Bed bugs were once considered eliminated from the United States, so recent resurgence of this pest has been cause for concern. Presence of these troublesome insects has resulted in the proposal of controversial policies. For example, the state of Ohio petitioned the EPA for a FIFRA Section 18 emergency exemption to use the insecticide propoxur, a neurotoxin, to treat bed bug infestations in the state. In this thesis, I analyzed public comments for the exemption, task force reports, and media to examine how health and the urban indoor environment are framed in this decision-making process. Though bed bugs carry stigma, those who have them are not overtly blamed for the pest. However, an inability to eliminate them effectively is situated as a lack of personal responsibility. A political ecology of health analysis and healthism are used to understand how narratives of health and personal responsibility justify use of this pesticide.

My graduate work focused on the syntheses and pharmacology of species-selective aryl methylcarbamate acetylcholinesterase inhibitors to combat the malaria-transmitting mosquito, Anopheles gambiae. We identified six novel carbamates that demonstrated levels of target selectivity exceeding our project milestone of 100-fold. Among the C2-substituted phenylcarbamates examined (class II), 2'-(2- ethylbutoxy)phenyl N-methylcarbamate (9bd*) was extraordinarily selective (570-fold ± 72). The high level of selectivity observed for many of the class II carbamates was attributed to a helical displacement within the active site of An. gambiae acetylcholinesterase, able to accommodate carbamates with larger C2-substituted secondary β-branching side chains. Conversely, this type of side chain forms unfavorable interactions within the active site of human acetylcholinesterase. The C3-substituted carbamates (class I), such as terbam (9c), were less selective than many of the class II carbamates; however, class I carbamates related to terbam (9c) were highly toxic to An. gambiae. In particular, the contact toxicity measured for 9c (LC₅₀ = 0.037 mg/mL) was equal to the commonly used agricultural insecticide, propoxur (9a, LC₅₀ = 0.037 mg/mL). In total, seventy aryl carbamates were screened for their inhibition potency and contact toxicity towards An. gambiae. The common final step in all of these syntheses was the carbamoylation of a phenol, which normally proceeded in a 70 to 90% yield. Thirty seven novel carbamates are reported out of the seventy two prepared. Although sixteen of the phenols were commercially available, the others were prepared with known and adapted synthetic methodologies. The emerging structure-activity relationships led us to focus on the synthesis of 3-tert-alkylphenols (Class I) and 2-alkoxy or 2-alkylthio-substituted phenols (Class II). Three methods particularly stand out: First, we applied the methods of Tanaka to prepare 3-tert-alkylphenols wherein a methyl group was replaced by a trifluoromethyl group. Second, we adapted the methods of Tanaka to prepare 3-tert-alkylphenols that lack fluorine substitution. This method is competitive with the little known method of Reetz to convert aryl ketones to the corresponding 1,1-dimethylalkyl group and allows one to access electron rich tert-alkyl-substituted aromatics that are not accessible by the Friedel-Crafts alkylation (Friedel-Crafts restricted). Third, we found a convenient and high-yielding method for selective S-alkylation of 2-mercaptophenol. In addition to the synthesis of carbamates, the preparation of one hundred three intermediates, phenols, and electron rich tert-alkyl arenes are reported. / Ph. D.

