Top PDF Synthesis of benzoprostacyclins using palladium catalysis

Synthesis of benzoprostacyclins using palladium catalysis

Synthesis of benzoprostacyclins using palladium catalysis

It is‘ceni?ed that error appears in the above-indenti?ed patent and that said Letters Patent is hereby corrected as shown below:... UNITED STATES PATENT AND TRADEMARK OFFICE.[r]

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Free radical catalyzed synthesis of benzoprostacyclins

Free radical-catalyzed synthesis of benzoprostacyclins

In accord with the present method, a compound of the formula III, wherein R2 is as defined above, and preferably isH; R' is as defined above, and preferably is C,-C12alkyl and A is as de[r]

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Facile construction of benzylic quaternary centers via palladium catalysis

Facile construction of benzylic quaternary centers via palladium catalysis

The synthesis of this architectural element has remained a challenge and continues to be an actively studied area over the past decade. 1,2 The convenience rendered by a selective and mild approach to install these units is so significant that it can shorten synthesis routes considerably and greatly increase yields. A clear example of this is the synthesis of (-)-α-cuparenone, in which this seemingly simple target, by non-catalytic approach, required a linear sequence of 16 steps to synthesize the molecule. 8 A straightforward conjugate addition, on the other hand, allowed the synthesis of the same compound in merely 2 steps (Section 4.5, Chapter 4).
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Versatile relay and cooperative palladium(0) N heterocyclic carbene/copper(I) N heterocyclic carbene catalysis for the synthesis of tri  and tetrasubstituted alkenes

Versatile relay and cooperative palladium(0) N heterocyclic carbene/copper(I) N heterocyclic carbene catalysis for the synthesis of tri and tetrasubstituted alkenes

terminal alkynes and symmetrical di-substituted alkynes. In addition, control of the regioselectivity remained challenging, especially in the case of unsymmetrical internal alkynes. Recently, Semba and Nakao have developed the arylboration of alkenes using a Cu/Pd dual catalysis system and applied it to one alkyne example, using diphenylacetylene and 4- bromoanisole. [18] Although limited to a sole example, this procedure supports the feasibility of a dual catalytic approach. Very recently, Brown extended the carboboration of internal alkynes with various aryl iodides. [19] Nonetheless, this strategy remains limited to aryl iodides at very high catalyst loading (10 mol% of [Cu(Cl)(PCy 3 )]). Our group has also contributed to the
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Tandem palladium and isothiourea relay catalysis : enantioselective synthesis of α amino acid derivatives via allylic amination and [2,3] sigmatropic rearrangement

Tandem palladium and isothiourea relay catalysis : enantioselective synthesis of α amino acid derivatives via allylic amination and [2,3] sigmatropic rearrangement

used in this protocol, giving syn-14 in reduced 58% yield, 92:8 dr and 97:3 er (Table 2, entry 11). 29 Screening alternative N,N- dimethylglycine aryl esters under the optimized conditions showed that the 3,5-bis-tri fl uoromethylphenyl ester gave good conversion into the corresponding rearrangement product with high stereoselectivity (Table 2, entry 12). However, use of either 2,4,6-trichlorophenyl, 2,3,5,6-tetra fl uorophenyl, or penta- fluorophenyl esters resulted in low conversions into the respective products. 25 This contrasts the fi ndings of both Snaddon 9 and Hartwig, 10 who showed that penta fl uorophenyl arylacetic esters were optimal in their enantioselective α - allylation protocols using isothioureas in combination with either Pd or Ir catalysis, respectively. To further probe the e ff ect of the allylic leaving group a range of alternative cinnamyl alcohol derivatives was also tested under the previously optimized conditions. While both cinnamyl acetate and cinnamyl methyl carbonate gave poor conversion into product 14, 25 use of cinnamyl tri fl uoroacetate gave 14 in good yield with high stereoselectivity (Table 2, entry 13).
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Palladium/Imadazolium Salt Mediated Cyclisations for the Synthesis of Heterocyclic Compounds

Palladium/Imadazolium Salt Mediated Cyclisations for the Synthesis of Heterocyclic Compounds

We describe herein our findings on palladium/imidazolium salt mediated protocols for intramolecular cyclisa- tion reactions on to aryl iodides. Our studies have revealed that palladium/imidazolium salt catalysis can be used to synthesize a range of heterocyclic compounds from cheaper and readily available starting materials and pre- cursors. Yields of these reactions are particularly good, and the products are free from contamination by phos- phine related by-products, making them easily isolable.

