Cycloaddition Reaction
Mostrando 13-24 de 47 artigos, teses e dissertações.
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13. Effect of Sulfamic Acid on 1,3-Dipolar Cycloaddition Reaction: Mechanistic Studies and Synthesis of 4-Aryl-NH-1,2,3-triazoles from Nitroolefins
A facile and new metal-free 1,3-dipolar cycloaddition reaction for the synthesis of 4-aryl-NH-1,2,3-triazoles from nitroolefins and NaN3 employing NH2SO3H has been developed. Sulfamic acid proved to be an efficient additive in this transformation by inhibiting the formation of triaryl benzene. Mechanistic aspects and key intermediates associated with this tr
J. Braz. Chem. Soc.. Publicado em: 2017-04
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14. Strategies for Molecular Diversification of 2-[Aminoalkyl-(1H-1,2,3-triazol-1- yl)]-1,4-naphthoquinones Using Click Chemistry
Click chemistry-based strategies for the synthesis of 2-amino-alkyl-1,2,3-triazole-1,4-naphthoquinone derivatives make it possible to obtain desired products from 1,4-naphthoquinone (1,4-NQ), and bio-based lawsone, nor-lapachol and lapachol. The first route (Strategy A) starting from 1,4-NQ and amino alcohols, then 2-amino-alkyl-1,4-NQ alcohols, were tosylat
J. Braz. Chem. Soc.. Publicado em: 2017-04
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15. An Efficient Protocol for Facile Synthesis of New 5-Substituted-1H-Tetrazole Derivatives Using Copper-Doped Silica Cuprous Sulfate (CDSCS) as Heterogeneous Nano-Catalyst
A facile and highly efficient protocol for synthesis of new 5-substituted-1H-tetrazoles derivatives using copper-doped silica cuprous sulfate (CDSCS) is described. In this method, the cycloaddition reaction of sodium azide with structurally diverse nitriles involving bioactive N-heterocyclic cores exploiting CDSCS in refluxing H2O/i-PrOH (1:1, v/v) furnishes
J. Braz. Chem. Soc.. Publicado em: 2017-01
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16. Ultrasound-Assisted Synthesis of Isatin-Type 5'-(4-Alkyl/Aryl-1H-1,2,3-triazoles) via 1,3-Dipolar Cycloaddition Reactions
This short report describes the preparation of twelve isatin derivatives, 5'-(4-alkyl/aryl-1H-1,2,3-triazoles), using 5-azido-spiro[1,3-dioxolane-2,3'-indol]-2'(1'H)-one in the presence of various alkynes under acidic conditions and ultrasound irradiation. Compared with conventional methods, yields increased to 78-98%, and reaction times decreased to 5 min.
J. Braz. Chem. Soc.. Publicado em: 2016-12
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17. The 1,3-Dipolar Cycloaddition of Nitrile Oxide to Vinylacetic Acid: Computational Study of Transition States Selectivity, Solvent Effects, and Bicyclo Formation
The 1,3-dipolar cycloaddition reaction is a powerful tool for the cycloaddition of nitrile oxides to olefins, and this reaction is of considerable interest to obtain isoxazolines. Density functional theory (DFT) was used to study the 1,3-dipolar cycloaddition reaction mechanism that initially occurs between benzonitrile oxide and vinylacetic acid to yield a
J. Braz. Chem. Soc.. Publicado em: 2016-06
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18. Synthesis of 3-(1H-1,2,3-Triazol-1-yl)-2-(arylselanyl)pyridines by Copper-Catalyzed 1,3-Dipolar Cycloaddition of 2-(Arylselanyl)-3-azido-pyridines with Terminal Alkynes
We present here our results in the synthesis of eleven new 3-(1H-1,2,3-triazol-1-yl)-2-(arylselanyl)pyridines by copper-catalyzed azide-alkyne cycloaddition reactions. The reactions were performed in the presence of catalytic amount of copper(II) acetate and sodium ascorbate using a mixture of tetrahydrofuran/water (1:1) as solvent at room temperature in air
J. Braz. Chem. Soc.. Publicado em: 2015-11
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19. Efficient Eco-Friendly Solvent-Free Click Synthesis and Antimicrobial Evaluation of New Fluorinated 1,2,3-Triazoles and their Conversion into Schiff Bases
A facile and convenient green click synthesis has been developed for the preparation of new fluorinated 1,2,3-triazoles under solvent-free conditions via a Huisgen 1,3-dipolar cycloaddition reaction between dimethylacetylene dicarboxylate (DMADC) and fluorophenyl azides in excellent yields within 2 min. Treatment of the resulting diesters with hydrazine hydr
J. Braz. Chem. Soc.. Publicado em: 2015-10
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20. ROMP como um método versátil para a obtenção de materiais poliméricos diferenciados
Ring Opening Metathesis Polymerization (ROMP) of cyclic olefins is a powerful transition metal-catalyzed reaction for syntheses of polymers and copolymers. The key feature of this reaction is the [2+2]-cycloaddition mechanism, with retention of the olefinic unsaturation in the polymer chain and occurrence of living polymerization. With the development of met
Química Nova. Publicado em: 2012
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21. Síntese e caracterização de novos polímeros líquido-cristalinos de cadeia lateral derivados do heterociclo 2-isoxazolínico 3,5-dissubstituído
This thesis presents the synthesis and characterization of new polymer liquid crystal materials based on heterocycle 2-isoxazoline 3,5-disubstituted. We studied the inversion effects of groups linked in position 3 and 5 in 2-isoxazoline in the mesogenic group attached by side chain polymer liquid crystal and the influence in liquid crystals properties. The m
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2012
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22. A reação "click" na síntese de 1,2,3-triazóis: aspectos químicos e aplicações
The Copper-catalyzed azide-alkyne cycloaddition (CuAAC), often referred to as "click" reaction, has become a very popular reaction in the last years. It affords exclusively 1,4-disubstituted 1,2,3-triazoles and has been widely used to connect readily accessible building blocks containing various functional groups. The great success of this reaction is based
Química Nova. Publicado em: 2011
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23. Síntese e avaliação preliminar da atividade antinociceptiva de novas isoxazolil-aril-hidrazonas
New 2-isoxazoline aldehydes were synthesized, in good yields, from cycloadduct of the 1,3-dipolar cycloaddition reaction between endocyclic enecarbamate and carboethoxyformonitrile oxide (CEFNO). Condensation of these 2-isoxazoline aldehydes with several phenyl-hydrazines produced new isoxazolyl-aryl-hydrazones, which showed low toxicity and excellent antino
Química Nova. Publicado em: 2011
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24. Síntese de 1,2,3- triazóis ligados a 1,4- naftoquinona via reação de cicloadição 1,3- dipolar. / Synthesis of 1,2,3- triazoles connected 1,4-naphthoquinone via reation of 1,3-dipolar cycloaddition.
No presente trabalho foi realizada a síntese de uma nova série de derivados 1,2,3-triazólicos 1,4-dissubstituídos contendo o grupo naftoquinona na posição 1 deste anel heterocíclico a partir da reação de cicloadição 1,3-dipolar entre o precursor 2-azido-1,4-naftoquinona e 10 alcinos terminais, utilizando um método que emprega o uso de CuI como es
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2011