Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.340503 Organic chemical synthesis

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Synthesis of planar chiral rhodium(II) paddlewheel catalysts : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2024) Staniforth, Samantha
    Catalysts are the most efficient tools for the construction of large complex molecules. They offer an unparalleled way to solve problems and new ways to build molecules. Site-selective catalysts control the site of reaction in molecules that contain multiple sites with similar reactivity. C-H groups are the most abundant sites in all organic molecules but are very unreactive and difficult to functionalise. C-H functionalisation catalysis aims to install functionality at these sites by replacing the C-H bond with a C-C, C-O, C-N or C-X bond. Controlling the selectivity of these reactions is extremely difficult but highly rewarding, as it allows complex molecules to be made from very simple starting materials. Rh(II) paddlewheels are a class of selective C-H functionalisation catalysts that are capable of highly site-selective and enantioselective transformations. The organic ligands of the complex create different shapes around the catalyst active site that force a single C-H site to be targeted. This project aimed to synthesise a new class of Rh(II) paddlewheel catalysts that possess a planar chiral ligand and to investigate their activity and selectivity in C-H insertion reactions. In this work a novel resolution route for dibromide [2.2]paracyclophane carboxylic acids was developed. The carboxylic acids ligands were then used to synthesise three Rh(II) catalysts. Two of these paddlewheels were used to develop a late-stage catalyst functionalisation method through Suzuki-Miyaura coupling. In total, five Rh(II) catalysts were synthesised, of which four were assessed in both intermolecular and intramolecular nitrene insertion reactions.
  • Thumbnail Image
    Item
    Planar chiral oxazolines based on [2.2]paracyclophane : a new toolbox for asymmetric synthesis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2024-03-07) Tewari, Shashank
    This thesis contains total 7 chapters, dealing with the synthesis of planar chiral Oxazolines based on [2.2]paracyclophane, enantiopure products obtained from their resolution, synthesis of metal-based chiral complexes, studies on C-H activation field, namely selective remote β-C-H activation of cyclic amines, and future ideas towards the goal. 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 outlines a brief overview of the role of 2-oxazolines. 2-Oxazolines have been utilized in the field of asymmetric catalysis as ligands and chiral auxiliaries. The chapter briefly discusses the synthesis and highlights some of the uses of 2-oxazolines as chiral ligands. Chapter 3 describes the concise synthesis of planar chiral oxazolines based on [2.2]paracyclophanes. Various oxazoline-based compounds that were synthesized are all discussed in Chapter 3. The synthesis of mono-oxazolines coupled to [2.2]paracyclophanes, based on the methodology developed in our lab was accomplished. The next were the synthesis of bis-oxazolines and tetra-oxazolines coupled to [2.2]paracyclophane. The chapter mentions all the details and substrate scope generated with oxazolines. Chapter 4 focuses on the resolution of [2.2]paracycoplane by the hydrolysis of the oxazolines. The enantiopure products like planar chiral mono-acids, bis-acids, and partial acids were obtained by hydrolysis of the oxazolines. Apart from them, a section in the chapter describes the decarboxylative phosphorylation that was achieved through our planar chiral acids. Synthesis of planar chiral diamines via Curtius rearrangement of the diacids is also described in the chapter, followed by phanol synthesis. A part of the above chapter describes about the rhodium paddle-wheel complex formed by partial chiral acids. An attempt to make dinuclear gold complexes was made that was also successful. Overall, chapter four is the highlight of the thesis, where a lot of pure chiral products are made and their utility is explained in the field of asymmetric catalysis. Chapter 5 describes the remote β-C-H activation of cyclic amines. Attempts were made to accomplish the functionalization through the directing group strategy. The directing groups based on heterocyclic piperidine and cyclic amines were synthesized successfully. These pre-made directing groups were used for the C-H bond functionalization but the functionalization possessed many challenges that made the functionalization difficult. Chapter 6 explains the future scope of the research work mentioned in this thesis. Finally, Chapter 7 describes the experimental procedures and characterization of the synthesized compounds mentioned in Chapters 3 to 5.
  • Thumbnail Image
    Item
    Developing novel 2,6-pyridinedicarboxamide-1,2,3 triazole ligands for luminescent lanthanide materials : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry, School of Natural and Computational Sciences, Massey University, Albany, New Zealand
    (Massey University, 2020) Jayasooriya, Nethmie
    Lanthanide complexes possess unique photophysical properties leading to a vast number of applications in a wide range of areas. Emission of lanthanides, however, show much lower absorption coefficients with slow emissive rates and longer lifetimes. Therefore, lanthanides are usually excited through organic ligands. Research reveals that ligands rich in oxygen and nitrogen atoms are more favourable for developing metallosupramolecular lanthanide systems. Recent studies have shown that PDC (2,6-pyridyldicarboxamide) based ligand systems are excellent candidates because of their predictable coordination number and structural advantage towards complexing with Lanthanides. In addition to that PDC-based ligands are easy to functionalize with various substituents to enhance coordination and sensitize emission of lanthanides. Therefore, this project is focused on developing new 1,2,3-triazole containing PDC-derived ligands for the subsequent preparation of luminescent complexes with europium and terbium. Six ligand systems; (four of them were symmetrical systems [L1-L4] while [L5, L6] were asymmetrical ligand systems) have been successfully synthesized using the CuAAC reaction. All ligands were characterized by UV-Vis, FTIR, ¹H NMR and ¹³C NMR spectroscopy. Europium and terbium complexes were synthesized using L1, L2, L4 and L5 ligands and photophysical studies were carried out in acetonitrile solution. The presence of characteristic europium and terbium emission bands demonstrate the successful coordination of lanthanides to the ligands. Complexation and self-assembly studies of L5 ligands with Eu³⁺ using UV-Vis and fluorescence spectroscopic titrations show that the expected 3:1 ligand:lanthanide ratio is observed and the bulky triazole substituents do not affect complex formation. This is important as it will allow us to move on to more complex and larger ligands that incorporate amino acids/peptides. This will allow for more favourable/stronger self-assembly and potentially self-assembly in water – giving access to biological (imaging) and sensing applications.