Stereoselectivity
Mostrando 1-12 de 57 artigos, teses e dissertações.
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1. DESENVOLVIMENTO NOS MÉTODOS DE GLICOSILAÇÃO: UMA CHAVE PARA ACESSAR SUAS APLICAÇÕES NA SÍNTESE DE MOLÉCULAS BIOATIVAS
Glycosylation reaction is an important class of reactions in organic chemistry, and the development of the method contributes to the synthesis of many biologically active compounds containing various glycoside bonds. Is arguably the most important, albeit challenging, reaction in the field of carbohydrate chemistry. Examples of the products of glycosylation
Quím. Nova. Publicado em: 2021-04
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2. Synthesis of Spiro-Pyrrolidinyloxindoles by Oxidative Rearrangement of N-Acyltetrahydro-β-carbolines Using an Oxone/Aqueous Acetone Mixture
Spiro-pyrrolidinyl-2-oxindoles were prepared by the oxidative rearrangement of Na-acetyl-1,2,3,4-tetrahydro-β-carbolines (THBC) using dimethyldioxirane generated in situ. The Na-acetyl THBC substrates were obtained by Pictet-Spengler and acyl-Pictet-Spengler reactions of L-tryptophan methyl ester, followed by Na-acetylation. The stereoselectivity of the oxi
J. Braz. Chem. Soc.. Publicado em: 2019-01
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3. Chiral Bistacrine Analogues: Synthesis, Cholinesterase Inhibitory Activity and a Molecular Modeling Approach
Cholinesterase enzymes are important targets for the therapy of Alzheimer’s disease. Tacrine-based dual binding site cholinesterases inhibitors are potential disease-modifying anti-Alzheimer drug candidates. In the present work, we described the synthesis of a series of chiral homo- and heterodimers of bis(7)-tacrine connected by a heptylene chain as a spa
J. Braz. Chem. Soc.. Publicado em: 2017-11
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4. NMR Studies on [2 + 3] Cycloaddition of Nitrile Oxides to Polyunsaturated Medium Size Rings
Site selectivity, regioselectivity and stereoselectivity of [2 + 3] cycloaddition of 4-trifluoromethylbenzonitrile oxide to polyunsaturated medium size rings including 1,5,9-cyclododecatriene, 11-membered sesquiterpenes, 1,3-cyclooctadiene and 5-vinyl-2-norbornene were examined. Site selectivity was correlated with electron charges of alkenyl carbon atoms. S
J. Braz. Chem. Soc.. Publicado em: 2016-11
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5. Synthesis of Organotin Substituted Tricyclic Macrodiolides
The radical addition of triorganotin hydrides, R3SnH (R =n-butyl, phenyl, neophyltin), to four unsaturated diesters of (11R,12R)-9,10-dihydro-9,10-ethaneanthracene-11,12-dimethanol leads to products of cyclohydrostannation with an average yield of around 80%. Whereas the addition of these hydrides to diacrylate and dimethacrylate leads to the expected mixtur
J. Braz. Chem. Soc.. Publicado em: 2016-03
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6. Zingiber officinale (GENGIBRE) COMO FONTE ENZIMÁTICA NA REDUÇÃO DE COMPOSTOS CARBONÍLICOS
Various vegetables as biological catalysts were evaluated in enantioselective reduction of carbonyl compounds. The stereoselectivity of the process was in agreement with Prelog's rule for twelve of the vegetables, whereas okra and green peppers formed anti-Prelog products. Zingiber officinale exhibited the best results with 30% conversion and 89% ee. The par
Quím. Nova. Publicado em: 2015-05
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7. Hydroxylation of 1,8-cineole by Mucor ramannianusand Aspergillus niger
The monoterpenoid 1,8-cineole is obtained from the leaves of Eucalyptus globulus and it has important biological activities. It is a cheap natural substrate because it is a by-product of the Eucalyptuscultivation for wood and pulp production. In this study, it was evaluated the potential of three filamentous fungi in the biotransformation of 1,8-cineole. The
Braz. J. Microbiol.. Publicado em: 2015-03
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8. Fatos e tendências da biocatálise
Brazil is renowned for its biodiversity; however, its economy is based on exotic plants, extraction and unsustainable use of natural resources. This issue was addressed in a recent QN review entitled "Chemistry without Borders." In order to explore the potential of Brazilian biodiversity fully, sustainable development is required in key technological areas,
Quím. Nova. Publicado em: 2013
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9. Triagem, aplicação e engenharia de biocatalisadores para transformações enantio e regiosseletivas / Screening, applying and engineering biocatalysts for enantio and regioselective transformations
Biocatalysts have been widely applied in recent decades for industrial processes yielding high value products under environmentally friendly reaction conditions. The development of biocatalysts often begins with screening to identify enzymes with suitable activities followed by characterization of the enzymes chemo-, regio- and stereoselectivity or stability
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 03/06/2011
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10. Diastereosseletividade na redução de enonas bicíclicas com hidretos volumosos
Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.
Química Nova. Publicado em: 2008
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11. Michael additions of thiocompounds to α, β-unsaturated carbonyl compounds in aqueous media: stereoselectivity with unambiguous characterization by NMR
As reações de crotonaldeído (8) com tiofenol (2) e benzalacetona (10) com 1,2-etanoditiol (11) levam aos produtos de adição de Michael. As reações de tiofenol (2) com (R)-carvona (13) e (S)-perilaldeído (15) levam aos produtos (2S,3R,5S)-5-isopropenil-2-metil-3-feniltio-cicloexanona (14) e (1R,2R,4S)-4-isopropenil-2-feniltio-cicloexano carbaldeído (
Journal of the Brazilian Chemical Society. Publicado em: 2008
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12. Study towards to enantioselective synthesis of malevamide D and Suzuki-Miyaura reaction involving tellurium species / Estudo visando à síntese enantiosseletiva da malevamida D e reações de Suzuki-Miyaura envolvendo espécies insaturadas de telúrio
Esta tese descreve, em dois diferentes capítulos, a síntese assimétrica da Malevamida D e a aplicação de compostos organotelúrio em reações de Suzuki-Miyaura. O primeiro capítulo refere-se ao estudo da síntese assimétrica da Malevamida D, um depsipeptídeo natural pertencente à família das dolastatinas, compostos estes com grande atividade citot
Publicado em: 2008