Recently, chiral auxiliary reagents have received great attention in asymmetric organic chemistry. One of the most well-known ligands, oxazoline, has been widely investigated in literatures because of its chelating abilities with metals. In catalytic reactions, oxazoline (bearing bulky substituants) metal complexes can result in excellent enantioselectivity. Therefore, we designed two novel bis-oxazoline ligands,1,4 - ((4 - phenyl-4,5 - dihydrotestosterone oxazole -2 - yl) methyl) benzene (89) and 2,2 '- (4,4', 5,5 ', 6,6' - Lioujia oxygen - [1,1 '- biphenyl] -2,2' - diyl) bis (4 - phenyl - 4 , 5 - dihydrotestosterone oxazoline) (99) and we anticipate both of them could play as good chiral ligands in the future. The synthesis of chiral oxazoline metal catalysts is still in progress in our laboratory

This thesis contains the preparation of a new design of ligand for the palladium catalysed allylic substitution reaction. The phosphine oxazoline ligands detailed in the thesis give high levels of enantiocontrol when used in conjunction with symmetrical allyl systems in the palladium catalysed allylic substitution reaction. For unsymmetrical allyl systems the palladium catalysed allylic substitution process proceeds with complete regiocontrol and high levels of stereocontrol are again observed. The products from the palladium catalysed allylic substitution reaction can be readily converted to succinic acids, γ-lactones and aryl propanoic acids.

This thesis contains the synthesis of a series of novelligands that include the enantiomerically pure 2-oxazoline moiety. The thesis also considers the application of new nucleophiles for the palladium catalysed allylic substitution reaction. The synthesis of enantiomerically enriched analogues of y-amino butyric acid (GABA) is presented. The first series of ligands are designed as analogues of acetyl acetonate (acac). The ligands include the enantiomerically pure 2-oxazoline ring and a carbonyl moiety. The ligands are available in good yield in two steps. The second series of ligands include a ligating sulfur atom. The synthesis of novel oxazoline-sulfide ligands is detailed. The diastereoselective oxidation of these ligands is considered. Diastereomerically pure oxazoline-sulfoxide ligands are prepared in good yield. New nucleophiles are applied to the palladium catalysed allylic substitution reaction. The substitution products are available in good yield and with excellent stereoselectivity. The synthesis of analogues of GABA is considered. The preparation of enantiomerically enriched a-substituted-y-amino butyric acids is presented. The stereocentre is introduced in the first step of the synthesis. The analogues are subsequently isolated in good yield after six steps.

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Poly(2-ethyl-2-oxazoline) (PEOX) is a nonionic, synthetic polymer which is soluble in both a variety organic solvents and water. The negative entropy of mixing of this polymer in aqueous solution suggested that it adopts a rigid conformation such as a helix in aqueous solution. Hydrogen bonding between PEOX and water molecules is thought to facilitate a special conformation that is specific to aqueous solution. The intent of this work is to investigate the conformation of PEOX in aqueous solution and consequently propose the mechanism by which it would adsorb onto cellulose and make it a valuable additive in paper processing. This work ultimately contributes to the greater matter of understanding the mechanisms by which water solvates nonionic polymers. Viscometry measurements of PEOX in water show that its shape scales similar to a random coil and that its molecules collapse in the presence of sodium chloride. Investigation into the molecular structure of PEOX through molecular scale simulations have revealed that although a rigid helical conformation does not exist, the potential exists for PEOX to have secondary helical structure in both water and other solvents. Without the rigid predicted structure, however, it is not surprising that PEOX does not adsorb well on cellulose. Comparing this folded helical conformation to a random coil conformation reveals that the random coil produces a lower energy system in water.

