The topic of this thesis is the catalytic and stoichiometric decarbonylation of aldehydes. A carbonylation reaction, the reaction of RuTPP(n-Bu₃P)₂ with CO gas was also studied. A catalytic decarbonylation system, using RuTPP(PPh₃)₂ as catalyst plus added excess tri-n-butylphosphine in acetonitrile-dichloromethane, was employed to decarbonylate several organic aldehydes. This system proved to be an effective decarbonylation agent, which also exhibited some selectivity. Some mechanistic studies were carried out in an attempt to elucidate the details of the reaction mechanism. From these and other findings in this laboratory, a tentative mechanism was proposed for the decarbonylation reaction. A radical mechanism, involving Ru(III) intermediates was favoured on the basis of e.s.r. data, spectral evidence and cyclic voltammetry studies. However, no intermediates were isolated. The full details of the mechanism, such as the precise nature of the postulated intermediates, have not been fully determined, although there are indications that solvated species, like RuTPP(CO)(CH₃CN), may be important. The stoichiometric reaction between RuTPP(n-Bu₃P)₂ and phenylacetaldehyde was also studied. The kinetic analysis indicated that the reaction, equation i, RuTPP(n-Bu₃P)₂ + C₆H₅CH₂CH0 --> RuTPP(CO)(n-Bu₃P) + n-Bu₃P + C₆H₅CH₃ equation i followed a pseudo-first-order rate law in the absence of excess phosphine, however, the actual k obsd values were found to be irreproducible. Some features of this reaction, such as the failure of the reaction to go to completion, and also the effect of trace oxygen on the reaction were investigated. The carbonylation of RuTPP(n-Bu₃P)₂ by CO gas was of interest, with respect to the catalytic reaction, which seems to involve pretreatment with CO (or aldehyde) to form a phosphine monocarbonyl. The reaction was found to follow a simple dissociative mechanism, which is similar to that observed for analogous M(porp)L₂, where M = Ru or Fe. A K value of 0.054 at 26°C was obtained and individual rate constants were calculated also. The temperature dependence of K was used to find the thermodynamic parameters ΔS° and ΔH° for the reaction. Some electrochemical studies were performed on RuTPP(n-Bu₃P)₂ and the corresponding monocarbonyl, RuTPP(CO)(n-Bu₃P). Electrochemical oxidation of RuTPP(CO)(n-Bu₃P) yielded a ir-cation radical, whereas bromine oxidation appeared to effect oxidation of the metal. / Science, Faculty of / Chemistry, Department of / Graduate

We have elucidated the structures of a series of Werner Clathrates with systematically changing guest molecules. The host is the inorganic coordination compound bis(isothiocyanato)tetra(4-vinylpyridine)nickel(II), [Ni(NCS)2(4-ViPy)4]. The guests are mixtures of tetrahydrofuran and the cyclic hydrocarbons: cyclohexane, cyclohexene, 1,3-cYclohexadiene, 1,4-cyclohexadiene and benzene. Host to guest ratios were elucidated by density and proton nuclear magnetic resonance spectroscopy. The thermal characteristics of the compounds were analysed by thermogravimetric analysis and differen.tial thermal analysis. The structures of two related compounds [Ni(NCS)2(Py)4] and [Ni(NCS)2(Py)4].nbenzene were also studied.

Thesis advisor: James P. Morken / This dissertation will discuss the development of three methodologies for the enantioselective synthesis of organoboron compounds. The first chapter will discuss the initial discovery and development of a palladium-catalyzed reaction that enables the combination of an organolithium, an organoboronic ester and C(sp2)-OTf electrophiles in an enantioselective fashion. This conjunctive cross-coupling takes place through a 1,2-metallate shift which is induced from an alkenylboron ‘ate’ species through interaction with the palladium catalyst. The second chapter of this manuscript will discuss the development of the first nickel-catalyzed version of the conjunctive cross- coupling reaction, which operates enantioselectively with in situ generated 9-BBN boranes. The third and last chapter will discuss the development of complementary method to the conjunctive cross-coupling which enables the enantioselective addition of organozinc reagents and alkyl halides across alkenylboronic esters. This system departs from the metal-induced 1,2-metallate shift mode of reactivity in favor of a Ni- catalyzed radical/addition cross-coupling cascade reaction. This process can be operated in both an inter- and intra-molecular fashion to afford enantiomerically-enriched alkylboronic ester compounds. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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Thesis advisor: James P. Morken / Thesis advisor: Marc L. Snapper / This dissertation presents three projects focusing on catalytic, site-selective and stereospecific functionalization of organoboronate compounds. First, we have developed a Cu-catalyzed regioselective coupling of 1,2-bis(boronic esters). This transformation provided an effecient route to a range of enantiomerically enriched secondary boronic esters. Mechanistic studies indicated that a chelated cyclic boron “ate” complex may promote transmetallation to Cu catalyst. We have also developed a Cu-catalyzed sterespecific cross-coupling of alkylboronic esters. Boron “ate” complexes derived from alkylboronic pinacol esters and tert-butyllithium underwent stereospecific transmetallation to copper cyanide. The so-formed organocopper species engaged alkynyl bromides, allyl halides, propargylic halides, β-haloenones, hydroxylamine esters, and acyl chlorides in coupling reactions. Finally, we have developed non-directed site-selective activation of bis(boronic esters), followed by Cu-catalyzed cross-coupling. A bulky activator was shown to selectively activate the less hindered boronic ester, enabling it to undergo stereospecific cross-coupling to a variety of electrophiles. This steric-based site-selectivity offered a simple and efficient route to prepare propionate derivatives as well as other valuable difunctional molecules. The appendix describes an ongoing study towards the synthesis of a novel analog of amphidinolide H. In an effort to elucidate the relationship between biological activity and structure of amphidinolide H, we designed a simplified analog that is likely to resemble amphidinolide H in shape. Development of its synthesis is currently underway. With an anticipated streamlined route to the analog, we expect to carry out rapid interrogation of its biological activity in collaboration with other research groups. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy