Organic Chemistry Commons^™

Synthesis Of N-Heterocyclic Molecules And Their Applicability Towards Ion Sensing: Polymeric Chemosensors, Aikohi M. Ugboya

College of Graduate Studies: Theses & Dissertations

Critical to biological and environmental processes are anions because often times their relative concentration in our body can be an indicator of one’s well-being. Therefore, highly sensitive and cost-efficient methods for ions recognition is necessary for human health. In recent times, polymeric chemosensors have become a vital tool for sensing ions because of its higher sensitivity and good mechanical properties compared to their monomeric counterparts. These sensors are designed to produce a measurable response in the presence of a targeted ion such as an electrochemical or optical signal. The unique structure and the photophysical properties of the 1,2,3-triazole core coupled …

Copper-Mediated N1-Arylation Of Benzotriazoles, Magdalena R. Andrzejewska

Dissertations and Theses

Benzotriazoles are group of bicyclic heterocyclic compounds that contain three nitrogen atoms fused to a benzene ring. Along with their derivatives, they possess a wide range of properties. They are used in medical field, as they exhibit such properties as antibacterial,antiplasmoidal,antiprotozoal, antifungal and anti-inflammatory activities, among others. They are also used in various industries as herbicides, UV absorbers, deicing and antiicing agents and corrosion inhibitors, to list a few. Because of their wide range of applications, we designed a new two-step synthesis for the formation of N-1-aryl benzotriazoles. 1-Hydroxy-1H-benzotriazole N-oxides were synthesized using phenylboronic acid (PhB(OH) …

In Situ Infrared Spectroscopic Study Of Iron-Catalyzed Hydromagnesiation Of Vinyl Arenes, Jessica Ann Rogers

Graduate Theses, Dissertations, and Problem Reports (ETD)

Iron catalysis, especially homogeneous catalysis, has been a resurging topic of organometallic chemistry research. Discussions of past and present mechanistic analyses for homogeneous iron catalysis will be discussed in Chapter 1. As an expansion of homogeneous iron catalysis, in situ infrared spectroscopy will be used to develop a full mechanistic study of iron-catalyzed hydromagnesiation of vinyl arenes. The kinetic analyses by both initial and observed rate measurements indicate complex concentration dependencies on the (PDI)iron catalyst as well as sacrificial Grignard reagent and styrene. These complexities are not limited to non-linear catalyst and Grignard initial rate and inhibition by styrene/Grignard at …

Avoiding Adverse Effects: New Ideas In Drug Discovery For Targeting Pparγ, Trey M. Patton

Graduate Student Theses, Dissertations, & Professional Papers

Peroxisome proliferator-activated receptor gamma (PPARγ) has been a drug target to treat type 2 diabetes for the last 20 years when rosiglitazone and pioglitazone were approved by the FDA in 1999. While effective at increasing insulin sensitivity, these drugs cause serious adverse effects due to their full agonist characteristics. For that reason, drug discovery efforts have attempted to reduce or prevent the amount of agonist character of new PPARγ targeting ligands. Unfortunately, there have been no new FDA approved drugs for the receptor. There is a need for new ideas to produce better quality pharmaceuticals that lessen the impact of …

Photoluminescent Zirconium Complexes For Visible Light Photoredox Catalysis, Yu Zhang

Graduate Theses, Dissertations, and Problem Reports (ETD)

Early transition metals like zirconium are attractive candidates for the design of luminescent molecules based on earth-abundant elements. Here, a series of zirconium complexes carrying two pyrrolyl-based ligands have been synthesized and characterized. These complexes are photoluminescent upon excitation with visible light and exhibit remarkably long emission lifetimes of hundreds of μs in solution at room temperature. Computational studies using time-dependent density functional theory (TD-DFT) were conducted to identify the nature of the luminescent excited states as mixed intra-ligand/ligand-to-metal charge-transfer (ILCT/LMCT) states. The electrochemistry studies revealed multiple reversible redox events for each zirconium complex. Furthermore, the excited state of the …

Copper-Catalyzed Regioselective Boracarboxylation Of Vinyl Arenes: Catalytic Efficiency And Synthetic Utility, Trina M. Perrone

Graduate Theses, Dissertations, and Problem Reports (ETD)

Hetero(element) carboxylation is an appealing transformation that involves the installation of CO2 and another hetero(element) in one step. This transition metal-catalyzed one-pot synthesis provides a route to achieve highly functionalized carboxylic acid products with an abundant and cheap C1 feedstock. This difunctionalization also avoids the use of reactive metal hydride species, which is a prominent limitation of hydrocarboxylation chemistry. A copper-catalyzed regioselective boracarboxylation of vinyl arenes has been developed to access pharmaceutically relevant β-boryl-α-aryl propionic acid products. One drawback of this reaction is the necessity for high catalyst loading to achieve catalytic turnover. To circumvent this issue, the reduction of …

The Chemical Analysis And Biological Activities Of The Secondary Metabolites From Dalea Mollis And Dalea Albiflora, Nicholas Peter Hansen

