|
|
Synthesis of N-(per)fluoroalkyl azoles by rhodium(II)-catalyzed transannulation of N-(per)fluoroalkyl-1,2,3-triazoles
Bakhanovich, Olga ; Beier, Petr (advisor) ; Kočovský, Pavel (referee) ; Kvíčala, Jaroslav (referee)
This Thesis deals with the synthesis of N-fluoroalkyl azoles via rhodium(II)-catalyzed transannulation of N-fluoroalkyl-1,2,3-triazoles obtained through copper(I)-catalyzed azide- alkyne cycloaddition (CuAAC) of N-fluoroalkyl azides and alkynes. The introductory chapter describes general approaches towards N-fluoroalkyl azoles, focusing on the synthesis of N-fluoroalkyl pyrroles and azoles. In the first part of the Thesis, rhodium(II)-catalyzed transannulation of N-fluoroalkyl-1,2,3- triazoles with terminal alkynes is described. The reaction provides access to N-fluoroalkyl pyrroles. The regioselectivity of the reaction is investigated and modifications of the primary product are suggested. In the second part of the Thesis, the reactivity of 4-cyclohexyl-N-fluoroalkyl-1,2,3-triazoles is investigated. A one-pot two-step reaction is presented, providing access to novel N- fluoroalkyl indoles. Several modification routes are suggested.
|
|
|
Application of fluoroalkyl hypervalent iodine reagents in C-H functionalization of small molecules and aromatic amino acid residues
Rahimidashaghoul, Kheironnesae ; Beier, Petr (advisor) ; Kvíčala, Jaroslav (referee) ; Urban, Milan (referee)
The chemistry of fluorolkyl hypervalent iodine reagents has witnessed a great boast in recent years. These compounds are highly attractive as drug candidates, advanced materials and agrochemicals as described in detail in the Introduction. Despite this fact, applications of these reagents in biological studies are rather rare and under developed. The goal of this thesis is therefore the development of mild and metal-free methods in order to fill this gap. Two ways of application of fluoroalkyl hypervalent iodine reagents in labeling of biologically relevant compounds was explored. First, the applicability of previously reported parent Togni CF3 and their analogous tetrafluoroethyl reagents in radical fluoroalkylation of electron-rich substrates such as indole and pyrrole derivatives using sodium ascorbate as reductant was described. This afforded trifluoromethyl or 1,1,2,2-tetrafluoroethyl containing products in moderate to high yields. Next, same reagents were applied for labeling of several peptides and proteins bearing aromatic amino acids in their structure. This way, peptides and proteins containing electron-rich aromatics such as Trp, Phe, Tyr and His were reacted with fluoroalkyl groups with high selectivity toward Trp. In the second part of the work, a different approach of radical...
|
|
|
Azidoperfluoroalkanes: Synthesis and Application
Blastik, Zsófia Eszter ; Beier, Petr (advisor) ; Církva, Vladimír (referee) ; Kvíčala, Jaroslav (referee)
The incorporation of the trifluoromethyl and perfluoroalkyl motifs into organic compounds has been a hot topic in synthetic organofluorine chemistry. There is a plethora of methods for the introduction of the CF3 moiety at carbon, oxygen and sulfur centers. In sharp contrast, methods for synthesizing N-trifluoromethyl and N-perfluoroalkyl compounds are very limited and new approaches are highly sought-after. The scarcity of these compounds prompted us to develop reagents capable of transferring the perfluoroalkyl unit to nitrogen atom. To fulfil this purpose, we have regarded azidoperfluoroalkanes as ideal reagents, therefore, this thesis is concerned with the synthesis and applications of these azides. The first part describes the preparation of azidoperfluoroalkanes. Upon activation by cesium fluoride, TMSCF3 transfers the trifluoromethyl group to an electrophilic azide to produce the desired azidotrifluoromethane. Longer carbon chain azidoperfluoroalkanes were prepared in a similar way, starting from the corresponding organosilane. A different synthetic strategy was applied for the preparation of azidopentafluoroethane where the perfluoroalkyl anion was generated from pentafluoroethane with n BuLi, followed by the addition of tosyl azide. The isolation of these fluorinated azides was...
|
|
|
Direct monitoring of metal-catalyzed reactions using electrospray ionization mass spectrometry
Tsybizova, Alexandra ; Roithová, Jana (advisor) ; Jahn, Ullrich (referee) ; Kvíčala, Jaroslav (referee)
The current dissertation thesis is focused on the investigation of metal-catalyzed reactions using electrospray ionization mass spectrometry as the primary research technique. However, other gas- phase methods such as tandem mass spectrometry, infrared multiphoton dissociation spectroscopy and quantum chemical calculations have also been involved to unravel and support the findings and proposals. As organometallic chemistry is a very broad and complicated topic, this thesis is only focused on a few projects. The fist of them is dedicated to copper acetate speciation in organic solvents, the second - to the mechanistic investigation of copper catalyzed aerobic cross coupling of thiol esters and arylboronic acids, the third studied coordination and bond activation of nickel(II) - phenylpyridine complexes and the last investigated carboxylate assisted C-H activation reactions.
