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Reactions of Alkenes Iniciated by Transition Metals Alkyls and Hydrides
Nečas, David ; Kotora, Martin (advisor) ; Jindřich, Jindřich (referee) ; Starý, Ivo (referee) ; Mazal, Ctibor (referee)
l0 5. Conclusion 1) The first and practical catalýic method for smooth deallylation of 2-substituted-2-allylmalonates to 2-substituted malonates via selective cleavage of the C-C bond under mild reaction conditions has been developed' The reaction seems to be general with respect to the transition-metal complexes; however, the comparison of Ru and Ni catalysts indicates considerable differences in their specific activity and selectiviý. Last but not least, the smooth deallylation offers an opportuniý to use the allyl group as an effective protective group for acidic hydrogen of malonic esters. 2) It has been shown that it is possible to re-route the course of the reaction from c{ bond cleavage (deallylation) to c{ bond formation (cyclization) in Ni hydride cataryzed, reactions by a change in the amount of organoaluminium. It proceeded in high yields even in cases where deallylation could compete with cyclization (e.g. diallylmalonate, etc.) in high selectiviý. In addition, generation of Ni hydride species in sinr provides an effective means for fast and selective cyclization of variously substituted 1,6- heptadienes to cyclopentanes. Moreover, it is possible exert certain level of control for the preferential formation of methylidene(methyl)cyclopentanes or cyclopentenes by the appropriate choice of thb...
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Chemical and Physical Properties of Single Molecules and Their Assemblies Adsorbed on Solid Surfaces
Houska, Václav ; Starý, Ivo (advisor) ; Mazal, Ctibor (referee) ; Církva, Vladimír (referee)
Interaction of organic molecules with solid surfaces represents a key area of physical-chemistry research. From heterogenous catalysis to OLED displays, in numerous such systems molecules interact on interfaces, and understanding their behavior is crucial for the correct operation of such applications. In this work, I focused on the study of large π-conjugated macrocycles based on dibenzo[5]helicenes with emphasis on their behavior on graphite surface. The chemical synthesis of the investigated macrocycles was initially impeded by a number of obstacles, particularly by their extremely low solubility. In this work, an efficient solubilization strategy based on the modification of the macrocycles with trityl groups was discovered, which effectively diminishes the intense intermolecular π-π interactions. This opened a path towards a subsequent study of the compound's properties. The attention was focused mainly on a trimer, which was successfully fully characterized, enabling further experiments. Since only a few tens of milligrams of the trimer was prepared, and some stereoisomers were isolated in only microscopic amounts, it was important to develop a suitable experimental methodology. These methods were successfully employed in the measurement of the isomerization kinetics, which allowed us to map...
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Toward Asymmetric Total Syntheses of Podophyllotoxin Derivatives
Svoboda, Tomáš ; Jahn, Ullrich (advisor) ; Starý, Ivo (referee)
Podophyllotoxin is a naturally occurring lignan with a wide range of biological activities, including anti- cancer and anti-viral properties. Total synthesis of podophyllotoxin has been a long-standing challenge in organic synthesis due to its complex and highly functionalized structure. In this work, we present our approach toward the total synthesis of podophyllotoxin using a fully stereoselective strategy. Our approach involves the enantioselective vinylation of 2-bromo-piperonal followed by a stereoselective conjugate addition reaction combined with the addition of methylene unit and a metathesis reaction, that provides starting material for another conjugate addition, which could lead to the target. The key step of our synthesis is the stereoselective conjugate addition of an organolithium to an α,β-unsaturated ester, which leads to the formation of a chiral quaternary center with high selectivity and metathesis that successfully joins parts into the desired cycle. Despite the success of our strategy in achieving the desired stereoselectivity, we encountered some challenges in the subsequent steps of the synthesis, which prevented us from completing the total synthesis of podophyllotoxin. However, our results demonstrate the potential of enantioselective vinylation and stereoselective...
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The synthesis of π-electron systems suitable for transfer and retention of charges
Nejedlý, Jindřich ; Starý, Ivo (advisor) ; Tobrman, Tomáš (referee) ; Storch, Jan (referee)
The aim of my Thesis was to develop a general synthetic methodology for the preparation of long helicenes equipped with suitable functional groups that control their solubility or serve as anchoring groups for attachment to metallic surfaces, especially gold. The well-established transition metal catalyzed [2+2+2] cyclotrimerization of triynes was selected as the key scaffold-forming transformation in the synthesis of long helicenes because of its high regioselectivity, atom efficiency, functional group tolerance and general robustness. A modular approach was used for the preparation of the starting oligoynes, thus enabling a high level of their structural diversity. Individual resorcinol- based aromatic building blocks were interconnected by Sonogashira cross-coupling reactions, providing complex cyclization precursors encompassing up to twelve alkyne units pre-arranged for the multiple [2+2+2] cycloisomerization to produce three six- membered rings from each set of three neighboring alkyne units. Thus, a small series of long helicenes with up to 19 rings constituting the helical scaffold was synthesized. The quadruple cyclization leading to the longest oxahelicene prepared to date was performed in a high-temperature-high-pressure flow reactor at 250 řC in the presence of CpCo(CO)2. The set of...
