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Synthesis of helical aromatics for applications in enantioselective catalysis and nanoscience
Klívar, Jiří ; Stará, Irena (advisor) ; Hrdina, Radim (referee) ; Církva, Vladimír (referee)
The aim of this work was to explore the scope and limitations of [2+2+2] co- cyclotrimerization of cyanodiynes in the preparation of conformationally stable and optionally optically pure azahelicenes, helically chiral bipyridines and helicenes laterally extended by a pyridine unit. As a key reaction for the construction of a helical skeleton, crucial [2+2+2] (co-)cyclotrimerization mediated by various transition metal complexes was chosen for the preparation of racemic azahelicenes. Oligoynes as key intermediates were prepared by a sequence of Sonogashira and Suzuki-Miyaura coupling. For optically pure azahelicenes and bispyridohelicenes, a sequence of Sonogashira and Suzuki-Miyaura coupling and Mitsunobu reaction was used. Importantly, the Mitsunobu reaction was used for its extraordinary ability to transfer chirality from the starting chiral alcohol to the early helicene precursor without configurational scrambling. It is worth noting that optical purity of the key oligoynes have crucial role in the chirality transfer to final azahelicenes or bispyridohelicenes. An in situ generated Ni(0) catalyst was used for bispyridohelicenes with a connection in the 2,2'-position, which enabled both [2+2+2] cyclotrimerization and Ullmann-type coupling. The conformationally stable racemic aza[6]- and...
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Synthesis and catalytic properties of ferrocenophane phosphines
Škoch, Karel ; Štěpnička, Petr (advisor) ; Veselý, Jan (referee)
6 Title: Sythesis and catalytic properties of ferrocenophane phosphines Author: Karel Škoch Institution: Faculty of Science, Charles University in Prague, Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Keywords: ferrocene, ferrocenophane, phosphine ligands, palladium, asymetric catalysis, aza- Morita-Baylis-Hillman reaction, asymetric allylic alkylation Abstract: This Thesis describes the preparation of five sterically and electronically different ferrocene phosphines, (R)-1,1'-[1-(diarylphosphino)propan-1,3-diyl]ferrocenes (R)-1a-e, and a study into their coordination and catalytic properties. The key precursor of the phosphine synthesis, chiral alcohol (R)-2, was prepared according to the procedure described in the literature. Alcohol (R)-2 was converted with retention of configuration to diarylphosphines (R)-1a-e in one-step reaction with trimethylsilylchloride and sodium iodide and then with the corresponding diarylphosphine. Phosphines 1a-e were characterized by NMR and MS methods. For the basic representative 1a the following palladium(II) complexes were prepared: [PdCl(LNC )(1a)] (10, LNC = 2-[(dimethylamino)methyl]phenyl-C1 ,N) and trans- [PdCl2(1a)2] (9a). In addition, the isomeric complex cis-[PdCl2(1a)2] (9b) was isolated from the reaction mixture after catalytic...
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Synthesis and catalytic properties of ferrocenophane phosphines
Škoch, Karel
6 Title: Sythesis and catalytic properties of ferrocenophane phosphines Author: Karel Škoch Institution: Faculty of Science, Charles University in Prague, Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Keywords: ferrocene, ferrocenophane, phosphine ligands, palladium, asymetric catalysis, aza- Morita-Baylis-Hillman reaction, asymetric allylic alkylation Abstract: This Thesis describes the preparation of five sterically and electronically different ferrocene phosphines, (R)-1,1'-[1-(diarylphosphino)propan-1,3-diyl]ferrocenes (R)-1a-e, and a study into their coordination and catalytic properties. The key precursor of the phosphine synthesis, chiral alcohol (R)-2, was prepared according to the procedure described in the literature. Alcohol (R)-2 was converted with retention of configuration to diarylphosphines (R)-1a-e in one-step reaction with trimethylsilylchloride and sodium iodide and then with the corresponding diarylphosphine. Phosphines 1a-e were characterized by NMR and MS methods. For the basic representative 1a the following palladium(II) complexes were prepared: [PdCl(LNC )(1a)] (10, LNC = 2-[(dimethylamino)methyl]phenyl-C1 ,N) and trans- [PdCl2(1a)2] (9a). In addition, the isomeric complex cis-[PdCl2(1a)2] (9b) was isolated from the reaction mixture after catalytic...
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Synthesis and application of helicene-based N-heterocyclic carbene ligands
Gay Sánchez, Isabel ; Starý, Ivo (advisor) ; Veselý, Jan (referee) ; Pour, Milan (referee)
The aim of my PhD Thesis was to explore the potential of helically chiral N-heterocyclic carbene (NHC) ligands in asymmetric catalysis. Helicenes and helicene-like molecules are inherently chiral. Their application in this field has been rather limited. To date, only a few examples of enantiopure helically chiral NHCs have been described in the literature. Using a well-established method based on the diastereoselective metal catalysed [2+2+2] cycloisomerisation of centrally chiral triynes as the key step, I have synthesised a series of optically pure 2H-pyran based penta- and hexahelicenes bearing an amino group on the terminal benzene ring. The triynes were prepared by a sequence of Sonogashira and Mitsunobu coupling reactions using the commercially available (S)-but-3-yn-2-ol as the source of chirality. The resulting aminooxa[5]- and aminooxa[6]helicenes were then converted into the corresponding 1,3-disubstituted imidazolium salts, from which, upon deprotonation, the helically chiral N- heterocyclic carbenes were generated. To evaluate the performance of the new helically chiral ligands, the enantioselective Ni0 - catalysed [2+2+2] intramolecular cycloisomerisation of prochiral triynes to nonracemic dibenzohelicenes was chosen as a model reaction. All the synthesised imidazolium salts provided,...
