Cette thèse porte sur la préparation de nouveaux catalyseurs chiraux à partir de composés naturels issus de la biomasse, et leurs applications en organocatalyse asymétrique. La première partie décrit la synthèse de thiourées énantiomériquement pures dérivées de l'isosorbide et l’isommanide. Ces thiourées ont été évaluées comme catalyseurs organiques dans des réactions asymétriques de Friedel-Crafts, d’alkylation, d’addition de type aza-Michael, d’hydroamination et de type Morita-Baylis-Hillman (MBH). Les meilleurs résultats en termes de réactivité et d’induction asymétrique, ont été obtenus dans le cas de la réaction de Friedel-Crafts. La deuxième partie est consacrée à la conception et la synthèse de thiourée-phosphines chirales à partir de la L-proline. Ces thiourée-phosphines sont capables de promouvoir la formation de liaisons C-N et C-S, selon un processus de substitution allylique énantiosélectif d’adduits modifiés de MBH. De très bons rendements (jusqu’à 98%) et énantiosélectivités (jusqu'à 93%) ont été obtenus. Dans la troisième partie, nous avons développé le premier exemple de cyclisation [4 + 2] entre un allénoate et un alcène tétrasubstitué, catalysée par une amine tertiaire. Nous avons montré que des composés de type 4H-pyranniques peuvent être sélectivement obtenus, avec d’excellents rendements, en utilisant le DABCO comme catalyseur. Dans le cas de catalyseur organique de type alcaloïde, le β-ICD conduit sélectivement aux composés 2H-pyranniques avec des excès énantiomériques jusqu’à 71 % ee. / The thesis focused on the preparation of new chiral catalysts derived from biomass and their applications in asymmetric organocatalysis. The first part described the synthesis of chiral thioureas derived from isosorbide and isomanide, naturally renewable resource, in moderate to good overall yields. These thioureas were evaluated in asymmetric reactions such as Friedel-Crafts alkylation, aza-Michael addition, hydroamination, Morita-Baylis-Hillman reaction. Good yields and enantioselectivities were obtained. The second part of our work went on the design and synthesis of chiral thiourea-phosphines from L-Proline. These thiourea-phosphines promoted C-N and C-S bond formation via the asymmetric allylic substitution of tert-butoxycarbonyloxy adducts. Good yields (up to 98 %) and enantioselectivities (up to 93 %) were observed. In the third part, we have developed the first example [4+2] annulation of allenoate and all-carbon tetrasubstituted alkenes catalyzed by an amine. In the case of DABCO catalyst, 4H-pyrans were isolated exclusively in good to excellent yield under mild reaction conditions. While employing β-ICD as catalyst, the enantioenriched 2H-pyran derivatives were obtained with enantiomeric excess up to 71 % ee.

Reported herein is a brief summary of the history, properties, and applications of amine-boranes. The past methods devised for their preparation are described and the routes used to produce the compounds used in the work presented here are detailed. Building on prior synthetic approaches to amine-boranes, a new carbon dioxide mediated synthesis is presented. Proceeding through a monoacyloxyborane intermediate, the borane complexes of ammonia, primary, secondary, tertiary, and heteroaromatic amine are provided in 53-99% yields. Utilizing the amine-boranes obtained from the methods described, two divergent methods for direct amidation are introduced. The first uses amine-boranes as dual-purpose reagents, where the carboxylic acid is first activated by the borane moiety to form a triacyloxyborane-amine complex. This allows the delivery of the coordinated amine to form the amide products. A series of primary, secondary, and tertiary amides were prepared in 55-99% yields using this protocol, which displays a broad functional group tolerance. Extended from this dual-purpose methodology, a catalytic amidation is described. Utilizing ammonia-borane as a substoichiometric (10%) catalyst, a series of secondary and tertiary amide are prepared directly from carboxylic acids and amines in 59-99% yields, including amines containing typically borane reactive functionalities including alcohols, thiols, and alkenes. Amine-boranes are additionally used in two borylation methodologies. By reaction with <i>n</i>-butyl lithium, the amine-boranes are converted to the corresponding lithium aminoborohydrides, which upon reaction with a terminal alkyne provides the alkynyl borane-amine complexes in 65-98% yields. This process is compatible with both alkenes and internal alkynes, as well as a range of aprotic functionalities. A new strategy for aminoborane synthesis is also described and applied to the borylation of haloarenes. Activation of a series of amine-boranes with iodine produces the iodinated amine-borane, which undergoes dehydrohalogenation with an appropriate base to produce either monomeric or dimeric aminoboranes. Several aminoboranes were synthesized exclusively as the monomeric species, which due to their greater reactivity, were used directly in the synthesis of a series of aryl boronates in 65-99% yields.