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Iridium Complexes with Cp* Ligand: Synthesis, Characterization and Application in Catalysis.

Iridium Complexes with Cp* Ligand: Synthesis, Characterization and Application in Catalysis.

reactions in industry often undergo radical autoxidation processes. For example, in the oxidation of terephthalic acid, a starting compound for the manufacture of polyester, used in clothing and to make plastic bottles. [6] These methods are limited to substrates that proceed via selective radical chemistry. An example of aerobic oxidations in industry by non-radical metal mediated process is the Wacker process which was developed more than 40 years ago. [6] It is the first organometallic or organopalladium reaction applied on industrial scale. However, it remains a rare example of a nonradical aerobic oxidation. In the Wacker process, ethylene is oxidized to acetaldehyde by oxygen in presence of palladium catalyst in water.
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Pd catalysed synthesis of phosphines for homogeneous catalysis

Pd catalysed synthesis of phosphines for homogeneous catalysis

The microwave-mediated palladium catalysed P-C bond forming reaction was then investigated. The bulky o-trifluoromethyl-bromobenzene was chosen for use in a model study, as we were interested in finding out if the reaction could proceed on bulky substrates. Different nucleophiles were tested and secondary diphenylphosphine in the presence of DABCO was found to be the best nucleophile, allowing the reaction to proceed with high yield in just 20 minutes, giving high conversions. Moreover, different catalysts were also tested in the reaction and dippf base palladium complex was found to be the catalyst of choice. This reaction was proven to be applicable to different bromoaryl substrates, always producing high yields. It was interesting to discover that not the strongest nucleophiles did not produce the best results. Also of interest was the fact that increasing the amount of nucleophile meant the reaction would not proceed. This difference might be due to interference of the nucleophile with the active palladium catalyst. However, some mechanistic and kinetic studies are necessary to clarify the reasons behind this behaviour.
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Improved Synthesis and New Applications of N-Heterocyclic Carbenes for Catalysis.

Improved Synthesis and New Applications of N-Heterocyclic Carbenes for Catalysis.

Initial studies indicated that reactivity of the NHC-cyclopropanone adduct under transition- metal conditions occurred at high temperatures (>80ºC) without the assistance of other ligands or reagents. Combining this information with known cyclopropanol transformations, we explored a variety of palladium-catalyzed reaction conditions as shown in Table 2.4 below. Most notably, we failed to see any product formation under these selected conditions, regardless of the palladium source, coupling partner, or other reaction condition changes, each producing a similar complex mixture of undesired products with various amounts of recovered starting material. As observed
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Preparation of Palladium Particles-decorated Manganese Dioxide and Its Catalysis towards Oxygen Reduction Reaction (ORR)

Preparation of Palladium Particles-decorated Manganese Dioxide and Its Catalysis towards Oxygen Reduction Reaction (ORR)

oxidation reaction (MOR) [7], and ethanol oxidation reaction (EOR) [8]. For example, Zhang [9] synthesized carbon-supported Pd–Co alloy electrocatalysts, and found that the optimal heat-treatment temperature in the synthesis of Pd-Co alloys was 300 ℃. Wong [10] reported the preparation of palladium nanoplates array (PdNPA) directly grown on a gold substrate, and addressed that PdNPA electrode showed extraordinary electrocatalytic activity towards MOR.

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Synthesis, structure and dynamics of NHC based palladium macrocycles

Synthesis, structure and dynamics of NHC based palladium macrocycles

N-heterocyclic carbenes (NHCs) have quickly emerged as a powerful class of carbon-based ligand in organometallic chem- istry and catalysis. 1 With generally stronger σ -donating charac- teristics and orthogonal steric profiles to widely used phosphine ligands, NHCs are rapidly being established as ligands of choice for many transition metal catalysed reac- tions. Aided by simple and e ffi cient synthetic protocols, intri- cate polydentate ligand topologies can be readily constructed based on NHC donors. 2,3 Building on the flourishing chem- istry of phosphine-based pincer complexes, 4 analogous NHC- based tridentate architectures have received considerable attention in particular. 2,5 Archetypical NHC pincer ligands are derived from bis(imidazol-2-ylidene)-benzene, pyridine, xylene or lutidine frameworks (Fig. 1) and the coordination chemistry of these CNC and CCC pincer ligands has been explored for a variety of late transition metals. 2,5,6 Notably, palladium CNC based complexes have been thoroughly investigated, following
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A Facile Green Tea Assisted Synthesis of Palladium Nanoparticles Using Recovered Palladium from Spent Palladium Impregnated Carbon60-73

