May, Jeremy A.2019-12-17December 22019-12December 2Portions of this document appear in: Rastelli, Ettore J., Andrew A. Bolinger, and Don M. Coltart. "Stereodivergent Synthesis of β, γ-Fused Bicyclic γ-Lactones via a Multicomponent Ring-Expansion Cascade." Chem 4, no. 9 (2018): 2228-2238.https://hdl.handle.net/10657/56003-Alkoxy-1-N-aryl azopropene structural motifs in the Eschenmoser-Tanabe Fragmentation pathway have been known for almost 50 years, yet one unexploited feature of these intermediates is their putative 1,3-dipole. Described here is a transformation leveraging this reactivity to synthesize an important class of oxygen heterocycles, β,γ-fused bicyclic γ-lactones, by the simple combination of an ester or acyl pyrrole, an α-epoxy-2-nitrophenyl hydrazone, and a base. The products of this reaction, including those containing quaternary centers, are generated with high (up to >25:1) diastereoselectivity. Conveniently, both syn- and anti-fused bicyclic systems can be generated stereoselectively by simply changing the counter-ion of the base, LiHMDS and KHMDS, respectively. This dissertation also describes the development of a new functional group, 3-amino-1-azopropene, and its use in novel annulation strategies leading to N-heterocycles, which are important structures found in drugs and biologically active natural products. The 3-amino-1-azopropene functional group possesses multiple nucleophilic sites and, as such, is expected to inspire the development of a wide range of new synthetic methods and/or find applications in the development of new drugs and materials. Lastly, as part of the continuing effects to develop new reactions for the formation of saturated heterocycles, the conjugated π systems of azoalkenes in 3-hydroxy-azopropenes and 3-amino-1-azopropene were utilized in a [4+2] cyclization reaction in order to achieve ring closure. Compounds were prepared in high (up to >25:1) diastereoselectivity from a cascading Tsuji-Trost [4+2] cycloaddition, producing a wide array of fused tetrahydrofuran- and pyrrolidine- tetrahydropyridazine derivatives.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).Eschenmoser-Tanabe Fragmentation1,3-dipole1,3,6-tripoleOxygen heterocyclesNitrogen heterocycles3-amino-1-azopropene3-hydroxy-azopropenes2019-12-17Thesisborn digital