Costimulation blockade based on a donor-specific transfusion and anti-CD154 mAb is effective for establishing mixed allogeneic hematopoietic chimerism and inducing transplantation tolerance. Despite its potential, recent evidence suggests that the efficacy of costimulation blockade can be reduced by environmental perturbations such as infection or inflammation that activate toll-like receptors (TLR). TLR agonists prevent costimulation blockade-induced prolongation of solid organ allografts, but their effect on the establishment of hematopoietic chimerism has not been reported. In this dissertation, we hypothesized that TLR activation during costimulation blockade would prevent the establishment of mixed hematopoietic chimerism and shorten skin allograft survival. To test this hypothesis, costimulation blockade-treated mice were co-injected with TLR2 (Pam3Cys), TLR3 (poly I:C), or TLR4 (LPS) agonists and transplanted with allogeneic bone marrow and skin grafts. Supporting our hypothesis, we observed that TLR agonists administered at the time of costimulation blockade prevented the establishment of mixed hematopoietic chimerism and shortened skin allograft survival. To investigate underlying cellular and molecular mechanisms, we first determined that LPS administration during costimulation blockade did not increase production of alloantibodies or activate natural killer cells. Similarly, costimulation blockade-treated mice depleted of CD4+ or CD8+ cells did not become chimeric when co-injected with LPS. In contrast, mice depleted of both CD4+ and CD8+cell subsets were resistant to the effects of LPS. We next observed that alloreactive T cells were activated by TLR agonists in mice treated with costimulation blockade, and this activation correlated with LPS-induced maturation of donor and host alloantigen-presenting cells. In contrast, TLR4-deficient mice treated with costimulation blockade and LPS did not upregulate costimulatory molecules on their APCs, and mixed chimerism and permanent skin allograft survival were readily achieved. We further observed that injection of recombinant IFN-β recapitulated the detrimental effects of LPS, and that LPS-injected mice deficient in the type I IFN receptor were partially protected. Importantly, alloantigen-presenting cells did not upregulate costimulatory molecules in response to LPS, and mixed chimerism and permanent skin allograft survival were readily established in type I IFN receptor and MyD88 double deficient mice treated with costimulation blockade. We conclude that the TLR4 agonist LPS prevents the establishment of mixed hematopoietic chimerism and shortens skin allograft survival in mice treated with costimulation blockade by inducing the production of type 1 IFN and MyD88-dependent factors that upregulate costimulatory molecules on APCs, leading to the generation of activated alloreactive T cells.

A complicating factor for peptide identification by MS/MS experiments is the presence of “chimeric” spectra where at least two precursor ions with similar retention time and mass co- elute in the mass spectrometer. This results in a spectrum that is a superposition of the spectra of the individual peptides. These chimeric spectra make peptide identification more difficult, so chimeric detection tools are needed to improve peptide identification rates. GLEAMS is a learned embedding algorithm for efficient joint analysis of millions of mass spectra. In this work, we first simulate chimeric spectra. Then we present a deep neural network- based classifier that learns to distinguish between chimeras and pure spectra. The result shows that GLEAMS captures a spectrum’s chimericness, which can lead to a higher protein identification rate in samples or support biomarker development processes and the like. / En komplicerande faktor för peptididentifiering genom MS / MS- experiment är närvaron av “chimära” spektra eller “chimera”, där åtminstone två föregångare med liknande retentionstid och massa sameluerar in i masspektrometern och resulterar i ett spektrum som är en superposition av individuella spektra. Eftersom dessa chimära spektra gör identifieringen av peptider mer utmanande behövs ett detekteringsverktyg för att förbättra identifieringsgraden för peptider. I detta arbete fokuserade vi på GLEAMS, en lärd inbäddning för effektiv gemensam analys av miljontals masspektrum. Först simulerade vi chimära spektra. Sedan presenterar vi en ensembleklassificering baserad på olika maskininlärnings- och djupinlärningsmetoder som lär sig att skilja på simulerad chimera och rena spektra. Resultatet visar att GLEAM fångar “chimärheten” i ett spektrum, vilket kan leda till högre identifieringsgrad av protein samt ge stöd till utvecklingsprocesser för biomarkörer.

