Search results for "Catalysis"
showing 10 items of 5944 documents
Heterogenizing palladium tetraiodide catalyst for carbonylation reactions
2022
We report the first example of successful heterogenization of the classical PdI42- carbonylation catalyst, achieved in two simple steps from ionic liquid-functionalized multi-walled carbon nanotubes (MWCNTs). The newly developed materials (PdI4@MWCNT-imi-X, X = Br, I) present the PdI42- anion supported on an imidazolium network (imi) grown on MWCNTs and have been fully characterized. The activity of PdI4@MWCNT-imi-X has been successfully tested in a paradigmatic carbonylation reaction, the oxidative monoaminocarbonylation of 1-alkynes with amines to give high value added 2-ynamides (obtained in good yields, 50–84%, starting from various substrates). The heterogeneous catalyst could be easil…
Amide functionalized aminobisphenolato MoO2 and WO2 complexes: Synthesis, characterization, and alkene epoxidation catalysis
2023
The use of dioxidomolybdenum(vi) and -tungsten(vi) complexes supported by a variety of structurally different tri- and tetradentate aminobisphenolato ligands as pre-catalysts in the epoxidation of alkenes is well established. However, under the widely used standard 1 mol-% catalyst loadings these types of complexes generally show modest activity only. Recently, amide functionalities in the ligand design of various aminomonophenolato MoO2 complexes have been shown to lead to heightened catalytic activity in alkene epoxidation. In this paper we show that similar ligand amide functionalization can lead to significant enhancement in the alkene epoxidation activity of aminobisphenolato MoO2 comp…
Structure-Based Design of an RNA-Bindingp-Terphenylene Scaffold that Inhibits HIV-1 Rev Protein Function
2013
Inside Back Cover: Structure-Based Design of an RNA-Bindingp-Terphenylene Scaffold that Inhibits HIV-1 Rev Protein Function (Angew. Chem. Int. Ed. 50…
2013
P-chirogenic secondary phosphine oxides : new synthesis and applications
2015
A new stereoselective synthesis of phosphinous acid boranes is described by hydrolysis of aminophosphines boranes prepared by reaction of the oxazaphospholidine complex derived from ephedrine with organolithium reagents.By reaction with a strong acid, the phosphinous acid boranes lead to the corresponding P-chirogenic secondary phosphine oxides in very good yields (90%) and with complete retention of the configuration at the phosphorus atom. The secondary phosphine oxides have been used in asymmetric hydrogenation and intramolecular Heck cyclisation using rhodium and palladium complexes, respectively. In a second part, a new synthesis of P-chirogenic ortho-halogenophenyl phosphine oxides is…
Sequential Suzuki/Asymmetric Aldol and Suzuki/Knoevenagel Reactions Under Aqueous Conditions
2012
Here we describe for the first time a sequential Suzuki/asymmetric aldol reaction. Such sequential approach was achieved through the combined use of an ionic liquid supported palladium catalyst and the organocatalyst trans-4-(2,2-diphenylacetoxy)proline. Suzuki and asymmetric aldol reactions were performed under aqueous conditions. The use of a palladium catalyst under basic conditions allowed also the first example of sequential Suzuki/Knoevenagel reaction. Reactions were carried out under aqueous conditions and products were isolated in good to high yields and, in the case of the Suzuki/aldol reaction, with diastereoselectivities up to 91:9 and enantioselectivities up to at least 99 %.
Solvent Exchange in Thermally Stable Resorcinarene Nanotubes
2006
The assembly of C-methyl resorcinarene into a tubular supramolecular solid-state structure, its thermal stability, and its hosting properties are reported. Careful control of the crystallisation conditions of C-methyl resorcinarene and 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane (1,4-dimethyl DABCO) dibromide leads to a formation of two crystallographically different, but structurally very similar, solid-state nanotube structures. These structures undergo a remarkable variety of supramolecular interactions, which lead to the formation of 0.5 nm diameter nonpolar tubes through the crystal lattice. The formation of these tubes is templated by suitably sized small alcohols, namely, n-propano…
Folding induced supramolecular assembly into pH-responsive nanorods with a protein repellent shell
2018
We report the synthesis of ABA' triblock peptide-polysarcosine-peptide conjugates featuring two complementary phenylalanine-histidine pentapeptide strands A/A'. These sequences encode for antiparallel beta-sheet formation into folded conjugates, which promote the self-assembly into polysarcosine-shielded core-shell nanorods. These do not cause aggregation of serum proteins in human blood plasma underlining an enhanced stability.
Molecular-Level Characterization of Heterogeneous Catalytic Systems by Algorithmic Time Dependent Monte Carlo
2009
Monte Carlo algorithms and codes, used to study heterogeneous catalytic systems in the frame of the computational section of the NANOCAT project, are presented along with some exemplifying applications and results. In particular, time dependent Monte Carlo methods supported by high level quantum chemical information employed in the field of heterogeneous catalysis are focused. Technical details of the present algorithmic Monte Carlo development as well as possible evolution aimed at a deeper interrelationship of quantum and stochastic methods are discussed, pointing to two different aspects: the thermal-effect involvement and the three-dimensional catalytic matrix simulation. As topical app…