Introduction: The introduction provides a survey of the natural product and pharmaceutical targets accessible from dihydropyridines and dihydropyridones as well as an overview of previous work carried out towards the synthesis of these valuable intermediates. The mechanism, scope and limitations of the various approaches are covered, along with the goals of this project. Results and Discussion: A Regioselective Route to Dihydropyridones. The regioselective addition of nucleophiles to a range of disubstituted pyridinium salts has been achieved, with selectivity determined by hard/soft factors. Certain nucleophiles can be added with complete regioselectivity to either C-2 or C-6 of these salts, depending on the conditions employed. Addition at C-2 allows the generation of a quaternary centre in high yield. The conditions discovered can be applied to pyridinium salts with different substitution patterns and an effective procedure has been developed for the removal of the nitrogen protecting group post reduction. The Preparation of Enantiopure Dihydropyridones.After unsuccessful attempts to find a reagent-controlled asymmetric synthesis of dihydropyridones, a highly diastereoselective and non-chiral auxiliary based substrate-controlled procedure has been developed. By prompting an intramolecular hydride migration from a secondary silyl ether onto the pyridinium core, the corresponding dihydropyridones are available in high yield, with the diastereoselectivity being controlled by the minimization of 1,3-allylic strain between the N-allyl group and the hydride-bearing side chain. Thus, an enantiopure pyridyl alcohol may be converted to the corresponding dihydropyridone without loss of enantiomeric purity. Furthermore, the dihydropyridones can be easily converted to complex bicyclic systems via a ring closing metathesis reaction. Experimental: Full experimental procedures and spectroscopic characterization of compounds are provided.

La synthèse d’hétérocycles azotés énantiopurs est un enjeu important dans la chimie du vivant et représente l’un des axes de notre laboratoire depuis quelques années. L’ensemble du travail a bénéficié pour cela du « pool chiral » constitué par les acides aminés naturels. Dans la première partie de notre travail, nous avons utilisé l’acide aspartique à partir duquel des exemples variés de β-amino-ynones ont été construits. Leur cyclisation par catalyse à l’or a donné accès à des pyridones, précurseurs de dérivés pipécoliques énantiopurs. Un travail analogue a été entrepris sur des γ-amino-ynones et a donné un résultat moins prévisible : cyclisation à cinq sommets suivie du réarrangement de Meyer-Schuster. Cette synthèse s’est montrée plus efficace en milieu acide méthane sulfonique qu’en présence d’or et représente un nouveau mode d’accès aux vinylogues d’amides de la pyrrolidine, intermédiaires-clé en synthèse totale. Enfin, l’utilisation d’un acide de Lewis, ZnCl₂, sur des γ- et δ-amino-ynones a fourni des imines cycliques, à cinq ou six sommets et portant un alcyne, que nous avons isolées sous forme libre ou complexée par l’acide de Lewis. / The synthesis of enantiopure nitrogen heterocycles is an important issue in chemistry and has been part our laboratory work for several years. The entire work took advantage of the chiral pool consisting of natural amino acids. In the first part of our work, we used aspartic acid from which various examples of β-amino-ynones were built. Their catalytic cyclization gave access to pyridones that were used as enantiopure pipecolic acid precursors. A similar work was undertaken on γ-amino-ynones and gave a less predictable result: cyclization to a five members ring followed by Meyer-Schuster rearrangement. This synthesis was more effective in a methane sulfonic acid medium than in the presence of gold and represents a new mode of access to pyrrolidine vinylogous amides that are key-intermediate in total synthesis. Finally, the use of a Lewis acid -ZnCl₂- on γ- and δ-amino-ynones provided five and six members cyclic imines, carrying an alkyne, which we isolated in the free form or complexed with the Lewis acid.