Allogeneic hematopoietic chimerism leading to central tolerance has significant therapeutic potential. Establishment of hematopoietic chimerism created by stem cell transplantation has been shown to prevent and cure a number of autoimmune diseases and induce the most robust and long-lasting form of transplantation tolerance known. However, the realization of the vast clinical potential of hematopoietic chimerism for induction of transplantation tolerance has been impeded by the toxicity of the host conditioning regimen and the development of graft-versus-host disease (GVHD). This thesis describes the development of stem cell transplantation protocols that 1) reduce the host conditioning regimen; and 2) abrogate the development of GVHD. When applied to the treatment of autoimmune diabetic NOD mice, a model of type 1 diabetes, stem cell transplantation was able to 3) prevent autoimmune recurrence; and 4) permit curative pancreatic islet transplantation. I first describe a tolerance-based stem cell transplantation protocol that combines sub-lethal irradiation with transient blockade of the CD40-CD154 costimulatory pathway using an anti-CD154 antibody. With this protocol, I established hematopoietic chimerism in BALB/c mice transplanted with fully allogeneic C57BL/6 bone marrow. All chimeric mice treated with anti-CD154 antibody remained free of graft vs.host disease (GVHD) and accepted donor-origin but not third party skin allografts. It was similarly possible to create allogeneic hematopoietic chimerism in NOD/Lt mice with spontaneous autoimmune diabetes. Pancreatic islet allografts transplanted into chimeric NOD/Lt mice were resistant not only to allorejection but also to recurrence of autoimmunity. I conclude that it is possible to establish robust allogeneic hematopoietic chimerism in sub-lethally irradiated mice without subsequent GVHD by blocking the CD40-CD154 costimulatory pathway using as few as two injections of anti-CD154 antibody. I also conclude that chimerism created in this way generates donor-specific allograft tolerance and reverses the predisposition to recurrent autoimmune diabetes in NOD/Lt mice, enabling them to accept curative islet allografts. In order to further reduce the impediments associated with the implementation of allogeneic hematopoietic chimerism as a therapeutic modality, I adapted a costimulation blockade-based protocol developed for solid organ transplantation for use in stem cell transplantation. The protocol combines a donor-specific transfusion (DST) with anti-CD154 antibody to induce peripheral transplantation tolerance. When applied to stem cell transplantation, administration of DST, anti-CD154 antibody, and allogeneic bone marrow led to hematopoietic chimerism and central tolerance with no myeloablation (i.e. no radiation) and no GVHD in 3 different strains of mice. The development of donor-specific tolerance in this system was shown to involve deletion of both peripheral host alloreactive CD8+ T cells and nascent intrathymic alloreactive CD8+ T cells. In the absence of large numbers of host alloreactive CD8+ T cells, the cell transfusion that precedes transplantation need not be of donor-origin, suggesting that both allo-specific and non-allo-specific mechanisms regulate engraftment. Agents that interfere with peripheral transplantation tolerance partially impair establishment of chimerism. I conclude that robust allogeneic hematopoietic chimerism and central tolerance can be established in the absence of host myeloablative conditioning using a peripheral transplantation tolerance protocol.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

