No description available.

Raw bio-oil is produced by fast pyrolysis of biomass. The high level of oxygen content in bio-oil causes negative properties of polymerization over time, high acidity, pungent odor and low heating value relative to petroleum fuels. The objective of this study was to develop and identify upgrading processes to produce a boiler fuel with reduced acid value, reduced polymerization over time and increased higher heating value. By one upgrading method, raw bio-oil was upgraded by esterification over acid catalyst by batch reaction; a second approach was an in-reactor reaction, produced by injecting methanol or 1-butanol with acid catalyst into the pyrolysis vapor stream. An olefination reaction method combined with an alcoholation reaction was also studied. The resulting fuel produced from in-reactor esterification fuel was compared in terms of physical and chemical properties with esterifed bio-oil produced by the batch method. The olefination reaction was examined in terms of higher heating value, acid value, viscosity, and water content. The influence of reaction conditions such as reaction time, reaction temperature, and catalyst content relative to upgraded bio-oil properties were examined, and optimal conditions were identified. Analysis of variance (ANOVA) and empirical analysis was utilized to analyze the difference in physical and chemical properties between treatment groups.

This dissertation research is based on two reactions, including those of cyclic ketene acetals with acid chlorides and acid catalyzed olefination reactions in bio-oil. In first four chapters, reactions of in situ generated cyclic ketene acetals were explored. Highly functionalized heterocycles such as pyrrollo-[1,2-c]imidazolediones, were synthesized in one-pot reactions of 2-alkylimidazoles or 2-methylbenzimidazoles with 1,3-diacid chlorides. Some reactions proceed through in situ generated cyclic-N,N′-ketene acetal intermediates. 2-Alkylimidazoles and 2-methylbenzimidazole can be considered as tridentate nucleophiles in these reactions that can give four consecutive attacks on electrophiles which ultimately generate new heterocycles. Reactions of substituted oxazoles and thiazoles with different acid chlorides in the presence of different bases were explored. Arylvinyl esters of substituted benzoic acids containing substituted oxazoles or thiazoles were formed when aroyl chlorides were used. Most reactions occurred through in situ generated cyclic ketene acetals. Reactions of 2-methylbenzoxazole and 5-phenyl-2-methylbenzoxazole with acid chlorides and base in THF generated a series of ortho-amidoesters. All of these reactions showed that aromatic heterocycles based in situ generated cyclic ketene acetals could be used to make highly functionalized heterocycles under mild conditions. These one-pot reactions generated various heterocycles, which might have useful bioactivities. For example, arylvinyl esters of substituted benzoic acids have been reported to show insecticidal activities. The last two chapters describe the olefinations of bio-oil and model bio-oil compounds using acid catalysts. Two different branched olefins were used, representative of those available at petroleum refineries. Amberlyst-15 and Nafion NR-50 were used as heterogeneous acid catalysts. The acid catalyzed olefination of bio-oil was explored using an excess of 1- octene. Some olefinations were performed in the presence of ethanol. Ethanol was used to make the olefin and bio-oil phases partially miscible. Acid catalyzed olefination of raw bio-oil induced some changes in the resulting bio-oil by generating variety of alcohols, ethers and oligomeric mixtures of the starting olefin. Olefination with excess 1-octene showed the decrease of the water content and the acid value and increase of the heating value of the bio-oil. Thus, the acid catalyzed olefination of bio-oil can be considered as a potential bio-oil upgrading technique.

An efficient, stereoselective method for the synthesis of α-phosphonoenamines based on a modified Peterson olefination was developed. The carbanion derived from Diethyl 1-dimethylamino-1-trimethylsilylmethanophosphonate reacted with aromatic or aliphatic aldehydes selectively eliminating in Peterson fashion to deliver functionally rich α-phosphonoenamines. A highly efficient method was developed for the one-carbon homologation of aldehydes to carboxylic acid derivatives employing the reaction of a 1, 1-bis-dimethylphosphonate derivative with the aldehyde and controlled acid hydrolysis of the derived α-phosphonoenamine intermediate. The reaction of bis(trimethylsilyl)chloromethane with s-BuLi was found to proceed via transmetallation rather than deprotonation yielding the nucleophilic bistrimethylsilylmethyl anion quantitatively which reacted readily with aldehydes providing a general entry to vinylsilanes. The reaction of α-silylated ylides with non-enolizable aldehydes proceeded via selective Peterson-type elimination, in contrast to prior literature reports, providing a direct route to synthetically useful vinylphosphonium salts. The chemoselective formation of trialkylbenzyl phosphoranes in water and their Wittig reaction with aromatic and aliphatic aldehydes provided a practical, stereoselective and environmentally benign route to valuable trans-stilbenes and alkenes. The synthesis of the phytoalexin resveratrol was described. In addition, the method allowed for a gramscale synthesis of the anticancer agent DMU-212 utilizing no organic solvent at any stage. A direct synthesis of 1,3-dienes and 1,3,5-trienes from the reaction of semi-stabilized ylides and a range of saturated and unsaturated aldehydes was reported in water as solvent, employing sodium hydroxide as base. The water-soluble phosphine oxide side product was removed simply by aqueous partitioning of the organic products. / Thesis / Doctor of Philosophy (PhD)

