[Rh(CO]2Cl]2 has been shown to catalyze sequential, mechanistically- distinct transformations in one pot. Tandem allylic alkylation/cycloisomerization sequences have been developed to access valuable, complex structures from relatively simple substrates. A methodology for the enantioselective conjugate addition of 2-heteroaryl nucleophiles to a variety of Michael acceptors has been developed. This method was used successfully in an ongoing approach to the synthesis of cortistatin A. 10 linear steps have been completed towards the synthesis of cortistatin A, including a highly regioselective propargylation to install a quaternary carbon and a diastereoselective intramolecular Diels-Alder reaction. / text

Thesis advisor: Marc L. Snapper / A catalyst of notoriety Decomposes with great variety. Transformations after metathesis Facilitate tandem catalysis. This reaction has a proclivity For new regioselectivity With methanolic modification: Tandem enyne hydrovinylation. From a diene protonation event, Unexpected reaction with solvent, During catalyst optimization: One-pot enyne hydroarylation. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

The chemical industry is an essential part of modern society and therefore has a responsibility to develop solutions for the problems facing it. A major problem is continuing to match the material demands of a growing global population whilst simultaneously decreasing the consumption of finite natural resources and limiting the emissions of greenhouse gasses. An optimised catalytic system that shortens, or intensifies, the process chain for the production of chemicals can be an effective solution to this challenge. Auto-tandem catalysis is where a single metal-ligand complex facilitates two or more sequential transformations. For example: alkenes are hydroformylated into aldehydes which are then hydrogenated into alcohols. The alcohols have use as plasticisers or surfactants for metal extraction. A previously reported auto-tandem catalysis system was shown to be capable of sequential hydroformylation-hydrogenation of 1-octene to nonanol. It consisted of the neutral rhodium precursor [Rh(acac)(CO)2] and the bidentate ligand xantphos in 10% iPrOH/H2O co-solvent at temperatures of 160°C. Investigations, reported in this thesis, revealed that xantphos type ligands, with their large bite-angle, and high temperatures are required to generate the hydrogenation activity. However, in contrast to the previous system, water is not necessary; with the same results produced in toluene:iPrOH solutions and water:iPrOH solutions. It is proposed that the iPrOH or H2O has a direct influence in the catalytic cycle, either as a hydrogen-shuttle or generates a cationic rhodium species, known to be active in hydrogenation. High temperature NMR studies show the standard resting state of the hydroformylation catalyst is still predominant at high temperatures therefore the proposed catalytic cycle starts from this step. A recurring problem in the industrial process chain is the separation of the catalyst from the final products. Combing a TiO2 ceramic membrane with a POSS (polyhedral oligomeric silsesquioxane) modified tin catalyst and phosphonium iodide co-catalyst, for the coupling of epoxides and CO2 to make cyclic carbonates, was investigated. The catalyst system showed good substrate compatibility for a range of epoxides. In a prototype membrane set-up the system demonstrated a long catalyst life time, however significant leaching was also observed.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20404号 / 工博第4341号 / 新制||工||1673(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 澤本 光男, 教授 中條 善樹, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

La tuberculose est une maladie causant encore aujourd'hui plus d'un million de mort chaque année. De nouvelles solutions vaccinales sont nécessaires pour enrayer cette épidémie. Les sulfoglycolipides, trouvés chez Mycobacterium tuberculosis, se sont révélés capables d'activer le système immunitaire et pourraient ainsi représenter une solution thérapeutique intéressante dans la création d'un nouveau vaccin. Dans ce cadre, nous avons souhaités élaborer de nouveaux analogues de sulfoglycolipides. Pour cela, nous avons employé une méthode de protection régiosélective par catalyse tandem au chlorure de fer(III) hexahydrate précédemment développée au laboratoire pour préparer les cœurs glycosidiques des différents mimes. La méthode d'alkylation asymétrique développée par Myers a également été utilisée pour la préparation des acides polydéoxypropionates portés par les différents analogues. / Tuberculosis is still responsible for more than one million deaths each year. New therapeutic solutions are needed to fight this disease. Sulfoglycolipids, found in Mycobacterium tuberculosis's cell wall, seem to be able to activate immune system and could represent an interesting therapeutic solution for the development of a new vaccine. In this context, we wished to elaborate new sulfoglycolipid analogues. For the synthesis of the glycoside moieties of these analogues, we have used a tandem regioselective protection catalyzed by iron(III) chloride, previously developed in our laboratory. Myers's asymmetric alkylation has also been used for the synthesis of polydéoxypropionate chains.

L’accès par voie chimique à des oligosaccharides nécessite souvent le recours à de nombreuses étapes de protection-déprotection. Au cours de ce projet de thèse, une méthodologie pour la protection régiosélective et orthogonale des fonctions alcool de disaccharides dérivant de la biomasse a tout d’abord été développée. Les glycopyranosides protégés ont été préparés par catalyse tandem au FeCl3∙6H2O en réalisant dans le même pot des réactions d’acétalation, d’éthérification réductrice, d’acétylation et/ou d’ouverture réductrice régiosélective d’acétals. Dans un second temps, une stratégie de synthèse flexible, rapide et performante pour accéder à des sulfoglycolipides diacylés et tétraacylés comportant un cœur tréhalose a été mise au point. Ces molécules sont produites par Mycobacterium tuberculosis, l’agent pathogène responsable de la tuberculose, et les sulfoglycolipides diacylés pourraient permettre l’élaboration d’un nouveau vaccin contre cette maladie. Des sulfoglycolipides diacylés et tétraacylés comportant des chaînes monométhylées chirales ont été obtenus. Les précurseurs des acides gras chiraux utilisés au cours de la synthèse ont été analysés par spectroscopie RMN du deutérium en abondance naturelle dans des cristaux liquides chiraux. / The synthesis of oligosaccharides often requires long sequences of protection-deprotection steps. For a rapid access to suitably protected glycopyranosides, we have developed a one-pot regioselective protection strategy based on FeCl3∙6H2O-tandem catalyzed reactions (acetalation, acetylation, reductive etherification, regioselective ring opening of acetal). This procedure was applied to persilylated disaccharides derived from biomass. This methodology allowed the development of a fast, efficient and flexible access to diacylated and tetraacylated sulfoglycolipids based on a trehalose core. These molecules are found in the cell wall of Mycobacterium tuberculosis and the diacylated sulfoglycolipids appear to be promising candidates for the development of a new tuberculosis vaccine. Synthetics diacylated and tetraacylated sulfoglycolipids bearing chiral monomethylated fatty chains were produced. The chiral fatty-acid precursors, used in the procedure, were synthetized and analyzed by NMR spectroscopy of natural abundance deuterium in chiral liquid crystals.