CO-ethene copolymerization in H2O-H(CH2)nCOOH (n = 0, 1 or 2). The influence on the productivity, the limiting viscosity number and the average viscosity molecular weight MWˉv of the following reaction conditions is investigated: (i) solvent composition; (ii) temperature; (iii) CO and ethene partial pressure at a given pressure of one monomer; (iv) monomers ratio at a given total pressure; (v) total pressure at CO/ethene = 1/1; (vi) reaction time. The productivity passes through a maximum with a H2O molar fraction of 0.55-0.70 (14,800 gPK(g Pd h)-1 in H2O-HCOOH, H2O molar fraction = 0.58, 45 bar, CO/ethene = 1/1, 90°C; LVN = 0.48 dLg-1, MWˉv = 21,194 Da). The productivity is in the order of the strength of the acid n = 0 > n = 1 > n = 2, whereas the activation energy is in the opposite order. These findings suggest that the protonation of the resting states β- and γ-chelate rings destabilizes them, thus favoring the chain-growing process. Proposed power rate laws fit the productivity data obtained at different monomer pressures. The productivity lowers with time, but in the first hour the rate remains almost constant. The morphology and crystallinity of selected PKs determined by solid state NMR is also discussed.
- Pagot, Matteo,Toniolo, Luigi,Antonetti, Claudia,Forte, Claudia,Galletti, Anna Maria Raspolli
-
-
Read Online
- Tandem palladium-catalyzed cyclocarbonylation of isolimonene: A mechanistic investigation and theoretical calculations on the fully diastereoselective step
-
Cyclocarbonylation of isolimonene catalyzed by complexes of the type [HPd(SnCl3)L2] provides two cyclopentanone isomers (2a and 2b) containing two new stereogenic centers with a good diastereomeric excess (up to 69% with L2 = dppf). These results show that chiral phosphane ligands are not necessary to ensure asymmetric induction. The diastereomeric excess is due, in fact, to the substrate itself, assisted by the steric hindrance of the diphosphanes. A full characterization of the two isomers by 1H, 13C and DPFGSE NOE NMR spectroscopy gives all the signal assignations and all the positions of the substituents of interest on the chiral carbon atoms. In order to have a better understanding of the catalytic process, we also present a density functional study of the crucial intermediate species 4 involved in the proposed catalytic cycle. Our calculations show that there is no coordination of the C=C bond in an exo mode. Conversely, we have found a pentacoordinate species with a trigonal bipyramidal geometry in which the C=C bond is coordinated in an endo mode. Selected bond lengths and bond orders are reported. The calculated net charge distribution supports the cyclization process, which proceeds through a C-C(O) and a C-Pd coupling. A β-hydride elimination reaction of 4 provides the two 2a and 2b isomers. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Lenoble, Geraldine,Lacaze-Dufaure, Corinne,Urrutigoity, Martine,Mijoule, Claude,Kalck, Philippe
-
-
Read Online
- Meso -Tetra-(4-pyridyl)porphyrin/palladium(ii) complexes as anticancer agents
-
This study reports the synthesis, structural characterization and cytotoxic activity of four new palladium/pyridylporphyrin complexes, with the general formula {TPyP[PdCl(P-P)]4}(PF6)4, where P-P is 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)butane (dppb) or 1,1′-bis(diphenylphosphino)ferrocene (dppf). The complexes were characterized by elemental analysis, and by FT-IR, UV/Vis, 1H and 31P{1H} NMR (1D/2D) spectroscopy. The slow evaporation of a methanolic solution of {TPyP[PdCl(dppb)]4}(PF6)4 (in an excess of NaBF4 salt) resulted in single crystals suitable for X ray diffraction, allowing the determination of the tridimensional structure of this complex, which crystallized in the P21/a space group. The cytotoxicity of the complexes against MDA-MB-231 (breast cancer cells) and MCF-10A (non-tumor breast cancer cells), was determined by the colorimetric MTT method, which revealed that all four complexes show selective indexes close to 1.2, lower than that of cisplatin for the same cells (12.12). The interaction of the complexes with CT-DNA was evaluated by UV-visible and viscosity measurements and it was determined that the complexes interact moderately with CT-DNA, probably by H-bonding/π-π stacking and electrostatic interactions. This journal is
- Alves, Kamilla M.,Ayalla, Alejando P.,Batista, Alzir A.,Dutra, Jocely De L.,Ellena, Javier,Gon?alves, Pablo J.,Guedes, Adriana P. M.,Honorato, Jo?o,Li?o, Luciano M.,Velozo-Sa, Vivianne S.
