Alkane activation by homogeneous palladium complexes

The conversion of adamantane exclusively to 1-adamantyl trifluoroacetate in a refluxing trifluoroacetic acid solution of palladium acetate at 1 atm of air or nitrogen was confirmed. The conversion can be made quantitative. The 1-adamantyl trifluoroacetate was hydrolysed to yield 1-adamantanol in 90% isolated yield. The adamantane functionalization is accompanied by concomitant formation of a palladium mirror.     

Polymer-protected palladium nanoparticles. Morphologies and catalytic selectivities

Colloidal palladium nanocatalysts prepared by in situ reductions of palladium chloride were immobilized and protected by either of two water-soluble polymers. The particle sizes and size distributions of the palladium colloids were determined by transmission electron microscopy. Their selectivities as catalysts were determined by comparing the extents of hydrogenation of carefully chosen pairs of small-molecule olefins. There was found to be high hydrogenation selectivity with regard to cyclic vs. noncyclic olefins. Selectivity was relatively low, however, among olefins that differed only in size (such as hexene vs. octene), or olefins differing only with regard to the positions of the double bonds (such as 1-octene vs. 3-octene). Selectivity could be improved by careful choice of the immobilizing polymer, and by its use at relatively high concentrations.     

固载化催化剂在烯烃氧化合成醛酮中的应用

总结了固载化催化剂在烯烃氧化合成醛酮中的应用。着重介绍了钯配合物固载在无机载本上,钯盐和杂多化合物固载在无机载体上,钯盐固载在化催化剂在烯烃氧化合成醛酮中的应用。对负载型液相催化剂,负载型水相催化剂,负载型熔融盐Wacker催化剂,活性C固载的Pd膜及Pt膜催化剂催化烯烃氧化合成醛酮也作了简单介绍。     

Palladium chloride and polyethylene glycol promoted oxidation of terminal and internal olefins

Both terminal and internal olefins can he efficiently converted to ketones in polyethylene glycol and water using palladium chloride as the catalyst.     

Heck Reactions without Salt Formation: Aromatic Carboxylic Anhydrides as Arylating Agents

Environmentally benign and economical production of arylated olefins can be achieved by a new variant of the Heck reaction in which no halogen salts are formed. The trick is the use of aromatic carboxylic anhydrides 1 as arylating agents. With halide-activated palladium chloride as catalyst, which requires no phosphane ligands, the olefins 2 can be prepared according to Equation (a) in good yields.     

聚苯乙烯苄基(8-氨基喹啉)负载鈀催化剂的催化加氢性能

本文在带有8-氨基喹啉螯合基团的树脂上负载了二氯化钯,再经甲醇-水还原合成混合价态钯催化剂。考察并比较了两类催化剂的加氢活性及选择性,发现混合价态钯催化剂具有活性高、选择性强、金属不易流失的特点。     

On the mechanism of the palladium(II)-catalyzed decarboxylative olefination of arene carboxylic acids. Crystallographic characterization of non-phosphine palladium(II) intermediates and observation of their stepwise transformation in Heck-like processes

Mechanistic studies of a palladium-mediated decarboxylative olefination of arene carboxylic acids are presented, providing spectroscopic and, in two instances, crystallographic evidence for intermediates in a proposed stepwise process. Sequentially, the proposed pathway involves carboxyl exchange between palladium(II) bis(trifluoroacetate) and an arene carboxylic acid substrate, rate-determining decarboxylation to form an arylpalladium(II) trifluoroacetate intermediate (containing two trans-disposed S-bound dimethyl sulfoxide ligands in a crystallographically characterized form), then olefin insertion and beta-hydride elimination. Because of the unique mode of generation of the arylpalladium(II) trifluoroacetate intermediate, a species believed to be substantially electron-deficient relative to phosphine-containing arylpalladium(II) complexes previously studied, it has been possible to gain new insights into those steps that are common to the Heck reaction, namely, olefin insertion and beta-hydride elimination. The present results show that there are notable differences in reactivity between arylpalladium(II) intermediates generated by decarboxylative palladation and those produced in conventional Heck reactions. Specifically, we have found that more electron-rich alkenes react preferentially with an arylpalladium(II) trifluoroacetate intermediate formed by decarboxylative palladation, whereas an opposite trend is found in conventional Heck reactions. In addition, we have found that the aralkylpalladium(II) trifluoroacetate intermediates that are formed upon olefin insertion in the present study are stabilized with respect to beta-hydride elimination as compared to the corresponding phosphine-ligated aralkylpalladium(II) complexes. We have also crystallographically characterized an aralkylpalladium(II) trifluoroacetate intermediate derived from arylpalladium(II) insertion into norbornene, and this structure, too, contains an S-bound dimethyl sulfoxide ligand; the ipso-carbon of the transferred aryl group and trifluoroacetate function as the third and fourth ligands in the observed distorted square-planar palladium(II) complex.     

