Chemistry Commons^™

Development Of Chiral Lewis Base Catalysts For Chlorosilane-Mediated Asymmetric C-C Bond Formations, Changgong Xu

Theses and Dissertations

The chiral hydrazine is a crucial structural motif that serves as pivotal structural elements in numerous natural products and biologically significant molecules. We are particularly interested in the catalytic asymmetric reduction of hydrazones, as well as the catalytic asymmetric propargylation and allenylation of hydrazones, because they provide direct pathways to these enantio-enriched chiral building blocks. In this work, we will explore the potential of two different categories of chiral Lewis base catalysts in the said transformations.

Developed by another student in our group, axial-chiral 3,3’-triazolyl biisoquinoline N,N’-dioxides derived catalysts are tested and demonstrated its capability in activating various hydrazone …

A Conceptual Understanding Of Concepts In Organic Chemistry, Timerra Chisham

Theses/Capstones/Creative Projects

As students continue to make the transfer into organic chemistry from general chemistry, they will have to adjust to the new type of thinking required so that they will not fall behind in understanding material and will have success in the course. For this research project, I explored which concepts taught in organic chemistry are the most difficult for students to grasp. I had two main goals for this project. The first one is the central idea that I focused on, which was to see which concepts that have been taught in Organic Chemistry 1 the students are most confident …

Covalent Inhibition Of Enzyme Sortase A As A New Pathway Against Bacterial Resistance Of Staphylococcus Aureus, Umyeena Bashir

Master's Theses

The continued rise of antibiotic-resistant bacteria, such as MRSA (methicillin-resistant Staphylococcus aureus), has made the discovery of novel antibiotics critical. While bacteriostatic and bactericidal antibiotics inevitably exert evolutionary pressure on bacteria to develop resistance, small molecules that target mechanisms of bacterial virulence present a promising alternative for treatment. Sortase A (Srt A), a cysteine protease of S. aureus, promotes bacterial virulence by covalently attaching proteins such as pilin to the bacterial surface, enabling bacterial adhesion to mammalian cells. Inhibitory studies of this enzyme have gained prominent interest as a new pathway for drug development since blocking this enzyme's ability to …

The Effects Of Prior Calculus Classes On Success In Organic Chemistry, Tori Williamson

Theses/Capstones/Creative Projects

Within University of Nebraska – Omaha (UNO) chemistry-based degree programs, organic chemistry along with at least two semesters of calculus are required courses. There is, however, no requirement for the order in which these courses should be taken. This is mainly due to the notion that for chemistry courses, organic chemistry is detached from the typical quantitative concepts studied in other chemistry-based courses. This is untrue, however, as many organic chemistry concepts rely on three-dimensional spatial visualizations and manipulations. Spatial awareness skills are strengthened within higher-level calculus classes. A survey was administered to organic chemistry students enrolled in 2022-2023. The …

Asymmetric Cuh-Catalyzed Reductive Coupling Of Allenamides With Carbonyl Electrophiles & Development Of Nanocatalysts For Heterogeneously Catalyzed Buchwald-Hartwig Amination, Raphael K. Klake

Theses and Dissertations

Many drugs and natural products contain multiple stereogenic carbons bearing heteroatoms throughout their carbon framework. Therefore, methods that can efficiently install multiple heteroatoms on a molecule are valuable. Reductive coupling reactions have been extensively studied, and the allylation of carbonyls via the reductive coupling approach has been a key method for generating chiral tertiary and secondary allylic alcohols. This work utilizes inexpensive Cu for the asymmetric reductive coupling of allenamides with carbonyls to simultaneously install two heteroatoms (oxygen and nitrogen) on the product. These molecules have a polarity profile that make them difficult to make using traditional methods. Herein, we …

Synthesis, Characterization And Cell Viability Of Novel Tripodal Amines, Kinsley Lupton

Honors College Theses

Cancer, over the years, has become a much more prevalent focus for the scientific community. Organizations and laboratories all over the world have spent countless hours searching for a cure, trying to learn more about what makes cancer so powerful and what is the best way to stop its growth. Iron-chelation drugs were already on the market, and it was shown that they did have the ability to act as both iron-chelators and anticancer drugs. Most of these iron-chelating drugs are not as effective at killing cancer cells as the medical field desires. Novel iron-chelating tris-indolyl derivatives, GSO2, GSO4 and …

