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Doctoral Thesis
DOI
10.11606/T.46.1978.tde-02032011-131831
Document
Author
Full name
Joao Valdir Comasseto
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1978
Supervisor
Title in Portuguese
Selenofosforanas e selenofosfonatos: preparação e reatividade. selenetos vinílicos
Keywords in Portuguese
Selenetos vinílicos
Selenofosfonatos
Selenofosforanas
Abstract in Portuguese
Tetrahalogenoarilteluratos (IV) foram preparados e suas propriedades químicas e espectrais estudadas. Com base nos espectros Raman e infravermelho foi sugerida a estrutura piramidal quadrada para o ânion complexo. A reação de Wittig entre (fenilseleno)fosforanas e compostos carbonílicos foi investigada. A reação com cetonas, β-dicetonas e β-ceto-ésteres, ao invés do produto normal de uma reação de Wittig, forneceu compostos carboní1icos α-fenilseleno substituidos. O mecanismo desta reação foi estudado. (Fenilseleno)fosfonatos substituidos foram preparados por alquilação do (fenilseleno)metildietilfosfonato, obtido pela reação entre selenofenóxido de sódio e iodometildietilfosfonato. Reação do carbânion (fenilseleno)fosfonato com compostos carbonílicos forneceu os selenetos vinílicos esperados com bons rendimentos. Estudou-se a influência do solvente e da presença de sais de lítio no decurso estérico das reações de (fenilseleno)fosforanas e fosfonatos com aldeídos. Foi realizado um estudo crítico dos modelos propostos na literatura para explicar o decurso estérico das reações de Wittig e Horner Emmons. Investigou-se a adição de selenofenol a acetilenos. A temperatura ambiente formou-se exclusivamente o isômero Z, à temperatura elevada (130°) formou-se uma mistura de estereoisômeros. Redução de (fenilseleno)acetilenos, preparados a partir dos acetiletos de lítio correspondentes e brometo de fenilselenenila, forneceu selenetos vinílicos de configuração E. Selenetos vinílicos nos quais R≠H são hidrolisados facilmente, usando-se ácido trifluoroacético ou cloreto de mercúrio em acetonitrila e água, fornecendo as cetonas correspondentes com bons rendimentos.
Title in English
Selenophosphoranes and selenophosphonates: preparation and reactivity vinylic selenides
Keywords in English
Selenophosphonates
Selenophosphoranes
Vinylicselenides
Abstract in English
Tetrahalogenoariltelurates (IV) were prepared and their chemical and spectral properties studied. On the basis of Raman and infrared spectral data, the square pyramidal structure was suggested for the complex anion. The Wittig reaction between (phenylseleno)phosphoranes and carbonyl compounds was investigated. The reaction with ketones, β-diketones and β-ketoesters furnished the α-phenylseleno substituted carbonyl compound instead of the normal Wittig product. The mechanism of this reaction was studied. Substituted (phenylseleno)phosphonates were prepared by alkylation of (phenylseleno)methyldiethylphosphonate, the latter obtained by reaction of sodium selenophenoxide with iodomethyldiethylphosphonate. Reaction of the (phenylseleno)phosphonate carbanion with carbonyl compounds furnished the expected vinylic selenides in good yield. The influence of the solvent and the presence of lithium salts on the steric course of the reaction of phenylseleno)phosphoranes and phosphonates with aldehydes was investigated. The results were analysed in accord with the models proposed in the literature to explain the steric course of the Wittig and Horner-Emmons reactions. The addition of selenophenol to acetylenes was investigated. At room temperature there was exclusive formation of the Z isomer; at high temperatures (130°) a mixture of stereoisomers was formed. Reduction of (phenylseleno)acetylenes, prepared from the corresponding lithium acetylides and phenylselenenyl bromide, furnished vinylic selenides with the E configuration. Vinylic selenides with R≠H are easily hydrolised using trifluoroacetic acid or mercuric chloride in aqueous acetonitrile, furnishing the corresponding ketones in good yields.
 
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Publishing Date
2011-03-02
 
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