New routes to planar chiral ligands and their use in asymmetric catalysis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand

This thesis contains 8 chapters detailing 3 optimised methods to synthesise [2.2]paracyclophane derivatives and our studies in the C-H activation field, namely selective remote β-C-H activation of cyclic amines, and enantioselective γ-C(sp³)-H functionalisation of cyclic amines, as well as a future direction. As the main focus of this thesis is on the development of novel planar chiral [2.2]paracyclophane derivatives, Chapter 1 starts with a brief description of [2.2]paracyclophane chemistry. A short introduction about the synthesis of key enantioenriched [2.2]paracyclophane derivatives is given. Finally, a short introduction of the recent applications of [2.2]paracyclophane-based ligands in asymmetric catalysis is also mentioned. Chapter 2 describes the synthesis of (RSp,SRP)-4-tert-butyl[2.2]paracyclophane phosphine oxide (SPO) and attempts to synthesise its asymmetric variant. Further, its synthetic utility is investigated, mainly in Suzuki-Miyaura cross-coupling, Buchwald-Hartwig amination, and Au(I)-catalysed cyclisation reactions. Additionally, a general route to the P-stereogenic [2.2]paracyclophane-derived phosphines via the reduction of tertiary phosphine oxides is reported. Chapter 3 mainly outlines attempts for β-C(sp³)-H activation of cyclic amine to target the shortest route of epibatidine moiety. A stepwise approach is mentioned. Firstly, a range of heteroatom-substituted secondary phosphine oxides (HASPOs) is evaluated to access (chiral) indolines via intramolecular C(sp³)-H activation. Next, an intramolecular C(sp³)-H activation of 7-azanorbornane, a core skeleton of epibatidine, is investigated. The third approach is mainly targeted for the directing-group-assisted intermolecular C(sp³)-H activation of 7-azanorbornane. Lastly, enantioselective γ-C(sp³)-H activation of N-cyclohexylpicolinamide using various chiral Brønsted acids, again targeting the epibatidine moiety by the late-stage cyclisation, is described. In a search for suitable planar chiral Brønsted acid, an optimised single-step protocol for the synthesis of [2.2]paracyclophanes carboxylic acid derivatives is reported in Chapter 4. This protocol proceeds via C(sp²)-H activation of chiral oxazolines and their coupling with bromo[2.2]paracyclophanes. Chapters 5 & 6 are related to pyridine sulfinates. Chapter 5 describes an attempted regioselective C-H functionalisation of aromatic acids via desulfitative coupling with pyridine-2-sulfinate. A detailed study with catalytic Pd(OAc)₂ and pre-formed palladacycle is mentioned. The effect of catalytic Pd(OAc)₂ on homo-coupling of pyridine-2-sulfinates is also investigated. The potential of sulfinates as nucleophilic coupling partners is investigated in Chapter 6. A novel methodology to synthesise pyridyl[2.2]paracyclophanes is described. The method involves desulfitative cross-coupling reactions between pyridine sulfinates and bromo[2.2]paracyclophanes. One of the interesting results of the desulfitative coupling with the unreactive (±)-4-bromo-5-amino[2.2]paracyclophane is also mentioned. Chapter 7 explains the future scope of the research work mentioned in this thesis. Finally, Chapter 8 describes the experimental procedures and characterisation of the synthesised compounds mentioned in Chapters 2 to 6

Electron-rich Alkynes and Azodicarboxylates Chemistry Towards Vicinal Diamine Motif Containing Small Molecules and N-Heterocycles

