Chemistry Commons^™

Expansion Of The Diazacyclobutene Motif For Antiparasitic Evaluation, Brock Alexander Miller

All Dissertations

Molecules containing N-heterocycles are prevalent in pharmaceutical settings. The ability to generate highly functionalized molecules containing N-heterocycles in very few synthetic operations is valuable for drug discovery. Our group has developed a two-step synthesis to access a rarely studied diazacyclobutene scaffold via a formal [2+2] cycloaddition between 4-phenyl-1,2,4-triazolinedione and electron-rich thioalkynes. Our interest in this scaffold increased exponentially from promising preliminary biological evaluations against a protozoan parasite, Trypanosoma brucei. While we were able to double the number of historical examples of this scaffold, there were significant limitations in our methodology. The most notable limitations were the lack …

Synthesis Of Functionalized Tetrahydropyridine Derivatives Via Sncl4-Promoted [4+2] Cycloaddition Of Donor-Acceptor Cyclobutanes And Nitriles, David Tong

Electronic Thesis and Dissertation Repository

The formation of carbon-heteroatom bonds is pivotal in obtaining structural frameworks present in a variety of important natural products and bioactive molecules. In that regard, Lewis-acid promoted cycloadditions of strained carbocycles have proven to be powerful tools for the construction of heterocyclic frameworks. The Pagenkopf group was the first to discover the cycloaddition of donor-acceptor (DA) cyclopropanes with nitriles. Since the strain energy of cyclobutane is comparable to that of cyclopropane, our group has sought to extend to the comparatively unexplored homologous cyclobutane scaffold. Disclosed here is the first [4+2] cycloaddition of nitriles with DA cyclobutanes via Lewis-acid activation. This …

From The Making To The Tuning To The Use Of Chlorins For Biomedical Applications, Junior Gonzales

Dissertations, Theses, and Capstone Projects

Chlorins are porphyrins missing a double bond. These pigments are optimal platforms for the development of novel dyes that display drug-like attributes such as photodynamic therapy (PDT) agents. More recently, it was demonstrated that chlorins can serve both as a PDT agent and as a modality for fluorescence or PET imaging. Thus, multifunctional chlorins eliminate the differences that may occur in specificity, uptake, and distribution between separate compounds or constructs for imaging and therapy. The overall goal of this dissertation is to take advantage of the reputed intrinsic attributes of chlorins as a viable tool in biomedical applications. In this …

New Chemistry Of Donor-Acceptor Cycloalkanes And Studies Towards The Synthesis Of Streptorubin B, Naresh Vemula

Electronic Thesis and Dissertation Repository

This dissertation presents two separate chapters within the broad area of synthetic organic chemistry. The first chapter describes the annelation chemistry of donor-acceptor (DA) cyclopropanes and cyclobutanes for the synthesis of heterocycles. The Yb(OTf)₃-catalyzed [4+2] cycloaddition between DA cyclobutanes and nitrosoarenes facilitated the synthesis of tetrahydro-1,2-oxazines in good to excellent yields as single diastereomers. Additionally, an unexpected deoxygenation occurred with electron-rich nitrosoarenes under MgI₂-catalysis that afforded pyrrolidine products. The GaCl₃-catalyzed [4+2] cycloaddition of DA cyclobutanes and cis-diazenes provided hexahydropyridazine derivatives in good to excellent yields as single diastereomers. Furthermore, a procedure to make …

[3+2] Annulation Of Cyclopropylanilines With Alkynes Under Photocatalysis, Theresa Ha Nguyen

Graduate Theses and Dissertations

Over the past decade, pharmaceutical industries have prioritized their focus on discovering new innovative drugs, yet the syntheses are often either inefficient or the approach of environmental sustainability presents a great deal of concern. Moreover, the methodology developments for amine syntheses have continued to flourish due to their important role and wide use in pharmaceutics. Yet their syntheses often lack sustainability and efficiency. Synthetic chemists have continued to explore potential innovative avenues for conducting chemical reactions more effectively and efficiently. One of the most abundant, renewable natural resources is solar energy and to harvest, use, and store it directly is …

