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1,3-Dialkyl-4,5-dymethylimidazol-2-ylidene Amines as a New Class of Strong Electron Donors in Design and Synthesis of Organosuperbases and Stable Cations
Kunetskiy, Roman ; Jahn, Ullrich (advisor) ; Hájíček, Josef (referee) ; Kvíčala, Jan (referee)
Roman A. Kunetskiy Syntéza organosuperbazí a stabilních kationtů na bázi 1,3-dialkyl-4,5-dimethylimidazol- 2-ylidenaminů jako nového druhu silných elektron-donorů / 1,3-Dialkyl-4,5- dimethylimidazol-2-ylidene Amines as a New Class of Strong Electron Donors in Design and Synthesis of Organosuperbases and Stable Cations Abstrakt Byla vyvinuta jednoduchá a efektivní metoda pro zavedení nové silně elektron-donorní 1,3-dialkyl-4,5-dimethylimidazol-2-yliden aminové skupiny (IMAM) do různých organických molekul za použití 2-fluorimidazoliových nebo 2-chlorimidazoliových solí. Touto metodou byly syntetizovány a studovány tři nové druhy katalyzátorů fázového přenosu a dva nové druhy stabilních nefosforných organických superbazí (SB). Vybrané katalyzátory fázového přenosu se ukázaly velice stabilní vůči hydrolýze za různých silně bazických podmínek. Byla studována velmi vysoká bazicita připravených SB v roztoku či v plynné fázi a bylo zjištěno, že je způsobena aromatizací a uvolněním sterického napětí po protonaci. Byla vyvinuta nová efektivní metoda pro aminaci 1,3-dialkylimidazol-2-ylidenů a tris(dimethylamino)fosfinu terc-butylazidem. Byla určena bazicita nových vysoce stericky bráněných 1,3-di-terc-butyl- 4,5-dimethylimidazol-2-ylidenů, pKBH + (DMSO) = 24.8. Abstract Simple and efficient method for the...
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Synthesis of selaginpulvilins
Beytlerová, Nela ; Kotora, Martin (advisor) ; Hájíček, Josef (referee)
This bachelor thesis is focused on the application of [2+2+2] cyclotrimerization in the total synthesis of natural fluorene derivate, selaginpulvilin D, which was isolated from the plant Selaginella pulvinata. The plant is used in the traditional Chinese medicine for treatment of asthma and traumatic injuries. The study is focused on development of the catalytic cyclotrimerization reaction that is used to prepare the key intermediate. The integral part of the project is a study how various catalysts and catalytic systems, solvents and reaction temperatures affect the course of the reaction. Synthesis of the suitable cyclotrimerization precursor was achieved from benzaldehyde and the formal synthesis of selaginpulvilin D was completed by conversion of cyclotrimerization product to the known intermediate of the selaginpulvilin D synthesis. Key words: [2+2+2] cyclotrimerization, selaginpulvilin D, natural compound, fluorene core
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Synthesis of all-carbon quaternary centres
Orlovská, Ľubica ; Matoušová, Eliška (advisor) ; Hájíček, Josef (referee)
In this diploma Thesis I dealt with the synthesis of nitrogen compounds that contain quaternary carbon centres and their structure resembles natural substances, specifically alkaloids from the Amaryllidaceae family. Halocarbocyclization or Heck reaction was planned as a key step of the synthesis, which should lead to the formation of quaternary carbon centres. First, starting nitriles and esters with five- and six-membered rings were prepared. Subsequently, the method for the preparation of a stable bicyclic ketone with a five-membered ring from an ester was optimized. The next part of the Thesis is devoted to the synthesis of a substrate for the Heck reaction from the prepared ketone, which was then used for the preparation of the alkaloid skeleton with a quaternary carbon centre, unfortunately without success so far. In the last part of the work, a bicyclic ketone with a six-membered ring, from which it is possible to prepare a substrate for the Heck reaction in several steps already used for five-membered substances, was prepared from the nitrile by carbopalladation. Key words: synthesis, quaternary carbon centres, Heck reaction, halocarbocyclisation, Amaryllidaceae alkaloids
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Organocatalytic reactions leading to a stereoselective formation of piperidine derivatives
Reiberger, Róbert ; Veselý, Jan (advisor) ; Hájíček, Josef (referee)
This bachelor thesis deals with the stereoselective preparation of chiral piperidine derivatives by using an organocatalytic approach. It is aimed at optimizing the reaction conditions and extent of the organocatalytic tandem Michael/cyclization reaction of 2-nitrocarboxamides with α,β-unsaturated aldehydes. Key words organocatalysis, iminium activation, enantiomer, diastereoisomer, piperidine, Michael addition, stereoselective synthesis, DPP-4
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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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1,3-Dialkyl-4,5-dymethylimidazol-2-ylidene Amines as a New Class of Strong Electron Donors in Design and Synthesis of Organosuperbases and Stable Cations
Kunetskiy, Roman ; Jahn, Ullrich (advisor) ; Hájíček, Josef (referee) ; Kvíčala, Jan (referee)
Roman A. Kunetskiy Syntéza organosuperbazí a stabilních kationtů na bázi 1,3-dialkyl-4,5-dimethylimidazol- 2-ylidenaminů jako nového druhu silných elektron-donorů / 1,3-Dialkyl-4,5- dimethylimidazol-2-ylidene Amines as a New Class of Strong Electron Donors in Design and Synthesis of Organosuperbases and Stable Cations Abstrakt Byla vyvinuta jednoduchá a efektivní metoda pro zavedení nové silně elektron-donorní 1,3-dialkyl-4,5-dimethylimidazol-2-yliden aminové skupiny (IMAM) do různých organických molekul za použití 2-fluorimidazoliových nebo 2-chlorimidazoliových solí. Touto metodou byly syntetizovány a studovány tři nové druhy katalyzátorů fázového přenosu a dva nové druhy stabilních nefosforných organických superbazí (SB). Vybrané katalyzátory fázového přenosu se ukázaly velice stabilní vůči hydrolýze za různých silně bazických podmínek. Byla studována velmi vysoká bazicita připravených SB v roztoku či v plynné fázi a bylo zjištěno, že je způsobena aromatizací a uvolněním sterického napětí po protonaci. Byla vyvinuta nová efektivní metoda pro aminaci 1,3-dialkylimidazol-2-ylidenů a tris(dimethylamino)fosfinu terc-butylazidem. Byla určena bazicita nových vysoce stericky bráněných 1,3-di-terc-butyl- 4,5-dimethylimidazol-2-ylidenů, pKBH + (DMSO) = 24.8. Abstract Simple and efficient method for the...
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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....
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