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| Author(s): |
Rogério Aparecido Gariani
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2011-02-22 |
| Examining board members: |
Joao Valdir Comasseto;
Leandro Helgueira de Andrade;
Antonio Luiz Braga;
Liliana Marzorati;
Cristiano Raminelli
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| Advisor: | Joao Valdir Comasseto |
| Abstract | |
This thesis contains three chapters: 1st chapter - Kinetic enzymatic resolution of sulfides, selenides and tellurides in supercritical CO2. Initialy, the stability of the β-hydroxy organochalcogenides in suprecritical CO2 was evaluated. As the variation in the pressure and temperature affect the fluid density in a non-linear way, a systematic study on the influence of these parameters was performed, aiming a high enantiomeric excess for the products. The enantiomeric excesses of the β-hydroxy sulfides and selenides were determined by high performance chiral liquid chromatography (HPLC). The β-hydroxy tellurides were not stable under the same conditions. In view of this fact, a new method to determine the enantiomeric excess of the β-hydroxy tellurides was developed, using 125Te NMR spectroscopy for this end. 2nd chapter - Use of chiral telluroferrocenes as chiral probes for the enantiomeric excess determination using 125Te NMR spectroscopy. Chiral telluroferrocenes, substituted by amides, oxazolines and amines were prepared. These chiral tellurium containing molecules interact with chiral samples, forming diastereomeric transient complexes in which the tellurium atoms are submitted to different chemical environments, what leads to different 125Te chemical shifts for each diastereomeric complex integration of the 125Te NMR spectra allowing the determination of the enantiomeric excess of the chiral samples. 3rd chapter - Chalcogenation of activated olefines. In situ gererated lithium organochalcogenolates were reacted with activated olefines. In the presence of a proton source, the β-functionalized chalcogenides were formed. Under anhydrous conditions, the intermediate enolate can be trapped with carbonyl compounds in a three components process to give precursors of Morita-Baylis-Hillman adducts when Y = S, Se. (AU) | |