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Catalytic Enantioselective Desymmetrization of meso-Epoxides
Malatinec, Štefan ; Kotora, Martin (advisor) ; Baszczyňski, Ondřej (referee)
Catalytic enantioselective desymmetrization of meso-epoxides is widely used in many areas of chemistry. Such process is usually catalyzed by a transition metal complex with a chiral ligand. Recently, a synthesis of an analogue of Bolm's 2,2'-bipyridine ligand was developed and its combination with metal salts were tested in various reactions. In this master's thesis, a catalytic system composed of Sc(OTf)3/Bolm's ligand analogue was studied in alcoholysis and aminolysis of the meso- epoxides. The reaction has been extended to a broad range of alcohols providing 1,2-diol monoethers in excellent enantioselectivity up to 99% ee. The aminolysis of meso-epoxides has been optimized, as well. The catalyst loading could be lowered to 1 mol% with only marginal effects on the enantioselectivity. Key words: epoxides, enantioselective catalysis, chiral ligands.
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Synthesis and catalytic properties of ferrocenophane phosphines
Škoch, Karel
6 Title: Sythesis and catalytic properties of ferrocenophane phosphines Author: Karel Škoch Institution: Faculty of Science, Charles University in Prague, Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Keywords: ferrocene, ferrocenophane, phosphine ligands, palladium, asymetric catalysis, aza- Morita-Baylis-Hillman reaction, asymetric allylic alkylation Abstract: This Thesis describes the preparation of five sterically and electronically different ferrocene phosphines, (R)-1,1'-[1-(diarylphosphino)propan-1,3-diyl]ferrocenes (R)-1a-e, and a study into their coordination and catalytic properties. The key precursor of the phosphine synthesis, chiral alcohol (R)-2, was prepared according to the procedure described in the literature. Alcohol (R)-2 was converted with retention of configuration to diarylphosphines (R)-1a-e in one-step reaction with trimethylsilylchloride and sodium iodide and then with the corresponding diarylphosphine. Phosphines 1a-e were characterized by NMR and MS methods. For the basic representative 1a the following palladium(II) complexes were prepared: [PdCl(LNC )(1a)] (10, LNC = 2-[(dimethylamino)methyl]phenyl-C1 ,N) and trans- [PdCl2(1a)2] (9a). In addition, the isomeric complex cis-[PdCl2(1a)2] (9b) was isolated from the reaction mixture after catalytic...
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Phosphinoferrocene conjugates of selected amino acids
Tauchman, Jiří ; Štěpnička, Petr (advisor) ; Růžička, Aleš (referee) ; Dvořák, Dalimil (referee)
A series of chiral phosphinoferrocene amides was prepared by the condensation either of 1'- (diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) or its planar-chiral 1,2-isomers and amino acid methyl esters in the presence of peptide coupling agents. The resulting phosphinoamides were tested as ligands in Cu-catalyzed asymmetric conjugate additions of diethylzinc to chalcones and in Pd-mediated asymmetric allylic substitution reactions of 1,3- diphenylallyl acetate with the respective nucleophile (alkylation, amination and etherification). The catalytic tests were focused on an optimization of the reaction parameters (solvent, temperature, base, metal/ligand ratio) and on survey of various substrates. Compounds based on Hdpf proved to be better ligands in both catalytic reactions than their planar chiral analogues. In order to rationalize the influence of the ligand structure on the reaction course and also to interpret the catalytic results, several model complexes were prepared and structurally characterized. Other three series of non-chiral complexes were prepared from the corresponding (η6 - arene)ruthenium(II) precursor and Hdpf-glycine conjugates; the neutral complexes of the type [(arene)RuCl2(Hdpf-Gly(R)-κP)] (arene = benzene, p-cymene, hexamethyl-benzene; R = OMe, NH2, OH) as well as two...
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Synthesis and catalytic properties of ferrocenophane phosphines
Škoch, Karel ; Štěpnička, Petr (advisor) ; Veselý, Jan (referee)
6 Title: Sythesis and catalytic properties of ferrocenophane phosphines Author: Karel Škoch Institution: Faculty of Science, Charles University in Prague, Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Keywords: ferrocene, ferrocenophane, phosphine ligands, palladium, asymetric catalysis, aza- Morita-Baylis-Hillman reaction, asymetric allylic alkylation Abstract: This Thesis describes the preparation of five sterically and electronically different ferrocene phosphines, (R)-1,1'-[1-(diarylphosphino)propan-1,3-diyl]ferrocenes (R)-1a-e, and a study into their coordination and catalytic properties. The key precursor of the phosphine synthesis, chiral alcohol (R)-2, was prepared according to the procedure described in the literature. Alcohol (R)-2 was converted with retention of configuration to diarylphosphines (R)-1a-e in one-step reaction with trimethylsilylchloride and sodium iodide and then with the corresponding diarylphosphine. Phosphines 1a-e were characterized by NMR and MS methods. For the basic representative 1a the following palladium(II) complexes were prepared: [PdCl(LNC )(1a)] (10, LNC = 2-[(dimethylamino)methyl]phenyl-C1 ,N) and trans- [PdCl2(1a)2] (9a). In addition, the isomeric complex cis-[PdCl2(1a)2] (9b) was isolated from the reaction mixture after catalytic...
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