Doctor of Philosophy (PhD), Science / A concise stereo-selective synthesis of a protected form of APTO 1, an unusual amino acid component of microsclerodermin C 2, was undertaken. Sequential Sharpless Asymmetric Aminohydroxylation (AA) and Asymmetric Dihydroxylation (AD) reactions were used to introduce the chiral amino and hydroxyl groups. Specific directing groups were chosen to ensure high regio- and enantio-selectivity in these reactions. The target compound was reached in a linear reaction sequence of fourteen steps. The strategy was designed to generate common intermediates which could be used to access analogous amino acid fragments in other microsclerodermins. A protected form of AETD 3, from microsclerodermin E, was synthesised via a late-stage common intermediate. Initial studies into the modification of the sequence to allow access to AMPTD 4 and 10-methyl AMPTD 5 were made.

Doctor of Philosophy (PhD), Science / A concise stereo-selective synthesis of a protected form of APTO 1, an unusual amino acid component of microsclerodermin C 2, was undertaken. Sequential Sharpless Asymmetric Aminohydroxylation (AA) and Asymmetric Dihydroxylation (AD) reactions were used to introduce the chiral amino and hydroxyl groups. Specific directing groups were chosen to ensure high regio- and enantio-selectivity in these reactions. The target compound was reached in a linear reaction sequence of fourteen steps. The strategy was designed to generate common intermediates which could be used to access analogous amino acid fragments in other microsclerodermins. A protected form of AETD 3, from microsclerodermin E, was synthesised via a late-stage common intermediate. Initial studies into the modification of the sequence to allow access to AMPTD 4 and 10-methyl AMPTD 5 were made.

The Wittig reaction has constantly evolved during the last half-century and is one of the most strategic, reliable, widely-applicable carbon-carbon olefin bond forming processes available in organic synthesis. The reaction allows for olefination with complete positional selectivity, relatively high chemoselectivity and may be conducted in many cases with predictable stereocontrol. Triphenylphosphoranylides are ubiquitously employed and despite the myriad benefits these reagents bestow there are known disadvantages to their use—most prominently related to issues surrounding stereoselectivity and phosphine oxide removal which is notoriously problematic. Trialkylphosphoranylides, by contrast, undergo olefination in the presence of carbonyls with high (E)-stereoselectivity and the corresponding short chain trialkylphosphine oxides are water soluble. Previous work in our group has shown that semi-stabilised ylids of this type readily undergo olefination with a broad range of aldehydes under mild aqueous conditions. This aqueous Wittig reaction was then extended to the synthesis of substituted styrenes using aqueous formalin. In the search for ever milder conditions for the Wittig reaction we were also able to develop an organocatalytic Wittig reaction which was amenable to a bioorthogonal process. Thus, we were able to perform the first Wittig reaction in vivo by feeding the two reactants to Castylegia sepium. Alkenals (colloquially enals) are strategic intermediates in organic synthesis; their importance is growing each year due to the expanding breadth of iminium and vinylogous enamine organocatalysis. Unfortunately their preparation remains problematic requiring labour and reagent intensive multi-step sequences. A new pincolacetal-phosphonium salt (DualPhos) for the stereoselective two-carbon homologation of aldehydes has been developed which allows for the one-pot homologation of aldehydes to enals under aqueous and/or anhydrous conditions; its application to the total synthesis and stereochemical reassignment of phomolides G & H is discussed. / Thesis / Doctor of Philosophy (PhD)

No description available.

