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Preparation of biologically active compounds using organocatalysis
Šimek, Michal ; Veselý, Jan (advisor) ; Kočovský, Pavel (referee)
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.
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Enantioselective reactions catalyzed by chiral heterocyclic compounds
Vlašaná, Klára ; Kotora, Martin (advisor) ; Starý, Ivo (referee) ; Sedlák, Miloš (referee)
Novel bis(tetrahydroisoquinoline) N,N'-dioxides 1,2 belong to the group of compounds with axial chirality that act as a Lewis base. These properties make them useful chiral catalysts in reactions such as allylation, opening of epoxides, etc. that exhibit high enantioselectivity. The prepared chiral bis(tetrahydroisoquinoline) N,N'-dioxides (R,Rax,R)-1, (R,Sax,R)-1, (Rax,R)-2 a (Sax,R)-2 were tested as catalysts in enantioselective allylation of variously substituted α,β−unsaturated aldehydes and dienals with allyltrichlorosilane (Scheme 1). All the catalysts exhibited high catalytic activity as well as high asymmetric induction (up to 96% for α,β- unsaturated aldehydes;1 up to 98 % for dienals). Appropriate choice of solvent as a reaction medium3,4 and substitution in α-position in aldehydes were the crucial factors for the successful course of the reaction. The catalytic activity of (R,Rax,R)-1 and (R,Sax,R)-1 was also tested in asymmetric opening of meso-epoxides with tetrachlorosilane (ee up to 69 %) (Scheme 2). N N O O O O 1 N N O O O 2 Scheme 1 Scheme 2 1) Vlašaná, K.; Hrdina, R.; Valterová, I.; Kotora, M. Eur. J. Org. Chem. 2010, 7040. 2) Kadlčíková, A.; Hrdina, R.; Valterová, I.; Kotora, M. Adv. Synth. Catal. 2009, 351,1279. 3) Hrdina, R.; Opekar, F.; Roithová, J.; Kotora, M. Chem. Commun....
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Preparation of organocatalysts derived from monosaccharides
Nekvinda, Jan ; Veselý, Jan (advisor) ; Trnka, Tomáš (referee)
This bachelor thesis is focused on the synthesis of organocatalysts derived from monosaccharides, in particular D-glucose and D-glucosamine, with various protecting groups. Synthesis of various thiourea catalysts and the attempt to prepare new squaramide catalysts is described. ABSTRAKT Tato bakalářská práce je zaměřena na syntézu organokatalyzátorů odvozených od monosacharidů, zejména z D-glukózy a D-glukosaminu, s různými chránícími skupinami. Dále je popsána syntéza různých thiomočovinových katalyzátorů a pokus o přípravu katalyzátoru obsahující derivát kyseliny čtvercové.
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Preparation of organocatalysts derived from thiourea containing saccharide units
Řehůřková, Tereza ; Veselý, Jan (advisor) ; Smrček, Stanislav (referee)
4 ABSTRACT This diploma thesis is focused on the synthesis of new bifunctional thiourea organic catalysts containing a carbohydrate moiety, in particular D-glucose with modification on the primary hydroxyl group. The first part of this diploma thesis describes a modification of synthesis of the known bifunctional thiourea catalyst with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranose and (1R,2R)-diaminocyclohexane. The second part is dedicated to the synthesis of new bifunctional thiourea catalysts with modification of the carbohydrate moiety. We focused on per-O-acetyl-β-D-glucopyranose derivatives with pefluoroalkyl moiety on the primary hydroxyl group. We examined different ways of the preparation of 6-O-perfluoroalkylated glucose derivatives. These perfluoroalkylated carbohydrate compounds were transformed into corresponding glycosyl isothiocyanates. Those derivatives upon treatment of (1R,2R)-diaminocyklohexane or 3,5- bis(trifluormethyl)aniline afforded new bifunctional thiourea organocatalysts.
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Organocatalytic asymmetric synthesis of various organic compounds from α,β-unsaturated aledyhes
Kamlar, Martin ; Trnka, Tomáš (referee) ; Veselý, Jan (advisor)
With regard to a fast development in the field of fluoroorganic chemisty, the intention of this diploma thesis is focused to utilize of organocatalysis by secondary amines as catalysts for preparation enantiomerically pure compounds containing fluorine atom in its structure. The preparation of these subsances is realized by way of nucleofilic addition to α,β- unsaturated aldehydes using suitable fluorine containing nuclephilic agent 1-(fluoronitromethylsulphonyl)benzene, to get appropriate 1,4-adduct.
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Enantioselective synthesis of fluorinated organic compounds using iminium and enamine catalysis
Hejnová, Monika ; Veselý, Jan (advisor) ; Smrček, Stanislav (referee)
This diploma thesis deals with the scope of organocatalytic concept for the preparation of enantiomerically pure organic compounds, containing fluorine atom. Our attention was focused on the use of easily available α,β-unsaturated aldehydes and ketones as starting materials and commercially available secondary amines as catalysts. The first part of the work is dedicated to the enantioselective cyclization reaction of hydrazone (24) with cyclohex-2-enone (25). The second part describes a study of enantioselective nucleophilic addition of diethyl 2-fluoromalonate (31a) to α,β-unsaturated aldehydes (30) via enamine activation.
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