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Piotr Kielbasinski - One of the best experts on this subject based on the ideXlab platform.
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chiral organoSulfur ligands catalysts with a stereogenic Sulfur Atom applications in asymmetric synthesis
Chemical Reviews, 2017Co-Authors: Sylwia Otocka, Malgorzata Kwiatkowska, Lidia Madalinska, Piotr KielbasinskiAbstract:Asymmetric synthesis, in which chiral organocatalysts or metal complexes with chiral ligands are used, has become the most valuable methodology for the preparation of enantiomerically pure organic compounds. Among such catalysts/ligands, a growing number constitute various organoSulfur compounds. This Review provides comprehensive and critical information on the plethora of Sulfur-based chiral ligands and organocatalysts used in asymmetric synthesis, which have been published within the last 15 years. However, it is confined to the presentation of only those chiral catalysts/ligands that possess a stereogenic Sulfur Atom and includes sulfoxides, sulfinamides, N-sulfinyl ureas, sulfoximines, and some related S-chiral derivatives.
Rolf K. Berge - One of the best experts on this subject based on the ideXlab platform.
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Thia fatty acids with the Sulfur Atom in even or odd positions have opposite effects on fatty acid catabolism.
Lipids, 2006Co-Authors: Endre Dyrøy, Hege Wergedahl, Jon Skorve, Oddrun Anita Gudbrandsen, Jon Songstad, Rolf K. BergeAbstract:As tools for mechanistic studies on lipid metabolism, with the long-term goal of developing a drug for the treatment of lipid disorders, thia FA with the Sulfur Atom inserted at positions 3–9 from the carboxyl group were fed to male Wistar rats for 1 wk to determine their impact on key parameters in lipid metabolism and hepatic levels of thia FA metabolites. Thia FA with the Sulfur Atom in even positions decreased hepatic and cardiac mitochondrial β-oxidation and profoundly increased hepatic and cardiac TAG levels. The plasma TAG level was unchanged and the hepatic acyl-CoA oxidase activity increased. In contrast, thia FA with the Sulfur Atom in odd positions, especially 3-thia FA, tended to increase hepatic and cardiac FA oxidation and acyl-CoA oxidase and carnitine palmitoyltransferase-II activities, and decreased the plasma TAG levels. The effects seem to be related to differences in the catabolic rate of the thia FA. Differences between the two groups of acids were also observed with respect to the regulation of genes involved in FA transport and catabolism. Feeding experiments with 3- and 4-thia FA in combination indicated that the 4-thia FA partly attenuated the effects of the 3-thia FA on mitochondrial FA oxidation and the hepatic TAG level. In summary, the position of the Sulfur Atom in the alkyl chain, especially whether it is placed in the even or odd position, is crucial for the biological effect of the thia FA.
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The metabolic effects of thia fatty acids in rat liver depend on the position of the Sulfur Atom.
Chemico-biological interactions, 2005Co-Authors: Oddrun Anita Gudbrandsen, Endre Dyrøy, Jon Skorve, Pavol Bohov, Rolf K. BergeAbstract:The effects on oxidation and composition of fatty acids in rat liver were compared after administration of fatty acids with Sulfur substituted in different positions. It has been hypothesized that drugs with hydrophobic backbone have lipid-lowering effects because they are not easily catabolized by mitochondrial beta-oxidation. Thia fatty acids cannot be beta-oxidized when Sulfur is in 3-position, but beta-oxidation is possible when Sulfur is positioned further from the carboxyl group. To investigate whether catabolism of thia fatty acids would affect their ability to influence lipid metabolism, a series of thia fatty acids were synthesized and administered by oral gavage to male Wistar rats (300 mg/kg bodyweight/day for 7 days). Depending on the position of the Sulfur Atom and the chain length, the thia fatty acids were beta-oxidized, desaturated and/or elongated, and the accumulated amounts were lower as the Sulfur Atom were positioned further from the carboxyl group. All thia fatty acids led to high peroxisomal beta-oxidation of endogenous fatty acids, whereas the mitochondrial beta-oxidation was high when Sulfur was in 3-position, low when Sulfur was in 4-position and similar to controls when Sulfur was in 5- or 7-position. The changes in hepatic fatty acid composition were more pronounced when Sulfur was positioned close to the carboxyl group. In conclusion, both the position of the Sulfur Atom and the chain length appear to determine the catabolic fate of thia fatty acids, and the non-beta-oxidizable thia fatty acids were most potent in regulating oxidation and composition of endogenous fatty acids in rat liver.
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The metabolic effects of thia fatty acids in rat liver depend on the position of the Sulfur Atom.
Chemico-Biological Interactions, 2005Co-Authors: Oddrun Anita Gudbrandsen, Endre Dyrøy, Jon Skorve, Pavol Bohov, Rolf K. BergeAbstract:The effects on oxidation and composition of fatty acids in rat liver were compared after administration of fatty acids with Sulfur substituted in different positions. It has been hypothesized that drugs with hydrophobic backbone have lipid-lowering effects because they are not easily catabolized by mitochondrial β-oxidation. Thia fatty acids cannot be β-oxidized when Sulfur is in 3-position, but β-oxidation is possible when Sulfur is positioned further from the carboxyl group. To investigate whether catabolism of thia fatty acids would affect their ability to influence lipid metabolism, a series of thia fatty acids were synthesized and administered by oral gavage to male Wistar rats (300 mg/kg bodyweight/day for 7 days). Depending on the position of the Sulfur Atom and the chain length, the thia fatty acids were β-oxidized, desaturated and/or elongated, and the accumulated amounts were lower as the Sulfur Atom were positioned further from the carboxyl group. All thia fatty acids led to high peroxisomal β-oxidation of endogenous fatty acids, whereas the mitochondrial β-oxidation was high when Sulfur was in 3-position, low when Sulfur was in 4-position and similar to controls when Sulfur was in 5- or 7-position. The changes in hepatic fatty acid composition were more pronounced when Sulfur was positioned close to the carboxyl group. In conclusion, both the position of the Sulfur Atom and the chain length appear to determine the catabolic fate of thia fatty acids, and the non-β-oxidizable thia fatty acids were most potent in regulating oxidation and composition of endogenous fatty acids in rat liver.