All Master's Theses

Multidrug resistance has increased since the introduction of drugs used to prevent growth and kill microorganisms in a host. This has caused a worldwide search to discover new drugs effective against microorganisms. Mechanisms of drug resistance include, but are not limited to, the production of biofilms and efflux pumps. Efflux pumps prevent antimicrobial drugs from reaching their biological target, so the coordinated use of efflux pump inhibitors and antimicrobial drugs has been identified as a potential treatment for multidrug-resistant microorganisms. The secondary metabolites of Dalea mollis and Dalea albiflora were tested against multidrug-resistant (MDR) and engineered strains of the fungi …

Synthesis Of 4-Methylbenzoate(2ʹ,4ʹ,6ʹ-Trimethoxyphenyl) Iodonium Tosylate, Thomas Ludwig Seidl, Aaron Moment, Charles Orella, Thomas Vickery, David R. Stuart

Chemistry Faculty Publications and Presentations

Hypervalent iodine continues to intrigue organic chemists with its diverse breadth of reactivity. The use of diaryliodonium salts as aryltransfer reagents has increased dramatically in the past decade as they have become more available by the development of efficient “one-pot” synthesis methods. Unsymmetrical diaryliodonium salts that selectively, and predictably, transfer one aryl group over the other are particularly desirable reagents, especially for the transfer of elaborate aryl groups to nucleophilic moieties. While the mesityl (Mes; 2,4,6-trimethylphenyl) group effectively serves as a general auxiliary in metal-catalyzed reactions of diaryliodonium salts, a broadly applicable auxiliary has not been adopted in metal-free reactions. …

Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang

Theses and Dissertations--Chemistry

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with …

Oxidative Depolymerization Of Lignin To Low Molecular Weight Aromatics, Yang Song

Theses and Dissertations--Chemistry

To date, most lignocellulosic biorefinery strategies have focused on optimizing conversion of cellulose to ethanol, leaving lignin as an underutilized biomass constituent. Lignin is engineered by nature with the intent to protect plants from chemical and biological attack; this leaves lignin with high structural irregularity and recalcitrance, rendering conversion of the lignin macromolecule to valuable products particularly challenging. Nevertheless, given that the economics of cellulosic ethanol production are strongly dependent on the value that can be obtained for the lignin co-product, the successful valorization of lignin is a crucial step in the transition towards a bio-based economy.

This thesis focuses …

New Synthetic Methods Using Superelectrophiles, Sean Kennedy

Graduate Research Theses & Dissertations

The work outlined in this dissertation describes new synthetic methods in the synthesis of heterocyclic compounds mediated by superacid catalysis. Superacids are powerful reagents that enhance the reactivity of electrophiles, thereby opening the door to new reactive pathways with very weak nucleophiles. In this work, trifluoromethanesulfonic acid (triflic acid, CF3SO3H) is employed as a superacid catalyst to effect new transformations. These concepts are summarized in chapter 1. Chapter 2 describes a new acid-catalyzed cascade leading to the indolizidine ring system, which is present in a number of natural products. Experiments support a proposed mechanism involving vinylogous keto-enol tautomerization. The synthesis …

Modeling The Condensed-Phase Behavior Of Π-Conjugated Polymers, Walker Mask

Theses and Dissertations--Chemistry

It is well established that the morphology and physical properties of an organic semiconducting (OSC) material regulate its electronic properties. However, structure-function relationships remain difficult to describe in polymer-based OSC, which are of particular interest due to their robust mechanical properties. If relationships among the molecular and bulk levels of structure can be found, they can aid in the design of improved materials. To explore and detail important structure-function relationships in polymer-based OSC, this work employs molecular dynamics (MD) simulations to study various π-conjugated polymers in different environments. Two independent investigations are discussed in this work. One investigation examines how …

Development Of Synthetic Methodologies Of Nucleophile-Electrophile Chemistry, Michael R. Stentzel

Graduate Research Theses & Dissertations

The work outlined in this dissertation describes the development of synthetic methodologies utilizing a wide electrophilicity range of substrates towards the synthesis of new compounds. Substitution, addition, and superelectrophilic chemistry are powerful tools to afford potentially important compounds. These concepts are summarized in chapter 1.

Chapter 2 describes the capture of superacid catalyzed fluorenyl cations with nitriles (Ritter reaction) and alcohols. Optimization of reaction conditions and extensive scope studies were performed.

In chapter 3, the Michael addition of organometallic reagents with N-heterocyclic substituted olefins is explored. The nucleophilic carbanion intermediate species is shown to have reactivity towards strong electrophiles. With …

The Design, Synthesis, And Evaluation Of Inhibitors Of The Ispf Enzyme In The Mep Pathway, Christopher G. Stewart

Graduate Research Theses & Dissertations

Isoprenoids are a class of over 50,000 compounds that serve as key precursors for many compounds in plants and animals. These compounds play critical roles in many biological functions such as cellular growth, respiration, and go on to form critical compounds such as steroids and vitamins. Despite their overall necessity to life their biosynthesis only follows two synthetic pathways. These pathways are the Mevalonic Acid (MVA) Pathway and the 2-C-Methyl-D-Erythritol-4-Phosphate (MEP) Pathway also known as the non-mevalonate pathway. The MVA pathway is found primarily in humans and some higher plants while the MEP pathway is found in bacteria and some …

