A review of metal-mediated epoxidation is given. Jacobsen's catalyst and the Sharpless asymmetric epoxidation catalyst are discussed. The origins of enantioselectivity are explained using stereochemical models. Several new salen-type ligands were synthesized based on biphenol and binaphthol. The synthesis of these ligands and their subsequent coordination to transition metals were described. The transition metal complexes were structurally characterized by X-ray diffraction of single crystals. The manganese (III) complexes were evaluated for catalytic activity in epoxidation reactions. Despite the fact that these many of these complexes were optically active, little asymmetric induction was observed in any of the epoxidation reactions. The investigation of a soluble nickel salen complex for the epoxidation of olefins led to the discovery of a new heterogeneous catalyst for the epoxidation of α,β- unsaturated carboxylic acids. Nickel salen complexes, upon reaction with commercial bleach, yield a fine black powder, which we identified as nickel oxide hydroxide-a known but poorly characterized nickel peroxide containing species. The reaction of an aqueous nickel (II) source with commercial bleach also yields nickel oxide hydroxide. This material was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Extremely broad peaks in the X-ray diffraction pattern suggested that this material consisted of particles with a very small diameter and this was confirmed by TEM. This insoluble material was found to function as a heterogeneous catalyst for the epoxidation of α,β-unsaturated carboxylic acids in the presence of sodium hypochlorite. The high activity of this catalyst in the epoxidation of certain olefins is due in part to its small particle size, which increases the overall surface area of this heterogeneous catalyst. Large particles of nickel oxide hydroxide were prepared and the catalytic activity was comparatively less. The oxidation of several other organic substrates was also explored using this catalyst. Both primary and secondary alcohols can be oxidized with our nickel-based system. Primary alcohols go through an aldehyde intermediate which is then in turn oxidized to the carboxylic acid.

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 214 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 199-208).

A review on catalytic asymmetric hydrogenation of C=O double bonds is presented in the first chapter. Noyori’s pioneering research on ruthenium complexes containing both phosphine and diamine ligands using [i superscript]PrOH and [t superscript]BuOK is described, this system gave impressive highly chemeo-selectivity for C=O bonds and extremely high enantioselectivity for a range of acetophenone derivatives. Numerous groups have been inspired by Noyori’s catalyst of the type RuCl₂(chiraldiphosphine)(chiraldiamine), these systems often give excellent results for acetophenone. However, these catalysts have limitations, they are found to be either inactive or unselective for hydrogenation of tetralones, dialkylketones, bulky ketones, some heterocyclic ketones and imines prove difficult using this system. In this project, we are searching for a new catalyst for asymmetric hydrogenation of ketones that solve the difficult challenges faced when using Noyori’s [Ru(diphosphine)(diamine)Cl₂] catalysts system. Departing from Noyori’s type catalyst in the second chapter is described our effort to synthesise new diamines derived from amino acids and the synthesis of [Ru(diamine)(diphosphine)Cl₂] complexes. These catalysts are tested in asymmetric hydrgenation of ketones. In the next two chapters the finding of a new tridentate P N NH₂ type ligand is reported and the novel ruthenium complex containing the tridentate ligand has been synthesised and characterised by X-ray crystallography and been found to be active in the hydrogenation of a range of C=O and C=N double bonds, including the enantioselective hydrogenation of normally unreactive bulky ketones with up to 93 % ee. The last chapter explains the transfer hydrogenation activity for this new catalyst, involving a novel method of transfer hydrogenation reaction under microwave irradiation.

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This thesis presents the hydrogenation of substituted pyridines using N,P-ligated iridium catalystsin homogeneous media. These iridium catalysts were developed within this research group in thepast decade. This method of hydrogenation is highly stereoselective, and in several cases good to excellent ees were obtained.The hydrogenation of substituted pyridines was studied: by screening for the catalyst giving thehighest conversion and ee, by optimising the reaction conditions and by attempting to improve existingcatalysts. New substrates were synthesised for this process, in particular alkyl substituted Nprotectedpyridines. Their reduction provided chiral piperidines, which could be used as chiralbuilding blocks once deprotected.

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Graduate / 0485