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Application of enantioselective allylation for synthesis of compounds isolated from Streptomyces gramineus
Morávková, Terézia ; Kotora, Martin (advisor) ; Matoušová, Eliška (referee)
E-492, actinofuranone A, and JBIR-108 are natural compounds isolated from actinobacteria Streptomyces genus and can lead to the development of new pharmaceuticals as they have some biological interesting activities. Although the synthesis of these actinofuranones has been already published, this work brings new methods for the preparation of their fragments. The key step of the synthesis is enantioselective crotylboration of an aldehyde catalyzed by a chiral Brønsted acid and by which two centres of chirality are introduced in one step. The other crucial steps of the synthesis are composed of Ru-catalyzed alkene-alkene cross-metathesis and Pd- catalyzed Suzuki cross-coupling. Keywords: natural compound, enantioselective syntheses, crotylation, catalysis, actinofuranone fragment
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Catalytic Cycloaddition Reactions of Tribenzocyclyne
Jacko, Jaroslav ; Kotora, Martin (advisor) ; Schulz, Jiří (referee)
The main aim of the bachelor thesis was to investigate the reactivity of tribenzocyclyne, a triangular molecule, undergoing reactions with antiaromatic biphenylenes and their heteroanalogues. Those reactions consist of C-C activations of strained bond mediated by the complexes of the group 9 elements, followed by migratory insertion of present alkyne which leads to the formation of a substituted aromatic ring. Presented method facilitated the setting of a experiment as well as cutting down on reaction steps. These investigations will subsequently serve for further progress in the chemistry of cyclic hexa- ortho-phenylenes. Key words: catalysis, cycloaddition, tribenzocyclyne, the C-C bond cleavage
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Activity of new nickel-complexes in coupling reactions
Plaček, Martin
In this work, we report the study of the catalytic activity of newly prepared coordination compounds of nickel(II) (complexes were prepared by prof. Kyritsis, University of Athens). The activities in model reactions of Kumada and Suzuki coupling and polymerization of 2,5- dibromo-3-hexylthiophene were tested. For Kumada coupling, the activity is comparable with known complex [Ni(dppp)Cl2]. On the other hand, selected complexes exhibit only limited activity for Suzuki coupling. GRIM polymerization of 2,5-dibromo-3-hexylthiophene was successful. Properties of prepared polymers are comparable with polymers prepared via known route with [Ni(dppp)Cl2].
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Development of new syntheses of condensed aromatic compounds
Kaiser, Reinhard Peter
This work is divided into two parts that are focused on the synthesis and assessment of photophysical properties of two structurally related compounds: (i) 9,9'-spirobifluorenes (SBFs) and (ii) dispiroindeno[2,1-c]fluorenes (DS-IFs). (i) In the first part, a five-step synthetic approach to SBFs was developed and as the crucial step was used an intermolecular [2+2+2] cyclotrimerization of symmetrically or unsymmetrically substituted diynols with alkynes catalyzed by Rh-complexes. Catalyst screening showed that Wilkinson's catalyst (RhCl(PPh3)3) had the highest efficiency in yielding 1,2,3,4-substituted fluorenols - the key intermediates. The fluorenols were then converted into SBFs bearing various electron-donating and -withdrawing groups, aromatic substituents, and -extended aromatic hydrocarbon moieties (PAHs). Altogether 19 different SBFs were prepared and their photophysical properties screened. The fluorescent emission maxima em were in the range of 315-389 nm with excellent quantum yields s (up to 1.00). As far as the substituent effect is concerned the presence of electron-withdrawing substituents on the SBF scaffold results in the red-shift of the emission maxima. (ii) In the second part, a similar synthetic strategy was applied for synthesis DS-IFs. In this instance was utilized again the...
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Theoretical investigation of novel two-dimensional materials with application potential
Lyu, Pengbo ; Nachtigall, Petr (advisor) ; Maurin, Guillaume (referee) ; Straka, Michal (referee)
Electron confinement due to the two-dimensional (2D) nature of layered materials accounts for their fascinating electronic properties and for their applications in new-generation electronic devices. Moreover, the large specific surface area of 2D materials also enables their use in surface-related applications, such as catalysis and adsorption. In addition, these 2D materials are promising photocatalysts thanks to the shorter migration distance of photogenerated electrons and of electron holes. The research reported in this thesis aimed to provide atomistic insight into 2D layered materials, particularly into their structures, electronic properties and potential applications in the field of catalysis, photocatalysis and alkali metal ion batteries. Our findings are not only theoretically relevant but also open new research avenues for our experimental collaborators to improve specific properties and activities of their materials. The main results from this thesis, for five different classes of 2D materials, are summarized below. 2D covalent organic frameworks (COFs). CTF-type COFs with similar topology but different nitrogen-to-carbon ratios were investigated for their potential in photocatalytic water splitting. More specifically, torsion and bending effects on structure stability were investigated in...
