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Synthesis of the C15-C20 tiacumicin fragment
Havlíček, Vojtěch ; Kotora, Martin (advisor) ; Veselý, Jan (referee)
In the diploma thesis, a method for preparation of the unsaturated C15-C20 tiacumicin fragment was developed. Tiacumicin is classified as a macrolidone antibiotic. Although three syntheses of tiacumicin have been recently published, this study has aimed to develop a novel pathway for its preparation utilizing catalytic reactions instead of stoichiometric ones. In the second part, an enantioselective allylation of (E)-3-jod-2-methylpropenal has been developed applying catalysis by a series of N,N'-dioxide catalysts. The asymmetric induction achieved in the allylation was up to 99% ee. This procedure allows relatively simple, straightforward and efficient preparation of wide range of natural products. Keywords tiacumicin, asymmetric synthesis, allylation, catalysis, chiral Lewis bases, organocatalysis
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Transition metal complexes catalyzed synthesis of biologically active estrone derivatives
Prchalová, Eva ; Kotora, Martin (advisor) ; Moravcová, Jitka (referee) ; Hlaváč, Jan (referee)
This thesis relates to the preparation and use of new non-estrogenic ligands selective for certain types of the 17β-hydroxysteroid dehydrogenase superfamily (17βHSD). Such nonestrogenic compounds, which selectively regulate the activity of 17βHSD are believed to offer new solutions in endocrine therapy, diagnosis and treatment of estrogen-dependent types of diseases. In recent years in the laboratories of my supervisor prof. Kotora differently substituted steroid derivatives with interesting biological properties were prepared. Based on the gained experiences, it was decided to prepare C-15 estrone derivatives. Such compounds are mostly unexplored, and therefore they might be a new class of interesting biologically active compounds. A method was developed for the preparation of C-15 estrone derivatives. Estrone, the starting material for the synthesis, was first converted to the appropriate intermediate, protected estra-1,3,5(10),15-tetraene-17-one. Conjugate addition of vinylmagnesium bromide to this enone yielded the starting material for further reactions, 15β-vinylestrone. Cross metathesis of 15β-vinylestrone with suitable terminal olefins provided large series of C-15 estrone derivatives with perfluoroalkylated, aliphatic and aromatic side chains. Selected unsaturated derivatives were tested...
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Synthesis of Specifically Substituted Heterocycles via Catalytic Reactions
Kratochvíl, Jiří ; Pour, Milan (advisor) ; Kotora, Martin (referee) ; Dvořák, Dalimil (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Inorganic and Organic Chemistry Candidate Mgr. Jiří Kratochvíl Supervisor prof. RNDr. Milan Pour, Ph.D. Title of Doctoral Thesis Synthesis of Specifically Substituted Heterocycles via Catalytic Reactions This Ph.D. thesis deals with the synthesis of γ-alkylidene-α,β-unsaturated δ-lactones and lactams. Migita- Stille cross-coupling served as the key step in their preparation. Catalysis with palladium black was applied to the synthesis of the lactones and we demonstrated that it doesn't act as heterogeneous catalyst. Instead, it's only a precursor for catalytically active species, which is generated in situ and its true nature is unknown. The palladium nanoparticles are most likely responsible for the catalysis, although involvement of complexed atomic palladium cannot be excluded. Palladium black catalysis was also successfully applied to the synthesis of a series of structurally different substrates, which demonstrates its versatility and it was also proved that the catalyst can be easily recycled by simple filtration. An unusual Tsuji-Trost reaction then enabled transfer of the alkylidene substituent of the lactones to C5 furnishing polysubstituted heterocycles.
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Synthesis of New Types of Biologically Active Substances Using the Organometallic Compounds
Korotvička, Aleš ; Kotora, Martin (advisor) ; Dvořák, Dalimil (referee) ; Starý, Ivo (referee)
This work consists of four separate chapters. Although they are seemingly different projects, they have a common feature - the application of organometallic chemistry. 1. Lusianthridin and denbinobin, the phenanthrene derivatives, can be found in plants of the family Orchidaceae. They exhibit cytostatic activity against cancer of human lung and ovarian and against promyelocytic leukemia. Therefore, new synthetic methods for these substances may be applied in research and development of new bioactive compounds. I prepared 9,10- disubstituted phenanthrenes through reactions of biphenylene with alkynes, which were catalyzed by iridium complexes. Phenanthridine derivatives are found naturally in the group benzo[c]phenanthridine alkaloids. The most famous of these include sanguinarine and chelerythrine. Sanguinarine selectively induces apoptosis (planned cell death) of human cancer cells and, therefore, is investigated as a potential antitumor agent. Chelerythrine selectively inhibits protein kinase C, leading again to apoptosis. I have studied reactions of biphenylene with nitriles catalyzed by rhodium complexes that have not been described yet. By this, I prepared a series of 6-substituted phenanthridines. 2. Carboranes are artificially prepared organic compounds of boron, which are not represented in...