Sylwia Otocka - One of the best experts on this subject based on the ideXlab platform.
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chiral organoSulfur ligands catalysts with a stereogenic Sulfur Atom applications in asymmetric synthesis
Chemical Reviews, 2017Co-Authors: Sylwia Otocka, Malgorzata Kwiatkowska, Lidia Madalinska, Piotr KielbasinskiAbstract:Asymmetric synthesis, in which chiral organocatalysts or metal complexes with chiral ligands are used, has become the most valuable methodology for the preparation of enantiomerically pure organic compounds. Among such catalysts/ligands, a growing number constitute various organoSulfur compounds. This Review provides comprehensive and critical information on the plethora of Sulfur-based chiral ligands and organocatalysts used in asymmetric synthesis, which have been published within the last 15 years. However, it is confined to the presentation of only those chiral catalysts/ligands that possess a stereogenic Sulfur Atom and includes sulfoxides, sulfinamides, N-sulfinyl ureas, sulfoximines, and some related S-chiral derivatives.
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Chiral OrganoSulfur Ligands/Catalysts with a Stereogenic Sulfur Atom: Applications in Asymmetric Synthesis
Chemical Reviews, 2017Co-Authors: Sylwia Otocka, Malgorzata Kwiatkowska, Lidia Madalińska, Piotr KiełbasińskiAbstract:Asymmetric synthesis, in which chiral organocatalysts or metal complexes with chiral ligands are used, has become the most valuable methodology for the preparation of enantiomerically pure organic compounds. Among such catalysts/ligands, a growing number constitute various organoSulfur compounds. This Review provides comprehensive and critical information on the plethora of Sulfur-based chiral ligands and organocatalysts used in asymmetric synthesis, which have been published within the last 15 years. However, it is confined to the presentation of only those chiral catalysts/ligands that possess a stereogenic Sulfur Atom and includes sulfoxides, sulfinamides, N-sulfinyl ureas, sulfoximines, and some related S-chiral derivatives.
Johannes Kastner - One of the best experts on this subject based on the ideXlab platform.
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comment on computational evidence for Sulfur Atom tunneling in the ring flipping reaction of s4n4
Chemical Physics Letters, 2020Co-Authors: Ashim Nandi, Sebastian Kozuch, Johannes KastnerAbstract:Abstract In a recent article (Chem. Phys. Lett. 749 (2020), 137440), Kumar and Mallick predict by computations that a Sulfur Atom tunneling mechanism leads to a ring flipping reaction of S4N4 below 70 K. Herein, on the basis of their tunneling computations, it is shown that the Sulfur Atom tunneling is not viable, and therefore impossible to be probed experimentally. Based on this, we discuss the prerequisites for a chemical reaction to be driven by heavy Atom tunneling.
Gareth R Owen - One of the best experts on this subject based on the ideXlab platform.
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two synthetic routes to bis 1 methyl imidazole 2 thione methane and bis 1 benzyl imidazole 2 thione methane complexes including Sulfur Atom insertion into copper nhc bonds
Journal of Organometallic Chemistry, 2017Co-Authors: Miriam Slivarichova, Rosenildo Correa Da Costa, Joshua Nunn, Ruua Ahmad, Mairi F Haddow, Hazel A Sparkes, Thomas Gray, Gareth R OwenAbstract:Abstract The synthesis of novel bis-thione ligand, bis(1-benzyl-imidazole-2-thione)methane, SS Bn is reported for the first time. This ligand along with the previously reported bis(1-methyl-imidazole-2-thione)methane, SS Me has been utilised in the synthesis of a series of copper(I) halide complexes. The syntheses have been achieved by two methodologies. The first method involves the direct addition of the ligands to the copper halide salts, CuCl, CuBr and CuI. The second methodology involves an insertion of a Sulfur Atom into the copper‒NHC bond of the preformed organometallic complexes, [CuBr( CS Me )] 2 and [CuI( CS Me )] 2 {where CS Me = 1-(3-methyl-2H-imidazol-1-yl-2-thione)methyl-3-methyl-2H-imidazol-2-ylidene} and [CuBr( CS Bn )] 2 and [CuI( CS Bn )] 2 {where CS Bn = 1-(3-benzyl-2H-imidazol-1-yl-2-thione)methyl-3-benzyl-2H-imidazol-2-ylidene}. These Sulfur Atom insertion reactions provide an indirect route to the first copper−halide complexes containing the SS Me and SS Bn ligands. All six complexes prepared have been fully characterised by spectroscopic and analytical methods as well as X-ray crystallography. Dinuclear structures were obtained for the complexes containing SS Me , mononuclear complexes were obtained for the copper‒chloride and copper‒bromide complexes containing SS Bn and an extended network containing [Cu 4 I 4 ] clusters bridged by the SS Bn were formed for the corresponding copper‒iodide complex for the latter ligand. The coordination and structural features of the two bis-thione ligands are discussed.
