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

Thesis (M.S.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 50 pages. Includes vita. Includes bibliographical references.

Thesis (Ph.D.)--Ohio University, March, 2010. / Title from PDF t.p. Includes bibliographical references.

La menace bioterroriste que preprésente le virus de la variole et l’absence d’un traitement vaccinal ou curratif universel rend primordiale la mise au point d’un antiviral capable de soigner les poxvirus. Devant le grand nombre de nucléosides approuvés à ce jour, la recherche de nouveaux composés visant les enzymes virales et notamment celles des poxvirus reste toujours un axe majeur de recherche Dans cette optique, les réactions organo-métallliques sont des outils efficaces pour la synthèse de nouveaux composés à potentiel thérapeutique. Dans cette thèse, les cycloadditions 1,3 dipolaire de Sharpless catalysées au Cu et au Ru et les réactions de métathèse, croisée catalysées au Ru, nous ont ainsi permis de synthétiser efficacement trois nouvelles séries d’analogues nucléosidiques modifiés. L’évaluation biologique des composés synthétisés montre pour certains d’entre eux des activités supérieures à celles des molécules de référence sur les poxvirus comme sur d’autres virus à ADN. / The lack of a vaccine and of an antiviral to treat the smallpox virus, a potential bioterrorist weapon, makes necessary the development of new antivirals. Given the large number of nucleosides approved, the search for novel compounds targeting viral enzymes, including those viruses remains a major focus of research. In this context, organometallic reactions are effective tools for the synthesis of new compounds with therapeutic potential. During this PhD research program, the Huisgen cycloaddition (CuAAC or RuAAc) and cross coupling metathesis allowed us to efficiently synthesize three new series of modified nucleoside analogues. Biological evaluations show that some synthesized compounds are biologically more interesting than reference molecules on poxvirus as well as on other DNA viruses.

Orientador: Regina Buffon / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T22:19:34Z (GMT). No. of bitstreams: 1 Cavalcante_JoseAriMilton_M.pdf: 906597 bytes, checksum: 1b73e383b495e63cd6c110e0cb354848 (MD5) Previous issue date: 2007 / Resumo: Os catalisadores heterogêneos à base de rênio constituem-se importantes sistemas na metátese de ésteres insaturados provenientes dos óleos vegetais. No entanto, os sistemas heterogêneos à base de rênio são ativos na metátese de olefinas funcionalizadas somente se forem combinados com um promotor do tipo SnR4 ou PbR4. Acredita-se que o promotor tem a função de formar a espécie metal-alquilideno (no caso, rênio-alquilideno) que desencadeia o ciclo catalítico. Entretanto, ainda não é compreendido o mecanismo de formação dos promotores na superfície dos sistemas de óxidos. O objetivo principal desse trabalho consistiu em tentar identificar, através da RMN-C no estado sólido, a possível formação da espécie rênio-alquilideno sobre a superfície do sistema de óxidos (2%)Re2O7/(7,5%)B2O3/SiO2-Al2O3(75%) após a interação deste com o organometálico enriquecido com C, Sn( CH3)4. Buscou-se também caracterizar as interações entre os organometálicos (SnBu4, Bu3SnH e Bu2SnH2) com o mesmo sistema de óxidos através das técnicas de RMN-C no estado sólido e de espectroscopia no infravermelho. E finalmente, procurou-se identificar a estrutura do mesmo sistema de óxidos através das técnicas de RMN Al e Si no estado sólido, espectroscopia no infravermelho e difração de raios X / Abstract: Heterogeneous rhenium catalysts are importants systems for the metathesis of unsaturated esters obtained from vegetables oils. Nevertheless, the heterogeneous rhenium systems are actives for the metathesis functionalized olefins when combined with a promoter like SnR4 or PbR4. It is believed that it leads to the formation of the alkylidene species that will start the catalytic cycle. However, the role of the promoters on oxide system surface is not well understood. The main goal of this work was to identify, via CP-MAS C NMR, a possible rhenium-alkylidene species formed by the reaction between Sn(CH3)4 and (2%)Re2O7/(7,5%)B2O3/SiO2-Al2O3(75%). The reactions of SnBu4, Bu3SnH e Bu2SnH2 with (2%)Re2O7/(7,5%)B2O3/SiO2-Al2O3(75%) were also investigated by CP-MAS C NMR and in situ FT-IR experiments. Finally, the structure of the (2%)Re2O7/(7,5%)B2O3/SiO2-Al2O3(75%) material was studied by Al and Si MAS NMR, FT-IR and X ray diffraction / Mestrado / Quimica Inorganica / Mestre em Química

