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Transition metal mediated approaches to pumiliotoxinsMcAlonan, Helena M. January 1996 (has links)
No description available.
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A cascade approach toward indolizidine and quinolizidine alkaloids : highlighted by the total syntheses of (±)-epilupinine, (±)-tashiromine, and (-)-epimyrtine progress toward the total synthesis of (±)-meloscineAmorde, Shawn Marie 05 August 2013 (has links)
Several novel cascade processes have been designed and developed that involve sequential reactions of imines and iminium ions to form substituted quinolizidine ring systems in a single step from simple and readily available starting materials. The utility and promise of these cascades is evident from their application to extraordinarily concise syntheses of the representative quinolizidine alkaloids (±)-epilupinine, (±)-tashiromine, and (-)-epimyrtine. Within the context of a longstanding interest in aromatic heterocyclic natural product synthesis, a concise synthetic strategy incorporating new tactics for key chemical transformations, as well as novel applications of existing synthetic methods was developed constructing the natural product meloscine. Meloscine was isolated in the 1970's from the New Caledonian plant Melodinus Scandens Forst, which is used in Chinese folk medicine for the treatment of meningitis and rheumatic heart disease. In route to meloscine, a facile synthetic method was developed toward several carboline type indoles. Also, progress has been made toward the total synthesis of the natural product meloscine. / text
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Development of iminium ion cascade methodologies and their application to the synthesis of complex moleculesJewett, Ivan Tucker 04 September 2015 (has links)
In the interests of synthetic efficiency several cascade reactions involving iminium ion intermediates have developed to allow for the rapid assembly of complex molecules from relatively simple starting materials. A cascade methodology for the rapid, diastereoselective synthesis of quinolizidine ring systems has been expanded to encompass a greater range of substrates. The utility of this extension was demonstrated in the efficient syntheses of the tricyclic core structures found in halichlorine and the cylindricine family of alkaloids. Additionally a second cascade sequence has been developed that progresses through an S[subscript N]1 followed by nucleophilic attack on an N-acyl iminium ion to deliver the products of a formal [4+3] cycloaddition. This methodology has been successfully employed to synthesize a [3.3.2] bridgehead system that serves as a key intermediate in a proposed synthesis of (±)-actinophyllic acid. Synthesis of this compound represent progress in the ongoing effort to synthesize this natural product.
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1. Synthetic Study of Pyrrolizidine Skeleton 2. Synthetic Study Toward Tylophorine and Cryptopleurine 3. Synthetic Study of Fused Bicyclic GlutarimidesHsu, Ru-Ting 18 January 2005 (has links)
Reaction of 3-sulfonyl acetamides with various substituted methyl acrylate derivatives furnished pyroglutamate and glutarimidess via [3+2] and [3+3] cycloaddition respectively. The results were applied to the synthesis of pyrrolizidine skeleton, tylophorine, cryptopleurine and fused bicyclic glutarimides.
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Synthèse de composés polycycliques azotés par cyclisation de Vilsmeier-Haack et cyclisation de Mannich organocatalysée en séquenceOutin, Johanne January 2017 (has links)
Les recherches présentées dans cette thèse découlent de problématiques rencontrées lors de précédents travaux effectués dans notre groupe au sujet de cyclisations séquentielles de Vilsmeier-Haack et de Mannich par une activation chimiosélective d’amides. Deux limitations avaient été soulevées : une faible réactivité lors de la seconde cyclisation de Mannich et aucune possibilité d’obtention de produit de double cyclisation de façon énantiosélective.
Au chapitre un, une étude de double cyclisation de Vilsmeier-Haack et de Mannich est présentée, tout d’abord sur des substrats allylsilane-aldéhyde puis vératrol-aldéhyde. Une étude mécanistique est détaillée dans le but d’améliorer le rendement de la réaction. Les bases de notre méthodologie avec l’aldéhyde sont établies dans ce premier chapitre.