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Application of a Bolm ligand analog in catalysis
Malatinec, Štefan ; Kotora, Martin (advisor) ; Matoušová, Eliška (referee)
Bolm`s ligand belongs to the group of 2,2'-bipyridines, which represents a class of C2 symmetric ligands. These ligands form complexes with Lewis acids, which could be used in asymmetric catalysis, for example in the ring-opening of epoxides. Bolm`s ligand analogue was prepared and the enantioselectivity of the ring-opening reaction of cis-stilben oxide with aniline and variety of substituted benzyl alcohols catalyzed by scandium(III) triflate was studied as a part of this bachelor thesis. The enantioselectivity of the reaction using Bolm's ligand analogue was compared to that of Bolm`s ligand. Key words: synthesis, catalysis, bipyridines
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Development of new syntheses of condensed aromatic compounds
Kaiser, Reinhard Peter ; Kotora, Martin (advisor) ; Starý, Ivo (referee) ; Dvořák, Dalimil (referee)
This work is divided into two parts that are focused on the synthesis and assessment of photophysical properties of two structurally related compounds: (i) 9,9'-spirobifluorenes (SBFs) and (ii) dispiroindeno[2,1-c]fluorenes (DS-IFs). (i) In the first part, a five-step synthetic approach to SBFs was developed and as the crucial step was used an intermolecular [2+2+2] cyclotrimerization of symmetrically or unsymmetrically substituted diynols with alkynes catalyzed by Rh-complexes. Catalyst screening showed that Wilkinson's catalyst (RhCl(PPh3)3) had the highest efficiency in yielding 1,2,3,4-substituted fluorenols - the key intermediates. The fluorenols were then converted into SBFs bearing various electron-donating and -withdrawing groups, aromatic substituents, and -extended aromatic hydrocarbon moieties (PAHs). Altogether 19 different SBFs were prepared and their photophysical properties screened. The fluorescent emission maxima em were in the range of 315-389 nm with excellent quantum yields s (up to 1.00). As far as the substituent effect is concerned the presence of electron-withdrawing substituents on the SBF scaffold results in the red-shift of the emission maxima. (ii) In the second part, a similar synthetic strategy was applied for synthesis DS-IFs. In this instance was utilized again the...
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Enantioselective synthesis of an actinofuranone fragment
Morávková, Terézia ; Kotora, Martin (advisor) ; Machara, Aleš (referee)
This bachelor thesis is focused on the new preparation procedure of the unsaturated actinofuranone fragment JBIR-108 which was isolated from actinobacteria Streptomyces gramineu. This exotoxin appears to be cytotoxic to some types of cancer cells. Although the synthesis of this actinofuranone has already been published by the group of T. Doi,1 this work brings a new method for the preparation of fragment C7-C18. The key steps for this synthesis are crotylation reaction, cross metathesis and Suzuki cross-coupling. Key words: crotylation, natural compound, actinofuranone fragment, Suzuki cross-coupling, asymmetric synthesis
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Synthesis of polycyclic compounds containing quaternary carbon centers
Vašíček, Tomáš ; Matoušová, Eliška (advisor) ; Míšek, Jiří (referee)
In this diploma Thesis, a method for the preparation of polycarbocyclic compounds containing all-carbon quaternary centers embedded in triquinane skeleton was prepared. The key reaction sequence leading towards the preparation of these carbocycles was Pd-catalyzed tandem cyclization/Suzuki cross-coupling reaction followed by halocarbocyclization. In the first part of synthetic project, a model oxygen-containing polycyclic derivative was prepared. In the second part, 3 novel polycarbocyclic compounds containing all-carbon quaternary centers were successfully prepared. Synthetic procedure for the starting material required for the key reaction sequence was developed. This approach represents another pathway for the synthesis of polycarbocyclic natural products. Keywords: synthesis, polycyclic compounds, quaternary centers, catalysis
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Theoretical Investigation of ethanol dehydration catalyzed by acid sites in zeolites
Vacek, Jaroslav ; Nachtigall, Petr (advisor) ; Uhlík, Filip (referee)
Zeolites are a group of aluminosilicate minerals with catalytic properties. They may be used for many industrial applications such as catalytic cracking of oil. Zeolites are also capable of converting ethanol to diethylether and ethylen. This reaction is known as dehydration of ethanol. The reaction is potentially interesting as a way of converting ethanol to more valuable molecules. An experimental study (Shashikant A. Kadam, Mariya V. Shamzhy, 2018) has proven that diethylether is the preferred product when the temperatures are low and the partial pressure of ethanol is high. Ethylen is more significant product with higher temperature and lower partial pressure of ethanol. Aim of this thesis is to determine the mechanism of dehydration of ethanol. Furthermore it was attempted to explain the behavior of the reaction under different circumstances. The research was done in silico using the methods of computational chemistry. Such methods give information on the geometry and the energy of systems of molecules. Thus computational chemistry can be used to investigate the relational path and activation energy of the studied reaction. This thesis is a theoretical study of dehydration of ethanol catalysed by a zeolite.
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