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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Cyklizační reakce 1,5-enynů katalyzované komplexy zlata / Gold-Catalyzed Cyclizations of 1,5-Enynes

Matouš, Petr January 2020 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department Department of Organic and Bioorganic Chemistry Candidate Mgr. Petr Matouš Supervisor prof. RNDr. Milan Pour, Ph.D. Titel of Doctoral Thesis Gold-Catalyzed Cyclizations of 1,5-Enynes This Ph.D. thesis deals with the development of gold(I)-catalyzed cyclizations of propargylamino acrylates (3-aza-1,5-enynes) in the presence of an external nucleophile. A library of tetrahydropyridines with an unusual hemiaminal ether functional group was thus prepared via the cyclization of a series of substituted enynes. The influence of the protective group as well as the substitution on the chemoselectivity of the reaction was demonstrated. The tetrahydropyridines were further utilized as precursors for the preparation of pharmaceutically important nitrogen heterocycles. The reduction of selected compounds furnished substituted piperidines, while Diels-Alder cycloaddition of alkenylated tetrahydropyridines gave rise to isoquinoline derivatives. Additional ortho-fused heterocycles (furopyridine, pyrrolopyridine and chromenopyridine) were prepared by the intramolecular version of the cyclizations of enynes with pending internal nucleophiles.
22

Syntéza analogů aerothioninu jako potenciálních antimykobakteriálních sloučenin / Synthesis of aerothionin analogs as potential antimycobacterial agents

Šimovičová, Martina January 2021 (has links)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Author: Martina Šimovičová Supervisors: Assoc. Prof. PharmDr. Jan Zitko, Ph.D.; Adjunct Prof. Paula Kiuru, Ph.D. Title of diploma thesis: Synthesis of aerothionin analogs as potential antimycobacterial agents Key words: antimycobacterial; tuberculosis; synthesis; aerothionin; bromotyrosines Drugs currently used for the treatment of tuberculosis are the result of studies carried out 50 or 60 years ago. With the constantly growing bacterial resistance to these pharmaceuticals grows also the importance of research for new antimycobacterially active compounds. The marine environment undoubtedly holds an enormous potential for discovering new leads for the development of antitubercular agents. One of these leads is a spirocyclic compound called aerothionin (1), which was found to be active against multidrug-resistant strains of Mycobacterium tuberculosis, as well as three non-tuberculosis mycobacteria (Figure 1). In addition, several spirocyclic structures (not only from marine origin) were discovered to affect on the M. tuberculosis in recent years, making this structure segment attractive for antitubercular research. Figure 1: Aerothionin (1) and general structure of the...
23

Využití organokatalytického konceptu pro přípravu enantiomerně čistých laktamů / Preparation of enantiomerically pure lactams based on the organocatalysis

Humpl, Marek January 2012 (has links)
Different catalytic approaches have been applied to new -lactams preparations. olefin metathesis has been successfully performed with 3--methylidene--lactams. It was verified that 3--methylidene--lactams olefin metathesis is applicable to preparation of biologically active -lactam of Ezetimibe-type.
24

Přímý číslicový syntezátor pro mikrovlnné aplikace / Direct digital synthesizerfor microwave application

Dluhý, Vojtěch January 2015 (has links)
The aim of this thesis is introduce readers to the basics of digital frequency synthesis and design of direct digital synthesizer with circuit AD9951 by Analog Devices. The device will be controlled from a PC via USB. The device works with internal oscillator, with the ability to connect an external frequency standard of 10 MHz. On input is frequency doubler with transistor. Outpu signal is filtered by low-pass filter and amplified by monolitic amplifier ERA-3+.
25

Využití organokatalýzy na přípravu biologicky aktivních sloučenin / Preparation of biologically active compounds using organocatalysis

Šimek, Michal January 2015 (has links)
This diploma thesis deals with the use of organocatalysis in an asymmetric allylic substitution reaction of Morita-Baylis-Hillman carbonates by aniline derivatives leading to enantiomerically enriched allylic amines. The first part of the thesis is focused on optimizing the reaction conditions in the organocatalytic reaction with respect to the yields and enantiomeric excesses of the products. In the second part of the thesis prepared enantiomerically enriched allylic amines are used in the cyclization step to give β-lactame cycles that serve as the key intermediates in the total synthesis of Ezetimib as is demonstrated in the final part of the diploma thesis.
26

