Enantioselective Hydrogenation
Mostrando 1-10 de 10 artigos, teses e dissertações.
-
1. New Strategies in Enantioselective Hydrogenation on Supported Transition Metal Catalyst: Effects of Metal Sintering and Support Swelling
The effect of noble metal catalysts supported on an ionic exchange resin for the enantioselective hydrogenation of ethyl pyruvate to ethyl lactate was studied. High activity and moderate enantioselectivity levels were obtained. Pt was the best enantioselective metallic phase, followed by Pd and Au; Rh was the less enantioselective metallic phase. The effect
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
-
2. Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2
A hidrogenação enantiosseletiva de piruvato de etila e de 1-fenil-1,2-propanodiona foi estudada a 298 K e sob 40 bar de H2 sobre um catalisador de platina coloidal estabilizado com cinchonidina (CD) e suportado em sílica. O catalisador foi preparado por impregnação da platina coloidal em sílica, atingindo 1% em massa do metal no suporte. O colóide foi
Journal of the Brazilian Chemical Society. Publicado em: 2010
-
3. Ligantes quirais nitrogenados em reações de hidrogenação catalitica assimetrica e redução enantiosseletiva com oxazaborolidinas / Nitrogen chiral ligants in asymmetric hydrogenation and enantioselective reduction using oxazaborolidine
O presente trabalho tem como objetivo a síntese e aplicação de novos aminoálcoois e ligantes quirais fosforados derivados desses e sua aplicação em catálise assimétrica. Com este intuito, foram sintetizados os aminoálcoois (2R)-2-[(2R) azolan-2-il]-2-feniletan-1-ol (4) e (2R)-2-[(2R) hexaidro-2-piridinil]-2-feniletan-1-ol (6) que são inéditos na l
Publicado em: 2005
-
4. A Interação substrato-modificador e sua importância para a hidrogenação enantiosseletiva de alfa-cetoésteres
The heterogeneous asymmetric catalysis plays an important and crucial role in many chemical processes and has therefore become a growing and interesting field. The enantioselective hydrogenation of α-ketoesters is one of the best known examples of such process. Methyl pyruvate, which can be converted to (R)- and (S)-methyl lactate with an enantioselecti
Publicado em: 2004
-
5. Enantioselective synthesis of aziridines using asymmetric transfer hydrogenation as a precursor for chiral derivatives used as bonding agent for rocket solid propellants
A rapid, expedient and enantioselective method for the synthesis of beta-hydroxy amines and monosubstituted aziridines in up to 99% e.e., via asymmetric transfer hydrogenation of a-amino ketones and cyclisation through treatment with tosyl chloride and base, is described. (1R,2R)-N-(para-toluenesulfonyl)-1,2-ethylenediamine with formic acid has been utilised
Química Nova. Publicado em: 2002-11
-
6. Preparação, caracterização e avaliação de catalisadores heterogeneos a base de Pt na hidrogenação enantiosseletiva do piruvato de metila em presença de cinconidina
Platinum based catalysts were prepared by impregnation on different supports, namely C, Al303, TiO2 and La203. The commercial activated carbon was oxidized by different methods in order to modify its surface. The main surface groups identified were carboxylic acid, when HN03 is the oxidizing agent, and carbonyl, phenol and quinone, when the oxidation is made
Publicado em: 2000
-
7. Asymmetric hydrogenation of α,β-unsaturated phosphonates with Rh-BisP* and Rh-MiniPHOS catalysts: Scope and mechanism of the reaction
Optically active 1,2-bis(alkylmethylphosphino)ethanes and bis(alkylmethylphosphino)methanes are unique diphosphine ligands combining the simple molecular structure and P-stereogenic asymmetric environment. This work shows that these ligands exhibit excellent enantioselectivity in rhodium-catalyzed asymmetric hydrogenation of α,β-unsaturated phosphonic acid
National Academy of Sciences.
-
8. Catalysis-based enantioselective total synthesis of the macrocyclic spermidine alkaloid isooncinotine
A concise and efficient total synthesis of the spermidine alkaloid (-)-isooncinotine (1) incorporating a 22-membered lactam ring is outlined. The approach is largely catalysis-based, involving a selective iron-catalyzed alkyl–aryl cross-coupling reaction of a difunctionalized pyridine substrate, a heterogeneous asymmetric hydrogenation step to set the chir
National Academy of Sciences.
-
9. Artificial metalloenzymes based on biotin-avidin technology for the enantioselective reduction of ketones by transfer hydrogenation
Most physiological and biotechnological processes rely on molecular recognition between chiral (handed) molecules. Manmade homogeneous catalysts and enzymes offer complementary means for producing enantiopure (single-handed) compounds. As the subtle details that govern chiral discrimination are difficult to predict, improving the performance of such catalyst
National Academy of Sciences.
-
10. Helically chiral polymers: A class of ligands for asymmetric catalysis
Helically chiral polymers from achiral monomers containing N and P atoms have been shown to be ligands for transition metals such as Pd and Rh. The Rh complex of the phosphane-containing polyisocyanate p(18-co-17) was an active albeit hardly enantioselective catalyst in the asymmetric hydrogenation of the dehydro amino acid N-acetamidocinnamic acid (15% enan
National Academy of Sciences.