Apport de la modélisation en organocatalyse : sélectivités, mécanismes et propriétés.

Abstract : Nowadays, molecular modelling, and more particularly density functional theory methods (DFT), is a great way to describe and rationalize properties of chemical systems. In this work, we used these computational methods to study organocatalyzed reactions. Organocatalysis, which is part of the green chemistry field by the absence of metal atoms, proved to be a very successful mode of catalysis over the last decade in terms of yields, but also in terms of enantiomeric excesses when using a chiral catalyst. In this thesis we were interested in two types of organocatalysts : phosphines and phosphoric acids. Phosphines catalyze the reaction between a conjugated diene and an imine, yielding a pyrroline in a selective manner. The understanding of the regioselectivity of this reaction was the main topic of our theoretical study, in which we modelled different possible reaction pathways. These theoretical works were joined by experimental kinetic measures which allowed us to confirm the rate-determining step of the reaction. These studies lead us to propose a new reaction mechanism which explains the experimental results observed in the literature. Phosphoric acids catalyze the enantioselective reduction of quinolines by Hantzsch esters. A complete theoretical study of the mechanism of this reaction allowed us to reproduce the enantiomeric excesses obtained experimentally. On this basis, we were also interested in the rationalization between the chemical properties of these phosphoric acids and their ability to catalyze reactions.
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Contributor : Julien Pastor <>
Submitted on : Monday, December 1, 2014 - 3:24:57 PM
Last modification on : Thursday, June 20, 2019 - 10:14:01 AM
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Julien Pastor. Apport de la modélisation en organocatalyse : sélectivités, mécanismes et propriétés.. Chimie. École polytechnique, 2014. Français. ⟨tel-01089342⟩

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