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The study of self-assembly governed by the formation of donor-acceptor complexes
Warzecha, Tomáš ; Starý, Ivo (advisor) ; Betík, Robert (referee)
The study of self-assembly governed by the formation of donor-acceptor complexes This work deals with the preparation of 2-[(3-carboxyphenyl)ethynyl]benzoic acid, which a represents simplified model of monodisperse (p-phenylen)ethynylene oligomers, functionalized by carboxylic groups. Such a dicarboxylic acid was synthesized via Sonogashira coupling and then taken over to a series of diesters with corresponding alcohols. The theoretical part contains concise introduction to nanoscience, self assembly and donor - acceptor (D-A) interactions. The most frequently used synthetic reactions - Sonogashira coupling and Steglich esterification are described. The experimental part deals with the preparation of dimeric dicarboxylic acid and corresponding esters with alcohols containing electronacceptor functional groups. The synthetized compounds were characterized by spectroscopic methods (NMR, MS, IR, UV/VIS) and elemental composition established by HR MS. Melting points were measured for crystalline compounds.
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The pi-electron oligomers: Their synthesis and properties
Warzecha, Tomáš ; Starý, Ivo (advisor) ; Kotora, Martin (referee)
The pi-electron oligomers: Their synthesis and properties This diploma thesis is focused on the synthesis of p-oligophenyleneethynylene rods (dimer and trimer) containing laterally attached naphtalenediimide units as electron acceptor groups. These functionalised short oligomers are intended to serve as model oligodentate acceptors in the study on multiple interactions with electron rich molecules. The oligomers were assembled from building blocks such as aryl iodides and aryl alkynes bearing a naphthalenediimide unit. The functionalised monomers were combined in a stepwise way by using Sonogashira reaction to form the target p-oligophenyleneethynylene oligomers. The introductory UV-VIS spectroscopic studies on charge transfer complexes between electron donor (pyrene) and electron acceptor (a naphthalenediimide derivative) were performed. In addition, multiple noncovalent interaction between the electron acceptor dimer containing two naphthalenedimide moieties and the electron donor dimer containing two pyrene moieties were investigated by using 1 H NMR titration. The resulting oligomers and their precursors were characterized by using 1 H NMR, 13 C NMR, MS and IR spectroscopy.
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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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The synthesis of functionalised electron donors and acceptors and the study of their interaction
Rejchrtová, Blanka ; Starý, Ivo (advisor) ; Betík, Robert (referee)
This work is focused on the stepwise preparation of model dimer, containing tetrathiafulvalene as electron donor unit. Main method used in the synthesis was Sonogashira coupling. Theoretical part deals with current state of research in the field of nanoscience and nanotechnology and molecular electronics. It is focused on noncovalent interactions, especially of the electron donor - electron acceptor (CT complexes). Properties of tetrathiafulvalene and its derivatives are described in detail as well as mechanism of Sonogashira coupling. In the part devoted to the results and discussion is described preparation of monomeric precursor from known TTF alcohol and new iodobenzylbromide with protected acetylene function. Stepwise synthesis utilizing Sonogashira coupling leads to the preparation of model dimer in moderate yield. All new compounds were characterized by spectral methods (NMR, MS, FTIR) and by elemental analysis, eventually HR-MS.
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The synthesis and development of new catalyst with the bipyridine scaffold.
Kadlčíková, Aneta ; Kotora, Martin (advisor) ; Starý, Ivo (referee) ; Veselý, Jan (referee)
1 Abstract Chiral N,N'-dioxides serve as very useful catalysts in various enantioselective reactions. I developed a simple and efficient method for preparation of new unsymmetrically substituted axially chiral bis(tetrahydroisoquinolines)-N,N'-dioxides, based on "one-pot" [2+2+2]-cyclotrimerization of a tetrayne with benzonitrile and (R)-tetrahydrofurancarbonitrile catalyzed by CpCo(CO)2 under microwave irradiation (scheme 1)1,2 . First, the prepared chiral N,N'-dioxides were used as catalysts in highly enantioselective allylations of variously substituted aromatic, aliphatic and α,β-unsaturated aldehydes. The corresponding homoallylalcohols were obtained with ee up to 99%. Two obtained chiral homoallylalcohols prepared by allylation were used as a building-blocks for synthesis of some natural products such as (S)-(-)-Goniothalamin (scheme 2)3 . Second, the chiral N,N'-dioxides were also used for the epoxide ring opening of various meso-epoxides with tetrachlorosilane giving rise to chlorohydrines in moderate enantioselectivities (up to 64% ee) (scheme 3)4 . N N OScheme 1 + N N O O O CpCo(CO)2 MCPBA O NC NC SiCl3 Cat. (1-5mol%) O O (S)-(-)-Goniothalamin, 97% ee Ph R OH up to 99% ee Scheme 2 R R R = phenyl, alkyl O OHClSiCl4 up to 64% ee R H O R= Ar, alkyl, ArCH=CH, alkyl-CH=CH Ph H Scheme 3 Cat. O Cat....
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