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The Study of Lactides Syntheses from Esters of Lactic Acide
Tomala, Libor ; Chamradová, Ivana (referee) ; Petrůj, Jaroslav (advisor)
This master thesis deals with the synthesis of lactide from lactic acid esters. The theoretical part focuses on the current understanding of technology of lactic acid, its alkyl esters and the cyclic lactic acid dimer - lactide, which is mainly used as a precursor for the synthesis of high moleculat weight biodegradable polylactide (PLA) and other copolymers. Experimental part is then focused on the synthesis of lactide from lactic acid alkyl esters, especially ethyl lactate. Examines the design of a suitable apparatus for this synthesis and the application of the most appropriate reaction conditions (temperature, pressure, catalysis) to optimize the preparation of the desired product. In the end, parameters of prepared lactide are characterized by using of various analytical techniques.
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The study of using lactic acid esters for preparing lactides and PLA
Vida, Mikuláš ; Figalla, Silvestr (referee) ; Petrůj, Jaroslav (advisor)
This diploma thesis deals with use of lactic acid esters for preparation of lactides and PLA. In the theoretical part, it has been processed literature review focus on manufacturing technologies and properties of lactic acid and its esters (especially ethyl ester and lactides). In the experimental part, it has been designed and realized functional laboratory apparatus for preparation of cyclic dimer of lactic acid – lactides. On this apparatus, there were carried out principal laboratory experiments leading to optimization of lactides yields using various catalysts.
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Synthesis of the violet fragrances on MFI zeolite catalysts
Domenová, Alica ; Mazur, Michal (advisor) ; Kadam, Shashikant Arun (referee)
Zeolites are porous aluminosilicates widely used in acid catalysis due to their properties, such as Brønsted and Lewis acidity, thermal stability, and defined pore structure providing shape selectivity. Zeolites can be synthesized as nanolayered crystals that can be further modified by pillaring. These architectures are more open, thus can lead to novel applications of zeolites in catalysis. One of the acid-catalyzed reactions where 3D standard zeolites were shown to be active catalysts is cyclization of pseudoionone. This reaction is used for the synthesis of α-, β- , and γ-ionones, important organic compounds used in medicine and fragrance industries mainly as violet fragrances. Up to date, there are no reports on the catalytic activity of layered zeolites in ionone synthesis, however, these open structures have a potential to be utilized in such reactions due to the improved reactant diffusion through the catalyst. In this work, catalytic performance of the materials based on MFI zeolite layers was investigated in the conversion of pseudoionone-to-ionones. Catalysts were synthesized using hydrothermal crystallization followed by post-synthesis modification via pillaring. Structure and textural properties of the catalysts were thoroughly characterized using X-ray diffraction and nitrogen...
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Synthesis of Ortho-Condensed Nitrogen Heterocycles Using Gold Complexes
Makaj, Petr ; Matouš, Petr (advisor) ; Kuneš, Jiří (referee)
5 ABSTRACT Charles University, Faculty of Pharmacy in Hradci Králové Department of Organic and Bioorganic Chemistry Candidate: Petr Makaj Supervisor: PharmDr. Petr Matouš, Ph.D Title of Thesis: Synthesis of Ortho-Condensed Nitrogen Heterocycles Using Gold Complexes This diploma thesis is focused on the preparation of pyridopyridine derivatives using gold-catalyzed cyclizations. The synthesis is based on MBS-protected propargylamine, which after substitution with aryl using Sonogashira coupling reacts with tert-butyl (3- oxopent-4-ynyl)carbamate to form substituted 1,5-enyne. The enyne thus prepared then undergoes cycloisomerization using tris(2- furanyl)phosphinegold(I)chloride as a catalyst to form pyridopyridine. Substances with this scaffold can be further used to synthesize potentially biologically active structures. Keywords: gold catalysis, cyclization, pyridopyridine derivatives, 1,8-naphthyridine derivatives
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Synthesis of Chromenopyridines with the New All-Carbon Quaternary Centre
Sedláček, Patrik ; Matouš, Petr (advisor) ; Krátký, Martin (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Candidate: Patrik Sedláček Supervisor: PharmDr. Petr Matouš, Ph.D. Title of thesis: Synthesis of Chromeno[3,4-c]pyridines with New All-Carbon Quaternary Centre This diploma thesis focuses on the synthesis of 3,4-disubstituted pyridine derivatives and their subsequent cyclization to form chromeno[3,4-c]pyridine derivatives with a new all-carbon quaternary center. Phenyl-propiolate reacts with an aryl-substituted propargyl amine protected with 4- methoxybenzenesulfonyl group to form a 1,5-enyne. Substituted 1,5-enyne undergoes intramolecular cyclization catalyzed by tri(2-furyl)phosphinogold(I)chloride [AuCl(TFP)] to form the corresponding dihydropyridine. In the presenece of concentrated H2SO4, dihydropyridine undergoes carbocyclization forming the corresponding chromenopyridine with a new all-carbon quaternary center. The compounds prepared and their derivatives could find application as potentially biologically active substances and intermediates in organic synthesis.