O complexo [RuCl2(PPh2Bz)3] (1) é ativo em ROMP de norborneno. À 50 ºC na presença de EDA, observa-se prontamente precipitação de polímero. Obtendo-se cerca de 50% de rendimento tanto por 5 min como 30 min. O valor do IPD é alto quando aumenta-se o tempo de reação. Este complexo apresenta grandes rendimentos quando aumenta-se a razão [NBE]/[Ru], com quantitativo rendimento quando [NBE]/[Ru] = 15.000. Quando a razão [NBE]/[Ru] é 1.000, é obtido polímeros com cadeias polimodais. Trocando uma molécula de PPh2Bz em 1 por piperidina, o novo complexo [RuCl2(PPh2Bz)2pip] (2) é ativo a 25 ºC por 30 min com 92% de rendimento (PDI = 2.22). Observa-se rendimento quantitativo a 50 ºC por 30 min. O aumento da razão [NBE]/[Ru] diminui o rendimento para este complexo. Os complexos [RuCl2(PPh2Bz)2(nic)2] (3) e [RuCl2(PPh2Bz)2(isn)2] (4) não mostraram boa atividade a 25 ºC por 30 min. Obtém-se 7.2% de rendimento a 50 ºC por 5 min e 12.0% a 30 min com 5µL de EDA. / The complex [RuCl2(PPh2Bz)3] (1) is active in ROMP of norbornene. At 50 °C in presence of EDA, it is observed promptly precipitation of polymer. It is obtained c.a. 50% yield at 50 ºC for either 5 min or 30 min. The PDI value is larger when increasing the reaction time. This complex presents high yields when increasing the [NBE]/[Ru] ratio, with a quantitative reaction when [NBE]/[Ru] = 15,000. When the [NBE]/[Ru] ratio is 1,000, it is obtained polymodal polymer chains. Changing one PPh2Bz molecule in 1 for piperidine, the new complex [RuCl2(PPh2Bz)2pip] (2) is active at 25 ºC for 30 min with 92% yield (PDI = 2.22). Quantitative yield is obtained at 50 ºC for 30 min. The increase of [NBE]/[Ru] ratio affords the decrease in the yield when using this complex. The complexes [RuCl2(PPh2Bz)2(nic)2] (3) and [RuCl2(PPh2Bz)2(isn)2] (4) do not show good activity at 25 ºC up to 30 min. It is obtained 7.2% yield at 50 ºC for 5 min and 12.0% for 30 min with 5µL of EDA.

Olefin metathesis is a powerful tool for assembly of carbon-carbon bonds. Amines and related N-donors are problematic functional groups in Ru-catalyzed olefin metathesis - a well- documented, but poorly understood problem. The first part of this thesis focuses on amine-induced deactivation pathways; two of which are described in depth. Alkylidene abstraction, a previously unknown reaction for nitrogen nucleophiles, was observed for smaller and less Bronsted-basic amines. Deprotonation of the metallacyclobutane intermediate formed during catalysis is prominent for highly Bronsted basic or sterically bulky N-donors. Monosubstituted (and, by extension unsubstituted) metallacyclobutanes are particularly vulnerable to deprotonation. For each pathway, the fate of the alkylidene Ru=CHR functional group proved key in determining the nature of deactivation. Both pathways have been detected during catalysis, as evidenced by formation of diagnostic amine (RCH2NR2’) or substituted propene products. A combination of quantitative NMR and GC-MS analysis was used to identify these species on loss of the Ru-alkylidene functional group. The second part of this thesis focuses on incorporating amines into catalyst design – an under-utilized strategy in the context of Ru-catalyzed olefin metathesis. A modified Grubbs-type catalyst was developed featuring a bulky, relatively non-basic biaryldiamine ligand. Metathesis activity for this catalyst was comparable, and in some cases superior to the most widely-used homogeneous catalysts currently available. Several new, related Ru-benzylidenes were also prepared and fully characterized in conjunction with the mechanistic studies described above. Progress toward development of N-anion-containing metathesis catalysts is also discussed. Synthesis of Ru-hydride complexes originally intended for this purpose allowed for a fundamental study of the coordination chemistry and reductive elimination chemistry of the NPh2– anion.

