The central focus of this dissertation pertains to the synthesis and study of novel N-Heterocyclic carbene architectures. This pursuit has led to advances in carbine structure and bonding, and application of NHCs in materials chemistry in the role of monomer and catalyst / text

A unifying theme of the chemistry presented is the synthesis, study, and application of a novel N-heterocyclic carbenes. Pursuit of these materials has resulted in new advances in carbene structure and bonding, the discovery of highly-efficient reactions, and the development of new polymers with unusual properties. / text

Five tri- and tetra-substituted electron-poor olefins containing a β-leaving group, initiated cationic polymerization of p-methoxystyrene with widely varying results. As the electrophilicity of the electron-poor olefins increased, the yields and molecular weights of the polymers formed decreased. The same was true when the excellent leaving group, trifluoromethanesulfonate, was replaced by the poorer leaving group, chloride. Another series of tri-substituted olefins was prepared and reacted with p-methoxystyrene in the presence of excess methyl methacrylate or styrene. Terpolymer was formed as a major product when the electron-poor olefin used contained an α-ester group. The yield of the terpolymer increased with the increasing electrophilicity of the electron-poor olefin. The reactions of methyl α-cyanoacrylate with a number of electron-rich olefins were also studied and found to give new types of adducts, such as Diels-Alder adducts and pyrans. All these reactions were suggested to go through the formation of a tetramethylene intermediate, a resonance hybrid of a zwitterion and spin paired biradical.

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This thesis describes a new catalytic activity of a commonly used metathesis catalyst and demonstrates the viability of directly coupling two powerful C-C bond forming strategies: cross-metathesis and ylide transformations, both proceeding via metal-catalysed carbene transfer. Catalytic C-C bond formation reactions are highly significant; my studies focus on such transformations involving metallocarbenes. Grubbs' 2^nd generation Ru catalyst is the most commonly used catalyst in olefin metathesis to generate thermodynamically preferred trans-olefms. During the course of my studies, I established that Grubbs 2^nd generation catalyst (0.5 mol%) can also dimerise diazoacetates to give cis-enediesters (maleates) in good to excellent yields (74-99%) with high stereoselectivity (Z:E>95:5). The reaction between two different diazoacetates, catalysed by Grubbs catalyst gave access to unsymmetrical cis-enediesters with high stereoselectivity (Z:E>95:5, generally 99:1). The catalyst was found to retain its alkene metathetical activity during diazo coupling; building on this latter observation a novel route to access dienyl dilactones by head-to-head dimerisation of unsaturated diazoacetates was developed. Cross-metathesis was found to be chemoselective in the presence of diazo functionality (when flanked by two carbonyl groups), allowing the functionalisation of tethered olefin. The elaborated diazocarbonyl olefms were subjected to Rh₂(OAc)₄ catalysed ylide formation and subsequent transformations. Significantly, one-pot cross-metathesis/ylide transformations (1,3-dipolar cycloaddition and [2,3]-simgatropic rearrangement) also proved to be viable, establishing that the spent Ru catalyst following metathesis does not affect the subsequent Rh(II)-catalysed transformation.

Thesis (Ph.D.)--McMaster University (Canada), 1996. / Source: Dissertation Abstracts International, Volume: 58-06, Section: B, page: 3046. Adviser: J. Warkentin.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references (leaves 172-178). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.