Catalisadores orgânicos: síntese e aplicações em reações orgânicas estereosseletivas

• Ano de defesa: 2017
• Autor(a) principal: Arruda, Priscila Machado [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Organic synthesis; Organocatalysis; Henry reactions; Cinchona; Thiourea; Síntese orgânica; Organocatálise; Reações de Henry; Tiouréia
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5006604; http://repositorio.unifesp.br/handle/11600/50020

Organocatalysis has been shown as an important field in chiral synthesis, since the reactional planning of chiral catalysts has been a challenge to chemistry. The present work focuses on the development of new bifunctional organocatalysts based on Cinchona alkaloids and their applications in enantioselective Henry and Michael reactions. The work was developed in two steps, the first step was the synthesis and application of new organocatalysts in Henry reactions between nitromethane and benzaldehyde, the second step was the application of the same organocatalysts in Michael reactions between trans-nitrostyrene and ethyl 2-cyane-3-phenylpropanoate. Experimental conditions were varied for Henry reactions such as temperature, solvent, catalyst quantity and time of reaction, where organocatalyst XI catalysed the nitroalcohol in higher enantiomeric excess (ee) (33% ee, 64% of conversion), using nitromethane as solvent, however the best conversion occurred with organocatalyst II (89% of conversion and 4% ee) using ethylene glycol monoethyl ether. For Henry reaction the best reactional condition found was at ambient temperature, 10% mol of catalyst and 112h of reaction time. The second step consist on the appplication of the organocatalysts in Michael reaction, and experimental conditions as temperature, solvent, catalyst quantity and reaction time were varied. The best result found was using the organocatalyst XII on the formation of Michael adduct, with 89% of enantiomeric excess (ee), 100% of conversion at -80 °C in diethyl ether. An activation model of substrates with the organocatalyst XII was proposed where the active functional groups of the organocatalyst interacts by hydrogen bonds with the substrates.