Au chapitre deux, une étude de double cyclisation de Vilsmeier-Haack et de Mannich en présence d’une cétone est exposée. Les conditions de première cyclisation sont rapidement déterminées tandis que pour la seconde étape, les divers paramètres pouvant influencer la réaction sont examinés. Aussi, une tentative de formation de centres quaternaires produisant des squelettes carbonés de type quinolizidine et spirocyclique est présentée, ainsi qu’une variation de tailles de cycles formés.
Au chapitre trois, l’étendue de notre méthodologie est étudiée et celle-ci est appliquée sur divers substrats. Les nucléophiles de type indole, pyrrole, éther d’énol et allylsilane sont couverts et la variation de taille de cycle est également testée.
Au chapitre quatre, une étude sur le développement catalytique et un effort vers une version non racémique de notre méthodologie sera présentée. Diverses amines secondaires chirales sont investiguées et les excès énantiomériques mesurés.
Le chapitre cinq propose des suites au projet de thèse, incluant des pistes au sujet de l’induction asymétrique en s’appuyant sur des exemples concrets de la littérature.
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Lupinus lanatus Benth, Lupinus guaraniticus (Hassl.) C. P. Sm., Lupinus paranensis C. P. Sm. (Fabaceae) e Waltheria douradinha Saint Hilaire (Sterculiaceae): Isolamento e Identificação de seus Metabólitos e Atividade Biológica / Lupinus lanatus Benth, Lupinus guaraniticus (Hassl.) C. P. Sm.,Lupinus paranensis C. P. Sm. (Fabaceae) e Waltheria douradinhaSaint Hilaire (Sterculiaceae): Isolation and Identification of Biological Activity and its MetabolitesTiburski Neto, Alexandre 31 July 2015 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / The part of our constant search for new bioactive secondary metabolites of plant origin,
the aerial parts of three species of the genus Lupinus (Leguminoseae), and the bark of
the roots of the species Waltheria douradinha Sain Hilaire (Sterculiaceae), were
submitted to phytochemical investigation. In this research, they were isolated and
identified 14 compounds, which was exposid several biological activities. Among the
activities performed, the compounds were evaluated against antimicrobial, antioxidant
enzyme (POP and DPPIV) and also bacteriolityc activity. Two of the isolated
compounds, (+)Lanatina A (L. paranensis) and Antidesmona (W. douradinha) shawed
bacteriolityc activity. The test showed that these compounds have bacteriolityc activity,
especially against Gram-negative. The Antidesmona presented better lytic potential in
the concentration of 12.5 μg/mL against the microorganism Salmonella typhimurium
ATCC 14028. For this bacterium, Antidesmona alkaloid produced a cell wall lysis of
approximately 30% between 4-6 hours (P <0.0001). The alkaloid extracts W.
douradinha, collected in four different regions of Rio Grande do Sul - Brazil, was
analyzing its chemical composition by HPLC. Analysis of the chemical composition of
the basic extracts was compared with soil analyzes the place collection of plant. These results revealed significant differences in the chemical compositions of alkaloid extracts
of Waltheria douradinha Sain Hilaire and were important guides of new collection sites
these species. / Como parte da nossa busca permanente por novos metabólitos secundários bioativos,
de origem vegetal, as partes aéreas de três espécies do gênero Lupinus,
(Leguminoseae), e a casca das raízes da espécie Waltheria douradinha Sain Hilaire
(Sterculiaceae), foram submetidas à investigação fitoquímica. Dessa investigação,
foram isolados e identificados 14 compostos, os quais foram submetidos a diversas
atividades biológicas. Dentre as atividades realizadas, os compostos foram avaliados
frente a atividades antimicrobiana, antioxidante, enzimáticas (POP e DPPIV) e também
atividade bacteriolítica. Dois dos compostos isolados, (+)Lanatina A (L. paranensis) e
Antidesmona (W. douradinha), foram submetidos a atividade bacteriolítica. O teste
demonstrou que esses compostos possuem atividade de lise, principalmente frente a
Gram-negativos. A Antidesmona apresentou seu melhor potencial lítico na
concentração de 12,5 μg/ml frente ao microrganismo Salmonella typhimurium ATCC
14028. Para esta bactéria, o alcaloide Antidesmona produziu uma lise de parede celular
de aproximadamente 30% entre 4 e 6 horas (P<0,0001). Os extratos alcaloídicos de W.