The toxicity of 36 aliphatic amines on the embryos of the zebrafish Danio rerio were investigated. The DarT (Danio rerio Toxicity assay) was used to determine the lethal concentrations within a 48 h static acute toxicity test. A QSAR (Quantitative Structure-Activity Relationship) was performed using the LC50 values and molecular descriptors such as lipophilicity, maximum positive charge on hydrogen atom and the effective diameter of the molecule. In general, the toxicity of primary and secondary amines could be described by the lipophilicity as descriptor. The toxicity of the tertiary amines tested could be only described by a bilinear regression model. Further, regression models for other aquatic species such as the fathead minnow Pimephales promelas, Daphnia magna and Tetrahymena pyriformis showed that the toxicity of each species is a good predictor for each other.

This thesis details the synthesis of novel Rh(I) and Rh(III) bis-phosphine fragments, and their use, along with other known rhodium species, to investigate the reactivity of amine-boranes, with a particular focus on the dehydrocoupling of the secondary amine-borane H3B.NMe2H (DMAB). Chapter 2 utilises the new mixed phosphine, PtBuiBu2, to investigate the role of the phosphine with regard to the corresponding low-coordinate organometallic species isolated. Their coordination and reactivity with amine-boranes is studied, leading to the development of a mechanism for an alkene hydroboration catalyst that employs H3B.NMe3 (TMAB). The final section of the chapter studies several fluxional processes pertinent to rhodium and iridium complexes of the model amine-borane TMAB using H/D exchange and low temperature NMR experiments. In Chapter 3, the mechanism of dehydrocoupling of DMAB is investigated in detail, employing catalysts based on the cationic bis¬-phosphine Rh fragment, {Rh(PCy3)2Ln}+. A series of stoichiometric and catalytic reactions are probed using NMR spectroscopy and mass spectrometry, revealing a complex mechanistic landscape. Subtleties include: the product of dehydrocoupling, [H2BNMe2]2, acting in an autocatalytic role; and parallel dehydrogenation of DMAB by a neutral catalyst present in a low but constant concentration. The mechanism was additionally interrogated through kinetic simulations conducted by Prof. Guy C. Lloyd-Jones (University of Bristol). From this, a generic mechanistic scheme has been suggested, aspects of which can be applied to transition metal and main group systems reported to catalyse the dehydrocoupling of DMAB. The final chapter moves on from cationic rhodium fragments to investigate the reactivity of the neutral rhodium species, Rh(H)2(PCy3)2Cl and [Rh(PCy3)2Cl]2, with amine-boranes. The mechanism by which Rh(H)2(PCy3)2Cl catalyses the dehydrogenation of DMAB has been investigated through initial rate and H/D exchange experiments, leading to the proposal of a reaction scheme. Additionally, the formation and characterisation of a base-stabilised boryl species has been reported resulting from the reactivity of an amino-borane with [Rh(PCy3)2Cl]2.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks

Aqueous amine solutions loaded with CO2 were degraded in stainless steel sealed containers in forced convection ovens. Amine loss and degradation products were measured as a function of time by cation chromatography (IC), HPLC, and IC/mass spectrometry. A full kinetic model was developed for 15-40 wt% MEA (monoethanolamine) with 0.2 – 0.5 mol CO2/mol MEA at 100°C to 150°C. Experiments using amines blended with MEA demonstrate that oxazolidone formation is the rate-limiting step in the carbamate polymerization pathway. With 30 wt% MEA at 0.4 mol CO2/mol MEA and 120°C for 16 weeks there is a 29% loss of MEA with 13% as hydroxyethylimidazolidone (HEIA), 9% as hydroxyethylethylenediamine (HEEDA), 4% as the cyclic urea of the MEA trimer, 1-[2-[(2-hydroxyethyl)amino]ethyl]-2-imidazolidone, 3% as the MEA trimer, 1-(2-hydroxyethyl)diethylenetriamine, and less than 1% as larger polymeric products. In the isothermal experiments, thermal degradation was slightly more than first order with amine concentration and first order with CO2 concentration with an activation energy of 33 kcal/mol. In a modeled isobaric system, the amount of thermal degradation increased with stripper pressure, but decreased with an increase in amine concentration and CO2 concentration due to a reduction in reboiler temperature from the changing partial pressure of CO2. Three-fourths of thermal degradation in the stripper occurred in the reboiler due to the elevated temperature and long residence time which offset the decrease in CO2 concentration compared to the packing. The amount of degradation for other amines tested starting with the least degraded include; cyclic amines with no side chains < long chain alkanolamines < alkanolamines with steric hindrance < tertiary amines < MEA < straight chain di- and triamines. Piperazine and morpholine had no measurable thermal degradation under the conditions of this experiment and were the most resistant to thermal degradation. Diethyelenetriamine and HEEDA had the largest amount of degradation with over 90% loss at 135°C for 8 weeks. / text