|
|
|
Sulfur-based reagents for nucleophilic and radical introduction of tetrafluoroethyl and tetrafluoroethylene groups
Chernykh, Yana ; Beier, Petr (advisor) ; Kvíčala, Jaroslav (referee) ; Církva, Vladimír (referee)
Charles University in Prague, Faculty of Science Department of Organic Chemistry Ing. Yana Chernykh Sulfur-Based Reagents for Nucleophilic and Radical Introduction of Tetrafluoroethyl and Tetrafluoroethylene Groups Ph.D. Thesis Prague 2014 ABSTRACT This project was aimed at developing new methodologies for selective introduction of tetrafluoroethyl and tetrafluoroethylene groups into organic molecules. The study was focused on reactivities of fluorinated sulfones and sulfides as tetrafluoroalkylation reagents. In the Introduction part of the thesis, main aspects of organofluorine chemistry are outlined, illustrating beneficial effects of fluorine atoms on physical, chemical and biological properties of organic compounds. General synthetic methods for the selective introduction of fluorine atoms and fluoroalkyl groups to organic molecules are described. Particular attention is given to reactivity and applications of CF2CF2-containing compounds, indicating challenges in synthetic approaches toward tetrafluoroalkylation. The Results and discussion part describes reactivities of four new fluorinated organosulfur reagents as tetrafluoroethyl and tetrafluoroethylene building blocks. The application of these reagents as various carbanionic or radical synthons proved to be effective for the incorporation of CF2CF2...
|
|
|
Ruthenium alkylidenes immobilized on mesoporous molecular sieves as catalysts for olefin metathesis
Shinde, Tushar Raghunath ; Balcar, Hynek (advisor) ; Vohlídal, Jiří (referee) ; Kvíčala, Jaroslav (referee)
The main emphasis of the dissertation focuses on the preparation of new heterogeneous metathesis catalysts, their characterization, and testing their activity and selectivity in different metathesis reactions. This work has been completed at the Department of Synthesis and Catalysis, J. Heyrovský Institute of Physical Chemistry, AS CR. Hoveyda-Grubbs type catalyst ZC (Zhan catalyst 1-B) was immobilized on mesoporous molecular sieves of different architecture and pore diameter, d, (hexagonal: MCM-41, d = 4.0 nm; SBA-15, d = 6.8 nm; SBA-15 large pore (LP), d = 11.1 nm and cubic: MCM-48, d = 6.0 nm) and conventional silica (Merck) for comparison. The immobilization was done by simple mixing of ZC solution with appropriate support at room temperature. Ru loading in all immobilized catalyst was 0.93 wt%. The catalysts and supports were characterized by X-ray diffraction and nitrogen adsorption measurement. XPS and UV-Vis spectroscopic studies of ZC immobilized on SBA-15 (ZC/SBA-15) indicated the attachment of ZC on mesoporous sieve surface by non-covalent interactions. The immobilized catalysts exhibited high activity and 100% selectivity in ring-closing metathesis of diethyl diallylmalonate and 1,7-octadiene, in metathesis of methyl oleate and methyl 10-undecenoate, and in the ring-opening metathesis...
|
|
|
Nucleophilic introduction of fluorinated functional groups using organophosphorus compounds.
Opekar, Stanislav ; Beier, Petr (advisor) ; Veselý, Jan (referee) ; Kvíčala, Jaroslav (referee)
In the Introduction part of this thesis, the chemistry of organofluorine compounds is discussed, particularly the methods for the preparation of organofluorine compounds mainly by fluoroalkylation methods. Furthermore, the chemistry of fluorinated phosphonates, methods of their preparation, reactivity and biological activity is discussed. Additionally, the reactivity of fluoromethane derivatives is briefly mentioned and especially, the reactivity of diethyl fluoromalonate and fluorobisfenylsulfonylmethane is described. The Results and discussion part is devoted to the reactivity of three fluorinated phosphonates: tetraethyl fluoromethylenbisphosphonate, diethyl fluorophenylsulfonylphosphonate and previously not described diethyl fluoronitromethylphosphonate. These fluorinated phosphonates belong to the family of nucleophilic monofluoroalkylation reagents, meaning that these compounds are convenient starting materials for the synthesis of complex organic molecules containing the fluorine atom. The results deal with the reactivity of above mentioned fluorinated phosphonates, mainly with alkylation reactions, Horner-Wadsworth-Emmons reactions and conjugated additions. Also, other synthetic methods such as the Mitsunobu reaction or the palladium catalyzed allylation reaction were investigated; however,...
|
|
|
Synthesis of helical molecules and their application in enantioselective catalysis
Krausová, Zuzana ; Starý, Ivo (advisor) ; Kotora, Martin (referee) ; Kvíčala, Jaroslav (referee) ; Hájíček, Josef (referee)
9. Summary We have prepared a set of helical compounds using a modular approach based on 12+2+21 cycloisomerisation of aromatic triynes under cobalt (l) catalysis. [7]helicene-like compound (P,S)-(+)-10, which represents a new structural type of possible liquid crystalline materials, was obtained in an optically pure form on a preparative scale. We have explored the diastereoselective synthesis as a general methodology for the preparation of functionalised helical compounds. A series of methoxy- and bromo-substituted helicene derivatives was successfully prepared with diastereoisomer ratios up to 100:0. ln addition, we have developed a practical synthesis of racemic heptahelicene rac-87. Optically pure heptahelicene (M)-(-)-87 and optically highly enriched (P)-(+)-87 were obtained by resolution of rac-87 by semipreparative HPLC on a chiral column. we have developed an original approach to the synthesis of phosphite ligands bearing helically chiral moieties, which were subsequently used in enantioselective catalysis, namely in hydroformylation reactions and allylic aminations. A series of hydroformylations of styrene, 4-chlorostyrene and vinyl acetate performed with Rh(acac)(co)2 under various conditions revealed that all helically chiral ligands under study afforded good to excellent regioselectivities....
|
guest ::
RSS feed.