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Conjugate Addition Coupled with Enolate Oxidation in the Total Synthesis of Natural Polyphenols
Mašek, Tomáš ; Jahn, Ullrich (advisor) ; Pospíšil, Jiří (referee) ; Švenda, Jakub (referee)
1 ABSTRACT This thesis describes the development of the concept of C-C bond forming conjugate addition/oxidative cyclisation reactions and their application in the total synthesis of natural polyphenols. The first part deals with the development of methodology for conjugate addition of main- group organometallic reagents to unsaturated carbonyl compounds coupled with in situ single electron transfer oxidation. The resulting radical undergoes stereoselective cyclisation, that can be followed by a second SET oxidation, leading to further cationic cyclisation. This methodology is ideally suited for the synthesis of furoindane stilbenolignans (FIS), a neglected and structurally distinct class of natural polyphenols. Using this process, racemic synthesis of a derivative of kompasinol A was achieved, confirming the relative configuration of FISs. In an effort to develop asymmetric route to FISs, an unprecedented direct conjugate addition of aryllithiums to ylidenemalonates mediated by diethers and diamines was discovered, leading to asymmetric synthesis of gnetifolin F and 11- deoxykompasinol A. Based on X-ray evidence, a related annulation methodology consisting of direct conjugate addition/epoxide opening was shown to result in bridged lactones, instead of isomeric FISs. This finding led to an approach for the...
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Delipment of a new synthetic approach for synthesis of isoquinoline alkaloids
Pašek, Dominik ; Kotora, Martin (advisor) ; Pour, Milan (referee)
This bachelor work is focused on synthesis of a specifically substituted isoquinoline core which is the fundamental structure of natural isoquinoline alkaloids. The main aim is development of a new method for a synthesis of molecules with the isoquinoline framework which could lead to a more efficient way of total synthesis of these important natural substances. The main subject of interest is a cyclization providing a substituted piperidine ring condensed with the tetrahydroisoquinoline core. Zirconocene-based chemistry is used as the crucial synthetic step. Following the development of this new synthetic method, the goal was to study possibilities of cyclization of substituted 1,7-dienes by using the Negishi's reagent. Effects of temperature, reaction time, amount of Negishi's reagent on the course of the reaction as well as stereochemistry of the cyclization were studied. Key words: alkaloid, isoquinoline, synthesis, cyclization, zirconocene, Negishi's reagent
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Tandem Anionic Sigmatropic Rearrangement/Radical Reactions and Their Application Toward the Total Synthesis of Natural Products
Šimek, Michal ; Jahn, Ullrich (advisor) ; Urban, Milan (referee) ; Švenda, Jakub (referee)
The thesis describes the development of unprecedented tandem reactions merging anionic oxy-Cope rearrangement with single-electron transfer oxidation of thus generated metal enolates by ferrocenium hexafluorophosphate. The formed α-carbonyl radicals were utilized in oxygenation reactions by coupling them with persistent radical TEMPO, furnishing rearranged α-aminoxy carbonyl compounds. Suitable reaction conditions and factors influencing the rearrangement aptitudes were determined. The obtained polyfunctional products proved versatile in diversifications by polar reactions producing diverse scaffolds. Furthermore, rearranged α-aminoxy carbonyls with a double bond located in the δ-position of the carbonyl group are applicable in all-carbon 5-endo-trig radical cyclizations governed by the persistent radical effect. Despite the low kinetic rate, this rare cyclization mode furnished a number of substituted cyclopentanes. The reaction scope, including competitive cyclization modes, was studied. The developed methodology was utilized as a key reaction step to synthesize appropriately substituted cyclopentane core in a divergent approach to meroterpenoid fungal metabolites isolated from Ganoderma applanatum. The accomplished synthesis of applanatumols V and W and their epimers enabled the correction of...
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New Thermal and Oxidative Radical Cyclization Methodology and Application to the Total Synthesis of Bridged Diketopiperazine Alkaloids
Amatov, Tynchtyk ; Jahn, Ullrich (advisor) ; Pour, Milan (referee) ; Cibulka, Radek (referee)
This thesis describes the development of new thermal and oxidative radical cyclization methodologies and their application to the total syntheses of alkaloids, particularly to bridged diketopiperazine (DKP) alkaloids. A practical solvent free approach to diverse DKPs and quinazolines is described. The methodology proceeds by thermal silica gel mediated deprotection of the Boc protecting group and intramolecular condensation of the resulting free dipeptides and tripeptides. It was applied to the total syntheses of alkaloids glyantrypine and ardeemin. A major part of the thesis concerns with the discovery and applications of novel diketopiperazine derived alkoxyamines. Their propensity to undergo facile thermal C-O bond homolysis to generate captodative DKP radicals and persistent TEMPO radical allowed using them as radical surrogates. The methodology takes advantage of the persistent radical effect (PRE). The methodology based on PRE was applied in an asymmetric approach to the alkaloid asperparaline C. An asymmetric synthesis of a very advanced precursor to asperparaline C, 8- oxoasperparaline C, was accomplished in 11 steps and 15% overall yield. The key steps of the synthesis include a direct oxidative cyclization of DKPs, regioselective furan dearomatization with singlet oxygen and a reductive...
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