Heterocyclic molecules that contain nitrogens and consist of four, five and six-membered rings such as azetidinones (eg: β-lactams), pyrroles, indoles, azoles, triazoles, oxadiazines, and oxadiazinones, etc. are ubiquitous in the use of pharmaceutical fields. This also reflected in the recently FDA approved unique small-molecule pharmaceuticals, where about 90% of those molecules contain a nitrogen heterocycle. Particularly, the vicinal diamino motif has been appeared in leading drug directing candidates such as penicillin, cephalosporins, and oseltamivir (Tamiflu) over the past years. Historically, there has been minimal interest in synthesizing a broad scope of vicinal diamino motif-containing small molecules and heterocyclic compounds for the purpose of using them in the medicinal fields. Therefore, synthesizing the vicinal diamino motif in a few synthetic steps with a broad substrate scope has remained challenging. In this work, we assess the potential to access the vicinal diamino skeleton through the reactivity of various azodicarboxylates (as the main nitrogen source) with various electron-rich alkynes. With further investigations, this chemistry leads us to develop novel methods to generate several classes of vicinal diamino motif-containing products, such as diazacyclobutenes (four-membered heterocyclic compound) and 2-iminothioimidates (acyclic vicinal diimino compounds), and highly substituted tetrahydroindoles (fused bicyclic compound consist of a five-membered N-heterocycle) in good yields with a broad substrate scope. Additionally, with the divergent reactivity of this chemistry under the catalytic environment; a novel compound consist of a 6-membered 1,3,4-oxadiazin-2-one heterocyclic skeleton was produced. This dissertation further discloses the substrate dependent reactivity, divergent reactivity, mechanistic investigations and variable temperature dynamic NMR studies of these novel compounds. In overall, this electron-rich alkynes and azodicarboxylates chemistry described in this document has been validated a novel protocol to rapidly access diverse vicinal diamino motif containing acyclic and cyclic compounds which have potential utility in organic synthesis and medicinal chemistry. Last part of this dissertation describes the development of a protocol for the in-house synthesis of the cellulose nanocrystals, optimization and scale up synthesis of the poly(etheleneimne) functionalized cellulose nanocrystals to investigate the possibility of reducing the cost of the synthesis while maintaining the environmental remediation properties of these functionalized materials at the same efficiency

Advanced materials from gels. Proceedings of the Sixth International Workshop on Glasses and Ceramics from Gels

International workshop on glasses and ceramics from gels (6th. 1991. Sevilla

Self-Sorting Sergeant-Soldier, and Majority Rules Phenomena in Crystals and Gels of Polyurethane Model Compounds

Hydrogen bond-mediated self-assembling biscarbamates have been studied by our group as model compounds of polyurethanes with respect to the crystallization and gelation behaviour in both solid state and solution phase respectively. The aim of my thesis is to investigate the effects on the blending and the gelation of biscarbamates with different alkyl side chain lengths. Melt blending of these molecules shows molecular selectivity and self-sorting behaviour leading to immiscibility. We revealed that the difference in the growth rates of the individual species is responsible for the self-sorting behaviour in these non-chiral synthetic compounds. We discussed methods to bridge the self and non-self that would lead to a more homogeneous system. The gelation properties of biscarbamates with an odd number of carbon atoms in the alkyl side chains, such as the critical gelation concentration, gelation time, gelation temperature, and morphology of the gel fibres were examined. Biscarbamates show odd-even effects in their thermal and gelation behaviours as a function of carbon atom parity in the alkyl side chains in a similar manner to their crystallization behaviours. The blending of the biscarbamate gels shows three different types of blending behaviours. The C8/C9 blend and any gel blends composed of a biscarbamate smaller than C6 display the sergeant-soldier behaviour. The majority rules principle was observed for odd-odd gels blends with an intermediate difference in side chain length. The odd-odd gels blends with a small difference in side chain length self-sort. Organogels with a series of biscarbamates as gelators were prepared using microwave (MW) heating source as well as conventional heating. Biscarbamates with alkyl side chain lengths varying from C5 to C18 were used, with six solvents having dipole moments ranging from 0.07 to 4.3D. The minimum gelation concentration and the amount of heating for dissolution were significantly reduced with MW heating with benzonitrile, compared to the conventional heating for all the side chain lengths of the biscarbamates. MW is found to be effective with solvents possessing large dipole moments. Although the gels consist of fibers using both methods, an inherent orientation of these fibers was seen with MW heating

Liquid-phase hydrogenation of 1-hexene and phenylacetylene over multicomponent nickel skeleton catalysts