A doença do enxerto versus hospedeiro (DEVH) é uma grave complicação do transplante de órgãos sólidos, com alta mortalidade. Seu estudo tem sido limitado pela carência de modelos experimentais apropriados. Descreve-se um modelo de DEVH baseado no aumento do quimerismo, sua evolução clínica, histopatológica, do número das células quiméricas, do perfil das citocinas e da tolerância imunológica. Ratos Lewis (LEW) foram submetidos a transplante simultâneo de intestino delgado e medula óssea provenientes de ratos ACI (grupo de estudo - E) ou LEW (grupo controle - C), tratados com FK-506 (1 mg/Kg/dia) entre o 0 e 13o PO, e uma dose semanal daí por diante. Os ratos foram divididos nos seguintes grupos: E1- 6 ratos sacrificados no 120o PO. E2- 8 ratos após apresentarem sinais clínicos graves de DEVH entre o 189o e o 271o PO. Como controle, ratos LEW foram receptores dos mesmos tipos de enxertos provenientes de ratos LEW, submetidos à mesma imunossupressão e foram assim divididos: C1- 6 ratos sacrificados no 120o PO, C2- 5 ratos sacrificados entre o 223o e o 270o PO. A citometria de fluxo foi realizada para quantificar a porcentagem das células linfóides de ACI doadores no sangue periférico nos E1, E2 em 6 períodos: 30o PO, 65o PO, 95o PO, 120o PO, 160o PO, 200o PO. Os animais foram examinados 2 vezes por semana à procura de sinais de DEVH (rash cutâneo, perda de peso, de pelo e hiperqueratose). No sacrifício dos animais do grupo E1 e C1, foram colhidas amostras de língua (LI), de linfonodos cervicais (LC), intestino delgado do receptor e do enxerto para análise das citocinas IL-2, IL-4, IL-6, IL-10, IFN-gama e TNF-alfa por meio da reação em cadeia da polimerase. Em todos os grupos foram também colhidas amostras destes órgãos para histopatologia e nos animais do grupo E2 linfonodos cervicais foram processados para análise da reatividade celular por meio da reação mista dos linfócitos (MLR). A evolução clínica e histopatológica foi graduada de 0 a 3 de acordo com a severidade dos sintomas e do infiltrado mononuclear das amostras. Os ratos dos grupos E1 e E2 iniciaram sinais da DEVH entre o 84o e 115o PO. Os ratos dos grupos C1 e C2 não apresentaram evidência de DEVH. Amostras de LI e LC dos ratos do grupo E1 apresentaram alterações histopatológicas grau 2 e do grupo E2 apresentaram alterações histopatológicas grau 3, respectivamente. Nenhuma alteração histopatológica foi encontrada nos ratos do grupo controle e em amostras do ID. Nenhuma alteração histopatológica foi encontrada no intestino delgado do receptor e do enxerto. O aumento da porcentagem de células do doador no sangue periférico do receptor foi progressivo chegando a 5,4±2.3% no 10o período, 21±4,6% no 3o período e 39,3±4% no 6o período. IL-2, IL-6, IL-10, IFN-gma e TNF-alfa estiveram aumentados em língua e IL-4, IL-6, IL-10, IFN-gama e TNF-alfa em linfonodos cervicais. Os linfócitos de ratos do grupo E2 mostraram hiporreatividade aos de ratos ACI e hiperreatividade aos de ratos PVG (terceira parte) denotando tolerância imunológica. Neste modelo experimental há uma inexorável evolução imunológica para DEVH; existe correlação direta entre o aumento do quimerismo em sangue periférico e da expressão de citocinas em língua e linfonodos cervicais e a severidade da DEVH, além da indução de tolerância imunológica do rato do grupo E2 quimérico ao rato ACI normal. / Graft-versus-host disease (GVHD) has been a major concern after small bowel transplantation (SBTX) and the lack of suitable experimental models has limited the study of GVHD after solid organ transplantation. Here we describe a re1evant experimental model of GVHD after fully allogeneic SBTX based on chimerism augmentation, its clinical and histophatological evolution, cytokine involvement, responsible donor cell and immunologic tolerance analysis. LEW rat recipients received orthotopic SBTX and simultaneous donor bone marrow cell infusion (250x106), from ACI rats (experimental group - E) or LEW (control group C). FK-506 was administered dayly at a dose of 1 mg/kg on day 0 to 13, then continued as a weekly injection of same dose until the experimental end point. The recipients were divided in the following groups: E1 - 6 rats sacrificed at 120° POD. E2 - 8 rats sacrificed with