Search results for " reaction"
showing 10 items of 4906 documents
Fluorine-containing functionalized cyclopentene scaffolds through ring contraction and deoxofluorination of various substituted cyclohexenes
2018
The fluorination of some highly‐functionalized cyclopentene derivatives, obtained from various substituted cyclohexenes through a ring‐opening/ring‐contraction procedure, has been investigated. The transformations were found to be highly substrate dependent, and led to the formation of various functionalized alicyclic compounds or heterocycles containing allyl difluoride or vinyl fluoride moieties. peerReviewed
One-pot cross-enyne metathesis (CEYM)-Diels-Alder reaction of gem-difluoropropargylic alkynes.
2013
Propargylic difluorides 1 were used as starting substrates in a combination of cross-enyne metathesis and Diels–Alder reactions. Thus, the reaction of 1 with ethylene in the presence of 2nd generation Hoveyda–Grubbs catalyst generates a diene moiety which in situ reacts with a wide variety of dienophiles giving rise to a small family of new fluorinated carbo- and heterocyclic derivatives in moderate to good yields. This is a complementary protocol to the one previously described by our research group, which involved the use of 1,7-octadiene as an internal source of ethylene.
Stereoselective aldol reaction catalyzed by a highly recyclable polystyrene supported substituted prolinamide catalyst
2008
Polystyrene supported substituted prolinamide was used as catalyst in the aldol reaction between cyclohexanone or acetone and several substituted benzaldehydes in chloroform/water. This catalyst afforded aldol products in high yields and stereoselectivities, especially in the case of reactions performed with acetone. The catalyst was easily recovered by filtration and reused, after regeneration with formic acid, up to 22 times.
1,1prime-Binaphthyl-2-methylpyridinium-based peroxophosphotungstate salts: synthesis, characterization, and their use as oxidation catalysts
2009
A series of 1,1′-binaphthyl-2-methylammonium and pyridinium salts 6, 7, and 8 was synthesized through the coupling reaction of 2-(bromomethyl)-1,1′-binaphthalene (5) with the dendritic tetraallyl pyridinedicarbinol dendron 2 as well as triethylamine and 4-tert-butylpyridine. Tetraallyl pyridinedicarbinol dendron 2 was prepared by allylation of commercially available diethyl pyridine-3,5-dicarboxylate (1). The allylation of 2 with allyltrimethylsilane in the presence of boron trifluoride was unsuccessful, as tetraallyl pyridinedicarbinol trifluoroboron adduct 3 was obtained instead of expected hexaallylpyridine compound 4. The catalytic hydrogenation of allyl groups of the ammonium salt of 2…
DFT Prediction of Enhanced Reducibility of Monoclinic Zirconia upon Rhodium Deposition.
2018
Oxides are an important class of materials and are widely used, for example, as supports in heterogeneous catalysis. In a number of industrial catalytic processes, oxide supports actively participate in chemical transformations by releasing lattice oxygen anions. While this is intuitively understood for reducible oxides, the reducibility of irreducible oxides may be modified via nanoengineering or upon inclusion of foreign species. Our calculations predict that the ability of irreducible monoclinic zirconia to release oxygen improves substantially upon deposition of rhodium. Through a comprehensive screening of Rh/ZrO2 with different size of the rhodium species, we find that a Rh adatom and…
[60]Fullerene l -Amino Acids and Peptides: Synthesis under Phase-Transfer Catalysis Using a Phosphine–Borane Linker. Electrochemical Behavior
2017
International audience; A new method to link amino acid and peptide derivatives to [60]fullerene is described. It uses hydrophosphination with a secondary phosphine borane. First, the stereoselective synthesis of secondary phosphine borane amino acid derivatives was achieved by alkylation of phenylphosphine borane with gamma-iodo-alpha-amino ester reagents under phase transfer catalysis (PTC). Second, a sec-phosphine borane amino ester was saponified and coupled with alpha,gamma-diamino esters to afford the corresponding dipeptide derivatives in good yields. Finally, the hydrophosphination reaction of [60]fullerene by the sec-phosphine borane compounds was performed under PTC to obtain C-60…
Feedback and Communication in Active Hydrogel Spheres with pH Fronts: Facile Approaches to Grow Soft Hydrogel Structures
2021
Abstract Compartmentalized reaction networks regulating signal processing, communication and pattern formation are central to living systems. Towards achieving life‐like materials, we compartmentalized urea‐urease and more complex urea‐urease/ester‐esterase pH‐feedback reaction networks into hydrogel spheres and investigate how fuel‐driven pH fronts can be sent out from these spheres and regulated by internal reaction networks. Membrane characteristics are installed by covering urease spheres with responsive hydrogel shells. We then encapsulate the two networks (urea‐urease and ester‐esterase) separately into different hydrogel spheres to devise communication, pattern formation and attracti…
Methylprednisolone-induced hepatotoxicity in a 16-year-old girl with multiple sclerosis.
2018
Multiple sclerosis (MS) is a chronic inflammatory disease with demyelination of the central nervous system. High-dosage corticosteroids are the first-line therapy in the acute relapsing of MS. We report a case of severe high-dose methylprednisolone-induced acute hepatitis in a patient with a new diagnosis of MS. A 16-year-old girl was admitted for urticaria, angioedema, nausea and vomiting a month later she had been diagnosed with MS and treated with high-dosage methylprednisolone. Laboratory investigations showed hepatic insufficiency with grossly elevated liver enzymes. A liver biopsy showed focal centrilobular hepatocyte necrosis with interface hepatitis. Methylprednisolone-induced hepat…
Testing the nature of the Λ(1520)-resonance in proton-induced production
2006
The $\Lambda(1520)$ resonance has been recently studied in a unitarized coupled channel formalism with $\pi\Sigma(1385)$, $K\Xi(1530)$, $\bar{K}N$ and $\pi\Sigma$ as constituents blocks. We provide a theoretical study of the predictions of this model in physical observables of the $pp\to pK^+K^-p$ and $pp\to pK^+\pi^0\pi^0\Lambda$ reactions. In particular, we show that the ratio between the $\pi^0\pi^0\Lambda$ and $K^-p$ mass distributions can provide valuable information on the ratio of the couplings of the $\Lambda(1520)$ resonance to $\pi\Sigma(1385)$ and $\bar{K}N$ that the theory predicts. Calculations are done for energies which are accessible in an experimental facility like COSY at …
Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithioc…
2016
Abstract Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh3)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh3)Cl] (2) and [Pd(bzbudtc)(PPh3)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (1H, 13C and 31P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1–3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1–3 evidence…