Malaria is one of the deadliest diseases known to mankind. In 2010, 219 million cases were reported, and 666,000 deaths were attributed to this disease. In the past, pyrethroid-treated mosquito nets have shown efficacy in reducing malaria transmission in many malaria endemic regions. However, an upsurge in the mosquito population that is resistant to pyrethroids threatens to compromise the efficacy of pyrethroid-treated bed nets. In an effort to develop another class of insecticide with a different mode of action, we have explored three classes of five membered heterocyclic carbamates (isoxazol-3-yl, pyrazol-5-yl, and pyrazol-4-yl), and 3-oxoisoxazole- 2(3H)-carboxamide as acetylcholinesterase inhibitors (AChE) targeting wild type (G3) and resistant (Akron) malaria mosquito Anopheles gambiae (Ag). Isoxazole carboxamide and carbamates were obtained regioselectively through judicious use of two different protocols. The final products were characterized and identified using ¹H and ¹³C NMR, and mass spectroscopy. In addition, the carboxamide structure was confirmed using X-ray diffraction. Several of the novel carbamates and carboxamides evaluated exhibited excellent toxicity towards susceptible G3 and resistant Akron strain An. gambiae (48f LC₅₀ G3 = 41 μg/mL, LC₅₀ Akron = 58 μg/mL, and 47i LC₅₀ G3 = 38 μg/mL, LC₅₀ Akron = 40 μg/mL). Hence, achieving the resistance- breaking goal. On the contrary, the commercial aryl methylcarbamates currently approved for indoor residual sprays (IRS) showed no potency towards the resistant strain An. gambiae (LC₅₀ G3 = 16-42 μg/mL, and LC₅₀ Akron >5,000 μg/mL). Further, we observed low toxicological cross-resistance ratios (RR) for the toxic isoxazol-3-yl and pyrazol-4-yl carbamates, and 3- oxoisoxazole-2(3H)-carboxamides (RR = 0.5-2.0). Amongst the commercial AChE inhibitors approved for IRS, only aldicarb exhibited such low RR (RR = 0.5), whereas the RR for commercial aryl methylcarbamates exceed 130-fold. The low RR observed for these novel heterocyclic inhibitors would certainly be favorable for a new anticholinesterase-based mosquitocide targeting both the susceptible and resistant strain mosquitoes. Although the overall selectivity (Ag vs human) did not exceed 24-fold, the heterocyclic carbamates and carboxamides synthesized by the author showed appreciable inhibition of resistant AChE (G119S) in comparison to commercial aryl carbamates, which showed no inhibition at all. During the course of this project, the isoxazol-3-yl and pyrazol-5-yl methylcarbamates proved to be unstable, and thus could not be isolated. The synthesis of pyrazol-4-yl methylcarbamates using N-methylcarbamoyl chloride proved particularly challenging due to the formation of by-products called allophanates. The similar Rf of the by-product and the desired final product made the isolation laborious and time-consuming. We have successfully overcome this problem by employing a new protocol, where triphosgene served as the carbonylating agent and N-methylamine in THF was used as the amine source. In addition, we have also developed another one-pot protocol for a safer synthesis of pyrazol-4-yl methylcarbamates utilizing 1,1- carbonyldiimidazole (CDI), and N-methylamine hydrogen chloride salt. With the pyrazol-4-yl core, apart from achieving excellent toxicity towards both strains of An. gambiae, we have also achieved excellent AgAChE vs hAChE selectivity (Ag vs h >100-fold). Due to our continued interest in developing this core, we have devised a convenient, scalable, no-column approach for the synthesis an intermediate 103 that can be utilized to synthesize these compounds more efficiently. / Ph. D.

Malaria continues to cause significant mortality in sub-Saharan Africa and elsewhere, and existing vector control measures are being threatened by growing resistance to pyrethroid insecticides. With the goal of developing new human-safe, resistance-breaking insecticides we have explored several classes of acetylcholinesterase inhibitors. In vitro assay studies demonstrate that tri- and difluoromethyl ketones can potentially inhibit An. gambiae AChE (AgAChE). These compounds inhibit the enzyme by making a covalent adduct with the catalytic serine of AChE. Trifluoromethyl ketones however are poor inhibitors of the G119S resistant mutant of AgAChE. However difluoromethyl ketones can inhibit G119S AgAChE and compound 3-10g showed an IC₅₀ value of 25.1 nM after 23h incubation time. Despite this potent inhibition of AgAChE, the tri-, di-, and (mono)fluoroketones showed very low toxicity to An. gambiae, perhaps due to hydration and rapid clearance. In an attempt to improve An. gambiae toxicity, oximes and oxime ethers of these compounds were prepared as potential prodrugs. These structures identified trifluoromethyl ketone oxime 3-2d as a potent toxin against both wild-type (G3-strain) and a multiply resistant (Akron) strain of An. gambiae. This compound is within 3-fold of the toxicity of propoxur to wild type An. gambiae (LC₅₀ values of 106 and 39 µg/mL, respectively). Most significantly, 3-2d was much more toxic than propoxur to multiply-resistant (Akron) strain An. gambiae (LC₅₀ = 112 and >5,000 µg/mL, respectively). However, thus far we have not been able to link the toxicity of these compounds to a cholinergic mechanism. Pre-incubation studies suggest that significant hydrolysis of these compounds to TFKs does not occur over 22 h at pH 7.7 or 5.5. The mechanism of action of 3-2d remains unknown. Our enzyme inhibition studies have demonstrated that 3-2d does not hydrolyze to the trifluoromethyl ketone 2-9d at pH 7.7. The high Akron toxicity of 3-2d and poor inhibition of G119S AgAChE by 2-9d argue against enzyme mediated conversion of 3-2d to 2-9d within the mosquito. Thus, we can rule out an AChE inhibition mechanism for toxicity. Additional experiments by our collaborator (Dr. Jeffrey Bloomquist, University of Florida) also rule out inhibition of mitochondrial respiration or agonism of the muscarinic acetylcholine receptor. Future work will address other potential insecticidal modes of action. / Ph. D.