critical GVHD between DPO 189 to 271. LEW recipient of LEW grafts, under the same immunossupression were used as control and divided as: C1 - 6 rats sacrificed at POD 120; C2- 5 rats sacrificed between 223 and 270 POD the number of donor cell in the recipient circulation was determined by flowcytometry in 6 pos-operative time: 30, 65, 95, 120, 160, 200. The rats were analyzed twice a week for body weigh and searching for signs of GVHD (cutaneous rush, hiperkeratosis and loss of hair and body weigh). At the sacrificed, samples from tongue (TG), cervical lymph node (CLN), donor (SBD) and recipient (SBR) small bowel were taken from all animals for histophatology and from E1 and C1l animals for IL-2, IL-4, IL-6, IL-10, IFN-gama e TNF-alfa cytokines analysis using reverse transcription polymerase chain reaction. Samples from cervical lynph nodes of 5 animals from group E2 were used for mixed lymphocyte reaction for tolerance analysis. The clinical and histophatological evolution of the disease were evaluated from degree 0 to 3 according to the severity. GVHD in E1 and E2 animals started between 84 and 115 POD. Histophatological analysis of TG and CLN showed that E1 animals present GVHD grade 2 and E2 animals grade 3. The increase of donors cells in the recipient circulation was progressive and account for 5.4± 2.3% at POD 30, 21.4±4.6% at POD 95 and 39.3±4% at POD 200. IL-4, IL-6, IL-10, IFN-gama e TNF-alfa were upregulated in CLN and IL-2, IL-6, IL-10, IFN-gama e TNF-alfa were upregulated in TG when compared with the respective controls. The lymphocytes from E2 group showed hyporeactivety to lymphocytes of normal ACI and hypereactivety to those of PVG, meaning tolerance. No cytokines alteration was noted in SBD neither SBR. Animals from group C1 and C2 did not present any sign of disease. This result show that GVHD is a inexoravel evolution under the experimental conditions of this study and the evolution of the disease is near correlated with the augmentation of the donor cells in the recipient circulation and upregulation of cytokines gene expression in target organs. Tolerance to the same donor strain lynphocytes was also noted.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

The resolution of the complex physics of rotating configurations is critical for any engineering analysis that requires multiple frames of reference. Two well-known applications are in the rotorcraft and wind energy industries. Rotor wake impingement from rotor-fuselage and wind turbine-tower interactions impact structural and acoustic characteristics. Additionally, parasite drag resulting from rotorcraft hubs may result in severe limitations on forward flight vehicle performance. Complex turbulent wakes from rotors and hubs impinging on downstream empennage can create adverse aeroelastic behavior and can affect handling qualities. Numerical simulations of these flows require state-of-the-art Navier Stokes methods using dynamic overset grids. However, many current methods typically used in industry result in wakes that dissipate essential features. In order to address these concerns, two advancements are introduced in this thesis. Feature-based grid adaptation on dynamic overset grids has been developed and demonstrated with an unstructured Navier Stokes solver. The unique feature of the adaptation technique is that it is applied globally on the overset grid system except within the boundary layer. In concert with grid adaptation, an efficient parallelized search algorithm for solution interpolation over massively distributed systems has been created. This results in cost-effective interpolation that retains the numerical order of accuracy and has been verified in both space and time. The improvements have been demonstrated for rotor-fuselage interaction and a generic rotating hub. Detailed analysis of convergence of the methodology and sensitivity of the results to relevant parameters have also been included.