Fungos no ambiente podem ser patogênicos ou oportunistas, dependendo da imunidade do hospedeiro. Existem várias espécies de fungos, por exemplo, Cândida albicans, Cryptococcus e Aspergillus. A primeira espécie fúngica pode ser tratada com o antifúngico fluconazol, que é um composto que contém anéis heterocíclicos 1,2,4-triazólicos. Além disso, existem cepas de fungos que são resistentes à terapia com fluconazol, que é o caso das Cândida krusei, Cândida tropicalis; entre outras. A busca por novos tratamentos envolve o desenvolvimento de novas moléculas sintéticas. Neste trabalho, sintetizamos uma biblioteca de compostos oxazolínicos e seus derivados 1,2,3-triazólicos. A atividade microbiológica foi avaliada contra 10 tipos de Cândida, 2 tipos de Cryptococcus e 2 tipos de Aspergillus. Além disso, foram feitos os testes de hemólise, citotoxicidade, combinações de drogas e permeabilidade de membrana. Os resultados sugerem um alto potencial terapêutico dos compostos e os propomos como potenciais novos antifúngicos. / Fungi in the environment may be pathogenic or opportunistic depending on the immune status of the host. There are several species of fungi, for example, Candida albicans, Cryptococcus and Aspergillus. The first fungal species can be treated with the antifungal fluconazole, which is a compound containing 1,2,4-triazole heterocyclic rings. In addition, there are strains of fungi that are resistant to fluconazole therapy, which is the case of Candida krusei, Candida tropicalis; among others. The search for new treatments involves the development of new synthetic molecules. In this work, we synthesized a library of oxazoline compounds and their 1,2,3-triazole derivatives. Microbiological activity was evaluated against 10 types of Candida, 2 types of Cryptococcus and 2 types of Aspergillus. In addition, hemolysis, cytotoxicity, drug combinations and membrane permeability were performed. The results suggest the high therapeutic potential of the compounds and we propose them as potential new antifungals.

The design, effectiveness and versatility of the self-assembled monolayer-immobilized aza-bis(oxazoline) catalysts was explored here. The first part of this dissertation focuses on the immobilization of aza-bis(oxazoline) ligand with three different C2 groups onto self-assembled monolayer support material. In the homogeneous phase, the more steric bulk present at the C2 position of the catalytic system, the greater the selectivity. In the heterogeneous systems, those with the least amount of steric bulk had the greatest increase in selectivity compared to their respective homogeneous phase. The supports not only allowed for selectivity enhancements not observed in the homogeneous phase, but also demonstrated the effectiveness of this support material in the cyclopropanation reaction. <br>Self-assembled monolayer supports allowed for modification of the surface steric environment around the catalytic site. This was accomplished by varying the length of the background alkenethiol chains so that three steric environments were created. The three steric environments were the catalyst above the monolayer surface, level with the monolayer surface, and below the monolayer surface. Modification of the steric environment around the catalyst, in turn allows for control of the selectivity of the heterogeneous catalytic system. <br>Modification of the surface electronic environment around the catalytic site is accomplished by modification of alkanethiol tail groups. The five background tail groups investigated were hydroxyl, bromide, carboxylic acid, methyl ester, and nitrile. Modification of the background tail groups allows for control of the enantioselectivity in the cyclopropanation reaction. <br>Self-assembled monolayer supports also allow for the generation of effective reusable heterogeneous catalytic systems. One of the main positive aspects of heterogeneous catalysis is the ability to recycle the catalytic system multiple times without major reduction in selectivity. The duration of these heterogeneous aza-bis(oxazoline) systems is dependent on the stability of the gold substrate layer and the reaction solvent. <br>The last section of this dissertation focuses on the versatility of the aza-bis(oxazoline) copper complex immobilized onto self-assembled monolayers. The homogeneous and heterogeneous catalysts were investigated in the carbonyl-ene reaction of ethyl glyoxylate and á-methylstyrene. The three heterogeneous catalytic systems were the carboxylic acid surface, hydroxyl surface, and the catalyst above the methyl monolayer surface. / Bayer School of Natural and Environmental Sciences / Chemistry and Biochemistry / PhD / Dissertation