Search results for " Synthesis"
showing 10 items of 1625 documents
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(ii)–iminopyridine complexes
2008
The copper complex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.
Fluorinated Heterocyclic Compounds. An Effective Strategy for the Synthesis of Fluorinated Z-Oximes of 3-Perfluoroalkyl-6-phenyl-2H-1,2,4-triazin- 5-…
2005
The reaction of 3-benzoyl-5-perfluoroalkyl-1,2,4-oxadiazoles with hydrazine has been investigated, evidencing the possibility of competitive reaction paths. Nucleophilic addition of the hydrazine to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring opening and ring closure with enlargement, leads with high yield and in very mild experimental conditions to the formation of Z-oximes of 3-perfluoroalkyl-6-phenyl-2H-1,2,4-triazin-5-ones (11a-c) as major products of the reaction. In turn, the hydrazine can attack the electrophilic carbonyl carbon giving 4-perfluoroacylamino-5-phenyl-2H-1,2,3-triazoles (13a-c) through the well-known Boulton-Katritzky rearrangement of the inter…
Polymerization reactions and modifications of polymers by ionizing radiation
2020
International audience; Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers. For decades, low linear energy transfer (LLET) ionizing radiation, such as gamma rays, X-rays, and up to 10 MeV electron beams, has been the primary tool to produce many products through polymerization reactions. Photons and electrons in…
Kinetic Modeling of Ethyl Benzoylformate Enantioselective Hydrogenation over Pt/Al2O3
2014
A kinetic model was developed for the enantioselective hydrogenation of ethyl benzoylformate (EBF) on a modified Pt/Al2O3 catalyst. This model was based on the assumption of different numbers of si...
Knowledge formalization and recommendation in computational design synthesis for 4D printing
2022
Coined in 2013, 4D printing is considered as a promising technology that combines additive manufacturing (AM) processes and smart materials (SMs). Through this technology objects can change over time in terms of functionalities, shape, or properties under the effect of energy stimulation. Although AM processes allow shape, hierarchical, functional, and materials complexities to the 3D objects, the conjunction with SMs provides much more freedom in designing adaptive/transformative structures. Over the last decade, a growing body of research with ad hoc proofs-of-concept have been proposed at the physical level (i.e., by using different AM processes with commercial or customized 3D printers …
Litiju saturošu keramiku cietfāžu sintēze un raksturošana
2021
“Litiju saturošu keramiku cietfāžu sintēze un raksturošana”. Seņko M., darba vadītājs vadošais pētnieks Dr. chem. Zariņš A. Zinātniskie konsultanti pētniece, Mg. chem. Avotiņa L. un pētniece, Mg. chem. Trimdale A. Bakalaura darbs, 45 lapas, 31 attēls, 5 tabulas, 54 literatūras avoti, 5 pielikumi. Latviešu valodā. Literatūras apskatā apkopota informācija par procesiem kodoltermiskās sintēzes reaktoros, litiju saturošu savienojumu īpašībām un sintēzes metodēm, raksturotas darbā izmantotās analīžu metodes. Eksperimentālajā daļā ar cietfāžu sintēzes metodi ieguva vairākus litiju saturošus savienojumus, izmantojot dažādus sintēzes parametrus. Fāžu sastāva un termisko īpašību noteikšanai izmantoj…
Resveratrol-Related Dehydrodimers: Laccase-Mediated Biomimetic Synthesis and Antiproliferative Activity
2012
Seven resveratrol-related monomeric stilbenoids were submitted to biomimetic oxidative coupling in the presence of laccase from Trametes versicolor (TvL), and gave racemic dihydrobenzofuran dehydrodimers (±)-15 to (±)-21. These products, after spectral characterization, were submitted to an antiproliferative activity bioassay against SW480 human colon cancer cells. Five racemates were found to be active, and were resolved by chiral HPLC. The pure enantiomers were subjected to circular dichroism measurements to establish their absolute configurations at C-7 and C-8. These enantiomerically pure compounds were submitted to the antiproliferative activity assay towards SW480 cells, and were all …
Enantioselective Henry addition of methyl 4-nitrobutyrate to aldehydes. Chiral building blocks for 2-pyrrolidinones and other derivatives.
2010
A catalytic highly enantioselective Henry addition of methyl 4-nitrobutyrate to aldehydes using a Cu(II)-amino pyridine complex as catalyst is described. The products resulting from this reaction constitute a new, highly versatile family of chiral building blocks as a result of the presence of three different functional groups on the molecule. These products have been transformed into nonracemic chiral gamma-lactams, 5-hydroxy-5-substituted levulinic acid derivatives, and delta-lactones.
A Route to Grow Oxide Nanostructures Based on Metal Displacement Deposition: Lanthanides Oxy/Hydroxides Characterization
2012
Combining organocatalysis and lanthanide catalysis: a sequential one-pot quadruple reaction sequence/hetero-Diels-Alder asymmetric synthesis of funct…
2016
A stereoselective one-pot synthesis of functionalized complex tricyclic polyethers has been achieved using the combination of secondary amine and lanthanide catalysis. This one-pot quadruple reaction/Hetero-Diels–Alder sequence gave good yields (per step) as well as excellent diastereo- and enantioselectivities. Furthermore, the particular combination of lanthanide complexes with organocatalysis is one of the first examples described for sequential catalysis.