Asymmetric Catalysts
Mostrando 1-12 de 24 artigos, teses e dissertações.
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1. Determination of Enantioselectivities by Means of Chiral Stationary Phase HPLC in Order to Identify Effective Proline-Derived Organocatalysts
The pyrrolidine fragment is a privileged scaffold within chiral ligands employed in coordination complexes exhibiting catalytic activity in asymmetric reactions and, more recently, as enantioselective organocatalysts per se. Likewise, the employment of (S)-proline as starting material constitutes the most direct form to synthesize those chiral derivatives. A
J. Braz. Chem. Soc.. Publicado em: 2018-05
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2. Catálise assimétrica no Brasil: desenvolvimento e potencialidades para o avanço da indústria química brasileira
The preparation of enantiomerically pure or enriched substances is of fundamental importance to pharmaceutical, food, agrochemical, and cosmetics industries and involves a growing market of hundreds of billions of dollars. However, most chemical processes used for their production are not environmentally friendly because in most cases, stoichiometric amounts
Quím. Nova. Publicado em: 2013
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3. Evaluation of microbiological and biomimetic models in stereoselective metabolism of risperidone by high-performance liquid chromatography / Avaliação de modelos microbiológicos e modelos biomiméticos no metabolismo estereosseletivo da risperidona por cromatografia líquida de alta eficiência
Risperidone is an atypical antipsychotic drug. Its metabolism yields in two hydroxylated chiral metabolites, 7-hydroxyrisperidone (7-RispOH) and 9-hydroxyrisperidone (9-RispOH). The 9-RispOH metabolite presents the same pharmacologic activity of the parent drug risperidone. This led this drug to be marketed as drug under the generic name paliperidone. Studie
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 02/08/2012
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4. Calix[n]arenos como sistemas de encapsulamento e plataforma para catalisadores assimétricos / Calix[n]arenes as encapsulation systems and platform for asymmetric catalysts
A química supramolecular tem evoluído ao longo das últimas três décadas, e tem se mostrado um campo extremamente dinâmico e verdadeiramente interdisciplinar. O presente trabalho teve por meta sintetizar derivados do p-tert-butilcalix[4 e 6]areno, visando aplicá-los como plataforma para ligantes assimétricos e sistemas carreadores da isoniazida. Prime
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/07/2011
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5. SYNTHESIS AND APPLICATION OF CHALCOGENIDES PEPTIDES DERIVATIVES IN ASYMMETRIC CATALYSIS / SÍNTESE E APLICAÇÃO DE CALCOGENETOS DERIVADOS DE PEPTÍDEOS EM CATÁLISE ASSIMÉTRICA
In the present work, we have developed a flexible, modular synthetic route for the preparation of new chiral chalcogen peptide derivatives containing sulfur, selenium or oxygen and evaluate their application as catalysts in enantioselective reactions. This modular approach allowed the preparation of a series of chiral compounds with a high structural diversi
Publicado em: 2010
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6. Synthesis of unnatural α-amino acids, precursors of the inhibitors of thrombin - via Phase Transfer Catalysis (PTC) / Síntese de α-aminoácidos não naturais -precursores de agentes inibidores da trombina - via Catálise de Transferência de Fase (CTF)
Seven novel a-aminoacids precursors were prepared by the alkylation reaction of ethyl acetamidocyanoacetate 112 using bromohexane, benzyl chloride, allyl bromide, 9-(chloro-methyl)antracene, 3-nitrobenzyl bromide, 4-nitrobenzyl bromide, 4-metoxibenzyl bromide and 2-methyl-naphtyl bromide as alkylating agents via Phase Transfer Catalysis (PTC). These reaction
Publicado em: 2009
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7. Complexos de Ãons lantanÃdeos como catalisadores em reaÃÃes orgÃnicas: aplicaÃÃo à sÃntese assimÃtrica de cianidrinas e Ãlcoois
O uso de complexos de lantanÃdeos quirais como novos catalisadores em sÃntese assimÃtrica tem sido extensivamente estudado na Ãltima dÃcada. Neste contexto, a busca por novos ligantes quirais e novos compostos de lantanÃdeos tem despertado grande interesse. Neste trabalho, ligantes quirais contendo grupamento sulfÃxidos e aminoÃcidos N-protegidos for
Publicado em: 2006
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8. 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
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9. Asymmetric catalysis in aqueous media: use of metal-chiral crown ethers as efficient chiral Lewis acid catalysts in asymmetric aldol reactions
Complexos entre metal e éter de coroa quiral foram desenvolvidos como catalisadores do tipo ácido de Lewis quirais eficientes para reações aldólicas assimétricas entre éteres enólicos de silício e aldeídos em meio aquoso. Apesar de muitas reações assimétricas e catalíticas excelentes terem sido desenvolvidas recentemente, a maioria precisa ser
Journal of the Brazilian Chemical Society. Publicado em: 2001-10
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10. Catálise de transferência de fase
Since its discovery, phase transfer catalysis (PTC) has grown considerably and nowadays is one of the most versatile preparative methods. The search for new catalysts, their use in PTC asymmetric synthesis and the attempts to understand their mechanistic role are modern and exciting topics of investigation. A review on main achievements in the last two decad
Química Nova. Publicado em: 2000-10
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11. Computational predictions of stereochemistry in asymmetric thiazolium- and triazolium-catalyzed benzoin condensations
The catalytic asymmetric thiazolium- and triazolium-catalyzed benzoin condensations of aldehydes and ketones were studied with computational methods. Transition-state geometries were optimized by using Morokuma's IMOMO [integrated MO (molecular orbital) + MO method] variation of ONIOM (n-layered integrated molecular orbital method) with a combination of B3LY
National Academy of Sciences.
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12. 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.