A Facile Green Tea Assisted Synthesis of Palladium Nanoparticles Using Recovered Palladium from Spent Palladium Impregnated Carbon60-73

ash may also interfere with the carbon adsorption by competitive adsorption and catalysis (51). The obtained ash content for the material used in the present study was 8.62% as it also contains Pd. Since the pH values of most commercial carbons are produced by their inorganic components, the ash content may affect the pH of the carbon. The acidic or basic nature of an activated carbon depends on its preparation and inorganic matter content along with the chemically active oxygen groups on its surface. In addition, the kind of chemical treatment to which the activated carbon is subjected would also determine the pH. The pH of the Pd/C used in this study was slightly alkaline suggesting that the carbon surface was essentially negatively charged (1).
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The Synthesis and Characterization of Metal Oxide Nanoparticles and Its Application for Photo catalysis

The Synthesis and Characterization of Metal Oxide Nanoparticles and Its Application for Photo catalysis

Abstract- In the present study different metal oxide nanoparticles (Magnesium, Zinc and Copper) were synthesized using two different methods wet chemical method and hydrothermal method. These nanoparticles were characterized using FESEM, EDAX and XRD to investigate their structural and morphological properties. Their potential for dye degradation is experimentally verified. XRD data was used to calculate the particle size using Debye Scherrer formula and it was found to be in the nano-range. SEM analysis also supported that metal oxide particles are in the nano-range with varying morphology. EDAX confirms the presence of metals Zn, Mg and Cu in the respective oxides. The dye degradation activity of ZnO, MgO and CuO nanoparticles were investigated by the degradation of methylene blue (MB) and Eriochrome black-T(EBT) dye in aqueous medium under natural sunlight. Results indicate that MgO nanoparticles have better photocatalytic efficiency under natural sunlight as compared to ZnO and CuO nanoparticles for methylene blue dye and ZnO nanoparticles higher dye degradation for Erichrome Black-T dye. Such photocatalytic activity was not observed for metal oxides in bulk and also was not observed in dark conditions. Wet chemical route for synthesis of nano-metal oxides was found to be very simple, cost-effective technique for development of metal oxide nano-particles This can be developed as effective method for dye degradation thus reducing organic dye waste load from effluents of industries. Index Terms- Hydrothermal Method, Metal oxide nanoparticles, Photocatalysis, SEM, Wet-Chemical Method, XRD
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Synthesis and applications to catalysis of novel cyclopentadienone iron tricarbonyl complexes

Synthesis and applications to catalysis of novel cyclopentadienone iron tricarbonyl complexes

A series of cyclopentadienone iron tricarbonyl complexes with diverse structures were prepared, in each case using the intramolecular cyclisation of a diyne as a key step. The complexes were generated as enan- tiomerically enriched through (i) asymmetric synthesis of a C 2-symmetric diol following a reported proto- col, (ii) resolution of enantiomerically-enriched diastereoisomers formed from a chiral alcohol and (iii) kinetic resolution of a racemic ketone-containing iron tricarbonyl complex. The approaches underline the diversity of the synthetic routes which can be employed in the synthesis of homochiral cyclopentadie- none iron tricarbonyl complexes. Although the complexes proved to be e ff ective as catalysts for the reduction of ketones, the alcohol products were formed in low ees (not exceeding ca . 35%), highlighting the challenging nature of asymmetric catalysis using complexes of this type.
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Selective synthesis of Fe3O4Aux
              Agy
               nanomaterials and their potential applications in catalysis and nanomedicine

Selective synthesis of Fe3O4Aux Agy nanomaterials and their potential applications in catalysis and nanomedicine

The hybrid nanostructures with two or more compo- nents have attracted more attention due to the synergistic properties induced by their interactions. In the synthesis of nanocomposites, several techniques such as co-reduc- tion of mixed ions, organic-phase temporary linker and seed-mediated growth have been explored [28, 29]. All of them have proven their feasibility and advantages. The aim of the application is the main motivation of the cho- sen technique as the structure and surface composition of the shell or the core are among the primordial param- eters on which the properties of the nanocomposites are subjugated [30, 31].
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New oxides for oxygen evolution catalysis from hydrothermal synthesis