The Benefit Of Precise Chemical Shift And Concentration Referencing In Nmr Applications, Ming Huang

Doctoral Dissertations

“In Nuclear Magnetic Resonance (NMR) spectroscopy, the chemical shift and intensity of NMR signals provide critical information about a sample's molecular structure, reaction conditions, and material properties. For the precise determination of structures and properties, it is critical to know sample or reaction conditions such as temperature, pH, concentration, or absolute amount of material. Chemical-shift and signal-intensity calibrations play a key role for extracting the maximum amount of information from NMR experiments. In this dissertation, internal and external reference standards are used to calibrate NMR spectra with respect to chemical shift and signal intensity. Sealed capillary tubes filled with specific …

Towards The Discovery Of Oligonucleotide Cross-Linking Agents, Bhaskar Halami

Dissertations, Master's Theses and Master's Reports

Oligonucleotide cross-linking agents are expected to become a new class of antisense drugs. They function by first hybridizing with a complementary mRNA and then form a covalent bond to permanently link the mRNA to the oligonucleotide agent. Because of covalent cross-linking, this new class of antisense drugs are expected to have much higher potency than existing ones.

Some oligonucleotide cross-linking agents have appeared in the literature, but they have various drawbacks, which include slow cross-linking rate and reversible cross-linking. To address these problems, we designed a series of new cross-linking oligonucleotides with a range of different reactivities. These oligonucleotides were …

Near-Infrared Fluorescent Probes For Sensitive Determination Of Lysosomal & Mitochondrial Ph In Live Cells, Wafa Mazi

Dissertations, Master's Theses and Master's Reports

Varied intracellular pH levels are critical for various physiological processes such as enzymatic activity, cell proliferation and apoptosis, ion transport, and muscle contraction. Cellular compartments, like lysosomes, must retain an acidic environment (pH ~ 4.5) to activate hydrolytic enzymes necessary for the breakdown of large biomolecules. Another cellular organelle, the mitochondria, provides the cell with energy and must retain an alkalis environment (pH ~ 8.0) for proper function. Substantial lysosomal and mitochondrial pH deviation is associated with cellular dysfunction and disease. Therefore, the precise detection of lysosomal and mitochondrial pH is essential to provide a better understanding of cellular physiological …

Modular Synthesis And Hydroalkylation Of Vicinally Functionalized Ketopiperazines: A Solution To The Piperazine Problem, Antonio Moreno

All Master's Theses

The stereocontrolled synthesis of functionalized piperazines is of great interest to pharmaceutical companies owing to their multiple biological activities such as antidepressant, antiparasitic, anticancer and antiretroviral. Current methods towards functionalized piperazines include intramolecular cyclization of appropriately tethered on acyclic precursors as well as α-C–H functionalization of intact piperazine rings. Although effective for the most part, these methods suffer from drawbacks such as the use of expensive catalysts, potentially toxic reagents, limited scope and functional group compatibility. Seeking to side-step some of the aforementioned limitations, we herein describe a step-economical-, cost-effective-, transition metal-free-, and mild approach to highly functionalized piperazines, including …

Vibrational Analysis Of A Rate-Slowing Conformational Kinetic Isotope Effect, O. Maduka Ogba, Zichen Liu, Daniel J. O'Leary

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

An enthalpy-entropy approach to analyzing a rate-slowing conformational kinetic isotope effect (CKIE) in a deuterated doubly-bridged biaryl system is described. The computed isotope effect (kH/kD = 1.075, 368 K) agrees well with the measured value (kH/kD = 1.06, 368 K). The rateslowing (normal isotope effect) nature of the computed CKIE is shown to originate from a vibrational entropy contribution defined by the twenty lowest frequency normal modes in the ground state and transition state structures. This normal entropy contribution is offset by an inverse vibrational enthalpy contribution, which also arises from the twenty lowest frequency normal modes. Zero point vibrational …

Atom-Specific Activation In Co Oxidation, Simon Schreck, Elias Diesen, Jerry Larue, Hirohito Ogasawara, Kess Marks, Dennis Nordlund, Matthew Weston, Martin Beye, Filippo Cavalca, Fivos Perakis, Jonas Sellberg, André Eilert, Kyung Hwan Kim, Giacomo Coslovich, Ryan Coffee, Jacek Krzywinski, Alex Reid, Stefan Moeller, Alberto Lutman, Henrik Öström, Lars G. M. Pettersson, Anders Nilsson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report on atom-specific activation of CO oxidation on Ru(0001) via resonant X-ray excitation. We show that resonant 1s core-level excitation of atomically adsorbed oxygen in the co-adsorbed phase of CO and oxygen directly drives CO oxidation. We separate this direct resonant channel from indirectly driven oxidation via X-ray induced substrate heating. Based on density functional theory calculations, we identify the valence-excited state created by the Auger decay as the driving electronic state for direct CO oxidation. We utilized the fresh-slice multi-pulse mode at the Linac Coherent Light Source that provided time-overlapped and 30 fs delayed pairs of soft …