Michael, Forrest ETabor, John Raymond2020-10-262020-10-262020-10-262020Tabor_washington_0250E_22005.pdfhttp://hdl.handle.net/1773/46397Thesis (Ph.D.)--University of Washington, 2020The field of homogeneous catalysis is dominated by transition metals. There exists a vast array of methods available for the conversion of a huge variety of starting materials into an equally diverse collection of useful products through the use of the many transition metal elements as catalysts, and the state of the art of organic synthesis has benefited immensely from this research. However, this is not without disadvantages such as the cost, air/moisture sensitivity and toxicity of these transition metal reagents. The development of an alternative catalyst class that can achieve the same useful transformations that transition metals can, but without the disadvantages listed above, is highly desirable. This dissertation presents work aimed at that goal, with a focus on the development of a new class of organoselenium catalysts and the exploration of their ability to catalyze oxidative transformations of alkenes. Initial exploration established the relative reactivity of a variety of main group elements in an oxidative diacyloxylation reaction of alkenes. These main group elements can adopt hypervalent configurations, which give them attributes similar to transition metals that are key in enabling catalytic redox reactivity. This early work revealed that organoselenium reagents were uniquely effective in catalyzing oxidation reactions of alkenes, while other chalcogens (S, Te) and pnictogens (P, As, Sb, Bi) gave no desired reactivity. The growth of the field of organoselenium catalysis has been stunted due to the nearly universal dependence on diphenyl diselenide as a catalyst, which is not easily derivatized and whose derivatives are very restricted in functional diversity. With the aim of providing a better handle with which to tune reactivity, a new class of phosphine selenide catalysts was developed, encompassing much more steric and electronic diversity than has previously been allowed. These catalysts were used to develop a regioselective metal-free aza-Heck reaction of terminal alkenes with improved yields, regioselectivities and stereoselectivities. Deuterium labelling experiments and kinetic isotope effect studies enabled the proposal of a catalytic cycle, in which a key step is a syn-elimination through a selenium-fluorine bond to yield the products and regenerate the catalyst. Informed by these mechanistic studies, a selenophosphoramide-catalyzed 1,2-diamination and oxyamination of alkenes and esters/carbonates, respectively, was developed. This transformation was made possible by diversion from the typical syn-elimination pathway by introduction of a fluoride scavenger, allowing an atypical substitution to occur instead. Careful tuning of the catalyst revealed that selenophosphoramides were the optimum catalysts, giving the highest yields of the desired products. The transformation was successful for a wide array of terminal- and trans-1,2-disubstituted alkenes, giving the products in high yields with exclusive selectivity for trans-diamines and tolerating a variety of functional groups. Additionally, substrates bearing appropriate internal nucleophiles, such as esters and carbonates, were induced to undergo intramolecular substitution reactions, giving rearrangement and cyclization product in good yields.application/pdfen-USnoneAlkenesOxidative ChemistrySelenium CatalysisChemistryOrganic chemistryChemistryThesis