Organic Chemistry Commons^™

Studies Towards The Synthesis Of A Simplified Forskolin Core And Phomactin A, Fortune Ononiwu

Dissertations - ALL

Oxadecalins are privileged scaffolds found in various natural products that show biological activity, such as platelet aggregating factor antagonism and activation of adenyl cyclase. As such, various synthetic methods such as intramolecular substitution reactions and [4+2] cycloadditions have been developed for the construction of these important intermediates. Studies towards the synthesis of a simplified core of the labdane diterpene, forskolin, are described. Forskolin is the only known supplement to naturally raise cAMP levels, thereby displaying important pharmacological properties. The synthetic route described features a Lewis acid catalyzed dihydropyrone Diels-Alder reaction for rapidly assembly of the ABC tricycle. Modified Saegusa-Ito oxidation …

Synthetic Studies On Ship Activators And New Oxidative Methods Utilizing Ddq And Hypervalent Iodine Catalysts, Christos Nixarlidis

Dissertations - ALL

One important cell signaling pathway is the PI3K pathway because it influences many key cellular functions such as proliferation and apoptosis. Among the enzymes that are involved in this pathway, the SH2-containing inositol-5’-phosphatase (SHIP) plays an important role by maintaining the balance of PI(3,4,5)P3 and PI(3,4)P2. SHIP activation promotes a higher rate of hydrolysis of PI(3,4,5)P3 and thus reduces the downstream activation of AKT, which influences many cell processes. Activation of SHIP using small molecules may be useful for certain diseases such as inflammatory disorders and some types of cancer. The synthesis and evaluation of a new class of sulfonamide …

An In-Depth Analysis And Comparison Of Eco And Non-Eco Surfboard Waxes, Markos Kaskaneas - Efthymiou

The Plymouth Student Scientist

Questions regarding the sustainability of petroleum-based surfboard waxes gave rise to the development and marketing of a sustainable alternative called “Eco” surf wax. The chemistry behind surf waxes is generally unknown and there is no published research on the area of surf waxes. In this analysis, the chemical properties of both types of waxes were investigated, to determine the difference between non-eco and eco waxes and between different water temperature rating waxes. 15 surf wax samples (10 non-eco, 5 eco) were extracted into organic and inorganic fractions and analysed by FT-IR, GC-MS, and HTGC-FID/MS. Multivariate statistical analysis was also performed. …

Developing A Method To Identify Tyre Particles By Detecting Benzothiazole Via Gc-Ms, Emma Paull

The Plymouth Student Scientist

Tyre particles are a dominant source of microplastic pollution in our environment. However, their chemical and physical properties are poorly understood and no standardised methods for identifying and quantifying them exist. This study looked to develop a method to identify tyre particles using two tyre samples of differing particle sizes, fine (62 - 125 µm) and coarse (250 – 500 µm). Both samples underwent ultrasound-assisted extraction before being analysed via gas chromatography-mass spectrometry (GC-MS) in both full scan and SIM mode, using benzothiazole as a marker. Both samples were also analysed via particle size analysis, scanning electron microscopy (SEM) and …

Synthesis And Characterisation Of An Acetylcholinesterase Inhibitor, Elijah Rahman-Riding

The Plymouth Student Scientist

Acetylcholinesterase (AChE) inhibitors are currently the only effective treatment for people with Alzheimer’s disease (AD), a fatal neurodegenerative disease that affects 50 million people worldwide at present but is expected to rise dramatically over the next 30 years. The aim of this research was to synthesise an AChE inhibitor derivative of tacrine, 4-chloro-2(((1,2,3,4-tetrahydroacridin-9yl)imino)methyl)phenol (chlorophenol tacrine). This was achieved by first synthesising tacrine, evidencing successful synthesis and assaying purity of the product, then, synthesising a simple derivative, acetyl tacrine, before chlorophenol tacrine. At every stage of the investigation comprehensive structural analysis of each product was obtained using FT-IR, CHN analysis, GC-FID, …

