Absolute Stereochemistry
Mostrando 1-12 de 30 artigos, teses e dissertações.
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1. Absolute Configuration of (−)-Cubebin, a Classical Lignan with Pharmacological Potential, Defined by Means of Chiroptical Spectroscopy
This work describes the first determination of the absolute configuration (AC) of (−)-cubebin by means of electronic circular dichroism (ECD), supported by quantum chemical calculations. The comparison of experimental ECD with the corresponding quantum chemical prediction for the proper diastereoisomer resulted in the definitive assignment of the AC of the
J. Braz. Chem. Soc.. Publicado em: 2020-10
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2. Antimicrobial Diterpene from the Brazilian Termite Nasutitermes macrocephalus (Isoptera: Termitidae: Natutitermitinae)
Termites are insects with a complex social organization on castes among which soldiers are the only responsible for the colony defense. The soldiers of the Nasutitermes genus use chemical defense, which comprises a mixture of mono, sesqui and mainly diterpenes. The new diterpene 2b,3a-dihydroxy-trinervita-1(15),11-diene, found in Nasutitermes macrocephalus,
J. Braz. Chem. Soc.. Publicado em: 2018-03
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3. Aspectos estruturais de algumas neolignanas hidrobenzofurânicas
The neolignans are defined as dimers of allylphenol and propenylphenol between itself or crossed, whose bond does not occur by the 8-8' carbons like lignans. This review centered on stereochemical aspects of the hydrobenzofuran type, a widespread skeleton among neolignans. The chemical structures established based on spectrometric data are registered in the
Quím. Nova. Publicado em: 2012
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4. Resolução do ibuprofeno: um projeto para disciplina de química orgânica experimental
A practical and didactic sequence of experiments was proposed to illustrate the stereochemistry concept, optically active compounds, resolution of racemates, and use of the NMR technique, including 2D-COSY for identification of organic compounds, on a laboratory course for undergraduate students. The sequence was: extractions of racemic ibuprofen and chiral
Quím. Nova. Publicado em: 2012
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5. Contribuição ao estudo químico e avaliação da atividade antioxidante dos frutos verdes de Clusia paralicola (Clusiaceae)
Clusia paralicola (Clusiaceae) occurrs in forests from northeastern Brazil, especially in the semi-arid and wet forests, is popularly known as pororoca. This work describes the chemical and antioxidant activity of the green fruits from Clusia paralicola G. Mariz Cunha and resulted in the isolation and identification of two biflavonoids (GB1-7"-Oglucoside and
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 201107
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6. CALEOL: MODIFICAÇÕES ESTRUTURAIS, ESTEREOQUÍMICA ABSOLUTA E ATIVIDADE ANTIMICROBIANA DOS DERIVADOS / CALEOL: STRUCTURAL MODIFICATION, ABSOLUTE STEREOCHEMISTRY AND MICROBIOLOGICAL ACTIVITY OF CALEOL
O óleo essencial das folhas de Calea clematidea, um arbusto da família Asteraceae utilizado popularmente como antigripal, estomáquico e contra úlceras gástricas, foi extraído e dele foi isolado o monoterpeno caleol. Este metabólito foi submetido a reações de modificação em sua estrutura por meio da abertura de seu grupo funcional epóxido. A reaç
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 24/02/2011
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7. SÃntese assimÃtrica de 3-carboxamidas enantiomericamente puras e de hidrazidas e arilhidrazonas, derivadas do novo heterociclo 7-(benzoil)- 2-isoxazolina[5,4-b] pirrolidina. AvaliaÃÃo das atividades biolÃgicas
In our previous studies, aza-bicyclic 2-isoxazolines were obtained, such as, 2- isoxazoline[5,4-b] piperidine and 2-isoxazoline[5,4-b] pyrrolidine. N-(benzoyl)-amides and, derived from these heterocycles, showed promising biological activity, (anti-inflammatory and toxicity). Compounds containing hydrazide and hydrazone functionalities are described in the l
Publicado em: 2008
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8. Contribuição ao conhecimento quimico do oleo-resina de copaiba : configuração absoluta de terpenos / Contribuiton for the chemical knowledge of the copaiba oleoresin : absolute configuration of terpenes
The commercial copaiba oleoresin is an exuded obtained from the trunk of many species of the Copaifera genus (Caesalpinoideae, Leguminosae). This oil is used in the popular medicine as cicatrizant, anti-inflammatory, in the treatment of bronchitis and for skin diseases, and also in the cosmetic industry as fixative of the perfumes and as solvent for inks and
Publicado em: 2007
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9. Reação de arilação de Heck regio e estereosseletiva da 3-desidroprolina com sais de arildiazonio : aplicação na sintese total de analogos neuroexcitatorios do acido acromelico / Regio and stereoselective Heck arylation of 3-dehydroprolines with aryldiazonium salts. Total synthesis of the neuroexcitatory acromelic acid analogues
The Heck arylation of chiral 3-dehydroprolines using various aryldiazonium salt resulted in the formation of a series of 4-aryl-dehydroprolines of potential biological interest. The application of aryldiazonium salt in this arylation reaction offers several advantages over traditional Heck reactions such as mild reactions conditions of phosphine-free conditi
Publicado em: 2006
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10. Synthesis of the C1-C13 fragment of migrastatin / Sintese do fragmento C1-C13 da migrastatina
Migrastatin was isolated from a cultured broth of Streptomyces sp. MK929-43F1 in 2000 by Imoto and co-workers, as well as from a cultured broth of Streptomyces platensis NRRL 18993 by researchers from Kosan Biosciences. Migrastatin has a remarkable inhibitory effect on the migration of human tumor cells, very important to the tumor metastasis treatment. Its
Publicado em: 2005
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11. Sintese total e elucidação estrutural da delactomicina
The natural polyketide delactonmycin isolated from Streptomyces strains displays potent inhibitory activity of the nucleo-cytoplasmic translocation of the HIV -1 regulatory protein Rev. The planar structure of delactonmycin was established by spectroscopic methods, but its relative as well as its absolute configuration remained unknown. In this work, we desc
Publicado em: 2003
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12. Adição diastereosseletiva de nucleofilos de carbono a ions N-aciliminios ciclicos: Aplicação na síntese de sistemas pirrolizidínico e indolizidínico monosubstituidos
Good diastereoeselection was observed in the addition of the carbon nucleophiles derived from S-tert-butyl thiopropionate 84, S-phenyl thiopropionate 96 and tert-butyl propionate 95 to the 6-membered N-acyliminium ion derived from 2-ethoxy carbamate 80. The 2RS, 1 SR relative stereochemistry of the major isomer formed in the addition of O-silylketeneacetal d
Publicado em: 1998