M.Sc. / In this study, the pyrazolyl-based ligands were synthesised and used in the synthesise of new ruthenium pyrazolyl-based complexes. The ruthenium pyrazolyl-based complex 2.4 was tested as a catalyst for the self-metathesis reaction of 1-octene. The N^N ligands: 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 4-(3,5- dimethylpyrazol-1-ylmethyl)pyridine (L2) were prepared from the reaction of 2- picolyl chloride (for L1) and 4-(bromomethyl)pyridine (for L2) with 3,5- dimethylpyrazole. Reactions of L1 and L2 with [RuCl2(PPh3)3] and [RuCl3·3H2O] produced [2-(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine) dichlorotriphenylphosphine]ruthenium (2.1) and bis[4-(3,5-dimethylpyrazol-1- ylmethyl)pyridine-trichloride]ruthenium (2.3), respectively. The N^O ligands: 2- (3,5-dimethylpyrazol-1-yl)ethanol (L3), 2-(3,5-diphenylpyrazol-1-yl)ethanol (L4), were prepared from the reaction of 2-hydroxyethylhydrazine (for L3) and dibenzoylmethane (for L4) with 2-hydroxyethylhydrazine. Reaction of L3 with (3-phenylindenylidene)dichlorobis-(triphenylphosphine)ruthenium produced [3-phenylindenylidene-(3,5-dimethylpyrazol-1-yl)-ethanolate chlorotriphenylphosphine]ruthenium (2.4). Ligands, 2-(3,5-dimethylpyrazol-1-ylmethyl)-phenol (L5) and bis(3,5- dimethylpyrazol-1-yl)acetic acid (L6), were prepared from the reaction of o-(α- bromo-methyl) phenyl methanesulfonate (for L5) and dibromoacetic acid (for L6) with 3,5-dimethylpyrazole. Reaction of L6 with [RuCl2(PPh3)3] produced bis-[(3,5-dimethylpyrazol-1-yl)-acetic-acid-chloro(bistriphenylphosphine)] ruthenium (2.6). The C^N ligands: 1-[2-(3,5,-dimethylpyrazol-1-yl)-ethyl]-3- methyl-3H-imidazol-1-ium bromide (L7) and 1-[2-(3,5,-dimethylpyrazol-1-yl)- ethyl]-3-methyl-3H-imidazol-1-ium bromide (L8) were prepared from the reaction of 1-(2-bromoethyl)-3,5-dimethyl-1H-pyrazole (for L7) and 1-(2- bromoethyl)-1H-pyrazole (for L8) with 1-methylimidazole. Reactions of L7 and L8 with silver(I) oxide (Ag2O) produced 3,5-dimethyl-1-[2-(3-methyl-2,3- dihydro-imidazol-1-yl)-ethyl-1H-pyrazole]silver bromide (2.7) and 1-[2-(3- methyl-2,3-dihydro-imidazol-1-yl)-ethyl-1H-pyrazole]silver bromide (2.8), respectively. Reactions of silver complexes (2.7) and (2.8), respectively, with [RuCl2(PPh3)3] produced 3,5-dimethyl-1-[2-(3-methyl-2,3-dihydro-imidazol-1- yl)-ethyl-1H-pyrazole-dichloro(triphenylphosphine)]ruthenium (2.9) and 1-[2- (3-methyl-2,3-dihydro-imidazol-1-yl)-ethyl-1H-pyrazoledichloro (triphenylphosphine)]ruthenium (2.10). The synthesised complexes were obtained in moderate to low yields and were characterised by 1H, 13C{1H}, 31P{1H} NMR, IR spectroscopy, mass spectrometry, elemental analyses and ligand L5 was also characterised by X-ray crystallography. Complex 2.4 was screened for self-metathesis reaction of 1-octene. Initial run from 30-90 oC showed no activity for 1-octene metathesis below 105 oC. At 105 oC small amounts of 7-tetradecene was obtained, indicating that metathesis reaction occurs at very high temperatures (105 oC). Thermal stability test of complex 2.4, showed that rearrangement in the proposed structure of complex 2.4 occurs after heating at 90 oC for 16 h, this was evident by the 31P{1H} NMR spectrum of complex 2.4 obtained as a singlet at 28.9 ppm (after being heated), (complex 2.4 appears at 30.0 ppm before heating). From the 31P{1H} NMR study, it could be proposed, that the pyrazole arm of the ligand dissociates thus influencing the environment of the phosphorus (of the triphenylphosphine), and therefore a shift in the peaks is observed.