Synthesis And Electrochemiluminescence Of Thiophene Substituted Benzosiloles, Tyler J. B. Day

Electronic Thesis and Dissertation Repository

There has been increasing interest in the synthesis of siloles over the past 20 years due to their applications as chemoselective sensors and light emitting diodes. The standard synthesis of siloles involves a one-pot reductive cyclization followed by Negishi cross-coupling, which was modified by the Pagenkopf group to allow the synthesis of dissymmetric siloles. This modified synthesis allows siloles to be tuned to improve their fluorescent properties via varying substituents on the silole. This culminated in the synthesis of a series of 2,5-bis(thiophene)siloles with bulky silyl substituents that displayed excellent electrochemiluminescent properties.

In the past decade there has been a …

Cycloaddition Chemistry For The Synthesis Of Heterocyclic Compounds And Progress Towards The Total Synthesis Of Grandilodine A, Andrew C. Stevens

Electronic Thesis and Dissertation Repository

This thesis describes three separate research projects within the broad topic of synthetic organic chemistry. The synthesis of alkyl-substituted siloles and their reactivity in Diels-Alder chemistry is reported. Furthermore, the cleavage of the bicyclic adducts by Tamao-Fleming oxidation has been achieved which reveals a highly substituted cyclohexene-1,4-diol structure.

The second chapter describes the cycloaddition chemistry of alkoxy-activated cyclobutane dicarboxylates with aldehydes, nitrones and nitrosoarenes. The cycloaddition occurs, in the case of aldehydes, with uniformly high diastereoselectivity to afford tetrahydropyrans in good to excellent yield. When nitrones were used as the dipolarophile the cycloaddition occurs in a rather unselective manner though …

Design And Syntheses Of Fluorescent Cytosine Analogues, David W. Dodd

Electronic Thesis and Dissertation Repository

The avid hybridization of peptide nucleic acid (PNA) to DNA and RNA along with the molecule’s biological stability has led it to be used in both antisense and antigene capacities. PNA acts against translation via a steric blockade mechanism. It is therefore reasonable to assume that increased heteroduplex stability could lead to increased potency. Two ways of doing this were explored. I) N-Terminal attachment of a platinous chloride chelating moiety to PNA complementary to Xenopus noggin was synthesized with the objective of selective, covalent platination of the target transcript in vivo. Phenotypes consistent with knockdown of the selected …

New Synthetic Methodologies Directed Toward Pharmacologically Active Compounds As Well As Silole Based Chromophores For Analytical And Optoelectronic Applications, Mahmoud M. Abd Rabo Moustafa

Electronic Thesis and Dissertation Repository

The development of new and efficient synthetic methodologies to prepare heterocyclic compounds has received great attention over the years due to their importance in the pharmaceuticals and fine chemicals industries. Described herein are several novel syntheses of a variety of heterocycles including siloles, azaindoles, piperideines, piperidines and tetrahydropyrans.

A one-pot, two-step methodology involving Tamao’s reductive cyclization followed by Negishi cross coupling was utilized to synthesize several new series of silole-based chromophores. The property studies revealed new electropolymerized poly(thienyl-silole)s with enhanced photoefficiency for all-polymer solar cells. In addition, a new procedure is developed for the synthesis of the first dissymmetric silole …

Synthesis Towards Fulminic Acid And Its Derivatives In 1, 3-Dipolar Cycloaddition Reactions., Ophilia Ndi Toh

Electronic Theses and Dissertations

A new approach to fulminic acid cycloadditions has been developed. At reduced temperatures, fulminic acid is generated in situ and undergoes 1, 3-diploar cycloaddition reactions with dipolarophiles to form isoxazolines and/or its dimers. This procedure represents a novel, safe general method for the one-step generation of fulminic acid, which complements existing potentially explosive protocols.