Síntese de derivados de furanos e isocalcogenocromenos via ciclização eletrofílica

• Ano de defesa: 2010
• Autor(a) principal: Schneider, Caroline Cassalha
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; Química; UFSM; Programa de Pós-Graduação em Química; Centro de Ciências Naturais e Exatas
• Palavras-chave em Português: Furanos; Ciclização eletrofílica; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: http://repositorio.ufsm.br/handle/1/21626

In this work, a range of (Z)-enynols 4 was prepared from telluroenynes 1 via tellurium-lithium exchange reaction followed by addition of different aldehydes or ketones. Subsequently the substrate 4 was subjected to an electrophilic intramolecular cyclization mediated by palladium salt. This methodology allowed the preparation of functionalized 2,5-dihydrofuran 5 and furan derivates 6, furnishing the corresponding products in good yields. After that, we developed a methodology to obtain isochalcogenchromenes 10 via electrophilic cyclization reaction of 2-alkynylbenzylchalcogenides 9. Using this protocol, a series of 2-alkynylbenzylchalcogenides 9 was prepared by substitution reaction with anions alkylchalcogenolates, followed by Sonogashira cross-couplig reaction. Subsequently, these substrates were cyclized with electrophiles, such as I2, furnishing the correspondent products in moderate to good yields.