Search results for "Suzuki"

Towards the synthesis of substituted porphyrins by a pyridyl group bearing a reactive functionality

2010

Pyridyl-substituted porphyrins bearing a reactive functionality were prepared via Suzuki cross-coupling reactions and resulted in very good yields. These compounds are precursors of new porphyrin architectures able to coordinate two metals: one in the porphyrin core and the second around the pyridyl moiety. During the coupling reactions, a higher reactivity of a chloro picolyl group was evidenced compared to a bromo function on the same reacting molecule.

Structurally characterized dipalladium(ii)-oxamate metallacyclophanes as efficient catalysts for sustainable Heck and Suzuki reactions in ionic liqui…

2018

A new generation of dipalladium-oxamate metallacyclophanes of formulas (n-NBu4)4 [Pd2(ppba)2] (1), (n-NBu4)4[Pd2(dpvba)2] (2), (n-NBu4)4[Pd2(dpazba)2] (3), (n-NBu4)4[Pd2(dpeba)2] (4) and (n-NBu4)4[Pd2(tpeba)2] (5) [n-NBu4+ = tetra-n-butylammonium cation, H4ppba = N,N′-1,4-phenylenebis(oxamic acid), H4dpvba = N,N′-4,4′-diphenylethenebis(oxamic acid), H4dpazba = N,N′-4,4′-diphenylazobis(oxamic acid), H4dpeba = N,N′-4,4′-diphenylethynebis(oxamic acid) and H4tpeba = N,N′-1,4-di(4-phenylethynyl)phenylenebis(oxamic acid)] was prepared. The crystal structure of the solvated species of 2–4, namely (n-NBu4)4[Pd2(dpvba)2]·6MeOH·2Et2O (2a), (n-NBu4)4[Pd2(dpazba)2]·8MeOH (3a), and (n-NBu4)2[Pd2(dpeba)2…

Synthesis and structural characterization of well-defined bis(oxamato)palladate(II) precatalysts for Suzuki and Heck reactions

2018

Abstract A family of tetra-n-butylammonium salts of bis(oxamato)palladate(II) complexes of formula (n-Bu4N)2[Pd(Lm)2]·pH2O [m = 1–9; L1 = N-phenyloxamate (pma) and p = 2 (1), L2 = N-2-methylphenyloxamate (2-Mepma) and p = 4 (2), L3 = N-4-methylphenyloxamate (4-Mepma) and p = 2 (3), L4 = N-2,3-dimethylphenyloxamate (2,3-Me2pma) and p = 3 (4), L5 = N-2,4-dimethylphenyloxamate (Me2pma) and p = 4 (5), L6 = N-2,5-dimethylphenyloxamate (2,5-Me2pma) and p = 7 (6), L7 = N-3,4-dimethylphenyloxamate (3,4-Me2pma) and p = 6 (7), L8 = N-3,5-dimethylphenyloxamate (3,5-Me2pma) and p = 5 (8)] have been prepared and characterized by spectroscopic methods. The crystal structure of 1 that has been solved by s…

Structural and transcriptional evidence of mechanotransduction in the Drosophila suzukii ovipositor

2020

Drosophila suzukii is an invasive pest that prefers to lay eggs in ripening fruits, whereas most closely related Drosophila species exclusively use rotten fruit as oviposition site. This behaviour is allowed by an enlarged and serrated ovipositor that can pierce intact fruit skin, and by multiple contact sensory systems (mechanosensation and taste) that detect the optimal egg-laying substrates. Here, we tested the hypothesis that bristles present in the D. suzukii ovipositor tip contribute to these sensory modalities. Analysis of the bristle ultrastructure revealed that four different types of cuticular elements (conical pegs type 1 and 2, chaetic and trichoid sensilla) are present on the t…

Reproductive site selection: evidence of an oviposition cue in a highly adaptive dipteran, Drosophila suzukii (Diptera: Drosophilidae)

2020

Abstract Drosophila suzukii (Matsumura) is a vinegar fly species that originates from Eastern Asia and has spread throughout Europe and the Americas since its initial detection in United States in 2008. Its relatively large, sclerotized, and serrated ovipositor enables the ability to penetrate ripening fruits, providing a protected environment for its egg and larval stages. Because the mechanism of oviposition site selection of D. suzukii is a matter of hypothesis, the aim of the present study was to elucidate behavioral and chemical aspects of short-range ovipositional site selection within the context of D. suzukii reproductive biology. The preference of D. suzukii to lay eggs on artifici…

2020

Cuticle barrier efficiency in insects depends largely on cuticular lipids. To learn about the evolution of cuticle barrier function, we compared the basic properties of the cuticle inward and outward barrier function in adults of the fruit flies Drosophila suzukii and Drosophila melanogaster that live on fruits sharing a similar habitat. At low air humidity, D. suzukii flies desiccate faster than D. melanogaster flies. We observed a general trend indicating that in this respect males are less robust than females in both species. Xenobiotics penetration occurs at lower temperatures in D. suzukii than in D. melanogaster. Likewise, D. suzukii flies are more susceptible to contact insecticides …

3D Printed Palladium Catalyst for Suzuki-Miyaura Cross-coupling Reactions

2020

Selective laser sintering (SLS) 3d printing was utilized to manufacture a solid catalyst for Suzuki-Miyaura cross-coupling reactions from polypropylene as a base material and palladium nanoparticles on silica (SilicaCat Pd(0)R815-100 by SiliCycle) as the catalytically active additive. The 3d printed catalyst showed similar activity to that of the pristine powdery commercial catalyst, but with improved practical recoverability and reduced leaching of palladium into solution. Recycling of the printed catalyst led to increase of the induction period of the reactions, attributed to the pseudo-homogeneous catalysis. The reaction is initiated by oxidative addition of aryl iodide to palladium nano…

Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aqueous Media

2010

A new PEG-tagged material, which was prepared by a threefold copper-catalyzed [3+2] cycloaddition (click chemistry), was found to act as an efficient stabilizer for palladium nanoparticles. The newly formed material proved to be active as a recyclable catalyst in Suzuki coupling; the presence of polyether chains allowed for the catalytic runs to be conducted in aqueous media.

ChemInform Abstract: Efficient Synthesis of Racemic and Chiral Alkenyl Sulfoxides by Palladium-Catalyzed Suzuki Coupling.

2010

Alkenyl sulfoxide derivatives are obtained in high yields through a palladium-catalyzed Suzuki/Miyaura cross-coupling reaction of racemic and chiral 1-halo sulfoxides with aryl and alkenyl boronic acids. Chiral substrates react with no loss of optical purity and high optical yields. The reaction takes place with different palladium catalysts, such as Pd(PPh 3 ) 4 or Pd(OAc) 2 /DABCO. Although nitrogen ligands like DABCO lead to an active palladium catalyst, they are less effective than the phosphine ones.

ORGANIC-INORGANIC HYBRID CATALYSTS BASED ON IMIDAZOLIUM AND THIAZOLIUM SALTS

In the last years, great attention was focused on immobilized ionic liquids for their application in the field of catalysis. The main challenge is represented by the possibility of combining the benefits of the ionic liquids to that of the supports. In order to achieve this ambitious objective both the choice of the support and the functionalization strategy are of fundamental importance. In this context, one of the aims of this doctoral project was to develop novel catalysts based on covalently mono- or multilayer imidazolium or thiazolium networks onto a high ordered mesoporous silica or carbon nanotubes materials. The second goal of this PhD thesis was to design novel imidazolium based c…