Thesis advisor: Kian L. Tan / Chapter 1. Catalytic directing group, I, which was designed with the ability to form a reversible covalent bond with a substrate and bind a metal, was shown to direct the hydroformylation of allylic amines. The efficient regioselective hydroformylation of a variety of 1,2-disubstituted allylic sulfonamides to form β-amino-aldehydes under mild conditions has been shown. Chapter 2. Building off of the successful application of I, enantioenriched catalytic directing group, II, was designed and synthesized. It retained the essential features to direct hydroformylation to obtain good regioselectivity while also providing a chiral environment to induce absolute stereocontrol. Under mild conditions, a variety of disubstituted olefins react to give good yields and excellent enantioselectivites. Thus, the first enantioselective reaction performed with a catalytic directing group was demonstrated. Chapter 3. A new set of organocatalysts was developed that benefits from reversible covalent bonding and induced intramolecularity. The desymmetrization of meso-1,2-diols was accomplished using organocatalyst III, which was synthesized easily and cheaply. Experimental results indicate that the selectivity and increased reactivity are a result of the ability of III to pre-organize the substrate through a reversible, covalent bond. A variety of cyclic and acylic substrates were shown to react efficiently with good enantioselectivities under mild conditions. The catalyst's ability to functionalize cis-1,2-diols selectively indicated it might be successfully applied to site selective catalysis. Thus, the selective functionalization of a secondary alcohol in the presence of a primary alcohol was developed using a combination of binding selectivity and stereoselectivity. The (S)-enantiomer forms the secondary functionalized product while the (R)-enantiomer forms the primary functionalized product with high selectivity. As the enantiomers preferentially form different functionalized products, a regiodivergent reaction on a racemic mixture resulted giving two valuable enriched products. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

This research aimed at improving p-xylene selectivity in toluene disproportionation over ZSM-5 zeolite by exploring the effect of crystal size and various post synthetic modification methods. A comprehensive study of the effect of different modifications on the physicochemical properties of ZSM-5 was investigated using X-ray diffraction (XRD), pyridine adsorption, Fourier transform infra-red (FTIR), 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR), BET surface area by N2 adsorption, inductively coupled plasma (ICP) and scanning electron microscopy (SEM). The catalytic performance of each catalyst was studied in a fixed bed reactor at a temperature 475 °C, WHSV 3-83 h-1 and two different pressures (1 and 10 bar). ZSM-5 zeolites with different crystal sizes (5, 50 and 100 ÂÂμm) were synthesized in house and compared with the commercially obtained ZSM-5 having a crystal size of 0.5 ÂÂμm. The increase in crystal size improved p-xylene selectivity which was attributed to the diffusion constraints imposed by the longer diffusion path lengths of large crystals. The highest p-xylene selectivity (58 %) was achieved over ZSM-5 with the largest crystal size 100 ÂÂμm at the highest WHSV 83 h-1. However, it was accompanied by a low conversion (2 wt. %). ZSM-5 with crystal size of 5 ÂÂμm delivered the best results in terms of the combination of para-selectivity (40 %) and toluene conversion (15 wt. %). The p-xylene produced in the channels of ZSM-5 can quickly isomerise to o-xylene and m-xylene on the external unselective acid sites. Different post modification methods were applied in this study in attempt to suppress the fast isomerization reaction by deactivating the external acid sites. This was achieved to some extent by depositing an inert silica layer using different silica agents, amounts and number of modification cycles and as a result p-xylene selectivity was significantly improved (84 %), especially over large crystals 5 ÂÂμm. The decrease in Brà̧nsted acidity (FTIR) suggested the success of the silylation method. Furthermore, impregnation of lanthanum and phosphorus on ZSM-5 improved p-xylene selectivity (40 %). FTIR measurements showed a drastic drop in the number of Brà̧nsted and Lewis acid sites after loading phosphorus which led to a large reduction in toluene conversion. Lanthanum impregnation had less effect on conversion and increased selectivity with decreased Brà̧nsted sites and pore volume reduction showed by N2 adsorption suggesting some pore narrowing. There are several approaches that can be considered in future to further improve p-xylene selectivity. Improving the synthesis of large crystals to balance acidity and crystal size can lead to the enhancement of p-xylene selectivity. Also, performing toluene disproportionation on optimised pre-coked ZSM-5 large crystals at high pressure can help to maintain the conversion while increasing p-xylene selectivity. Another approach would be to apply silylation modification to extruded large crystals ZSM-5.

