Organic Chemistry Commons^™

The Enzymatic Activity And Inhibition Of Dape Encoded N-Succinyl-L,L-Diaminopimelic Acid Dessucinylase, Tahirah Heath

Dissertations

The bacterial enzyme DapE is a hydrolase in the late stage of the mDAP/lysine biosynthetic pathway that catalyzes the hydrolysis of N-succinyl-L,L-diaminopimelic acid (L,L-SDAP) to succinic acid and L,L-diaminopimelate (DAP). The product DAP is ultimately converted to m-DAP and then to lysine which is used in the construction of proteins, whereas for humans, lysine is an essential amino acid obtained through diet. DapE has been shown to be conserved across many strains of bacteria. The m-DAP produced through the succinylase pathway is used by both gram negative and gram-positive bacteria in the construction of the essential peptidoglycan cell wall. Because …

Mechanistic Investigations Of The Iron(Iii)-Catalyzed Carbonyl-Olefin Metathesis Reaction, Susan Phan

Master's Theses

Iron(III)-catalyzed carbonyl-olefin ring-closing metathesis represents a new approach toward the assembly of molecules traditionally generated by olefinˆ’olefin metathesis or olefination. Herein, we report detailed synthetic, spectroscopic, kinetic, and computational studies to determine the mechanistic features imparted by iron(III), substrate, and temperature to the catalytic cycle. These data are consistent with an iron(III)-mediated asynchronous, concerted [2+2]-cycloaddition to form an intermediate oxetane as the turnover-limiting step. Fragmentation of the oxetane via Lewis acid-activation results in the formation of five- and six-membered unsaturated carbocycles.

Cellulose Modification For Use As Reinforcement In Bio-Based Composites, Ashley L. Rudolph

College of Graduate Studies: Theses & Dissertations

The goal of the research contained in this thesis is to provide an alternative method of developing polymers than the current petroleum-based polymeric products. Vegetable oil-based polymers are a popular alternative due to their low-cost and low toxicity. The carbon-carbon double bonds in the oil are ideal reactive sites for a free radical polymerization. Cellulose is a naturally occurring polymer. Modifying cellulose prior to making composites with tung oil allows a hydrophilic material to mix better with a hydrophobic resin. Vegetable oil-based polymers usually require the reinforcement of fibers to enhance the thermo-mechanical properties that would replace petroleum-based polymers. In …

Direct Measurement Of Rupture Force Of Single Triazole Molecule By Atomic Force Microscope And Solid Phase Synthesis Of Monodisperse Polyethylene Glycols, Ashok Khanal

Dissertations, Master's Theses and Master's Reports

This dissertation includes two topics, which are related to each other: (1) Rupture force measurement of single triazole molecule by atomic force microscope (AFM) and (2) Solid phase stepwise synthesis of polyethylene glycols (PEGs).

The reaction of an alkyne and an azide to form a 1,2,3- triazole has found wide applications. However, the stability of triazole under mechanical stress is unclear. We investigated the cycloreversion at the single molecular level using atomic force microscopy. A mica surface functionalized with a molecule containing a 1,2,3-triazole moiety in the middle and an activated ester at the end was prepared. An AFM tip …

Chalcone And Cinnamate Synthesis Via One-Pot Enol Silane Formation-Mukaiyama Aldol Reactions Of Ketones And Acetate Esters, C. Wade Downey, Hadleigh M. Glist, Anna Takashima, Samuel R. Bottum, Grant J. Dixon

Chemistry Faculty Publications

Aryl alkyl ketones, acetate esters, and acetamides undergo facile one-pot enol silane formation, Mukaiyama aldol addition, and dehydrosilyloxylation in the presence of an amine base and excess trimethylsilyl trifluoromethanesulfonate. The chalcone and cinnamate products are generally recovered in high yield. The relative stoichiometry of the trimethylsilyl trifluoromethanesulfonate and amine base reagents determines whether the reaction yields the β- silyloxy carbonyl product or the α, β -unsaturated carbonyl.