douradinha, coletada em quatro diferentes regiões do Rio Grande do Sul Brasil,
passaram por análise de sua composição química por HPLC. A análise da composição
química dos extratos básicos foi comparada com análises do solo do local de coleta da planta. Esses resultados revelaram diferenças significativas nas composições químicas
dos extratos alcaloídicos de W. douradinha, e também foram importantes guias de
novos locais de coleta dessa espécie.
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Estudo fitoquímico e atividade biológica de Lupinus lanatus / Phytochemical study and biological activity of Lupinus lanatusTiburski Neto, Alexandre 10 January 2011 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / As a part of our ongoing search of new bioactive secondary metabolites of plant origin,
the aerial parts of Lupinus lanatus were subjected to phytochemical investigation.
Lupinus genus, belonging to the family of Leguminosae (Fabaceae), is widely distributed
in south and western North America, in the Mediterranean region and Africa, with
approximately 600 species. In Rio Grande do Sul, Brazil, the genus is represented by 13
species, among them, L. lanatus. This is a small shrub native to South America, mainly
south Brazil (Rio Grande do Sul), Uruguai, Paraguai and Argentine. In Rio Grande do
Sul, L. lanatus is called tremoço, and it is used in folk medicine as an antidiabetic,
antifungal, antitumor and antioxidant agent. Quinolizidine alkaloids, such as lupanine,
multiflorine, sparteine and argirine, are widely distributed in plants of the genus. Their
biological effects, as antiarrhythmic, hypoglycemic, hypotensive, depressing CNS,
hallucinogenic and respiratory stimulant activities, among others, has been studied
previously. In the present paper, we describe the isolation and structural elucidation of a
new quinolizidine alkaloid, lanatine A together with 13-α-cinnamoyloxylupanine, and
hydroxylupanine from the leaves, and (-)multiflorine and (-)13-α-cis-tigloyloxymultiflorine
from the seeds of L. lanatus. / Como parte da nossa busca permanente por novos metabólitos secundários bioativos
de origem vegetal, as partes aéreas de Lupinus lanatus foram submetidas a
investigação fitoquímica. O gênero Lupinus, pertencente à família das leguminosas
(Fabaceae), é amplamente distribuída no sul e oeste da América do Norte, na região
mediterrânica e na África, representado por cerca de 600 espécies. No Rio Grande do
Sul, Brasil, o gênero está representado por 13 espécies, entre elas, L. lanatus. Este
apresenta-se como um pequeno arbusto e está presente na América do Sul, no Brasil,
Uruguai, Paraguai e Argentina. No Rio Grande do Sul, L. lanatus é conhecido
popularmente Tremoço, e seu gênero é utilizado na medicina popular como agente
antidiabético, antitumoral, antifúngico e antioxidante. Os alcalóides Quinolizidínicos,
como lupanina, multiflorina, esparteína e argirina, são amplamente distribuídas em
plantas do gênero. Seus efeitos biológicos, como antiarrítmicos, hipoglicemiante,
hipotensor, depressor do SNC, alucinógenos e estimulante respiratório, entre outros,
tem sido amplamente estudados. No presente trabalho, é descrito o isolamento e
elucidação estrutural de um novo alcalóide quinolizidínico, Lanatina A, juntamente com
o 13-α-cinnamoiloxilupanina e 13-α-hidroxilupanina oriundos das folhas, e (-)multiflorina
e (-)13-α-cis-tigloiloximultiflorina isolados a partir das sementes de L. Lanatus.
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