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Synthesis of biologically active compounds with quinazoline scaffold
Štěpánek, Ondřej ; Kotora, Martin (advisor) ; Hájíček, Josef (referee) ; Moravcová, Jitka (referee)
This thesis concludes my contribution to research of HIV-1 capsid assembly inhibitors. It has been shown that 2,4-disubstituted quinazoline derivatives are able to inhibit this process both, in competitive biochemical assay based on the AlphaScreen technology as well as in tissue cultures. The main objective of the work was to prepare the aforementioned quinazolines, to design and prepare new candidates with higher activity based on results of biochemical tests, and also to try to increase the solubility of otherwise poorly soluble compounds. Disubstituted quinazolines are relatively easily accessible from the commercially available anthranilic acid derivatives. These are converted to the corresponding quinazolin- 4(3H)-ones by the condensation reactions. In this work, two methods were used for the preparation of quinazolin-4(3H)-ones: reaction of acyl chlorides with aromatic anthranilamides provided 2-arylamidobenzamides whose subsequent cyclisation under basic conditions led to derivatives of 2-arylquinazolin-4(3H)-one; reaction of anthranilic acid esters with aromatic nitriles, which afforded desired quinazolin-4(3H)-one in one reaction step. Chlorination of 2-arylquinazolin-4(3H)-ones using POCl3 then led to 2-aryl-4- chloroderivatives as key intermediates. Nucleophilic substitution of...
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Development of new methods for the synthesis of compounds containing the pyridine ring
Frejka, David ; Kotora, Martin (advisor) ; Machara, Aleš (referee)
Tato diplomová práce se zabývá novými reakcemi v oblasti katalytických aktivací C-C vazeb v substrátech obsahující pnuté kruhy a jejich následné funkcionalizace při reakcích s trojnou vazbou alkynů vedoucí k rychlé a jednoduché přípravě regioselektivně substituovaných polyaromatických derivátů. V rámci této práce byly vyvinuty vůbec první postupy umožňující selektivní aktivace C-C vazeb v nesymetricky substituovaných systémech (1-azabifenylenech) vůči pnutému kruhu a jejich reakce se substituovanými alkyny na principu cyklotrimerizace. Místo inserce alkynu může být ovlivněno použitím některých katalytických systémů obsahující iridiové a rhodiové komplexy (schéma 1). Tento postup umožňuje jednoduchou, přímočarou a efektivní přípravu derivátů benzochinolinových skeletů, které jsou hojně využívány v mnoha oblastech chemie. Schéma 1 Regioselektivní aktivace C-C vazeb v 1-azabifenylenech Klíčová slova: aktivace C-C vazeb, 1-azabifenylen, cyklotrimerizace, inserce
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Synthesis of new organocatalysts based on bipyridines
Ulč, Jan ; Kotora, Martin (advisor) ; Veselý, Jan (referee)
1,1'-Bis(tetrahydroisoquinoline)-N,N'-dioxides represent a class of strong Lewis bases, which are used in organocatalysis for allylation of aldehydes. In this master thesis new chiral unsymmetrically substituted 1,1'- bis(tetrahydroisoquinoline)-N,N'-dioxides were prepared by a simple three-step synthesis (scheme 1). The first step of this approach was cyclotrimerization of octa-1,7-diyne with nitriles providing tetrahydroisoquinolines, which were oxidized to corresponding N-oxides. In final step two different N-oxides were subjected to oxidative coupling reaction, which produced unsymmetrically 3,3'-disubstituted 1,1'-bis(tetrahydroisoquinoline)-N,N'-dioxides. The main advantages of this method are short reaction times and easy availability of the starting materials. Scheme 1 The catalytic activity and asymmetric induction of these new N,N'-dioxides were explored in allylation of aldehydes by allyltrichlorosilane in different solvents. Key words: organocatalysis, allylation, N,N'-dioxide, cyclotrimerization
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The D-A and pi-pi interactions and their use in self-assembly
Rejchrtová, Blanka ; Starý, Ivo (advisor) ; Kotora, Martin (referee)
The D-A and π-π Interactions and Their Use in Self-Assembly Due to their well-defined shape, size and properties gold nanoparticles represent an advantageous platform for the study of non-covalent interactions between ligands anchored to their surface both in solution and in monolayers or thin films. The aim of this thesis was the synthesis of ligands for gold nanoparticles bearing an anchoring group at one end and a planar π-electron rich pyrene unit at the other. Six structurally variable ligands were prepared differing in the pyrene substitution pattern and the spacer between the aromatic part and the acetylated thiol function. Furthermore, a synthetic pathway leading to extended π-electron systems (both electron rich and electron poor) such as hexabenzocoronene derivatives and its fragments was explored. The key steps in the synthesis of these compounds are the cyclization reactions of alkynes leading to polycyclic intermediates and their ensuing cyclodehydrogenation (Scholl reaction). All of the prepared ligands and their intermediates were characterized by spectroscopic methods. The structure of the key hexakis(pentafluorosulfanyl-phenyl)benzene was confirmed by single crystal X-ray crystallography. The prepared ligands bearing a pyrene unit were deacetylated and anchored to the surface of...
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Syntehsis of coibacines
Kolská, Kristýna ; Kotora, Martin (advisor) ; Veselý, Jan (referee)
Development of new asymmetric processes is one of the objectives of catalysis in organic chemistry. These processes can provide access to chiral building blocks applicable in syntheses of various natural substances that can be used for medical purposes. One such process is the preparation of chiral homoallyl alcohols, which have been used for syntheses of variety of biologically active compounds. In view of the aforementioned, suitably substituted homoallyl alcohols could be used as intermediates in syntheses of koibacins A-D, which have a number of interesting biological properties. Natural koibacins A-D are metabolites isolated from the marine cyanobacterium Oscillatoria sp. that exhibits selective antileishmanial activity and potent antïinflammantory properties. Our synthetic plan is focused on an approach through the allylation of aldehydes, esterification, ring closing metathesis and finally cross metathesis with different lipophilic fragments. Key words: enantioselective allylation, asymmetric synthesis, natural compounds, coibacins.
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