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Master's Dissertation
DOI
10.11606/D.46.2010.tde-08112010-085846
Document
Author
Full name
Thais Bezerra Claudio
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2010
Supervisor
Committee
Marzorati, Liliana (President)
Andrade, Leandro Helgueira de
Mattos, Marcos Carlos de
Title in Portuguese
Estudos por RMN de 1H das interações de substratos carbonílicos e carboxílicos com agentes de discriminação quiral
Keywords in Portuguese
Agentes de discriminação quiral
Alcalóides
Cinchona
CTF assimétrica e modelos de interação molecular
RMN de 1H
Abstract in Portuguese
Os sais derivados de alcalóides da Cinchona têm sido muito utilizados como catalisadores de transferência de fase, em reações assimétricas. No entanto, sua performance como agentes de discriminação quiral tem sido pouco explorada. Com o objetivo de melhor compreender as bases moleculares que comandam o reconhecimento quiral dos isômeros ópticos de compostos carbonílicos e carboxílicos, quando em mistura com a quinina ou com sais de alcalóides da Cinchona, foi realizada uma série de experimentos, utilizando a técnica da RMN de 1H. A atribuição dos deslocamentos químicos aos solvatos de cada enantiômero foi feita pelo registro do espectro de RMN de 1H de misturas dos agentes de discriminação quiral com amostras enantiopuras ou enantiomericamente enriquecidas dos substratos. A estabilidade relativa dos solvatos foi estimada utilizando-se modelos moleculares, nos quais foi possível identificar a existência de interações do tipo π-π e de ligações de hidrogênio. As conclusões baseadas nos experimentos de RMN de 1H foram concordantes com as resultantes da análise dos modelos moleculares, construídos para cada par substrato/agente de discriminação quiral
Title in English
1H NMR investigations of the interactions of carbonyl and carboxyl derivatives with chiral discriminating agents
Keywords in English
1H NMR
Alcaloids
Asymmetric PTC and modelling interactions
Chiral discriminating agents
Cinchone
Abstract in English
Salts of Cinchone alcaloids are common chiral catalysts for asymmetric phase-transfer reactions. However, studies on their performance as chiral discriminating are still scarce. In order to investigate the molecular basis of chiral recognition for such compounds, the 1H NMR spectra of admixtures of quinine or Cinchone alkaloids salts with carbonyl and carboxyl derivatives were recorded and analyzed. The relative stabilities of the solvated complexes were estimated on the basis of preferential π-π and hydrogen bonding interactions between substrates and the chiral discriminating agent. Conclusions based on results of the 1H NMR experiments were in line with those arising from the analysis of molecular models for the substrate/chiral discriminating agent pairs
 
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Publishing Date
2011-01-14
 
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