An integrated approach to the design of potential rutheniun-based metathesis catalysts is described, in which closely defined synthetic forays provide the focus and rationale for detailed computational and mechanistic studies. The ground-state geometry of a 1st-generation Grubbs catalyst has been explored at the molecular mechanics, semi-empirical and DFT levels, and the resulting structures have been shown to compare favourably with literature data and with the structure of a known crystalline analogue. The DMol³ DFT code has also been shown to represent accurately both the geometry of the corresponding co-ordinatively unsaturated monophosphine derivative, and the ligand dissociation energy associated with its formation. A DFT free-energy profile of the degenerate metathesis of ethylene has been generated, using a truncated model of the 1st-generation Grubbs catalyst, permitting location, for the first time, of the three expected transition states and providing new information regarding the rate-determining step. DFT methods have been used to facilitate the design of a tridentate camphor-derived ligand for use in the construction of a novel Grubbs-type catalyst. The phosphine ligand dissociation energy of the putative catalyst and the ethylene metathesis energy profile of a truncated model have also been studies at the DFT level. The attempted synthesis of the proposed ligand proceeded via a novel 8-bromocamphoric anhydride intermediate and afforded several unexpected and novel products, including a cisfused γ-Iactone, and a bromo camphoric acid derivative. Single crystal X-ray analysis of the latter reveals a chiral, polymeric H-bonded packing arrangement, rendering it suitable for chiral inclusion studies. Computational methods, including the GAUSSIAN-based GIAO NMR prediction technique, were used to support the structural characterisation of the novel camphor derivatives. DFT-Ievel computational analysis of the C-8- and C-9 bromination of camphor has afforded theoretical insights which permit the reconciliation of two earlier empirical explanations regarding the regioselectivity of these transformations; moreover, the theoretical results suggest that a third, previously disregarded factor, plays a significant role. A coset analysis, in conjunction with DFT-Ievel energy profiling, has also been used to resolve conflicting opinions regarding the origin of the major byproduct. Computed electronic parameters (CEP's) have been calculated for the anionic ligands involved in a series of 2nd-generation Grubbs-Hoveyda-type catalysts, and used to explain some apparently anomalous trends in catalyst activity. A linear relationship between ligand CEP's and selected ¹H NMR chemical shifts has also been demonstrated and used to identify a transient ruthenium complex in solution. The ability of the malonate di-anion to bind to ruthenium in a bidentate manner has been explored and demonstrated, under suitable conditions. DFT methods have been used to design and assess the ruthenium-chelating potential of a novel tridentate malonate derivative. A synthetic pathway to this ligand has been designed and several novel heterocyclic intermediates have been isolated and characterised. An NMR-based kinetic study of the Grubbs-catalysed self-metathesis of l-octene has been completed, and the effects of temperature, concentration and solvent variations on the kinetic parameters have been studied. Application of the Guggenheim method and a simplified mechanistic model has permitted the accurate calculation of pseudorate constants for the initiation and, for the first time, the propagation phase of the reaction. Theoretical studies of this reaction at the DFT and molecular mechanics levels have been shown to support previous assumptions regarding the selectivity and temperature-dependence of metallacycle formation.

This work has focussed on the preparation of a variety of tridentate ligands, designed to form ruthenium complexes as potential metathesis catalysts. Various approaches to the tridentate, malonate-tethered imidazolidine system have been investigated, and a promising route to accessing ligands of this type is discussed. A tridentate malonate-tethered pyridine ligand has been successfully prepared and its dithallium salt has been accessed by hydrolysis with thallium carbonate; approaches to a longer-chain analogue have also been investigated. A thallium pyridine-2,6- dicarboxylate ligand has been has been successfully prepared, as have a range of pyridine diamine ligands, with various alkyl and aromatic substituents on the amine donor atoms. Preliminary investigations into the potential of these compounds as ligands for alkylidene ruthenium complexes are reported using molecular modelling techniques. The geometries and steric energies of the ligands and their corresponding complexes have been analysed, and results obtained from two different software packages are compared. Finally, some preliminary complexation studies have been undertaken.