One-Pot Synthesis Of Disubstituted Primary Amines From Nitriles Via Grignard Addition And Metal-Alcohol Reduction, Joshua Peltan

Honors Theses

The process of developing a working base case procedure for a novel one-pot-two-step synthesis of primary amines from Grignard reagents, nitriles, sodium metal or alkali metal loaded silica gel, and alcohol is described. Initial steps towards applying the process broadly are detailed. The process has the potential to be an affordable, convenient, safer, greener, and more accessible alternative to exiting methods of accomplishing the same transformation. The reaction scheme has been proven to provide yields and purity comparable to existing methods for certain pairs of substrates; however, its utility as a general-purpose method for transforming arbitrary pairs of Grignard reagent …

The Development Of Fluorine-18 Imaging Agents Targeting The Ghsr, Marina D. Childs

Electronic Thesis and Dissertation Repository

Molecular imaging is an interdisciplinary field of study that allows for real-time visualization of biological processes in both healthy and disease states. Fluorine-18 positron emission tomography (PET) imaging is a highly sensitive technique where molecular probes containing fluorine-18 serve to specifically locate and visualize the expression of relevant disease biomarkers. The growth hormone secretagogue receptor 1a (GHSR) is differentially expressed in cancer and cardiac pathology, making it a biomarker of interest for imaging such diseases. This thesis discusses the development and optimization of GHSR-targeting ¹⁸F-PET imaging probes as well as proposes a new imaging agent discovery technique.

Chapter 2 …

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

Synthesis And Biological Evaluation Of Azide- Tagged Biomimetic Probes For Global Labeling Of The Saccharomyces Cerevisiae Glycerolipidome, Matthew R. Johnson

Masters Theses

Lipid metabolism is an extremely complex, interconnected process that, when dysregulated, is strongly linked to cellular disease states including cancer. Study of these metabolic processes is complicated by the characteristic intricacy of these systems; nonetheless, it is achievable through metabolic labeling. Visualization of biosynthesis is an advantage offered by metabolic labeling through the incorporation of fluorescent tags. In this technique, synthetic probes bearing a clickable tag such as azide are fed into live cells where they are directly incorporated using the native enzymatic and cellular processes to metabolically label lipid products. These labeled lipid products are capable of being studied …

Synthesis Of Biologically Active Phosphorus Heterocycles, Giri Gnawali

Dissertations

This dissertation work is divided into two parts. The first part is focused in the development of methodology for the synthesis of phostones and phosphonosugars and advancement thereof. The second part is focused in the development of affinity probes based on analogs of natural products cyclophostin and the cyclipostins.

Phostone (3) and phosphonosugars are cyclic phosphonates. The anomeric carbon of sugar is replaced by a phosphorus atom. The synthesis of phostones has been achieved starting form the key intermediate, γ,δ-epoxy vinyl phosphonate (1). The palladium catalyzed ring opening of γ,δ-epoxy vinyl phosphonates by a nucleophile results …

Elucidation Of Radical Cation Trapping Chemistry: Using Electrochemical And Photochemical Techniques To Qualitatively Assess The Kinetics Behind Anodic Oxidative Cyclizations, Luisalberto Gonzalez

Arts & Sciences Electronic Theses and Dissertations

While the field of organic chemistry has grown throughout the decades, its primary concern has always been on the generation, conversion, and study of molecular structures. Within that philosophy, the development of new reactions affords chemists the ability to overcome previous synthetic barriers or develop more elegant and simple synthetic routes to difficult-to-construct molecules. Within that realm, electrochemistry is seeing increased attention due its ability to generate highly reactive intermediates, recycle chemical reagents, and reverse the polarity of known functional groups. One example of such an application is the use of electrochemistry to form radical cations. While radical cations have …

New Catalytic Reactions In Carbohydrate Chemistry, Scott Geringer

Dissertations

Carbohydrates or sugars are some of the most diverse and abundant biological molecules. They are involved in a multitude of processes in the body such as fertilization, cell-cell communication, and cancer metathesis. Because of these vital functions, the study of sugars is rapidly growing field. The field however is limited due to the complex nature of sugars which results in difficulties in obtaining large quantities for study.

