Fases de líquidos iônicos imobilizados em poliestireno contendo ácidos de Lewis como catalisadores para reações de Gröebke-Blackburn-Bienaymé
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Data
2023-10-20
Autores
Santos, Naara Isabel dos [UNIFESP]
Orientadores
Longo Junior, Luiz Sidney [UNIFESP]
Tipo
Trabalho de conclusão de curso de graduação
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Resumo
As reações multicomponentes (Multicomponents reactions, MCRs) são uma alternativa vantajosa para a obtenção rápida de bibliotecas de compostos orgânicos, levando a compostos com alta diversidade e complexidade estrutural. As reações de Gröebke-Blackburn-Bienaymé (GBB) são MCRs que combinam três reagentes, aldeídos, aminoazóis e isonitrilas, para formação de heterocíclicos nitrogenados, como as imidazo[1,2-a]piridinas, no caso de utilizar a 2-aminopiridina como componente aminoazol. Este trabalho apresenta o estudo das condições reacionais da reação GBB utilizando como catalisadores fases de líquidos iônicos ácidos de Lewis imobilizados em poliestireno, sob aquecimento por irradiação de micro-ondas para obtenção de imidazo[1,2-a]piridinas com potencial atividade biológica. Inicialmente, uma combinação dos materiais de partida benzaldeído, terc-butil-isonitrila e 2-aminopiridina, utilizando metanol como solvente, foi utilizada como reação modelo, tendo como variável a atividade catalítica de PS-ImC8Cl/InCl3 e PS-ImC8Cl/ZnCl2, em três razões molares diferentes (= 0,5, 0,33 e 0,25). Os rendimentos obtidos para as imidazo[1,2-a]piridinas de interesse variaram entre 50-96%. A melhor condição reacional foi aquela em que a reação foi efetuada à 100 °C em reator de micro-ondas utilizando MeOH e o catalisador PS-ImC8Cl/InCl3 na razão molar de = 0,33, durante 45 minutos. Em seguida, a melhor condição reacional foi aplicada na preparação de novas imidazo[1,2-a]piridinas, utilizando diferentes aldeídos (aromáticos e alifáticos), e isonitrilas, levando aos produtos de interesse em rendimentos que variaram de 58% a 94%. De modo geral, é possível concluir que a fase de líquido iônico suportada em poliestireno contendo InCl3 = 0,33 foi eficiente para obtenção das imidazo[1,2-a]piridinas de interesse em reações de GBB sob aquecimento por micro-ondas.
The multicomponent reactions (MCR) are a efficient methods for the rapid synthesis of organic compound libraries, which can be obtained with high diversity and structural complexity. The Gröebke-Blackburn-Bienaymé (GBB) reactions are MCRs that combine three reagents, aldehydes, aminoazoles and isocyanides, to form nitrogen-based heterocycles, such as imidazo[1,2-a]pyridines, when 2-aminopyridine is used as aminoazole component. Herein, we present the study of the reaction conditions of the GBB reaction using phases of Lewis acid ionic liquids immobilized in polystyrene as catalysts, under microwave irradiation heating to obtain imidazo[1,2-a]pyridines with potential biological activity. Initially, it was studied a model reaction between benzaldehyde, tert-butyl isocyanide and 2-aminopyridine in methanol as solvent, variable amounts of catalysts PS-ImC8Cl/InCl3 and PS-ImC8Cl/ZnCl2, in three different molar rations (= 0,5, 0,33 e 0,25). The yields obtained for the imidazo[1,2-a]pyridines varied between 50-96%. The best reaction condition was identified when the reaction was performed at 100 °C under microwave heating, using MeOH and the catalyst PS-ImC8Cl/InCl3 = 0,33, for 45 minutes. Then, the best reaction condition was applied in the preparation of new imidazo[1,2-a]pyridines using different aldehydes (aromatic and aliphatic) as well as isocyanides, leading to the products in yields ranging from 58% to 94%. So far, it is possible to conclude that the ionic liquid phase supported on polystyrene containing InCl3 = 0,33 was efficient to catalyze GBB reactions under microwave heating applied to the synthesis of imidazo[1,2-a]pyridines.
The multicomponent reactions (MCR) are a efficient methods for the rapid synthesis of organic compound libraries, which can be obtained with high diversity and structural complexity. The Gröebke-Blackburn-Bienaymé (GBB) reactions are MCRs that combine three reagents, aldehydes, aminoazoles and isocyanides, to form nitrogen-based heterocycles, such as imidazo[1,2-a]pyridines, when 2-aminopyridine is used as aminoazole component. Herein, we present the study of the reaction conditions of the GBB reaction using phases of Lewis acid ionic liquids immobilized in polystyrene as catalysts, under microwave irradiation heating to obtain imidazo[1,2-a]pyridines with potential biological activity. Initially, it was studied a model reaction between benzaldehyde, tert-butyl isocyanide and 2-aminopyridine in methanol as solvent, variable amounts of catalysts PS-ImC8Cl/InCl3 and PS-ImC8Cl/ZnCl2, in three different molar rations (= 0,5, 0,33 e 0,25). The yields obtained for the imidazo[1,2-a]pyridines varied between 50-96%. The best reaction condition was identified when the reaction was performed at 100 °C under microwave heating, using MeOH and the catalyst PS-ImC8Cl/InCl3 = 0,33, for 45 minutes. Then, the best reaction condition was applied in the preparation of new imidazo[1,2-a]pyridines using different aldehydes (aromatic and aliphatic) as well as isocyanides, leading to the products in yields ranging from 58% to 94%. So far, it is possible to conclude that the ionic liquid phase supported on polystyrene containing InCl3 = 0,33 was efficient to catalyze GBB reactions under microwave heating applied to the synthesis of imidazo[1,2-a]pyridines.