<p> This thesis describes the development of the Wittig olefination reaction of stabilized, semistabilized allylic trialkylphosphorus ylides with various aldehydes to afford E olefins mainly (E>89%). Since the steric demand of trialkylphosphorus ylides was decreased, aldehydes achieved high E selectivity. On the other hand, predominant or exclusive formation of Z olefms was achieved by using allylic triphenylphosphorus ylides and aromatic aldehydes like benzylaldehyde, while the combination of allylic triphenylphosphorus ylides and such sterically hindered aldehydes as cyclohexanecarboxaldehyde led to E olefm formation upon ylide formation with LiHMDS. In the case of olefination reactions of aldehydes with dimethyl thiazole ylide, it was shown that among the aromatic aldehydes only 4-nitrobenzaldehyde reacted with this ylide and provided a pure E olefin product (41% yield). Dimethylmalonyltributylphosphorane (DMTP) reacted with aromatic aldehydes in toluene at 125 °C to give the corresponding alkenes. 4-Nitrobenzaldehyde· gave the alkene in a much higher yield (81%), followed by 4-chlorobenzaldehyde (31%). With benzaldehyde, the corresponding olefin was isolated in only 14% yield under these conditions. Clearly, this highly stabilized ylide only enters into reaction with electron deficient aldehydes. A possible approach to Z-a, P-unsaturated aldehydes was investigated through the olefination of an acetal-ylide followed by hydrolysis. However, E acetal olefins were in fact isolated from this 2'-(1,3-dioxolanyl)-triethylphosphorus ylide with aromatic aldehydes in good yields (62%-76%). This result is still mechanistically interesting in view of the chemoselective formation of such an ylide in the presence ofthree ethyl substituents on phosphorus. </p> <p> Class of flavonoids: Sakuranetin, Naringenin and (28)-7-methoxy-6hydroxyflavanone, have been isolated from the diseased bark of Prunus sp. The structures were elucidated based on the spectroscopic data. Locations of 4-keto, 5-0H and 7-methoxy were deduced from COSY and HMBC spectra. Such compounds are of interest for their potential antibiotic activity against vancomycin-resistant strains of microbes. </p> / Thesis / Master of Science (MSc)

O presente trabalho descreve 3 abordagens divergentes para obtenção do esqueleto bicíclico presente nos alcaloides indolizidínicos. A primeira abordagem consiste no desenvolvimento de um novo método de preparação de diazocetonas &alpha;,&beta;-insaturadas a partir da reação de Horner-Wadsworth-Emmons (HWE) entre diazofosfonato e aldeídos. As dizocetonas &alpha;,&beta;-insaturadas obtidas foram utilizadas como bloco de construção do esqueleto cabocíclico indolizidínico, onde o intermediário chave foi obtido através do rearranjo de Wolff. A segunda estratégia consiste no desenvolvimento do acoplamento redutivo entre derivados &alpha;-aminocarbonílicos e acrilato de metila mediado por SmI2, onde em apenas duas etapas foram obtidos os intermediários avançados da síntese da (-)-pumiliotoxina 251D e da (+/-)-epiquinamida. A terceira estratégia utiliza como etapa chave a reação de Wittig/HWE intramolecular para preparação do intermediário bicíclico contendo o sistema &alpha;,&beta;-insaturado que pode ser utilizado na síntese divergente dessas substâncias. / Herein were described three diverted oriented approaches for the construction of the bicyclic scaffold of indolizidines alkaloids, that figures between one of the most important classes of natural products. In the first approach, a new method to prepare &alpha;,&beta; - unsaturated diazoketones was described using the Horner-Wadsworth-Emmons (HWE) reaction between diazophosphonate and aldehydes. The unsaturated diazoketones were used as powerful plataforms to construct the indolizidine carbocyclic scaffold, enploying the Wolff rearrangement as the key step. The second approach was the development of a reductive coupling between &alpha;-aminocarbonyl derivatives and methyl acrylate, mediate by SmI2, from this approach, the well-known advanced intermediate for the synthesis of (-)-pumiliotoxin 251D e of the (+/-)-epiquinamide was obtained in only two steps. The third approach uses the intermolecular Wittig/HWE reaction as the key step in the construction of a bicyclic intermediate containing an &alpha;,&beta; -unsaturated moiety that could be used for a diverted oriented approach in the indolizidine alkaloids synthesis.