Protecting group manipulation is a large emphasis area in carbohydrate chemistry due to the need to selectively protect different functional groups of each molecule during synthesis. Catalytic and selective cleavage of protecting groups …

N,N’-Dimethyimidazolium-2-Carboxylate As A Ligand Precursor For The Accession Of A Constrained Olefin Dimerization Catalyst, Michael Harris

Honors Projects

A significant market share of modern plastics is held by long-chain hydrocarbon polymers, such as polyethylene and polypropylene, properties of which can be dramatically changed by addition of linear α-olefins. Production of linear α-olefins involves the creation of many unwanted byproducts, representing significant quantities of both economic and ecological waste. While catalysts have been designed to selectively produce industrially useful olefins, these catalysts often encounter challenges such as synthesis of other unwanted byproducts, slow reaction times, and difficulty of synthesis. Based on one such prior catalyst, we report here synthetic work towards a cobalt catalyst with a constrained N-heterocyclic carbene …

Exploration Of Cis-1,2-Diaminocyclohexane-Based Conformationally Locked Chiral Ligands In Asymmetric Synthesis, Carim Van Beek

University of the Pacific Theses and Dissertations

Natural products have been demonstrated to be of great significance to the pharmaceutical industry in the development of new drugs and medicine. Unfortunately, synthetic approaches to obtain these natural products often prove increasingly challenging due to the complexity of synthesizing the target drug in the proper stereochemistry. The availability of enantioselective reactions can play a pivotal role in overcoming this challenge, yielding access to optically pure intermediates and products. Chiral ligands based on a trans-1,2-diaminocyclohexane motif are often employed for this purpose and their complexes with transition metals have been demonstrated to act as efficient chiral catalysts in asymmetric reactions. …

Development Of Ni-Catalyzed Alkene Dicarbofunctionalization Reactions, Shekhar Kc

Chemistry and Chemical Biology ETDs

Alkenes serve as one of the most important feedstocks for organic synthesis, having two vicinal sites for bond formation. In alkenes, both vicinal sites can be functionalized with two reagents in a process commonly known as alkene difunctionalization, which results in the formation of two new bonds. A number of alkenes difunctionalization reactions, such as diamination, dioxygenation, carboamination and carbooxygenation, are known. However, difunctionalization of alkenes with two carbon-based entities, termed alkene dicarbofunctionalization, is relatively less common. Development of such a process could provide a powerful method to introduce two different carbon fragments across an alkene in a regioselective manner, …

The Synthesis Of Highly Substituted Aromatics And The Reaction Of Alkene Pi Systems With Vinyl Cations, Nicholas Jarrod Dodge

Graduate College Dissertations and Theses

Aldol cyclotrimerizations have been used to achieve the rational chemical synthesis of both fullerenes and fullerene fragments in the past. Under certain conditions this reaction produces the corresponding cyclotetramer which has sometimes been regarded as an undesired byproduct. This work details efforts to synthesize and use these cyclotetramers toward a synthesis of a C240 fullerene fragment. One principal focus in this work is tridecacyclene, a cyclic tetramer of acenaphthylene given its name by our group for its thirteen rings. Relatively low yields for the synthesis of tridecacyclene and its derivatives drove us to investigate the mechanism of its formation and …

Design And Synthesis Of Analogs Of Myo-Inositol, Serine, And Cysteine To Enable Chemical Biology Studies, Tanei J. Ricks

Doctoral Dissertations

Phosphorylated myo-inositol compounds including inositol phosphates (InsPs) as well as the phosphatidylinositol polyphosphate lipids (PIP_ns) are critical biomolecules that regulate many of the most important biological processes and pathways. They are aberrant in many disease states due to their regulatory function. The same is true of the phospholipid phosphatidylserine (PS) which can serve as a marker to begin apoptosis. However, the full scope of activities of these structures is not clear, particularly since techniques that enable global detection and analysis of the production of these compounds spatially and temporally are lacking. With all of these obstacles in …

Iodine-Initiated Hydration Of Internal Alkynes, Nicholas J. Shuber, Karelle Aiken

