Racemization
Mostrando 1-12 de 35 artigos, teses e dissertações.
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1. A Straightforward Synthesis of Enantiopure (1S,2R)-Ephenamine
An enantioselective six-step synthesis of (1S,2R)-ephenamine starting from readily available chiral amino acid is disclosed presenting 26% overall yield and high optical purity. The use of chiral phenylglycine as starting material was also studied and did not present satisfactory results due to a very sensitive a-carbonyl/benzylic stereogenic center that, in
J. Braz. Chem. Soc.. Publicado em: 2020-12
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2. ENANTIOPURE R(-)-3-AMINOISOBUTYRIC ACID SYNTHESIS USING Pseudomonas aeruginosa AS ENANTIOSPECIFIC BIOCATALYST
Abstract The main goal of this research was the synthesis of enantiopure R(-)-3-aminoisobutyric acid from dihydrothymine with good yield, high stereospecificity and relative simplicity. Seventy two percent yield of the product was obtained in three steps. Step one consisted of dihydrothymine racemization. Step two was a dihydropyrimidinase reaction involving
Braz. J. Chem. Eng.. Publicado em: 2015-03
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3. Métodos de análise da rosiglitazona e pioglitazona e de seus principais metabólitos: aplicações em estudos de metabolismo in vitro / Methods for the analysis of rosiglitazone and pioglitazone and their metabolites: application to in vitro metabolism studies
Estudos de metabolismo in vitro possuem o intuito de caracterizar e quantificar possíveis metabólitos, elucidar as vias metabólicas e sugerir modelos a serem seguidos para a realização de estudos in vivo. Com o intuito de estudar o metabolismo in vitro não estereosseletivo da rosiglitazona (RSG) empregando fração microssomal de fígado de ratos,foi d
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 02/04/2012
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4. Reação entre fenilnitrometanos e enoato derivado do D-manitol na presença de TBAF ou DBU: adição conjugada sin-seletiva e reação de NEF consecutiva
A tandem syn-selective conjugate addition - Nef reaction was observed when phenylnitromethane and oxygenated derivatives were allowed to react with an enoate derived from D-mannitol at rt in the presence of TBAF or DBU. While nitro-adducts predominate after 4h of reaction, the corresponding ketones were the main products after 12-24h of reaction. The Nef rea
Química Nova. Publicado em: 2008
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5. Resolução cinetica dinamica da ( + OU - ) -2-hidrox-1-indanona mediada por Trichosporon Cutaneum / Dinamic kinetic resolution of ( + OU - ) -2-hydroxindan-1-one mediated by Trichosporon Cutaneum
Diante a notável capacidade da levedura Trichosporon cutaneum de resolver uma mistura racêmica da 2-hidroxi-1-indanona através da redução para o (1S,2R)-1,2-indanodiol por um processo de resolução cinética dinâmica (RCD), resolveu-se estudar a reação de redução com os enantiômeros puros do substrato a fim de esclarecer o mecanismo da RCD bem co
Publicado em: 2006
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6. Aspartic acid racemization in tooth enamel from living humans.
The aspartic acid in human tooth enamel shows increasing racemization with age. This increase is not seen in the metabolically active protein hemoglobin. The rate constant for the racemization reaction of aspartic acid in human tooth enamel was found to be 8.29 X 10(-4) yr-1. This rate constant suggests that in any protein with a long in vivo lifetime, D-asp
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7. Concordance of Collagen-Based Radiocarbon and Aspartic-Acid Racemization Ages
By determining the extent of racemization of aspartic acid in a well-dated bone, it is possible to calculate the in situ first-order rate constant for the interconversion of the L and D enantiomers of aspartic acid. Collagen-based radiocarbon-dated bones are shown to be suitable samples for use in “calibrating” the racemization reaction. Once the asparti
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8. Racemization of aspartic acid and phenylalanine in the sweetener aspartame at 100 degrees C.
The racemization half-lives (i.e., the time required to reach a D/L = 0.33) at pH 6.8 for aspartic acid and phenylalanine in the sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester) were determined to be 13 and 23 hours, respectively, at 100 degrees C. Racemization at this pH does not occur in aspartame but rather in its diketopiperazine decompositi
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9. Racemization Reaction of Aspartic Acid and Its Use in Dating Fossil Bones
In the time interval datable by radiocarbon, and at the temperatures of most archeological sites, a substantial amount of racemization of aspartic acid takes place. By determination of the amount of racemization of aspartic acid in bones from a particular location which have been dated by the radiocarbon technique, it is possible to calculate the in situ fir
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10. RACEMIZATION OF LYSINE BY A PSEUDOMONAD
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11. Aspartic acid racemization in heavy molecular weight crystallins and water insoluble protein from normal human lenses and cataracts.
High D/L aspartic acid ratios are observed in heavy molecular weight aggregates and in water-insoluble protein extracted from whole lenses and nuclear and cortical regions. Purified alpha-, beta-, and gamma-crystallins have low D/L ratios. Fractionation of urea-solubilized material from the water-insoluble protein yields four molecular weight classes of prot
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12. A COMPARISON OF THE RACEMIZATION CURVES FOR URINARY, EDEMA FLUID, AND BLOOD PLASMA PROTEINS 1