Oxidative palladium(II) catalysis: A highly efficient and chemoselective cross-coupling method for carbon-carbon bond formation under base-free and nitrogenous-ligand conditions

We report herein the development of a general and mild protocol of oxygen-promoted Pd(II) catalysis resulting in the selective cross-couplings of alkenyl- and arylboron compounds with various olefins. Unlike most cross-coupling reactions, this new methodology works well even in the absence of bases, consequently averting undesired homo-couplings. Nitrogen-based ligands including dimethyl-phenanathroline enhance reactivities and offer a highly efficient and stereoselective methodology to overcome challenging substrate limitations. For instance, oxidative palladium(II) catalysis is effective with highly substituted alkenes and cyclic alkenes, which are known to be incompatible with other known catalytic conditions. Most examined reactions progressed smoothly to completion at low temperatures and in short times. These interesting results provide mechanistic insights and utilities for a new paradigm of palladium catalytic cycles without bases.     

A method for the palladium-catalyzed allylic oxidation of olefins

Olefins are converted into allylic acetates by treatment in acetic acid with a catalytic amount of palladium bis(trifluoroacetate) and one equivalent of benzoquinone as oxidant. The reaction is selective for oxidation of a terminal methyl group of geranylacetone.     

Metal Carbonyl Spectra : by P.S. Braterman,Academic Press,London/New York/San Francisco, 1975, vii + 286 pages, $22.25.

Vinyl halides react with alkyllithium compounds in the presence of tetrakis(triphenylphosphine)palladium to give olefins stereospecifically in excellent or fairly good yields. When less reactive Grignard reagents are employed instead of alkyllithium compounds, these reactions can be carried out catalytically with palladium.     

Achieving Vinylic Selectivity in Mizoroki–Heck Reaction of Cyclic Olefins

In Heck reactions of cyclic olefins, the products usually have aryl groups that end up at the allylic and/or homoallylic position. We herein report new selectivity that adds aryl groups to the vinylic position. Cyclic olefins of various ring size worked well. The desired isomers were produced by palladium–hydride‐catalyzed isomerization of the initial products. Thus, a specific catalyst must be used so that it can perform two jobs under one set of reaction conditions.     

The Synthesis of 1-Methyl-6,7,8,8a-tetrahydro-5H-indolizin-3-one by the Palladium-Catalyzed Cyclization of N-Bromoacetyl-2-vinylpiperidine

N-Bromoacetyl-2-vinylpiperidine underwent cyclization to give indolizidine derivative in the presence of a base and a catalytic amount of palladium trifluoroacetate.     

Vinylation of aryl iodides catalyzed byMCM-41supported poly-g-mercaptopropylsiloxanePd(0,II)complexes

Summary MCM-41-supported poly-γ-mercaptopropylsiloxane palladium (0,II) complexes were easily prepared from poly-γ-mercaptopropylsiloxane and MCM-41 in chloroform, followed by coordination to palladium chloride in ethane at room temperature. These catalysts are highly active and stereoselective for vinylation of aryl iodides with olefins, and give a variety of trans substituted products in high yields at 70^oC, and can be reused without loss in activity.</o:p>     

Phosphine sulfides: Novel effective ligands for the palladium-catalyzed bisalkoxycarbonylation of olefins

Phosphine sulfides were found to be effective as a ligand in the palladium(II)-catalyzed bisalkoxycarbonylation of olefins. Aromatic olefins and vinylsilanes were converted into the corresponding succinates in high yields under mild conditions. Enantioselection was observed when chiral bisphosphine sulfides were used as ligands.     

Photoactivation of alkene oxidation by molecular oxygen in the presence of palladium

A catalytic cycle which leads to α,-β ethylenic ketones and methyl ketones from terminal alkenes in the presence of palladium trifluoroacetate,oxygen and U.V. light is described.     

New hydrogenating systems for ionic hydrogenation

Conclusions Ethyldichlorosilane and alkylisopropylbenzenes in the presence of aluminum halides are hydride ion donors in the ionic hydrogenation of olefins, alkyl halides, and trifluoroacetate derivatives of alcohols.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1322–1326, June, 1982.     

Aerobic oxidative-carbonylation of olefins. A convenient preparation of β-hydroxyalkanoic acid derivatives from olefins

A variety of β-hydroxyalkanoic acid derivatives were prepared by palladium catalyzed aerobic oxidative-carbonylations of terminal olefins at normal pressure of carbon monoxide and oxygen mixed gas.     

烯烃在HZSM-5分子筛上原位芳构化反应的研究

烯烃在ZSM-5分子筛上转化成芳烃的反应是一个非常复杂的反应,既包括聚合裂解反应,又包括氢转移、脱氢环化反应,同时也包括烷基转移和脱烷基等反应,对于这一复杂反应的机理研究较少.Vedrine等人[1]认为烯烃首先在酸性位上通过氢转移生成戊二烯正碳离子,接着环化以及扩环反应生成     

Oxydation regioselective de sulfones allyliques catalysee par le palladium et la lumiere: Formation d'aldehydes et alcools α,β-ethyleniques β-sulfonyles

The irradiation of oxygenated solutions of allyl sulfones containing small amounts of palladium trifluoroacetate led to regioselective oxidation of the allylic position furthest from the electron-withdrawing group. The efficiency of this reaction increased in the presence of copper(II).     

Aromatic-amide-derived olefins as a springboard: isomerization-initiated palladium-catalyzed hydrogenation of olefins and reductive decarbonylation of acyl chlorides with hydrosilane

A highly efficient catalytic protocol for the isomerization of substituted amide-derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl(2)(PPh(3))(2)] and HSi(OEt)(3). The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis-trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide-derived olefin ligand, and the products were obtained in high isolated yields (up to >99?%). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)-olefin with an aromatic amide moiety was used as a ligand.