Diels Alder Reaction
Mostrando 13-24 de 30 artigos, teses e dissertações.
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13. Estudos de Novas Metodologias Sintéticas para Heterocíclicos Quinolônicos, Triazólicos e Síntese de Catalisadores Quirais
In order to obtain quinolone nucleosides a new methodology based on construction of the heterocyclic ring at the carbohydrate moiety was devised. The carbohydrates: 1-methoxy-2,3-O-isopropylidene-α-D-ribofuranose (108), 1-methoxy-2,3-O-isopropylidene-5-O-methanesulfonyl-β-D-ribofuranose (109a) and 1-methoxy-2,3-O-isopropylidene-5-O-p-toluenesulfony
Publicado em: 2004
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14. Synthesis of sulfinylated methylbenzoquinones and study of their facial diastereoselectivity in Diels-Alder reactions aiming the obtention of terpenic natural products precursors. / Síntese e estudo de diastereosseletividade facial, em reações de Diels-Alder, de metilbenzoquinonas sulfiniladas visando a obtenção de precursores de produtos naturais terpênicos
Our main objective is to take advantage of the well known π-facial diastereoselectivity of (SS)-2-tolylsulfinyl-1,4-benzoquinones, in the Diels-Alder reactions, to obtain, via photo-thermal olefin metathesis, enantiopure precursors of capnellene and ikarugamycin. The formation of an inseparable mixture of products in the reaction of commercially availab
Publicado em: 2003
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15. About the synthesis of furanoheliangolides through the Diels-Alder reaction / Sobre a síntese de furanoeliangolidos pela reação de Diels-Alder
Furanoheliangolides are biologically active natural products containing a 11-oxabicyclo[6.2.1]undecane skeleton. In this work we have investigated two different approaches to synthesize a model of the core structure of goyazensolide. Both approaches involve a Diels-Alder reaction and a bond breaking reaction to produce the polycyclic structure. In the first
Publicado em: 2003
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16. The Diels-Alder reaction: an update
Na última década tem havido um enorme progresso na reação de Diels-Alder, principalmente nas aplicações sintéticas da versão intramolecular (IMDA) e sua variação macrocíclica transanular (TADA). Esta revisão pretende abordar estas inovações, enfocando a relação fundamental entre os conceitos sintéticos e os avanços experimentais, e com o en
Journal of the Brazilian Chemical Society. Publicado em: 2001-10
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17. Reações orgânicas em meio aquoso
The use of water as solvent in organic reactions has been uncommon for several reasons, among them the low solubility of the reactants, the incompatibility of the intermediates with water, and the competition between the desired reaction and hydrolysis. Breslow in 1980, demonstrated that the hydrophobic effect accelerates Diels-Alder reactions and gives a hi
Química Nova. Publicado em: 2001-10
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18. Hetero Diels-Alder adduct formation between nitrosobenzene and tetra-methyl purpurogallin and its retro-Diels-Alder reaction
É descrita uma síntese eficiente de um aduto de Diels-Alder da tetrametilpurpurogalina (TMPG) e o nitrosobenzeno (NOB). A cinética da decomposição térmica do aduto, que segue um mecanismo de retro-Diels-Alder foi estudada usando espectroscopía de ¹H-RMN.
Journal of the Brazilian Chemical Society. Publicado em: 2001-08
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19. Studies on the synthesis of heliangolides throught the Diels-Alder reaction. / Estudos sobre a síntese de heliangolidos pela reação de Diels-Alder.
O objetivo deste trabalho foi desenvolver métodos para sintetizar o esqueleto carbônico básico de furanoeliangolidos. Goiazensolido é um típico exemplo destes produtos naturais, cujo núcleo estrutural podemos considerar como sendo de um biciclo[6.2.1]undecano. Imaginamos que este tipo de estrutura poderia ser preparado através da reação de Diels-Ald
Publicado em: 2001
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20. Sintese formal enantiosseletiva do (-)-disidiolidio e outros estudos sinteticos envolvendo vinilcicloexenos
With the present research work we envisaged both the preparation and the application of vinylcyclohexene-type dienes as pivotal intermediates in synthetic pathways aiming the preparation of natural products (terpenoids) possessing bicyclic, partially-rearranged skeletons. Convergent construction of the decalin framework was turned to the Diels-Alder reaction
Publicado em: 2000
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21. Estudos sinteticos para a obtenção de derivados do biciclo [4.4.0]deceno, via reações de Diels-Alder
Assessing the synthesis of compounds possessing the bicycle[ 4.4.0]decene skeletons like 6-hydroxy-1,2,5,5-tetramethyl-1,2,3,5,6,7,8,8a-octahydronaphthalene derivatives via Diels-Alder was the primary objective of the present thesis. The (1S)-(-)- and (1R,S)-()-2,2-dimethyl-3-vinyl-3-cyclohexenol (17 e 17a, respectively) were the dienes four choice to react
Publicado em: 1999
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22. p-substituted methyl thiocinnamates: Diels Alder reactions and cyclic hydrodimerization / Tiocinamatos de metila p-substituídos: reações de Diels-Alder e de ciclo-hidrodimerização catódica
O interesse acadêmico por tioésteres vem de longa data devido ao papel que desempenham em processos biológicos. A presente dissertação versa sobre as reações de Diels-Alder de tiocinamatos e cinamatos de metila p-substituídos por grupos atraentes e repelentes de elétrons, com ciclopentadieno em diferentes condições reacionais e na presença de div
Publicado em: 1998
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23. Unified synthesis of caged Garcinia natural products based on a site-selective Claisen/Diels–Alder/Claisen rearrangement
A unified synthetic strategy toward caged Garcinia natural products has been designed and implemented. Central to the strategy is a tandem Claisen/Diels–Alder/Claisen rearrangement of a suitably substituted xanthone precursor to form forbesione (1a). Serving as a template, forbesione is then used to deliver representative members of this family, including
National Academy of Sciences.
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24. Synthesis of (-)-longithorone A: Using organic synthesis to probe a proposed biosynthesis
We present a full report of our enantioselective synthesis of (-)-longithorone A (1). The synthesis was designed to test the feasibility of the biosynthetic proposal for 1 put forward by Schmitz involving intermolecular and transannular Diels–Alder reactions of two [12]-paracyclophane quinones. We have found that if the biosynthesis does involve these two
National Academy of Sciences.