Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 260-271). Also available via World Wide Web.

We report here the development of a Lewis acid catalyzed method for the dehydrative coupling of cyclic alcohols and nitriles to form amides with retention of configuration. By contrast, the formation of amides by nitrile trapping of carbocations (Ritter reaction) usually affords racemic product. The present reaction was accomplished by first converting alcohol starting materials to their corresponding chlorosulfites in situ. Even after an extensive search, only copper (II) salts were able to produce the desired conversion of these chlorosulfites to amides though with low catalytic turnover. Improving the turnover without deteriorating the stereochemical outcome was eventually accomplished by a careful selection of the reagent addition sequence and through the removal of gaseous byproducts. This Ritter-like coupling reaction proceeds in good yields with secondary cyclic alcohols under mild conditions. The stereochemical outcome likely due to fast nucleophilic capture of a non-planar carbocations (hyperconjomers) stabilized by ring hyperconjugation. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The study of catalysis is a fundamental aspect of chemical engineering, as its implications affect all chemical transformations. Traditionally, catalysis has been subdivided into two areas: homogeneous and heterogeneous catalysis. Homogeneous catalysis refers to single-sited catalysts that exist in the same phase as the reaction media. These catalysts tend to be highly active and selective but often difficult to recover and reuse. In contrast, heterogeneous catalysts are typically multi-sited catalysts that exist in a different phase from the reaction media. These catalysts tend to be less active and selective than their homogeneous counterparts. However, the vast majority of industrial scale catalysts are heterogeneous because they can be easily separated, making them easily implemented in continuous processes, allowing for efficient, large scale operations. Due to the limitations of traditional homogeneous and heterogeneous catalysts, researchers have increasingly investigated hybrid catalysts that incorporate aspects of homogeneous and heterogeneous catalysis. This is accomplished via immobilization of homogeneous catalyst analogues onto solid-phase supports, thereby preserving the activity and selectivity of homogeneous catalysts while allowing for facile recovery and reuse from the insoluble, heterogeneous support. A variety of systems is presented here including organic and organometallic catalysts immobilized on organic and inorganic supports. Five cases are included. The first discusses utilization of supported acid and base catalysts for use in one-pot cascade reactions. The second example illustrates use of silica-coated magnetic nanoparticle supported acid catalysts for organic transformations. The third case presents novel polymer brush supported Cobalt-salen catalysts for the enantioselective, hydrolytic kinetic resolution of epoxides. A fourth case presents novel, magnetic polymer brush supported organic and organometallic catalysts for organic transformations. The fifth example illustrates polymer and silica supported ruthenium-salen catalysts for the asymmetric cyclopropanation of olefins. The overall goal of this thesis work is to develop novel supports and immobilization techniques to advance the field of hybrid organic/inorganic catalysts for the production of fine chemical and pharmaceutical intermediates.

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: N. Werstiuk. Includes bibliographical references (leaves 148-156). Also available via World Wide Web.

We report here the development of very efficient sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), to accelerate the rate of nucleophilic substitution reactions involving poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. Indeed NALGs have shown exceptional ability in improving rate of nucleophilic substitution reactions. New very mild stereoretentive halogenations and azidation reactions have also been developed for secondary cyclic alcohols using NALGs involving titanium(IV) reagents. This reaction is particularly significant since the carbon-halogen bond is found widely in natural products and is used extensively as a synthesis intermediate. Azide is also a synthetically important functional group from which a variety of biologically important functional groups are conveniently obtained. Though stereoretentive chlorination and bromination reactions are known, we have developed, for the first time, a stereoretentive azidation reaction using titanium(IV) azide, a reagent not previously used in organic synthesis. During our development of stereoretentive reactions, we eventually developed very efficient, mild, two-step one-pot stereoretentive halogenations (chlorination and bromination) using titanium(IV) halides as catalysts or stoichiometric reagents. These reactions were found to be particularly efficient for cyclic alcohols. An efficient one pot stereoretentive amidation reaction for secondary cyclic alcohols is also reported. The important features of this reaction are that, for the first time, chlorosulfite (prepared in situ from alcohol using thionylchloride) has been used as a leaving group and titanium(IV) fluoride as an activator. / Utilization of those two reagents is unique as thionylchloride has never been used for nucleophilic substitution reactions except in chlorination procedures. In addition, this work has found new and creative applications for titanium (IV) fluoride, a reactant rarely used in organic synthesis. Further exploiting the unique reactivity of titanium(IV), reactions of alkenes with various nucleophiles have been developed with this reagent in both catalytic and stoichiometric quantities. It was observed that a-substituted aromatic conjugated alkenes dimerize to generate important indan class of compounds which are very important in the polymer industry. In addition, non conjugated unactivated alkenes react with various nucleophiles to yield the adduct. / by Deboprosad Mondal. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

We report here the development of very efficient aryl- and quinolinyl- sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), which substantially accelerate the rate of nucleophilic substitution reactions with metal halides. Detailed synthesis and kinetics study are described herein. Our synthesized NALGs have shown great reactivity towards poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. The abundant existence of halide, azide and amine in natural products demands new synthetic pathway. To fulfill this requirement, new mild stereoretentive halogenations (chlorination, bromination and iodination) reactions have also been developed for secondary cyclic alcohols using NALGs involving titanium (IV) reagents. The novel methodology can be extended to Azidation reactions as well with titanium (IV) azide, in which Ti (N3)4 is the first time being engaged in organic synthesis. Beased on the NALGs theory we discover the chlorosulfite can be a simplest NALG and applied as the intermediate in mild one-pot stereoretentive halogenations (chlorination and bromination) using titanium (IV) halides as catalysts or stoichiometric reagents. These reactions were found to be particularly efficient for cyclic alcohols. Finally, an efficient mild bromination and iodination reaction for primary and secondary alcohols with Grignard reagents is also reported. This reaction exhibits the generality with substrates with various leaving groups. The important features of this reaction are that, for the first time, bromide formation using Grignard reagents without the Cu (I) catalysts. / by Songye Li. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 149-161). Also available via World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 161-184).