A series of cationic Rh(I) diphosphine and phosphine-alkene complexes have been isolated and fully characterised. The reactivity of these species towards hydrogenation, dehydrogenation and dehydrocoupling reactions has been investigated. The use of potentially hemilabile ligands DPEphos and XANTphos in the intramolecular dehydrogenation chemistry of tricyclopentylphosphine is reported. The comparison in reactivity of these isolated diphosphine phosphine-alkene complexes towards hydrogenation and with acetonitrile is discussed along with their ability to dehydrocouple secondary silane, Ph₂SiH₂, and amine-borane H₃B·NMe₂H. The acceptorless dehydrogenation of a tethered cyclopentane with cationic Rh(I) diphosphine complexes has also been extended to include thioethers. Isolated cationic Rh(I) phosphine-alkene complexes with labile fluorobenzene ligands are found to act as a source of the reactive 12-electron [Rh{PR₂(ƞ²-C₅H₇)}]+ (R = cyclopentyl (Cyp)/ iPr) fragment in solution and can coordinate two amine-borane ligands (either H₃B·NMe₃, H₃B·NMe₂H or H₃B·NMeH₂) in a novel and unique bis-σ-binding mode. The catalytic activity of some of these isolated complexes in the dehydrocoupling of H₃B·NMe₂H and H₃B·NMeH₂ has been determined. With a view to further understanding the mechanism of catalytic transition metal assisted amine-borane dehydrogenation and dehydrocoupling, known B-N intermediates H₃B·NMe₂BH₂·NMe₂H and [H₂B·NMeH]₃ were also coordinated to the [Rh{PCyp₂(ƞ²-C₅H₇)}]+ fragment and investigated with regard to their role in the catalytic cycle. Structure activity relationships determined from stoichiometric reactions of cationic Rh(I) diphosphine fluorobenzene complexes with amine-boranes enabled the design of a highly efficient homogeneous catalyst capable of dehydrogenating H₃B·NMe₂H to [H₂BNMe₂]₂ at 0.2 mol% loading in 30 minutes at 298 K. Rapid dehydrogenation and dehydrocoupling of H₃B·NMeH₂ to form high molecular weight poly(N-methylaminoborane) with a low PDI has also been achieved. Investigations using model aminoborane H₂B=NiPr₂ and intermediate B-N species H₃B·NMe₂BH₂·NMe₂H and [H₂B·NMeH]₃ has helped establish an overall mechanistic rationale for this process.

Abstrakt   Det förnyelsebara bränslet biogas har fått mer och mer intresse runt om i världen, men för att biogasen ska gå att använda som fordonsbränsle måste den först uppgraderas. I den processen separeras kolväten och andra föroreningar för att metanhalten ska ökas och därmed kommer biogasen att bli optimal för användning i förbränningsmotorer (Enefalk och Ersöz 2016).   Syfte med det här arbetet var att undersöka hur bra olika filter kan fungera för att ta bort orenheter från aminen i Puregas Solutions AB anläggningar. När undersökning av olika filter var gjord studerades underhållet för dessa filter. Experimentet utfördes i Puregas Solutions AB verkstad. Där användes ett aminprov från deras anläggning i Sverige för att den var extremt förorenad och därmed var det lättare att se hur bra de olika filtren filtrerar föroreningar.   Efter att mottagit provsvaren från DOW Chemical Company sammanställdes analyserna. Provsvaren visade på att de testade filtren inte tog bort orenheter från aminen. / Abstract   Renewable biogas fuel has become increasingly interesting around the world, however before biogas is used as fuel in vehicles it must first be upgraded. During that process the hydrocarbons and other pollutions are separated to increase the concentration of methane and make the biogas better suited for combustion engines (Enefalk and Ersöz 2016).   The purpose of this study was to examine how efficiently different filters can remove impurities from amine at Puregas Solutions AB upgrading plant. After the investigation of the different filters was completed we wanted to further study the maintenance of the filters. Experiments were performed at Puregas Solutions AB workshop, where the amine samples from their plant in Sweden were used to see how well the various filters performed.   After receiving the test results from Dow Chemical Company, the results were compiled and they showed that the tested filters did not remove impurities from the amine.

<strong>Introduction</strong> The introduction describes the importance of arylamine compounds to society and provides a brief overview of the methods available for their synthesis. The application of metathesis catalysis to the de novo synthesis of heteroaromatic compounds is also described. <strong>Results and discussion</strong> The first section describes efforts towards the de novo synthesis of arylamines using a cross metathesis/oxidation protocol to form a 1,5-unsaturated dicarbonyl followed by an amine mediated cyclisation. The scope with respect to the 1,5-unsaturated dicarbonyl and amine is covered as well as the utility of some of the products. The section concludes with a modification of the Bohlmann Rahtz pyridine synthesis to furnish arylamines. The next section describes the applications of our methodology to the synthesis of naphthylamines, specifically using the palladium catalysed &alpha;-arylation reaction. A discussion of the α-arylation reaction is included as well as our efforts to explore the scope of the reaction. The third section follows our efforts to apply this methodologyy to the synthesis of five benzo[c]phenanthridine alkaloids including the first reported synthesis of maclekarpine B and C. The final section concludes with a discussion of our efforts towards the de novo synthesis of furans bearing a benzylic stereocentre.

This work deals with the preparation of amine derivatives of 3-chloro-5(8?)-nitro-1,4-naphthoquinone which are to be tested for anti-tubercular activity by Parke, Davis and Company.