Application Of Two-Directional Carbonyl Ene Reaction To The Synthesis Of Complex Tetrahydropyrans, And Studies Toward The Synthesis Of C26-C39 Subunit Of Spirastrellolide B., Md Abid Abid Hasan

Dissertations - ALL

The use of exocyclic enol ethers as nucleophiles in carbon-carbon bond forming reactions has been underutilized in organic synthesis. This work describes the use of 6-iodomethyl-2-methylenetetrahydropyran as a bis-exocyclic enol ether equivalent for the synthesis of pyran derivatives. Use of this linchpin allows for bidirectional elaboration of the pyran core by two directional carbonyl ene. The development of a convergent, modular synthesis of 2,6-disubstituted-4H-pyrans in a three-step sequence starting from 6-iodomethyl-2-methylenetetrahydropyran is described. Initial carbonyl ene reaction of 6-iodomethyl-2-methylenetetrahydropyran with aldehydes or activated ketones was followed by elimination of iodide to give cross oriented bis-enol ethers that contain both endocyclic …

Design, Synthesis, And Nmr-Guided Characterization Of A Targeted Covalent Inhibitor-Like Molecule Against Ivyp1 From P. Aeruginosa, Samuel Taylor Moore

Master's Theses

Multi-drug resistance poses a serious threat to future generations and historical antibiotic pipelines; consequently, the medical and economic burdens associated with treating multidrug-resistant bacteria are substantiated. In this context, P. aeruginosa (PA) emerges as one of the most significant healthcare challenges, being a leading cause of resistance-associated mortality worldwide. Despite modern efforts to combat these poor outcomes, drug-resistant cases continue to rise, and the need for novel antibiotic treatment is apparent. To this end, we investigated relevant resistance mechanisms and past antibiotic targets within PA, and in doing so, we identified relationships between peptidoglycan biology and a periplasmic protein, Inhibitor …

Investigation Of Polybenzoxazine Vitrimers Based On Dynamic Transesterification Exchange, Jaylen Davis

Dissertations

With the ever-increasing issue of plastic waste production, a greener approach to synthetic processes and increased sustainability in plastic materials is still a high demand. Thermosets, which find uses in applications such as coatings, adhesives, and aerospace composites account for 15% of global plastics production, are particularly problematic in this context, as covalent crosslinks within the material serve both as a source of high-performance stability during use and as a barrier to conventional recycling after use. Therefore, our efforts focus on the incorporation of dynamic transesterification exchange chemistry into polybenzoxazine thermosets, which allows these materials to undergo reprocessing. This investigation …

Sufex-Enabled Stereospecific Deoxygenative Diversification Of Alcohols, Amaechi Odoh

All Dissertations

Alcohols represent an important class of functional group in organic synthesis and medicinal chemistry, given that they are structurally diverse and prevalent in many natural products, biomolecules and renewable feedstocks. As such, they are highly attractive precursors for building-block synthesis, late-stage functionalization, and numerous synthetic transformations. However, existing strategies for the deoxygenative diversification of alcohols operate under constrained conditions, often leading to competing pathways (such as elimination), poor stereospecificity, low efficiencies, and limited substrate compatibility. To address these challenges, we have developed a conceptually novel use of sulfonyl fluorides as bifunctional reagents for the one-step deoxygenative diversification of complex alcohol …

Selective Hydroxyl Functionalization Using Novel Bifunctional Macrocyclic Catalysts And Sufex-Based Methodologies, Austin Seilkop

All Dissertations

The research behind this dissertation explores innovative strategies for the functionalization of alcohols. Alcohols are abundant in biologically relevant molecules and pharmaceutical drugs, so designing new methods for modifying them has gained significant interest over the years. The first and second chapters of this dissertation focus on the selective functionalization of a particular class of alcohols, amino alcohols, a well-represented functional handle in biomolecules. The hydroxyl functionalization of amino alcohols often demands multiple synthetic steps. We developed a new class of macrocyclic catalysts to enable precise and efficient transformations of amino alcohols, advancing the scope and efficiency of amino alcohol …

Recyclable Composites Prepared From Animal Coproducts And Industrial Waste Sulfur, Perla Y. Sauceda-Oloño

All Dissertations

Pursuing sustainable and environmentally friendly materials has become a significant objective in materials science, particularly flame retardants and construction materials. This dissertation explores the development and evaluation of novel composites and high sulfur-content materials (HSMs) as potential alternatives to conventional, environmentally harmful materials.