Honors College Theses

The iodine-initiated hydration of internal alkynes is a novel, green, and inexpensive synthetic pathway in comparison with the commonly used transition metal catalyzed reactions. This can be a useful alternative in many fields, academic or industrial. This experimental design has been used successfully on terminal alkynes and is now being extended to internal alkynes. Through systematic probing of the reaction conditions, we have gleaned sufficient information to determine a strong mechanistic hypothesis based on neighboring group participation. Here in, we will report our result with a series of internal, keto alkynes reacted under ambient conditions with iodine in “wet” solvent. …

Synthesis Of Unnatural Amino Acids For Genetic Encoding By The Pyrrolysyl-Trna/Rna Synthetase System, William A. Knight

Theses and Dissertations

The complexity of all biomolecules in existence today can be attributed to the variation of the amino acid repertoire. In nature, 20 canonical amino acids are translated to form these biomolecules, however, many of these amino acids have revealed posttranslational modifications (i.e. acetylation, methylation) after incorporation. Amino acids that exhibit PTM are known for their involvement in cellular processes such as DNA repair and DNA replication; these PTMs are commonly found on histones within the chromatin complex. Utilization of in vivo site-specific incorporation has recently reported functionality of post-translationally modified amino acids.1 xii Here we report the synthesis and in …

Ferrocene Constrained Helical Peptides Via On-Resin Cyclization, Thomas A. Mcteague

Senior Theses and Projects

Previous research within the Curran group has demonstrated that ferrocene may be used as an organometallic constraint to induce the formation of α-helices in short peptides which traditionally possess undefined conformations. Through strategic placement of lysine residues at the i and i+3 positions within the peptide, such a constraint was accomplished via the crosslinking of the lysine side chains to ferrocene dicarboxylic acid chloride in solution phase synthesis. The aim of this work was to develop a method for solid phase peptide synthesis (SPPS) for the synthesis of these ferrocene-constrained helices. In particular, we seek to develop a method in …

Design, Synthesis And Study Of The Bridged And Cofacially-Arrayed Poly-P-Phenylene Molecular Wires, Matthew J. Modjewski

Master's Theses (2009 -)

Two novel series of bridged and cofacially-arrayed poly-p-phenylenes have been designed synthesized and studied. The bridged poly-p-phenylenes have been synthesized from a readily available diacetylenic precursor utilizing three high yielding steps, and their structures were determined by 1H/13C NMR spectroscopy as well as X-ray crystallography. The racemization barrier between the two atropoisomers was found to be ~12 Kcal mol-1; the versatility of the synthesis employed was extended to synthesis a triply bridged tetra-p-phenylene and a quadruply bridged penta-p-phenylene.

The cofacially-arrayed poly-p-phenylenes have shown that the X-ray crystal structures of the neutral compounds are largely dominated by C-H--π-interactions interactions while the …

Using Azahetercyclic Electrophiles To Synthesize Novel Bicyclooxacalixarenes And Oxacalix[2]N-Hexylnaphthalimide[2]Naphthyridines, Doug Rooke

Honors Theses

Various bicyclooxacalixarenes, tricyclooxacalixarenes and oxacalix[2]N-hexylnapthalimide[2]naphthyridines are synthesized via SnAr condensation. This research has involved synthesis optimization. The oxacalix[2]N-hexylnaphthalimide[2]naphthyridines have exhibited host-guest binding in fluorescence experiments. These compounds have been characterized by NMR spectroscopy as well as single crystal X-ray diffraction.

Synthesis Of Malathion, Malaoxon, And Isomalathion Enantiomers And Examination Of Their Interactions With Acetylcholinesterase, Clifford E. Berkman

Dissertations

No abstract provided.

Potential Pharmaceutical Derivatives Of Β-Aminoethylpiperazine, Brian A. Dementi

Master's Theses

This thesis is concerned with the design and preparation of certain organic compounds which are expected to have medicinal properties. A discussion will be given which has essentially a two-fold purpose. The first is to discuss somewhat briefly the currently accepted method of rug design, and the second to show to what extent this method has been followed in the design of the compounds prepared.

Itaconic Acid Derivatives Of P-Amino Alkyl Sulfone, Wilbur B. Clarke

Electronic Thesis and Dissertation

This investigation is concerned with the preparation of 1(p-R1 Sulfonyl)-phenyl-5-oxo-3-pyrrolidine carboxylic acid by direct fusion of itaconic acid with the respective p-Amino phenyl alkyl or aryl sulfone, and its continuation of work previously reported