-
p. 16254 - 16264
(2021/11/27)
-
- Bicyclic Lactams Derived from Serine or Cysteine and 2-Methylpropanal
-
Bicyclic lactams may be prepared from serine or cysteine and 2-methylpropanal; the resulting S, N -heterocycles are more stable than the corresponding O, N -heterocycles but both are synthetic intermediates capable of further elaboration.
- Bagum, Halima,Christensen, Kirsten E.,Genov, Miroslav,Moloney, Mark G.,Pretsch, Alexander,Pretsch, Dagmar,Shire, Bethany R.
-
supporting information
p. 378 - 382
(2020/02/27)
-
- Synthetic Access to 3-Substituted Pyroglutamic Acids from Tetramate Derivatives of Serine, Threonine, allo-Threonine, and Cysteine
-
A general route which provides direct access to pyroglutamates from tetramates, making use of Suzuki coupling on an enol mesylate, followed by reduction, is reported. This work permits direct scaffold hopping from tetramate to substituted pyroglutamates. Some compounds in the library showed modest antibacterial activity against Gram-positive bacteria.
- Bagum, Halima,Christensen, Kirsten E.,Genov, Miroslav,Pretsch, Alexander,Pretsch, Dagmar,Moloney, Mark G.
-
p. 10257 - 10279
(2019/08/20)
-
- A double (mortars; concrete ; artificial stone) alkane dichloride method for the preparation of palladium complexes (by machine translation)
-
The invention discloses a double (mortars; concrete ; artificial stone) alkane second palladium chloride complex preparation method, the method is:a, preparation chlorine arrowhead acid solution; b, the double (mortars; concrete ; artificial stone) alkane adding N, N-dimethyl formamide (mortars; concrete ; artificial stone) is made of the alkane-N, N-dimethyl formamide solution; three, under stirring condition to the double (mortars; concrete ; artificial stone) N of paraffins, N-dimethyl formamide solution adds by drops the chlorine arrowhead acid solution, stirring reaction after the completion of the dropping, cooling after-filtration, the filter cake obtained; four, washing the filter cake, the filter cake after washing is then subjected to vacuum drying, to get double (mortars; concrete ; artificial stone) alkane second palladium chloride complex. The invention directly the palladium source is palladium sponge, to double with the ligand chlorine arrowhead acid (mortars; concrete ; artificial stone) alkane in the solvent DMF in one-step synthesis target product, omits the intermediate palladium chloride, palladium chloride process for the preparation of acetonitrile, has the advantages of simple technique, cycle is short, low cost, and the like. (by machine translation)
- -
-
Paragraph 0027; 0028; 0029; 0030; 0031
(2017/02/24)
-
- Palladium-Catalyzed Formal Insertion of Carbenoids into Aminals via C-N Bond Activation
-
A new strategy for selective insertion of metal carbenes into C-N bond has been developed via Pd-catalyzed C-N bond activation. A series of aminals and α-diazoesters with different substituents were successfully incorporated even in 0.1 mol % of catalyst under mild conditions, affording a wide range of α,β-diamino acid esters with quarternary carbon-centers. Preliminary mechanistic studies uncovered that the unique electrophilic cyclopalladated species could easily react with diazoacetates to generate a Pd-carbenoid intermediate which was involved in the catalytic cycle.
- Qin, Guiping,Li, Lixin,Li, Jiawen,Huang, Hanmin
-
supporting information
p. 12490 - 12493
(2015/10/19)
-
- Pd complexes with trans-chelating ligands composed of two pyridyl groups and rigid π-conjugated backbone
-
1,2-Bis(2-pyridylethynyl)benzene derivatives, having two pyridyl groups and π-conjugated backbone, were prepared from the 1:2 Sonogashira reaction of 1,2-diiodobenzene with 2-alkynyl pyridines. The obtained ligands react with the palladium(II) complexes such as [PdCl2(cod)] and [PdCl 2(MeCN)2] to form the complexes with the ligands coordinated in a trans-chelating bidentate mode. The ligand obtained from 1,3-diiodobenzene and 2-alkynyl pyridine bridges two Pd(II) centers, yielding a dipalladium complex. A dichloropalladium complex with the trans-chelating ligand, containing two methoxy groups in the central arylene group, promotes coupling of phenyl lithium and of phenyl acetylene to yield the respective homo-coupling products. The ligand displacement reactions of {bis(2-pyridylethynyl)benzene}palladium(II) complex with phosphine and dinitrogen ligands, such as PPh3, dppe, dppb, en, tmeda, bpy and phen, takes place smoothly to release the trans-chelating ligand.