Chapter one reviews recent advancements in environmentally benign flame-retardant additives, highlighting the potential of bio-derived phenols, polysaccharide derivatives, and greener phosphorus sources. The review discusses how green additives can enhance the flame retardancy, thermal stability, and smoke suppression properties of various polymers while addressing the challenges and future directions in the field.

Chapter two investigates the production …

Phytoplankton Responses To Changing Irradiance And Carbon Fertilization, Alison Siersma

Graduate Theses and Dissertations (2019 - present)

Phytoplankton play a crucial role in marine ecosystems due to their innate ability to fix carbon. As atmospheric CO2 levels continue to rise from fossil fuel combustion, the resulting increase in dissolved CO2 and the concurrent decrease in ocean pH are likely to impact the phytoplankton community. The response of phytoplankton to elevated CO2 can vary significantly among species and environmental conditions (e.g. light, temperature, nutrient availability). To address these variations, an experiment was conducted using a controlled photobioreactor system, maintaining high and low light, constant temperature, nutrient levels, and two pCO2 concentrations. This study focused on two regionally relevant …

Composites Developed By The Reaction Of Elemental Sulfur With Biologically Derived Fats And Oils, Katelyn Tisdale

All Dissertations

Human civilization’s modern infrastructure relies mainly on cement and petrochemical products. However, the production of these building materials have harmful ecological effects such as green gas emissions, therefore intensifying the need to develop alternative, sustainable structural materials from renewably sourced or waste material precursors. The work presented herein investigates various biomass derived resources that serve as the olefin source for reaction with elemental sulfur, another abundant waste source, via inverse vulcanization to form high strength composites competitive with that of traditional building materials.

Chapter one reviews various techniques that have been developed and executed in an effort towards lignin valorization …

Physicochemical Property Effects On Immune Modulating Polymeric Nanoparticles: Potential Applications In Spinal Cord Injury, Daniel J. Kolpek, Jaechang Kim, Hisham Mohammed, John C. Gensel, Jonghyuck Park

Markey Cancer Center Faculty Publications

Nanoparticles (NPs) offer promising potential as therapeutic agents for inflammation-related diseases, owing to their capabilities in drug delivery and immune modulation. In preclinical studies focusing on spinal cord injury (SCI), polymeric NPs have demonstrated the ability to reprogram innate immune cells. This reprogramming results in redirecting immune cells away from the injury site, downregulating pro-inflammatory signaling, and promoting a regenerative environment post-injury. However, to fully understand the mechanisms driving these effects and maximize therapeutic efficacy, it is crucial to assess NP interactions with innate immune cells. This review examines how the physicochemical properties of polymeric NPs influence their modulation of …

Unraveling Phytosulfokine Trafficking In Arabidopsis Thaliana Using Fiber-Optic Fluorescence Microscopy, Issaka Obuaba

Electronic Theses and Dissertations

As sessile organisms, plants manage stress through complex signaling networks involving phytohormones such as phytosulfokine (PSK). PSK, a disulfated pentapeptide, regulates plant growth, development, and stress responses by interacting with specific PSK receptors (PSKRs). In this study, we explored the trafficking dynamics of PSK, its post-application fate, and the synthesis of an analog. We administered both native PSK and a fluorescent version tagged with TAMRA (5(6)-carboxytetramethylrhodamine) to various Arabidopsis thaliana genotypes, including wild type, a PSKR-deficient mutant, and a strain overexpressing PSKR1 tagged with green fluorescent protein (GFP) over the wild-type background. Fiber-optic fluorescence microscopy revealed that receptor presence influences …

Investigating Phytosulfokine Trafficking: Insights Into The Role Of Phytohormones In Plant Signaling, Martin Tindi