This thesis is focused on the development of new palladium and copper- mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. The synthetic utility of the 1,2-diborylated butadienes synthesized in one of these processes has also been demonstrated. We have developed an efficient procedure for the synthesis of allenyl boronates from propargylic carbonates and acetates. This was achieved by using a bimetallic system of palladium and copper or silver as co-catalyst. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. The reactivity of the 1,2-diborylated butadienes with aldehydes was studied. It was found that the initial allylboration reaction proceeds via an allenylboronate intermediate. The allenylboronate reacts readily with an additional aldehyde to construct 2-ethynylbutane-1,4-diols with moderate to high diastereoselectivity. We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used. In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for the selective synthesis of allylic silanes. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 1: Accepted.</p>

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No. of bitstreams: 1 perissinotto_ap_me_rcla.pdf: 4083559 bytes, checksum: 7362f582721fdb5515688043eff181ca (MD5) Previous issue date: 2016-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi estudar as características estruturais em géis úmidos de sílica preparados a partir da hidrólise ácida de Tetraetilortosilicato (TEOS) com adições do surfactante aniônico Dodecil Sulfato de Sódio (SDS). O surfactante foi removido após a gelificação. Os géis úmidos exibem uma estrutura fractal de massa com dimensão fractal de massa D (típicamente em torno de 2,25) numa escala de comprimentos que se estende desde o tamanho característico ξ (geralmente em torno de 10 nm) do domínio do fractal de massa até um tamanho característico a0 (típicamente entre 0,3 - 0,4 nm) da partícula primária que constituí o domínio fractal. ξ aumenta enquanto que D e a0 diminuem ligeiramente com o aumento da quantidade de SDS. Aerogéis SCD com superfície específica típica de 1000 m2 /g e massa específica aparente de 0,20 g/cm3 foram obtidos por secagem supercrítica (SCD) dos géis úmidos depois da lavagem com etanol. O volume de poros e o tamanho médio de poros aumentaram com o aumento da quantidade de SDS. Os aerogéis SCD preservaram a maior parte das características do fractal de massa dos géis úmidos originais em larga escala de comprimento e exibiram num nível de resolução em torno de 0,7 nm uma mudança („crossover‟) para uma estrutura de fractal de massa e superfície, com dimensão aparente de fractal de massa Dm ~ 2,4 e dimensão de fractal de superfície Ds ~ 2,6, conforme concluído a partir dos dados de espalhamento de raios-X à baixo angulo (SAXS) e adsorção de Nitrogênio. Aerogéis hidrofóbicos secos a pressão ambiente (APD) apresentaram superfície específica típica de 800 m2 /g e massa específica aparente de 0,20 g/cm3 e foram obtidos após sililação dos precursores géis úmidos com uma mistura de Hexametildisiloxano (HMDSO) e Trimetilclorosilano (TMCS). O volume de poros e o tamanho médio de poros dos aerogéis APD aumentaram com o aumento da quantidade de SDS. Os aerogéis APD preservaram a maior parte das características do fractal de massa do precursor gel úmido em larga escala de comprimento. O raio de giração dos clusters dos aerogéis APD (tipicamente 17 nm) aumentou com o aumento da quantidade de SDS, enquanto que o raio da partícula primária de sílica (tipicamente 2,0 nm) aumentou com a primeira adição de SDS (em relação à amostra sem SDS) e depois diminuiu regularmente com o aumento da quantidade de SDS. A partícula primária apresentou ainda alguma heterogeneidade interna e uma interface do contorno difuso com espessura em torno de 0,7 nm, de acordo com o modelo de gradiente linear para o contorno difuso. / This work aims to study the structural characteristics of silica wet gels prepared from hydrolysis of Tetraethoxysilane (TEOS) with additions of the anionic surfactant Sodium Dodecyl-Sulfate (SDS). The surfactant was removed after gelation. Wet gels exhibited massfractal structure with mass-fractal dimension D (typically around 2.25) in a length scale extending from a characteristic size ξ (typically about 10 nm) of the mass-fractal domains to a characteristic size a0 (typically between 0.3 - 0.4 nm) of the primary particles building up the fractal domains. ξ increased while D and a0 diminished slightly as the SDS quantity increased. Aerogels with typical specific surface of 1000 m 2 /g and density of 0.20 g/cm3 were obtained by supercritical drying (SCD) of the wet gels after washing with ethanol and n-hexane. The pore volume and the mean pore size increased with the increase of the SDS quantity. The aerogels presented most of the mass-fractal characteristics of the original wet gels at large length scales and exhibited at a higher resolution level at about 0.7 nm a crossover to a masssurface fractal structure, with apparent mass-fractal dimension Dm ~ 2.4 and surface-fractal dimension Ds ~ 2.6, as inferred from small-angle X-ray scattering (SAXS) and Nitrogen adsorption data. Hydrophobic ambient pressure drying (APD) aerogels with typical specific surface of 800 m2 /g and bulk density of 0.20 g/cm3 were obtained after silylation of the precursor wet gels with a mixture of Hexamethyldisiloxane (HMDSO) and Trimethylchlorosilane (TMCS). The pore volume and the mean pore size of the APD aerogels increased with increasing the SDS quantity. APD aerogels presented most of the mass-fractal characteristics of the precursor wet gels at large length scales. The radius of gyration of the clusters of the APD aerogels (typically 17 nm) increased with increasing the SDS quantity, while the radius of the silica primary particles (typically 2.0 nm) increased at first with the addition of SDS (with respect to the sample without SDS) and decreased regularly afterward with increasing the SDS quantity. The primary particles presented yet some internal inhomogeneity and a diffuse-boundary interface with thickness of about 0.7 nm, according to a linear-gradient model for the diffuse boundary.

