Showing papers on "Palladium published in 1985"
437 citations
397 citations
TL;DR: The palladium catalyzed cross-coupling reaction of organotin reagents with a variety of organic electrophiles that generates a new carbon-carbon bond has been discovered recently as mentioned in this paper.
Abstract: A novel, synthetically useful palladium catalyzed cross-coupling reaction of organotin reagents with a variety of organic electrophiles that generates a new carbon—carbon bond has been discovered recently. Because this mild, versatile reaction is tolerant of a wide variety of organic functionality on either coupling partner, is stereospecific, and gives high yields, it is ideal for use in the synthesis of complicated organic molecules. In the presence of carbon monoxide, instead of a direct coupling reaction, carbon monoxide insertion takes place, stitching the coupling partners together and generating a ketone. The utility of this coupling reaction has been demonstrated by the synthesis of a macrodiolide antibiotic, marine sesquiterpenes, insect pheremones and a number of key synthetic intermediates.
315 citations
TL;DR: In this article, conjugated dienoates, dienones and dienals are obtained with high stereospecificity (⩾95%) and in high yields from the corresponding (E,E) and (Z) vinylic halides, and substrates (methyl acrylate, methyl vinyl ketone or acrolein).
285 citations
TL;DR: Allylation de β-cetoesters and du malonate de diethyle a l'aide des (alcene-1yl methyl) carbonates as discussed by the authors.
Abstract: Allylation de β-cetoesters et du malonate de diethyle a l'aide des (alcene-1yl methyl) carbonates. Allylation par le diallylcarbonate de composes nitro, cyano, sulfonyles et carbonyles
217 citations
TL;DR: In this paper, a phase Pd-C is formee quand Pd est chauffe dans une atmosphere d'ethylene, acetylene ou CO, and the processus fait intervenir le depot d'une surcouche carbonacee, suivie d'un diffusion activee des atomes de C a travers le reseau metallique.
Abstract: Une phase Pd-C est formee quand Pd est chauffe dans une atmosphere d'ethylene, acetylene ou CO. Ce processus fait intervenir le depot d'une surcouche carbonacee, suivie d'une diffusion activee des atomes de C a travers le reseau metallique. Etude RX
215 citations
208 citations
TL;DR: In this article, the authors compare intra-and inter-molecular activations of carbon-hydrogen bonds in arenes by palladium(II) in terms of the ratio kintra/kinter is not less than 3.6 × 102 mol dm−3.2.
Abstract: Addition of excess of NN-dimethylbenzylamine to a chloroform solution of [Pd3(O2CMe)6] leads to instantaneous depolymerisation of the trimer giving the monomer trans-[Pd(O2CMe)2(PhCH2NMe2)2]. Reversible dissociation of the amine from the latter affords a pseudo-three-co-ordinate 14-electron intermediate [Pd(O2CMe)2(PhCH2NMe2)] which undergoes subsequent rate-limiting ortho-palladation to form the cyclopalladated acetate-bridged dimer [{Pd(O2CMe)(C6H4CH2NMe2)}2]. The rate-limiting step is electrophilic in character; the slope of the corresponding Hammett plot for differently ring-substituted NN-dimethylbenzylamines is –1.6. The kinetic isotope effect, kH/kD, for PhCH2NMe2 is 2.2 ± 0.2. The activation entropy for the rate-limiting step is very negative, ca. –250 J K–1 mol–1 for PhCH2NMe2, suggesting a highly ordered tight transition state. This dissociative path is a factor of ca. 100 faster than a parallel one, involving the 16-electron monomer trans-[Pd(O2CMe)2(PhCH2NMe2)2] but without loss of the amine. Ortho-palladation is not rate-limiting in acetic acid solvent, where slow cleavage of acetate bridges in polynuclear palladium species occurs, affording a vacant co-ordination site for subsequent rapid ortho-palladation. A comparison of intra- and inter-molecular activations of carbon-hydrogen bonds in arenes by palladium(II) in terms of ‘effective molarities’ shows that the ratio kintra/kinter is not less than 3.6 × 102 mol dm–3.
194 citations
TL;DR: In this article, the reaction of benzene solutions of arylacetylenes with 1 equiv of chloroacetone and 2 equiv. of Et3N, using a mixture of (PPh3)4 Pd and CuJ as catalyst, affords 1,4-diaryl-butadiynes in very good yields.
173 citations
TL;DR: Divers halogenures d'aryles sont convertis catalytiquement en α-cetoamides and amides par traitement avec des amines secondaires and le monoxyde de carbone.
Abstract: Divers halogenures d'aryles sont convertis catalytiquement en α-cetoamides et amides par traitement avec des amines secondaires et le monoxyde de carbone
TL;DR: Tributylstannyl alkyl or aryl sulfide and bis(tributyl stannyl) sulfide were found to be useful to prepare arylsides in good yields under the usual conditions of the palladium-catalyzed reaction with aryln bromides as discussed by the authors.