A doença do enxerto versus hospedeiro (DEVH) é uma grave complicação do transplante de órgãos sólidos, com alta mortalidade. Seu estudo tem sido limitado pela carência de modelos experimentais apropriados. Descreve-se um modelo de DEVH baseado no aumento do quimerismo, sua evolução clínica, histopatológica, do número das células quiméricas, do perfil das citocinas e da tolerância imunológica. Ratos Lewis (LEW) foram submetidos a transplante simultâneo de intestino delgado e medula óssea provenientes de ratos ACI (grupo de estudo - E) ou LEW (grupo controle - C), tratados com FK-506 (1 mg/Kg/dia) entre o 0 e 13o PO, e uma dose semanal daí por diante. Os ratos foram divididos nos seguintes grupos: E1- 6 ratos sacrificados no 120o PO. E2- 8 ratos após apresentarem sinais clínicos graves de DEVH entre o 189o e o 271o PO. Como controle, ratos LEW foram receptores dos mesmos tipos de enxertos provenientes de ratos LEW, submetidos à mesma imunossupressão e foram assim divididos: C1- 6 ratos sacrificados no 120o PO, C2- 5 ratos sacrificados entre o 223o e o 270o PO. A citometria de fluxo foi realizada para quantificar a porcentagem das células linfóides de ACI doadores no sangue periférico nos E1, E2 em 6 períodos: 30o PO, 65o PO, 95o PO, 120o PO, 160o PO, 200o PO. Os animais foram examinados 2 vezes por semana à procura de sinais de DEVH (rash cutâneo, perda de peso, de pelo e hiperqueratose). No sacrifício dos animais do grupo E1 e C1, foram colhidas amostras de língua (LI), de linfonodos cervicais (LC), intestino delgado do receptor e do enxerto para análise das citocinas IL-2, IL-4, IL-6, IL-10, IFN-gama e TNF-alfa por meio da reação em cadeia da polimerase. Em todos os grupos foram também colhidas amostras destes órgãos para histopatologia e nos animais do grupo E2 linfonodos cervicais foram processados para análise da reatividade celular por meio da reação mista dos linfócitos (MLR). A evolução clínica e histopatológica foi graduada de 0 a 3 de acordo com a severidade dos sintomas e do infiltrado mononuclear das amostras. Os ratos dos grupos E1 e E2 iniciaram sinais da DEVH entre o 84o e 115o PO. Os ratos dos grupos C1 e C2 não apresentaram evidência de DEVH. Amostras de LI e LC dos ratos do grupo E1 apresentaram alterações histopatológicas grau 2 e do grupo E2 apresentaram alterações histopatológicas grau 3, respectivamente. Nenhuma alteração histopatológica foi encontrada nos ratos do grupo controle e em amostras do ID. Nenhuma alteração histopatológica foi encontrada no intestino delgado do receptor e do enxerto. O aumento da porcentagem de células do doador no sangue periférico do receptor foi progressivo chegando a 5,4±2.3% no 10o período, 21±4,6% no 3o período e 39,3±4% no 6o período. IL-2, IL-6, IL-10, IFN-gma e TNF-alfa estiveram aumentados em língua e IL-4, IL-6, IL-10, IFN-gama e TNF-alfa em linfonodos cervicais. Os linfócitos de ratos do grupo E2 mostraram hiporreatividade aos de ratos ACI e hiperreatividade aos de ratos PVG (terceira parte) denotando tolerância imunológica. Neste modelo experimental há uma inexorável evolução imunológica para DEVH; existe correlação direta entre o aumento do quimerismo em sangue periférico e da expressão de citocinas em língua e linfonodos cervicais e a severidade da DEVH, além da indução de tolerância imunológica do rato do grupo E2 quimérico ao rato ACI normal. / Graft-versus-host disease (GVHD) has been a major concern after small bowel transplantation (SBTX) and the lack of suitable experimental models has limited the study of GVHD after solid organ transplantation. Here we describe a re1evant experimental model of GVHD after fully allogeneic SBTX based on chimerism augmentation, its clinical and histophatological evolution, cytokine involvement, responsible donor cell and immunologic tolerance analysis. LEW rat recipients received orthotopic SBTX and simultaneous donor bone marrow cell infusion (250x106), from ACI rats (experimental group - E) or LEW (control group C). FK-506 was administered dayly at a dose of 1 mg/kg on day 0 to 13, then continued as a weekly injection