Enantiomeric Excess
Mostrando 1-12 de 84 artigos, teses e dissertações.
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1. Chemoenzymatic Synthesis of Apremilast: A Study Using Ketoreductases and Lipases
The key step in the chemoenzymatic synthesis of apremilast was to produce the chiral alcohol (R)-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanol, (R)-3. Two enzymatic approaches were evaluated to obtain (R)-3, one using ketoreductases and the other lipases. Bioreduction of 1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanone (2), using ketoreductas
J. Braz. Chem. Soc.. Publicado em: 2021-05
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2. 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
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3. The Role of L-Proline and Co-Catalysts in the Enantioselectivity of OXA-Michael-Henry Reactions
The use of L-proline derivatives employed in OXA-Michael-Henry tandem reactions has been an efficient method to produce enantiomerically enriched compounds. In this work it was carried out a study of the OXA-Michael-Henry reactions between salicylaldehyde and β-nitrostyrenes, catalyzed by L-proline and its derivatives. The corresponding (R)-3-nitro-2-phenyl
J. Braz. Chem. Soc.. Publicado em: 08/04/2019
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4. Deracemization of sec-Alcohols through Sequential Application of C. albicans and Ketoreductases
A biocatalytic cascade process was developed using immobilized cells of the wild type yeast Candida albicans CCT 0776 in calcium alginate beads and a commercially available ketoreductase. The aim was to promote deracemization by stereoinversion of (±)-1-arylethanols in high substrate concentration (above 100 mmol L-1) to prepare the (R)-enantiomers of the a
J. Braz. Chem. Soc.. Publicado em: 2019-04
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5. Asymmetric bioreduction of β-ketoesters derivatives by Kluyveromyces marxianus: influence of molecular structure on the conversion and enantiomeric excess
ABSTRACT This study presents the bioreduction of six β-ketoesters by whole cells of Kluyveromyces marxianus and molecular investigation of a series of 13 β-ketoesters by hologram quantitative structure-activity relationship (HQSAR) in order to relate with conversion and enantiomeric excess of β-stereogenic-hydroxyesters obtained by the same methodology. F
An. Acad. Bras. Ciênc.. Publicado em: 07/08/2017
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6. Easy and Simple SiO2 Immobilization of Lipozyme CaLB-L: Its Use as a Catalyst in Acylation Reactions and Comparison with Other Lipases
In this study, lipase from Candida antarctica B (Lipozyme CaLB-L) was successfully immobilized on SiO2 through adsorption and used to obtain (R)-(+)-esters derived from (R,S)-1-phenylethanol. The new immobilized enzyme was compared with commercially immobilized lipases (Novozyme 435, Lipozyme 435 and Pseudomonas cepacia (PSC-II and PSD-I)). Lipozyme CaLB-L a
J. Braz. Chem. Soc.. Publicado em: 2017-07
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7. First Asymmetric Reduction of Isatin by Marine-Derived Fungi
In this study, whole cells of marine-derived fungi were used to reduce isatin (1H-indole-2,3-dione) to dioxindole (3-hydroxyindolin-2-one) for 7 days at 32 °C. The screening showed that several strains could reduce isatin and produce the enantioenriched dioxindole. The best conversions were obtained by Cladosporium sp. CBMAI 1237 and Westerdykella sp. CBMAI
J. Braz. Chem. Soc.. Publicado em: 2017-06
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8. The Influence of Organic Medium and Supports in the Resolution of (R,S)-Menthol Catalyzed by Lipases
In this study, various commercial and native lipases, free or immobilized, were used in the enantioselective resolution of (R,S)-menthol with vinyl acetate for the preparation of menthyl acetate. Lipase from Candida rugosa (AYL) was found to be the most appropriate. When the reaction was carried out at 35 ºC, using 40 mg of AYL and a molar ratio of 1:2 (alc
J. Braz. Chem. Soc.. Publicado em: 2016-12
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9. Coupling DLLME-CE for the Stereoselective Analysis of Venlafaxine and Its Main Metabolites after Biotransformation by Fungi
Fungal biotransformations have become very important in the study of chiral drugs because the reactions performed by these microorganisms may be enantioselective. However, analyses of analytes present in liquid culture medium have proved to be very difficult due to the complexity of this matrix. The aim of this work was to couple dispersive liquid-liquid mic
J. Braz. Chem. Soc.. Publicado em: 2015-09
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10. ASYMMETRIC SULFOXIDATION OF ALBENDAZOLE TO RICOBENDAZOLE BY FUNGI: EFFECT OF pH
Albendazole (ABZ) is an anthelmintic drug used for the treatment of infectious diseases in veterinary and human medicine. This drug is a prochiral drug that after administration, is rapidly oxidized in the pharmacologically active sulfoxide metabolite, which is also known as ricobendazole (ABZSOX). ABZSOX has a stereogenic center and possibly two enantiomers
Quím. Nova. Publicado em: 2015-08
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11. Improving the Toolbox of Bioreductions by the Use of Continuous Flow Systems
Packed bed reactors can be used as an interesting alternative on the bioreduction of β-ketoesteres mediated by immobilized microorganisms. Here in, we report our results on the bioreduction of ethyl 3-oxohexanoate by immobilized Kluyveromyces marxianus cells and tert-butyl 3-oxobutanoate by immobilized Rhodotorula rubra cells under continuous flow condition
J. Braz. Chem. Soc.. Publicado em: 2015-03
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12. High Throughput Enzymatic Enantiomeric Excess: Quick-ee
High throughput techniques to evaluate enantiomeric excess (ee) and enantiomeric ratio (E) of enzymatic reactions are fast and efficient tools that can be applied large quantities of enzymes, microorganisms and clones. The Quick-ee technique proposed in this study produces the ee and conversion values separately.
J. Braz. Chem. Soc.. Publicado em: 2015-02