The work in this thesis describes the development of new heteroarylation methodology based on transition metal-catalysed C-H functionalisation and the properties of organomain group compounds. The underlying reaction mechanisms and reactivity patterns of the (hetero)arene substrates are also investigated. The selective C2-H arylation indoles, which are key pharmaceutically-relevant units, was achieved using N-pyrimidyl directing groups, RuII catalysis and arylboronic acids as the coupling reagents (paper I). The use of this set of conditions enabled a remarkable functional group tolerance, highlighted by the preservation of halide substituents on both coupling partners. Mechanistic experiments suggest that cleavage of the C2-H bond occurs through an electrophilic aromatic substitution type pathway. The dehydrogenative C2-H silylation of unprotected gramine and tryptamine alkaloids and other related heteroarenes using hydrosilanes under Ru0 catalysis is described in paper II. The protocol does not require protecting groups and undirected C2-H silylation of heteroarenes is possible at higher temperatures. Significantly, H/D-exchange studies revealed deuterium incorporation at the C4 and C7 positions of the indole unit, apart from C2-H silylation. This study represents the first account of C4-H activation using an electron-rich metal catalyst. Paper III describes an unexpected and profound influence of boronate substituents on the regioselectivity of aryne trapping reactions. The boronates may be introduced easily to the backbone of established fluoride-activated precursors via Ir-catalysed C-H functionalisation. Optimisation and mechanistic studies on the unprecedented level of regioselectivity control these substituents permit using external additives is presented.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23027号 / 理博第4704号 / 新制||理||1675(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 依光 英樹, 教授 時任 宣博, 教授 若宮 淳志 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18232号 / 工博第3824号 / 新制||工||1586(附属図書館) / 31090 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 吉田 潤一, 教授 村上 正浩 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

N-Heterocyclic carbenes (NHCs) have attracted growing interest not only as successful ancillary ligands in a wide variety of transition-metal-catalyzed reactions but have also shown to offer photophysical and electrochemical properties. The metalation/transmetalation strategy using [Zr(NMe2)4] as initial metalating reagent offers an efficient approach to the preparation of CCC-NHC pincer complexes of the late transition metals such as Rh and Ir. In the process of investigating an intermediate and the mechanism of the metalation/transmetalation to Rh sequence, a mixed valent bimetallic CCC-NHC pincer Rh complex with two chloro ligands bridged between a [(CCC-NHC)Rh(III)] and a [Rh(I)(COD)] fragment was isolated and fully characterized for the first time. The investigation of the Rh(III)/Rh(I) bimetallic intermediate in the CCC-NHC pincer metalation/transmetalation methodology led to an improved stoichiometric synthesis of series of CCC-NHC pincer Rh complexes. The CCC-NHC pincer Rh complexes were characterized with 1H and 13C NMR spectroscopy, ESI-TOF MS and single crystal X-ray diffraction. The catalytic activity of the series of CCC-NHC pincer Rh complexes were evaluated. All the CCC-NHC pincer Rh precatalysts were found to promote the dehydrogenative silylation of vinylarenes with Et3SiH to form the corresponding (E)-vinylsilanes as the major silylation product under solvent-free conditions. The catalytic system displays wide substrate scope. Electron rich and electron deficient vinylarenes were well tolerated affording the corresponding vinyl silanes in good yields (65-86%). Mechanistic investigations indicated that Rh(III) center was responsible for the catalytic performance. The CCC-NHC pincer ligand architecture plays a role in achieving good regio- and stereoselectivities. Also, the complexes were evaluated as precatalysts towards hydrosilylation of aryl- and alkyl alkenes. The precatalysts, [(BuCiCiCBu)RhCl(µ-Cl)2Rh(COD)] and [(BuCiCiCBu)RhCl(µ-Cl)]2, were found to promote highly regioselective anti-Markovnikov hydrosilylation of aryl- and alkyl alkenes with excellent selectivity (>99%) using Et3SiH or PhMe2SiH as silane source and acetonitrile as solvent. Straight chain alkyl alkenes were tolerated without undergoing isomerization as it is the case with most known hydrosilylation catalyst systems. We extended the improved stoichiometric metalation/transmetalation methodology towards the synthesis of 1,3-di(1H-1,2,4-triazol-1-yl)benzene-based pincer Rh complexes. A series of 1,1'-(1,3-phenylene)bis(4-hexyl-1H-1,2,4-triazol-4-ium) salts were synthesized. Metalation/transmetalation of 1,1'-(1,3-phenylene)bis(4-hexyl-1H-1,2,4-triazol-4-ium) diiodide salt was successfully demonstrated to synthesize novel triazole-based CCC-NHC pincer Rh complexes.