One-Pot Enol Silane Formation-Alkylation Of Ketones With Propargyl Carboxylates Promoted By Trimethylsilyl Trifluoromethanesulfonate, C. Wade Downey, Danielle N. Confair, Yiqi Liu, Elizabeth D. Heafner

Chemistry Faculty Publications

Ketones readily undergo conversion to enol silanes in the presence of trialkylamine base and trimethylsilyl trifluoromethanesulfonate (TMSOTf) and add to propargyl cations to yield b-alkynyl ketones. The propargyl cations are generated in the same reaction flask through the TMSOTf-promoted ionization of propargyl acetates or propargyl propionates. A range of enol silane precursors and propargyl carboxylates reacts efficiently (20 examples, up to 99% yield). Cyclization of a representative product in the presence of TMSOTf provided 61% yield of the trisubstituted furan.

Identification Of 4-Isopropyl–Thiotropolone As A Novel Anti-Microbial: Regioselective Synthesis, Nmr Characterization, And Biological Evaluation, Mohamed Elagawany, Mohamed Elagawany, Lamees Hegazy, Feng Cao, Maureen Donlin, Nigam Rath, John Tavis, Bahaa Elgendy, Bahaa Elgendy

Chemistry & Biochemistry Faculty Works

We have synthesized and separated tosylated thujaplicin isomers for the first time, and elucidated their structures using 1D, 2D-NMR techniques and X-ray crystallography. The tosylated isomers were used to synthesize 4-isopropyl–thiotropolone and 6-isopropyl–thiotropolone in a regioselective manner. 1H and 13C Chemical shifts of synthesized isomers were fully assigned using several NMR experiments, and their isotropic magnetic shielding was calculated using the GIAO (Gauge Including Atomic Orbitals) method and the B3LYP def2-TZVPP level of theory. The calculated chemical shift values were in a good agreement with the experimental results. The biological activity of all synthesized compounds was evaluated against the fungal …

Part I: Design, Synthesis, And Studies Of Novel Age-Inhibitors And Age-Breakers; Part Ii: Novel Synthetic Methods For Organofluorine Compound, Jatin Mehta

Doctoral Dissertations

"Novel small molecule inhibitors and breakers of advanced glycation end-products (AGEs) have been synthesized and their in vitro inhibitory activities have been studied by ¹³C NMR, fluorescence, and UV-visible spectroscopy. We have demonstrated that these AGE-inhibitors and AGE-breakers were found to be more effective in their sequestration of AGE intermediates, such as dehydroascorbate (DHA) than the state-of-the art phenacylthiazolium bromide (PTB)-based AGE-inhibitors and AGE-breakers. Citric acid and other polyphenolic antioxidants have substantial AGE inhibitory effects in the D-glucose/leucine or benzylamine Maillard reaction model systems, and thus they are suitable as dietary additives for ameliorating AGE-induced complications.

Organofluorine compounds have …

An Interdisciplinary Approach To The Target Elucidation Of Novel Antibiotic 31g12, Larissa A. Walker

Graduate Student Theses, Dissertations, & Professional Papers

Staphylococcus aureus is a Gram-positive bacterial pathogen responsible for nosocomial and community-acquired infections that can quickly acquire antibiotic resistance. We have identified a novel triazole antimicrobial 31G12 based on the natural product core of nonactin isolated from the fermentation of Streptomyces griseus, that is active against many Gram-positive bacteria as well as antibiotic resistant methicillin-resistant S. aureus and vancomycin-resistant Enterococcus. The synthesis and characterization indicate that 31G12 exists as a mixture of two rotamers at room temperature and displays bacteriostatic activity against S. aureus with moderate mammalian cell toxicity. We have currently identified potential protein targets of 31G12 in …

The Effect Of Oxidation, Thionation, And Dimerization On The Self-Assembly And Photophysical Properties Of Novel Discotic Materials, Katie M. Psutka

Theses and Dissertations (Comprehensive)