Electronic Theses and Dissertations

Phytosulfokine is a critical signaling peptide involved in plant growth, development, and stress responses. This thesis investigates the trafficking mechanisms of Phytosulfokine (PSK) in Arabidopsis thaliana, employing fluorescently labelled PSK for non-destructive imaging using a custom-built fiber-optic fluorescence microscope. The study aims to determine the mobility and fate of PSK in plant tissues. Experimental results reveal the short-range and long-range movement of PSK across leaves. Additionally, the project highlights the optimization of non-destructive imaging techniques and the synthesis of caged dexamethasone to facilitate optogenetic studies. These findings provide new insights into PSK trafficking mechanisms in plants, enhancing our understanding …

The Application Of High-Resolution Mass Spectrometry For The Analysis Of Biopolymers, Metabolites, And Biologically Relevant Small Molecules, Christ Duc Tran

Graduate Doctoral Dissertations

High-resolution mass spectrometry (HRMS), as its name suggests, possesses high resolving power that enables the separation of ions with very close mass values. This is particularly beneficial for analyzing complex samples where numerous compounds may have similar masses, as it helps prevent signal overlaps and ensures an accurate spectral analysis. The current work explores the diverse applications of high-resolution mass spectrometry in oligonucleotide research, organic synthesis and medicinal chemistry. Oligonucleotide research: Chapters 2-5 present the research results from studies that employed ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) to understand the pharmacokinetics of RNA interference (RNAi) therapeutics. The …

Synthesis Of Photocleavable Molecules For Neurological Applications, Nishal Madujith Egodawaththa Arachchilage Don

Theses and Dissertations

In recent biomedical research, the precise control of molecular dynamics through light activation has emerged as a powerful tool, particularly in the field of neurobiology. This approach involves the use of photocleavable cages or photoprotective groups (PPGs) that are chemically tethered to biologically active molecules such as neurotransmitters or calcium chelators. These cages remain inert until exposed to specific wavelengths of light, typically in the visible range, triggering the release of the active compound with high spatiotemporal precision.

For neurotransmitter systems, such as glutamate (Glu), which plays a critical role in synaptic transmission and memory formation, researchers have developed novel …

Cyclization Of Diols Using Ferrocenium Cations & Other Iron-Based Catalysts, Cody D. Amann, Fnu Khushboo, Sai Anvesh Bezawada, Eike B. Bauer

Undergraduate Research Symposium

Our research involves the study and improvement of iron-based catalysts. The Bauer group has recently found that the ferrocenium cation, along with other iron-based compounds, are catalytically active in the cyclization of various diols to obtain five-membered tetrahydrofuran derivatives. My research involved comparing the effect of 2 different counter-anions of the ferrocenium cation along with 2 other iron-based catalysts that were previously synthesized in the Bauer lab for their catalytic activity in the title reaction. Cyclization test reactions were performed by reacting three different types of diols with each of four different iron catalysts. The three diols used were 4-methyl-1-phenyl-1,4-pentanediol …

Synthesis And Characterization Of Water Soluble Thiosemicarbazone-Alkylthiocarbamate Ligands And Their Cu(Ii) Complexes, John J. Garvey Iv, Sanjit Karki, Haixun Guo, Levi J. Beverly, Craig A. Grapperhaus, Robert M. Buchanan

The Cardinal Edge

Thiosemicarbazone-alkylthiocarbamate N₂S₂ hybrid ligands are emerging as an important class of potential bioactive molecules that possess important pharmacokinetic properties. Resulting metal complexes have electronic properties that are composites of their homolog forms, bis-thiosemicarbazones and bis-alkylthiocarbamates, allowing for tuning redox potentials over a nearly 450 mV range. These versatile ligand frameworks possess remarkable antiproliferation activity against a broad range of solid tumors and low toxicity towards normal cells¹ indicating great promise for future drug development. Herein, we describe recent synthetic efforts to improve water solubility of thiosemicarbazone-alkylthiocarbamate hybrid ligand Cu(II) complexes. The parent 4-methyl-3-thiosemicarbazide half arm was …