Evoluční resyntéza kombinačních obvodů / Evolutionary Resynthesis of Combinational Circuits

Kocnová, Jitka January 2017 (has links)
This master thesis is concerned about the resynthesis of combinational circuits with the help of evolutional principles. The first part of this text describes logic synthesis and its weak spots, evolutional synthesis and its advantages, and also some of the existing synthesis programs. The second part shows usage of graph algorithms in logic synthesis and their possible usage in an extension for the chosen synthesis program. Suggested design and practical implementation of the extension is also described in this part. In the third part extension testing is mentioned. The fourth part is the last one and concludes gained knowledge and results.
27

Aniontové receptory založené na symetricky tetrasubstituovaných kalix[4]arenech / Anion receptors based on symmetrically tetrasubstituted calix[4]arenes

Klimentová, Jana January 2011 (has links)
The submitted Ph.D. thesis concerns anion receptors based on symmetrically tetrasubstituted cone calixf4]arenes. These receptors are easily synthesized and display sufficient water solubility to function as receptors for tetrahedral oxoanions. The thesis starts with a brief survey of literature on calix[4larene anion receptors and sensors. The theoretical part of the thesis deals with a stereochemical investigation of calixf4]arenes from the Cambridge Structural Database (CSD) with emphasis on the influence of inter- and/or intramolecular interactions on the geometry and rigidity of the calix[4]arene scaffold. In order to describe the geometry of the calixf4]arene moiety, it was necessary to introduce new stereochemical parameters cr, B and 5. The utility of these parameters in evaluating the geometry of the calixf4]arene base frame was confirmed. The stereochemical investigation formed the basis for design of new potential anion receptors based on symmetric al ly tetrasub stituted c o n e calixl4 ] arene s. The experimental part of this work started with synthesis of symmetrically tetrasubstituted calixf4]arene derivatives containing 1-propoxy groups at the lower rim and synthesis of calixf4]arene derivatives with carboxymethoxy groups at the lower rim and enhanced water solubility. Identity and...
28

Příprava enantiomerně čistých cyklických sloučenin za využití organokatalýzy / Preparation of enantiomerically pure cyclic compounds via organocatalytic concept

Remeš, Marek January 2015 (has links)
Since 2000 the organocatalytic synthesis has developed massively in a third pillar of asymmetric synthesis standing next to catalysis with metal complexes and enzymatic catalysis. Organocatalysts, due to their various activation modes which could be combined in domino reactions, offer a way for a synthesis of complex molecules from a simple starting material. This thesis deals with investigation of usage of chiral secondary amines as catalysts for asymmetric synthesis of cyclic compounds. The main part of research was devoted to development of organocatalytic method leading to synthesis of enantiomerically pure cyclopentanecarbaldehydes and nitrocyclopentanecarbaldehydes. We focused also on the organocatalytic preparation of cyclohexanecarbaldehydes. During this work we developed an asymmetric domino Michael addition/α- substitution reaction of 2-(2-bromoethyl)malonates resp. 1-bromo-3-nitropropane with various enals catalyzed by chiral secondary amine. In the first case cyclopentanecarbaldehydes were formed where two chiral centres were created. In second case nitrocyclopentanecarbaldehydes were formed where three chiral centres were created. Yields of such developed reaction protocol reach up to 74 % and the reaction proceeds with excellent diastereo- and enantioselectivity (up to 19:1 d.r. and...
29

Syntéza koibacinů / Syntehsis of coibacines

Kolská, Kristýna January 2014 (has links)
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.
30

Syntéza cyklických sloučenin za využití organokatalýzy a katalýzy komplexy přechodných kovů / Synthesis of cycles using organocatalysis and catalysis with metal complexes

Hurný, David January 2014 (has links)
This thesis deals with an enantioselective synthesis of cyclic compounds by using a combination of organocatalysis and transition metal catalysis. The thesis deals mainly with usage of aminocatalyst for activation of aldehydes and copper catalyst for activation of terminal triple bond. The first part is focused on the preparation of starting compounds for cyclizations (α-oxoesters, α- substituted nitroalkanes and α-substituted aldehydes). The second part concerns carbocyclization itself and optimization of reaction conditions to achieve highly stereoselective reaction. Powered by TCPDF (www.tcpdf.org)

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