This thesis aims to increase understanding of the relationship between molecular structure and liquid crystalline temperature range by exploring the effects of oxidation, thionation, and dimerization on the self-assembly and properties of novel discotic materials. First, two alkoxy-substituted dibenzanthracenequinones were prepared by oxidation of the corresponding dibenzanthracenes. The quinone induced a liquid crystalline phase in the hexaalkoxy dibenzanthracene derivative, but not in the tetralkoxy derivative. However, both of the resulting materials were un-reactive to any further synthetic modifications that could be used to improve their properties. In comparison, two heteroaromatic dithienoanthracenedicarboximides were successfully prepared, although the addition of the thiophene …

Synthesis, Properties, And Solid-State Structures Of A Series Of 6,13-Dicyanoheteropentacene Analogues: Towards New Liquid Crystalline Materials, L Hiscock, Kenneth E. Maly, Louise N. Dawe

Theses and Dissertations (Comprehensive)

The focus of this thesis is the synthesis of novel heterocyclic pentacene analogs and the investigation of their self-organization for the development of new materials for organic electronics. The thesis consists of two interrelated projects: the first being development of an improved synthesis of a series of liquid crystalline dicyanotetraoxapentacenes (DCTOPs) while the second entails the exploratory synthesis of several novel dicyanoheteropentacene analogues and a preliminary investigation of their photophysical properties and solid-state structures. Both of these projects centre around the use of nucleophilic aromatic substitution reactions on tetrafluoroterephthalonitrile.

Soluble, tetrakis(bis(alkoxy)phenyl)-substituted DCTOPs were originally synthesised via a short synthesis complicated …

Synthesis And Catalytic Testing Of A Proline Functionalized Amphiphilic Block Copolymer, Eric Firestone

Master's Theses and Doctoral Dissertations

Catalysts are reagents used to reduce the amount of energy that a reaction needs to execute, allowing it to proceed at a higher rate while not being consumed. The use of catalyst functionalized amphiphilic copolymer allows easier recovery of the catalyst at the end of the synthesis and allows for the reaction. In water, under appropriate conditions, the amphiphilic block copolymers will form micelles and allow the reaction to occur on the interior of the micelle. The synthesis of amphiphilic copolymer with a hydrophobic O-methacryloyl-trans-4- hydroxy-L-proline and methyl methacrylate end and a hydrophilic acrylic acid end was characterized. The polymer …

The Role Of Catalytic Residue PKA On The Hydrolysis/Transglycosylation Partition In Family 3 Β-Glucosidases, Inacrist Geronimo, Christina M. Payne, Mats Sandgren

Chemical and Materials Engineering Faculty Publications

β-Glucosidases (βgls) primarily catalyze the hydrolysis of the terminal glycosidic bond at the non-reducing end of β-glucosides, although glycosidic bond synthesis (called transglycosylation) can also occur in the presence of another acceptor. In the final reaction step, the glucose product or another substrate competes with water for transfer to the glycosyl-enzyme intermediate. The factors governing the balance between the two pathways are not fully known; however, the involvement of ionizable residues in binding and catalysis suggests that their pK_a may play a role. Through constant pH molecular dynamics simulations of a glycoside hydrolase Family 3 (GH3) βgl, we …

Layer-By-Layer Assembled Membranes With Immobilized Porins, Sebastián Hernández, Cassandra Porter, Xinyi Zhang, Yinan Wei, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

New and advanced opportunities are arising for the synthesis and functionalization of membranes with selective separation, reactivity, and stimuli-responsive behavior. One such advancement is the integration of bio-based channels in membrane technologies. By a layer-by-layer (LbL) assembly of polyelectrolytes, outer membrane protein F trimers (OmpF) or “porins” from Escherichia coli with central pores ∼2 nm in diameter at their opening and ∼0.7 × 1.1 nm at their constricted region are immobilized within the pores of poly(vinylidene fluoride) microfiltration membranes, in contrast to traditional ruptured lipid bilayer or vesicle processes. These OmpF-membranes demonstrate selective rejection of non-charged organics over ionic solutes, …

Synthesis Of A Model Of The Bc Ring System Of Oxygenated Angucyclines, Xiaolan Wu, Abdullah Allaoa, Tony E. Nicolas