Abstract: Tributylstannyl alkyl or aryl sulfide and bis(tributylstannyl) sulfide were found to be useful to prepare aryl sulfides in good yields under the usual conditions of the palladium-catalyzed reaction with aryl bromides.
TL;DR: Ketones can be homologated to α,gb-unsaturated esters or amides via their enol triflates by a palladium-catalyzed reaction with carbon monoxide and alcohols or amines.
TL;DR: In this article, the authors studied the dispersion of PdO as a function of oxygen treatment and found that dispersion occurs only after complete oxidation and the temperature of redispersion depends on the particle size.
Abstract: The oxidation state of Pd as determined by TPR (temperature-programmed reduction) and its dispersion (measured by oxygen adsorption) are studied as a function of oxygen treatment. It is found that dispersion occurs only after complete oxidation. The temperature of redispersion depends on the particle size. Some evidence is given for the existence of a two-dimensional surface phase (PdO)/sub sc/. This species is proposed to be responsible for the redispersion process, i.e., spreading of PdO, as well as for sintering by its decomposition. 8 references, 2 figures, 1 table.
Book•
23 May 1985
TL;DR: The fundamentals of the primary process during collisions Adsorption and desorption Metallic structures and bonding Low energy electron diffraction Electron emission Surface potentials and vibrational spectra General background to heterogeneous catalysis and its application to the reaction o hydrogen isotopes The catalytic oxidation of carbon monoxide on palladium and platinum as mentioned in this paper.
Abstract: The fundamentals Primary process during collisions Adsorption and desorption Metallic structures and bonding Low energy electron diffraction Electron emission Surface potentials and vibrational spectra General background to heterogeneous catalysis and its application to the reaction o hydrogen isotopes The catalytic oxidation of carbon monoxide on palladium and platinum.
TL;DR: In this article, the authors investigated the cycle of carbon dioxide cycling on silica-supported palladium with different values of D, the percentage of metal exposed to carbon dioxide, and found that the selectivity of CO-H2 reactions might shift to methane at the expense of methanol with decreasing palladium particle size.
TL;DR: Synthese de la lipoxine A (acide trihydroxy-5,6,15 eicosatetraene-7,9,11,13oique) et de ses isomeres tout-trans
Abstract: Synthese de la lipoxine A (acide trihydroxy-5,6,15 eicosatetraene-7,9,11,13oique) et de ses isomeres tout-trans
TL;DR: In this paper, the reaction of vinyl cyclopentanes having two electron-withdrawing groups with α,β-unsaturated esters or ketones in the presence of Pd 2 (dba) 3.
TL;DR: Synthese regio-and diastereoselective de cis-diols-1,2 (sous forme de carbonate) a partir de vinylepoxydes par reaction avec le dioxyde de carbone en presence of (triisopropylphosphite) 3 palladium as mentioned in this paper.
Abstract: Synthese regio- et diastereoselective de cis-diols-1,2 (sous forme de carbonate) a partir de vinylepoxydes par reaction avec le dioxyde de carbone en presence de (triisopropylphosphite) 3 palladium
TL;DR: In this paper, a detailed study of the chemistry of the palladium-carbon bond was performed on η3-allylpalladium complexes, which are frequently involved as intermediates in the Pd-catalyzed transformations of dienes.
Abstract: The use of transition-metal complexes as homogeneous catalysts for the production of organic chemicals is of considerable industrial significance. Although palladium complexes have not attained the same importance as, for example, those of rhodium or cobalt, palladium is nonetheless one of the most versatile metals for synthetic organic purposes. An understanding of the role played by the metal in these reactions is essential for their optimal utilization. This necessarily entails a detailed study of the chemistry of the palladium-carbon bond. In this article we concentrate on η3-allylpalladium complexes, which are frequently involved as intermediates in the Pd-catalyzed transformations of dienes. The study of their behavior gives a deeper insight into the individual steps of a catalytic cycle.
TL;DR: Le palladium ancre sur du polystyrene phosphine avec un rapport Pd/P de 1:1 presente une activite elevee dans l'arylation de l'acrylate de methyle et du styrene par l'iodobenzene as mentioned in this paper.
Abstract: Le palladium ancre sur du polystyrene phosphine avec un rapport Pd/P de 1:1 presente une activite elevee dans l'arylation de l'acrylate de methyle et du styrene par l'iodobenzene. Une etude comparative montre que ce catalyseur est beaucoup plus efficace que Pd/C, Pd(OCOCH 3 ) 2 , PdCl 2 , Pd(OCOCH 3 ) 2 /2P(C 6 H 5 ) 3 ou P(P(C 6 H 5 ) 3 ) 4
TL;DR: In this paper, a modified carbon electrode for the amperometric determination of hydrogen peroxide is described, by deposition of a 15nm thick layer of a 40:60 mixture of palladium and gold on the surface of the electrode, the overvoltages for both the oxidation and reduction can be decreased by at least 800 mV.