of same dose until the experimental end point. The recipients were divided in the following groups: E1 - 6 rats sacrificed at 120° POD. E2 - 8 rats sacrificed with critical GVHD between DPO 189 to 271. LEW recipient of LEW grafts, under the same immunossupression were used as control and divided as: C1 - 6 rats sacrificed at POD 120; C2- 5 rats sacrificed between 223 and 270 POD the number of donor cell in the recipient circulation was determined by flowcytometry in 6 pos-operative time: 30, 65, 95, 120, 160, 200. The rats were analyzed twice a week for body weigh and searching for signs of GVHD (cutaneous rush, hiperkeratosis and loss of hair and body weigh). At the sacrificed, samples from tongue (TG), cervical lymph node (CLN), donor (SBD) and recipient (SBR) small bowel were taken from all animals for histophatology and from E1 and C1l animals for IL-2, IL-4, IL-6, IL-10, IFN-gama e TNF-alfa cytokines analysis using reverse transcription polymerase chain reaction. Samples from cervical lynph nodes of 5 animals from group E2 were used for mixed lymphocyte reaction for tolerance analysis. The clinical and histophatological evolution of the disease were evaluated from degree 0 to 3 according to the severity. GVHD in E1 and E2 animals started between 84 and 115 POD. Histophatological analysis of TG and CLN showed that E1 animals present GVHD grade 2 and E2 animals grade 3. The increase of donors cells in the recipient circulation was progressive and account for 5.4± 2.3% at POD 30, 21.4±4.6% at POD 95 and 39.3±4% at POD 200. IL-4, IL-6, IL-10, IFN-gama e TNF-alfa were upregulated in CLN and IL-2, IL-6, IL-10, IFN-gama e TNF-alfa were upregulated in TG when compared with the respective controls. The lymphocytes from E2 group showed hyporeactivety to lymphocytes of normal ACI and hypereactivety to those of PVG, meaning tolerance. No cytokines alteration was noted in SBD neither SBR. Animals from group C1 and C2 did not present any sign of disease. This result show that GVHD is a inexoravel evolution under the experimental conditions of this study and the evolution of the disease is near correlated with the augmentation of the donor cells in the recipient circulation and upregulation of cytokines gene expression in target organs. Tolerance to the same donor strain lynphocytes was also noted.

Les azacycles tels que les morpholines ou les pyrrolidines, sont très répandus dans le domaine de l’organocatalyse et de la chimie médicinale. Cette thèse traitera d’analogues contraints de ces azacycles, qui peuvent moduler de par leurs structures, les propriétés de certains médicaments ou la sélectivité de certaines réactions. Le cas de l’halopéridol, qui est connu pour son activité sur les récepteurs dopaminergiques D2 et D4, est au centre de la première partie de cette thèse, dans laquelle de nouveaux analogues contraints de type 2-oxa-5-azabicyclo[2.2.2]octane ont été développés pour pallier ses problèmes de stabilité métabolique. Dans une seconde partie, la synthèse de deux nouvelles chimères morpholine-proline pontées est rapportée. Leurs structures rigides et conformationnellement verrouillées permettent aux doublets d’électrons non liants sur les atomes d'azote et d'oxygène d’être respectivement orientés dans des directions « Est-Ouest » et « Nord-Est » spatialement différentes. En combinaison avec la présence d'un acide carboxylique, les propriétés électroniques de ces composés peuvent être utiles dans le contexte de la conception peptidomimétique de composés biologiquement pertinents. Des estimations quantitatives de la basicité des atomes d'azote ont été obtenues en utilisant une analyse DFT conceptuelle. Dans la troisième partie de cette thèse, la synthèse de nouvelles pyrrolidines oxabicycliques sera développée. Les cyclopentan[c]pyrroles sont très répandus dans la littérature, et connus pour leurs propriétés analgésiques. Des dérivés fonctionnalisés en positions 4 et 5, synthétisés par Servier, ont notamment présenté de bonnes activités en tant que ligands nicotiniques 7, mais aussi des problèmes d’inhibition de