Estudo de reações aldólicas diretas organocatalisadas: desenvolvimento esíntese de novos organocatalisadores assimétricos

• Ano de defesa: 2013
• Autor(a) principal: Soares, Bruna Miranda [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Organocatalysis; Aldol reaction; Reactions in water; Green chemistry; Organocatálise; Reação aldólica; Reação em água; Química verde
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=1066038; http://repositorio.unifesp.br/handle/11600/47476

The aldol reaction is one of the most efficient methodologies for the construction of carbon-carbon bonds in organic synthesis. It can be applied in the stereoselective synthesis of architecturally interesting and biologically active compounds. In 2000, the application of proline as a non-metallic catalyst in aldol reactions led to the investigation of the involved mechanism in this type of catalysis, as well the development of some organocatalysts. They are able to provide the desired products in high levels of stereoselectivities and yields, so the application of this methodology in organic synthesis is very useful. Based on these facts, this dissertation aimed to study stereoselective aldol reactions promoted by novel proline-derived organocatalysts which were prepared. The organocatalysts have been tested in the direct asymmetric aldol reaction of cyclohexanone and p-nitrobenzaldehyde, affording the syn and anti aldol products in a range of 42-52% yields and in a 60:40 and 40:60 anti:syn ratio. In these experiments the stereoselectivity levels of generated products and their yields were evaluated.Furthermore, the traditional organic solvents were replaced by green reaction media. Interesting synthetic and mechanistic results have been obtained in these reactions, because the syn diastereoisomer was formed as the major product, in opposition to what is found in the literature. The development of new sustainable methods for the stereoselective synthesis of β-hydroxy ketones is of great importance in synthetic organic chemistry, since this fragment is present in complex systems of molecules with biological significance.