New oxides for oxygen evolution catalysis from hydrothermal synthesis

There are many synthetic routes for preparing oxides with the majority of the oxides mentioned in the previous section produced through solid state (ceramic) methods. The ceramic method involves the heating of mixtures of separate precursors, typically carbonates and oxides, to temperatures of 1000 °C or above for extended periods of time, facilitating ion migration. Owing to the large distances the ions must migrate, materials synthesised in this fashion must be ground and fired multiple times. 107 Local inhomogeneity and concentration gradients are common among materials synthesised in this fashion. The synthesis of some phases calls for not only these high temperatures but vast pressures be applied during the synthesis. 95 Additionally some reactions require the use of oxidising or reducing atmospheres in order to control the oxidation state of the metals in the final material. 53,57 Because of the extreme temperatures used, only the most thermodynamically stable phases are formed and these techniques offer very little in terms of control of particle size, generally yielding materials with a high crystallinity and large particle sizes. This makes them poor candidates
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Preparative semiconductor photoredox catalysis : an emerging theme in organic synthesis

Preparative semiconductor photoredox catalysis : an emerging theme in organic synthesis

Heterogeneous semiconductor photoredox catalysis (SCPC), particularly with TiO 2 , is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i) interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii) interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabi- lized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalo- genations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic alde- hydes to be hydrogenated without the need for hydrogen gas.
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A Rapid Synthesis of Oriented Palladium Nanoparticles by UV Irradiation

A Rapid Synthesis of Oriented Palladium Nanoparticles by UV Irradiation

Abstract Palladium nanoparticles of average size around 8 nm have been synthesized rapidly by UV irradiation of mixture of palladium chloride and potassium oxalate solu- tions. A rod-shaped palladium oxalate complex has been observed as an intermediate. In the absence of potassium oxalate, no Pd nanoparticles have been observed. The synthesized Pd nanoparticles have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selective area electron diffraction and energy dispersive analysis by X-rays (EDAX) analyses. XRD analysis indicates the preferential orientation of cat- alytically active {111} planes in Pd nanoparticles. A plausible mechanism has been proposed for the formation of anisotropic Pd nanoparticles.
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Green Synthesis, Characterization and Uses of Palladium/Platinum Nanoparticles

Green Synthesis, Characterization and Uses of Palladium/Platinum Nanoparticles

Although platinum alloys have been used in the coron- ary artery disease, neuromodulation devices and catheters, [79] they are not selective for cancer because they influ- ence both the normal cells and cancer cells, leading to many complications. Functionalized platinum nanoparti- cles have shown size- and shape-dependent specific and selective therapeutic properties [64, 67, 80]. In many cases, platinum nanoparticles containing other organic substances have also been used as pro-drug [67, 70, 81]. Manikandan et al. [82] have shown that small platinum nanoparticles (5–6 nm) are biocompatible and exhibit apoptosis-inducing properties [49, 83]. This ability is en- hanced manifold when they are coated with polymers or fortified with phytochemicals. For instance, the herbal ex- tracts, generally used for green synthesis of nanoparticles, contain phenols, sugars and acids which act as reducing as well as stabilizing agents. Such phytochemicals in combin- ation with cis-platin synergise apoptosis in breast cancer and cervical cancer [52, 72, 84]. A combination of plat- inum nanoparticles with ion irradiation has been found to enhance the efficiency of cancer therapy [85].
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Continuous synthesis of hollow silver palladium nanoparticles for catalytic applications

Continuous synthesis of hollow silver palladium nanoparticles for catalytic applications

Figure 15b shows the increase of reduction activity of the Ag-Pd nanoparticles respect to the Ag nanoparticles seeds. It is well known that alloying of Ag-Pd leads to an increase of catalytic activities for a number of reactions such as formic acid decomposition 9 . More importantly, hollow Ag-Pd particles present an increase in activity respect to their solid counterparts, making this continuous synthesis tools a highly attractive tool for the preparation of designer catalysts with controllable morphologies and metal distributions. It is important to mention that the size and polydispersity of the alloy particles is different from the hollow ones and thus, these important factors in addition to the presence of metal salt
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