Low-k dielectrics with porosity are being introduced to reduce the RC delay of Cu/low-k interconnect. However, during the O2 plasma ashing process, the porous low-k dielectrics tend to degrade due to methyl depletion, moisture uptake, and densification, increasing the dielectric constant and leakage current. This dissertation presents a study of the mechanisms of plasma damage and dielectric recovery. The kinetics of plasma interaction with low-k dielectrics was investigated both experimentally and theoretically. By using a gap structure, the roles of ion, photon, and radical in producing damage on low-k dielectrics were differentiated. Oxidative plasma induced damage was proportional to the oxygen radical density, enhanced by VUV photon, and increased with substrate temperature. Ion bombardment induced surface densification, blocking radical diffusion. Two analytical models were derived to quantify the plasma damage. Based on the radical diffusion, reaction, and recombination inside porous low-k dielectrics, a plasma altered layer model was derived to interpret the chemical effect in the low ion energy region. It predicted that oxidative plasma induced damage can be reduced by decreasing pore radius, substrate temperature, and oxygen radical density and increasing carbon concentration and surface recombination rate inside low-k dielectrics. The model validity was verified by experiments and Monte-Carlo simulations. This model was also extended to the patterned low-k structure. Based on the ion collision cascade process, a sputtering yield model was introduced to interpret the physical effect in the high ion energy region. The model validity was verified by checking the ion angular and energy dependences of sputtering yield using O2/He/Ar plasma, low-k dielectrics with different k values, and a Faraday cage. Low-k dielectrics and plasma process were optimized to reduce plasma damage, including increasing carbon concentration in low-k dielectrics, switching plasma generator from ICP to RIE, increasing hard mask thickness, replacing O2 by CO2 plasma, increasing CO addition in CO/O2 plasma, and increasing N2 addition in CO2/N2 plasma. By combining analytical techniques with the Kramers-Kronig dispersion relation and quantum chemistry calculation, the origin of dielectric loss was ascribed to the physisorbed water molecules. Post-ash CH4 plasma treatment, vapor silylation process, and UV radiation were developed to repair plasma damage. / text

This thesis deals with different optimization problems encountered in organic synthesis. The use of response surface, sequential simplex and PLS techniques, for simultanious optimization of yield and suppression of side reactions is investigated. This is illustrated by an example of enamine synthesis, were a side reaction was a serious problem. The problem of efficient screening to find suitable catalysts and solvents in new reactions is also investigated. Here, the use of principal properties as selection criterion, is demonstrated with a new process for the silylation of a,ß-unsaturated ketones. The extension of the new method to bis silylation of 1,2- and 1,3-diketones is demonstrated. The total synthesis of (±)-geosmin is investigated by an approach aimed to reduce the number of necessary steps involved. The suggested strategy, is to find compatible solvents through several transformations in the sequence to accomplish one-pot multistep reactions. In this context an improved method for the preparation of 1,10-dimethyl-l(9)-octalone-2 was established. Comparison with previously reported total syntheses of (±)-geosmin was done. / digitalisering@umu