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Preparation of enantiomerically pure cyclic compounds via organocatalytic concept
Remeš, Marek
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...
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Organocatalytic reactions leading to functionalized cyclic compounds
Formánek, Bedřich ; Veselý, Jan (advisor) ; Jindřich, Jindřich (referee)
First part is focused on finding suitable reaction conditions for organocatalytic domino Michael/Michael reaction of ethyl (E)-3-(2-thiophenyl)acrylate with α,β-unsaturated aldehydes. Second part deals with the preparation of pyrazolone derivatives from commercially available compounds and describes effects of various substituents in α-position on chemical efficiency and stereoselectivity of amination with azodicarboxylate catalyzed by quinine.
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Syntehsis of coibacines
Kolská, Kristýna ; Kotora, Martin (advisor) ; Veselý, Jan (referee)
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.
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Preparation of enantiomerically pure cyclic compounds via organocatalytic concept
Remeš, Marek ; Veselý, Jan (advisor) ; Potáček, Milan (referee) ; Cibulka, Radek (referee)
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...
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Enantioselective synthesis of spiro compounds
Urban, Michal ; Veselý, Jan (advisor) ; Kotora, Martin (referee)
This thesis deals with the preparation of enantiomerically and diastereomerically pure spirocompounds using asymmetric organocatalysis. The first part is focused on the enantioselective synthesis of spirocompounds by organocatalytic reaction of α,β-unsaturated aldehydes with sulfur heterocyclic compounds catalysed with secondary amines. It is a domino Michael/Michael/aldol reaction using iminium and enamine activation. The second part is focused on the subsequent transformation of the prepared spirocompounds.
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The use of BH carbonates in organocatalytic transformations
Tichá, Iveta ; Veselý, Jan (advisor) ; Jindřich, Jindřich (referee)
This diploma thesis is focused on the preparation of enantiomerically pure compounds based on organocatalytic allylic substitution using Baylis-Hillman carbonates. As selected substrates for the allylic substitution were chosen α-azidoketones such as azidoacetophenone, 2-azido-1-indanone and then heterocyclic compounds (N-phenylrhodanine and its derivate) belonging to the pharmaceutical privileged compounds. Other substrate for allylic substitution was allylmalononitrile. In addition, this thesis includes with synthesis of cyclic compounds based on the reaction of products of allylmalononitrile with B-H carbonates using olefin metathesis.
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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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