This paper presents the results of a study of the process of hydrogenation of 1-hexene in ethanol and phenylacetylene in a hexanewater suspension over multicomponent nickel skeleton catalysts It was demonstrated that the activity of multicomponent skeleton nickel catalysts is substantially dependent on the nature of the additives introduced into the bearing alloy. Introduction of Cu, Pb and Ta leads to an increase in activity (W=196-295cm3/min-gNi). The major mechanism of the effect of emulsion composition on the rate and selectivity of hydrogenation of phenylacetylene involves a change in the coefficient of distribution of substances between the solution and the surface of the skeleton nickel catalyst. It was also shown that the presence of water, which competes with unsaturated hydrocarbons during adsorption, adversely affects the process of purification from acetylenic hydrocarbons, as well as the stereo-regular polymerization of monomer. The research results of the kinetics and direction of the processes of hydrogenation of phenylacetylene suggest significant effect of the adsorption factor, including the ratio of free energies, concentrations and spatial orientation of the molecules of the mixture components, as well as the interaction of reacting substances and hydrogen with thecatalyst surface.</jats:p

Computational understanding of heterocyclisation reactions and synthesis of fluorinated isoquinolines

275 p.The present thesis deals with three different topics that have in common the formation of carbo- and heterocycles. The whole work is organized as a synergy of experimental and computational studies to provide a deep understanding of the systems of interest.The first chapter contains an introduction about computational chemistry with a particular focus on DFT and its application. The second chapter regards asymmetric catalysis and includes two works made in collaboration with the group of Prof. Palomo at the Universidad del País Vasco. Bifunctional catalysts are employed to afford good levels of stereoselectivity in the alpha-functionalization of challenging substrates, as substituted dienolates and trienolates, with olefins. Computational studies were performed mainly to rationalize the role of the catalyst. The third chapter in collaboration with the group of Prof. E. Occhiato at the Universitá degli Studi di Firenze presents two examples of gold catalysis applied to the [3,3]-rearrangement/Nazarov reaction of propargylic esters and the tandem Claisen Rearrangement/Hydroarylation reaction of propargyl vinyl ethers. The mechanism of the reactions were studied computationally, as well as the effect of particular features in the substrates or in the catalysts. The last two chapters concern the synthesis of fluorinated isoquinolines and computational studies on particular issues encountered experimentally. The strategy employed is a two step reaction that includes a Rh-catalyzed CH activation of oximes with difluoroalkenes and an electrocyclisation

Towards a circular economy: fabrication and characterization of biodegradable plates from sugarcane waste

Bagasse pulp is a promising material to produce biodegradable plates. Bagasse is the fibrous residue that remains after sugarcane stalks are crushed to extract their juice. It is a renewable resource and is widely available in many countries, making it an attractive alternative to traditional plastic plates. Recent research has shown that biodegradable plates made from Bagasse pulp have several advantages over traditional plastic plates. For example, they are more environmentally friendly because they are made from renewable resources and can be composted after use. Additionally, they are safer for human health because they do not contain harmful chemicals that can leach into food. The production process for Bagasse pulp plates is also relatively simple and cost-effective. Bagasse is first collected and then processed to remove impurities and extract the pulp. The pulp is then molded into the desired shape and dried to form a sturdy plate. Overall, biodegradable plates made from Bagasse pulp are a promising alternative to traditional plastic plates. They are environmentally friendly, safe for human health, and cost-effective to produce. As such, they have the potential to play an important role in reducing plastic waste and promoting sustainable practices. Over the years, the world was not paying strict attention to the impact of rapid growth in plastic use. As a result, uncontrollable volumes of plastic garbage have been released into the environment. Half of all plastic garbage generated worldwide is made up of packaging materials. The purpose of this article is to offer an alternative by creating bioplastic goods that can be produced in various shapes and sizes across various sectors, including food packaging, single-use tableware, and crafts. Products made from bagasse help address the issue of plastic pollution. To find the optimum option for creating bagasse-based biodegradable dinnerware in Egypt and throughout the world, researchers tested various scenarios. The findings show that bagasse pulp may replace plastics in biodegradable packaging. As a result of this value-added utilization of natural fibers, less waste and less of it ends up in landfills. The practical significance of this study is to help advance low-carbon economic solutions and to produce secure bioplastic materials that can replace Styrofoam in tableware and food packaging production