Publications and Research

Angucycline is a subclass of natural antibiotics, containing a characteristic tetracyclic ring structure, and featuring a wide range of biological functions, including antitumor, antiviral and antifungal properties. This extraordinarily therapeutic character has interested many chemists to develop efficient methodologies for synthesizing the tetracyclic ring system of angucycline. Construction of the BC ring configuration appears as a synthetic challenge. Successful installation of hydroxyl groups at the AB junction would pave the way for efficient syntheses. As a continuation of the previous work done on this system, our synthetic methodology focuses on the coupling of a suitably substituted Phthalide and an activated …

Developing Functionalized Peroxide Precursors For The Synthesis Of Cyclic And Spirocyclic Ethers, Anna J. Diepenbrock

Department of Chemistry: Dissertations, Theses, and Student Research

There is increasing interest in the development of methods for the synthesis of oxetanes and spirocyclic oxetanes, a class of molecules of interest to chemists as they synthesize libraries of possible drug target scaffolds with tunable physiochemical and biological properties.^1,2 Although most ethers are prepared through reaction of nucleophilic oxygen with electrophilic carbon, this work explores new reagents and routes for the synthesis of spirocyclic oxetanes based upon an application of "umpolung" or polarity reversal involving attack of nucleophilic carbon on the electrophilic oxygen of a peroxide (Scheme 1). In this work, a 2-carbon peroxide synthon for reverse etherification …

Development Of An Improved Synthesis Of S-D-Ribosyl-L-Homocysteine (Srh) And Progress Toward Srh Analogs Modified At The C3 Position, Emily Rouse

Master's Theses

Quorum sensing is a system that facilitates bacteria turning on and off gene expression depending on population density. System 2 quorum sensing is utilized by both Gram positive and Gram negative bacteria, and the quorum sensing molecule used in this system is AI-2. AI-2 is biosynthesized by the enzyme LuxS from the precursor SRH. This thesis describes an improved synthesis of SRH through the exploration of different protecting group strategies. The knowledge gained from the improved synthesis of SRH is then applied toward the synthesis of SRH analogues with increased steric bulk installed through use of a stereoselective anti-Mannich reaction. …

Tunable Copper Complexes For Sustainable Photocatalysis, David Kline

Posters-at-the-Capitol

Photoredox catalysis has direct applications in sustainable chemistry and thus an immense impact on our environment. With the ability to harness energy directly from the sun to catalyze useful chemical reactions, photocatalysts can help to eliminate the need for harsh reaction conditions and reduce generation of hazardous chemical waste. Photocatalysts based on Earth-abundant metals such as copper have recently emerged as sustainable alternatives to rare-earth metals including iridium and ruthenium, which are no longer required for many photocatalyzed chemical transformations.

No Evidence For Trace Metal Limitation On Anaerobic Carbon Mineralization In Three Peatland Soils, Jason K. Keller, Jillian Wade

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Peatlands store roughly one-third of the terrestrial soil carbon and release the potent greenhouse gas methane (CH₄) to the atmosphere, making these wetlands among the most important ecosystems in the global carbon cycle. Despite their importance, the controls of anaerobic decomposition of organic matter to carbon dioxide (CO₂) and CH₄ within peatlands are not well understood. It is known, however, that the enzymes responsible for CH₄ production require cobalt, iron and nickel, and there is a growing appreciation for the potential role of trace metal limitation in anaerobic decomposition. To explore the possibility of …

Design And Synthesis Of Cpg-Lytic Peptide Conjugate, Brachytherapy Beads And A Combinatorial Library Of Primary Amines Used As Potential Therapeutics In The Treatment Of Cancers, Josanne-Dee Woodroffe

USF Tampa Graduate Theses and Dissertations

Cancer remains one of the most feared diseases affecting the modern world. Second to heart disease, it is the largest cause of deaths, affecting one in three persons. Cancer cells are formed when normal, healthy cells become damage, losing their normal regulatory mechanism that control cell growth. There are many different types and progression of these cancer cells that determine the type of treatment a patient receives. The primary focus of this dissertation is to propose three studies of anticancer agents. In Chapter one, a CpG-lytic peptide conjugate was designed to target receptors on the cell membrane to concentrate the …