- Jung, Miso,Suzaki, Yuji,Saito, Takashi,Shimada, Kyoichi,Osakada, Kohtaro
-
p. 168 - 174
(2012/08/28)
-
- [4-(Benzo[B]Thiophen-2-Yl) Pyrimidin-2-Yl]-Amine Derivatives As Ikk-Beta Inhibitors For The Treatment Of Cancer And Inflammatory Diseases
-
The present invention provides compounds of Formula I: useful in the treatment of cancer and inflammatory diseases.
- -
-
Page/Page column 4
(2009/01/20)
-
- Self-assembly and anion encapsulation properties of cavitand-based coordination cages
-
Two novel classes of cavitand-based coordination cages 7a-j and 8a-d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P-M-P angle close to 90° between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic 1H and 19F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d revealed the presence of a single triflate anion encapsulated. Guest competition experiments revealed that the encapsulation preference of cages 7b,d follows the order BF4- > CF3SO3- ? PF6- at 300 K. ES-MS experiments coupled to molecular modeling provided a rationale for the observed encapsulation selectivities. The basic selectivity pattern, which follows the solvation enthalpy of the guests, is altered by size and shape of the cavity, allowing the entrance of an ancillary solvent molecule only in the case of BF4-.
- Fochi,Jacopozzi,Wegelius,Rissanen,Cozzini,Marastoni,Fisicaro,Manini,Fokkens,Dalcanale
-
p. 7539 - 7552
(2007/10/03)
-
- The crystal and molecular structure of [1,4-bis(diphenylphosphino)butane]palladium(II) dichloride
-
The [(PPh2CH2CH2CH2CH 2PPh2)PdCl2] complex is prepared by the reaction of PdCl2 with 1,4-bis(diphenylphosphino)butane (Dppb) in acetonitrile; its structure is investigated by the X-ray diffraction method (an autodiffractometer, 25°C, MoKα radiation, 4299 reflections, R = 0.035, space group P1, Z = 2). The configuration of the palladium atom is square-planar. The Pd-Cl [2.353(1) and 2.354(1) A] and Pd-P [2.269(1) and 2.254(1) A] distances are normal. The dihedral angle between the Cl(1)PdCl(2) and P(1)PdP(2) planes is 8.6(3)°. In the seven-membered PdP(1)C(1)C(2)C(3)C(4)P(2) cycle, only the P(1)PdP(2)C(1) fragment is planar. Phenyl rings occupy the pseudoaxial and pseudoequatorial positions. The phenyl rings at the P(1) atom are turned by 85.5(3)° against one another, and the rings at the P(2) atom are turned by 113.7(3)°. No shortened intermolecular contacts are found in the structure.
- Makhaev,Dzhabieva,Konovalikhin,D'yachenko,Belov
-
p. 563 - 567
(2008/10/08)
-
- Reactivity of palladium(II) complexes with bidentate bis(phosphine) ligands toward the octahydrotriborate(1-) anion and dependence of the reaction upon halide arrangement: Molecular structure of the trans-(bis(diphenylphosphino)hexane)palladium(II) dichloride dimer
-
The reactivity of the palladium(II) bis(phosphine) complexes, (Ph2P(CH2)nPPh2)PdCl2 (n = 1-6), toward the octahydrotriborate(1-) anion, [B3H8]-, has been investigated. For n = 1-4, the metallaborane (Ph2P(CH2)nPPh2)Pd(B 3H7) is produced, although the yield depends upon the organic chain length of the phosphino ligand and is maximized when n = 2. Our observation that no reaction occurs between the [B3H8]- anion and (bis(diphenylphosphino)pentane)- or (bis(diphenylphosphino)hexane)-palladium(II) dichloride leads us to examine the structure of these starting materials. Unlike (Ph2P(CH2)nPPh2)PdCl2 for n = 1-4, which are cis monomers, complexes with n = 5 or 6 are dimeric with a trans arrangement of chloro substituents; the molecular structure of trans-[(Ph2P(CH2)6PPh2)PdCl 2]2 is presented: triclinic, P1; a = 9.448 (2), b = 11.772 (2), c = 16.983 (3) ?; α = 74.18 (2), β = 87.14 (2), γ = 77.59 (2)°; V = 1774.9 (9) ?3, Z = 2; RF = 5.17%. A detailed comparison of this structure with those of related complexes is made.
- Housecroft, Catherine E.,Shaykh, Bilal A. M.,Rheingold, Arnold L.,Haggerty, Brian S.
-
p. 125 - 130
(2008/10/08)
-