hERG. Afin d’obtenir des composés moins lipophiles et donc de pallier les problèmes d’inhibition hERG, de nouveaux analogues oxygénés de type furo[2,3-c]pyrroles ont été développés par différentes voies de synthèse. Ces nouveaux composés pourront notamment être obtenus sous formes énantiomériquement enrichies, grâce à une étape clé de résolution enzymatique. La proline a été largement utilisée ces dernières années comme organocatalyseur au sein d’importantes transformations asymétriques comme les aldolisations ou les additions de Michael. Cependant, malgré le succès de ce motif, plusieurs de ses dérivés ont été rapportés dans la littérature. C’est notamment le cas des 4,5-méthanoprolines qui furent rapportées pour la première fois par Hanessian en 1997, dont l’efficacité en tant qu’organocatalyseur pour la réaction de Hajos-Parrish ainsi que plusieurs autres types de réaction fut par la suite établie. Les dernières parties de cette thèse viennent compléter ces études. La synthèse de nouvelles 4,5-ethanoprolines a été développée, ainsi que leurs utilisations comme catalyseur lors de réactions de Hajos-Parrish et d’addition catalytique asymétrique de nitroalcanes sur des énones cycliques. Une étude DFT a été effectuée afin d’expliquer l’inversion de sélectivité observée pour ces nouveaux catalyseurs lors des réactions de Hajos-Parrish, le mécanisme de formation des énamines réactives a aussi été investigué. / Azacycles such as morpholines and pyrrolidines, are very widespread in chemistry, especially in the fields of organocatalysis and medicinal chemistry. This thesis will deal with constrained analogues of those azacycles, which, depending on their structures, can modulate the properties of certain drugs or the selectivity of certain reactions. The case of haloperidol, which is known for its activity on the dopamine D2 and D4 receptors, is at the center of the first part of this thesis, in which new constrained analogs of the 2-oxa-5-azabicyclo type [2.2.2] octane have been developed to overcome its metabolic stability problems. In a second part, the synthesis of two new bridged morpholine-proline chimeras are reported. Their rigid structures allow the lone pairs on the nitrogen and oxygen atoms to be oriented in spatially different "East-West" and "North-East" directions, respectively. In combination with the presence of a carboxylic acid, the electronic properties of these compounds could be useful in the context of the design of biologically relevant peptidomimetics. Quantitative estimations of the basicity of the nitrogen atoms were obtained using DFT analysis. In the third part of this thesis, the synthesis of new oxabicyclic pyrrolidines is described. Cyclopentan[c]pyrroles are widely encountered and known for their analgesic properties. The Servier laboratories have synthesized derivatives with substituents at positions 4 and 5, exhibiting good activities as 7 nicotinic ligands, but problems of hERG inhibition. In order to obtain less lipophilic compounds and therefore overcome the problems of hERG inhibition, new oxygenated analogs of the furo[2,3-c]pyrrole type have been developed by different synthetic routes. These new compounds were obtained in enantiomerically enriched forms, using enzymatic resolution. Proline has been widely used in recent years as an organocatalyst in asymmetric transformations such as aldolizations or Michael additions The success of this motif, has inspired synthesis of derivatives, such as 4,5-methanoprolines, which were first reported by Hanessian in 1997, and shown to be effective as organocatalysts in the Hajos-Parrish and other reactions. The last parts of this thesis develop further these studies by the synthesis of new 4,5-ethanoprolines which act as a catalysts in the Hajos-Parrish reaction and the asymmetric catalytic addition of nitroalkanes to cyclic enones. A DFT study was carried out to explain the reversal of selectivity observed for the new catalysts in Hajos-Parrish reaction and to investigate formation of a reactive enamine in the mechanism.

No description available.