The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Klaus Burger - One of the best experts on this subject based on the ideXlab platform.
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Hexafluoroacetone as a Protecting and Activating Reagent. N- and O-Glycosylation of Isoserine and Isocysteine
Monatshefte für Chemie Chemical Monthly, 2005Co-Authors: Christoph Böttcher, Fernando Albericio, Jan Spengler, Lothar Hennig, Klaus BurgerAbstract:Starting from HFA -protected malic and Thiomalic Acid a series of O - and N -glycoconjugates suitable for peptide and depsipeptide modification has been synthesized.
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Hexafluoroacetone as a Protecting and Activating Reagent. Regioselective Esterification of Aspartic, Malic, and Thiomalic Acid
Monatshefte für Chemie Chemical Monthly, 2004Co-Authors: Ksenia Pumpor, Elisabeth Windeisen, Jan Spengler, Fernando Albericio, Klaus BurgerAbstract:Hexafluoroacetone reacts with α-functionalized α,β-dicarboxy Acids like aspartic, malic, and Thiomalic Acid to give exclusively five-membered lactones. The β-carboxylic groups remain unaffected and can be derivatized separately. They can be linked i.a. to orthogonal protecting groups or multivalent alcohols like pentaerythritol to give synthetically valuable building blocks.
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Hexafluoroacetone as Protecting and Activating Reagent. Glycosylated Malic, Citramalic, and Thiomalic Acid Derivatives, New Glycosylated Building Blocks for Drug Design [1]
Monatshefte für Chemie Chemical Monthly, 2004Co-Authors: Christoph Böttcher, Jan Spengler, Klaus BurgerAbstract:Glycosylated α-hydroxy and α-mercapto Acids have been synthesized starting from malic/citramalic/Thiomalic Acid and Ac _4-β- D - Glc -NH_2/ Bzl _4-β- D - Glc -NH_2 using hexafluoroacetone as protecting and activating reagent.
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Hexafluoroacetone as a Protecting and Activating Reagent: Synthesis of New Types of Fluoro-Substituted α-Amino, α-Hydroxy and α-Mercapto Acids
Synthesis, 2004Co-Authors: Sergej N. Osipov, Jan Spengler, Lothar Hennig, Beate Koksch, Salah M. El-kousy, Torsten Lange, Pavel Tsouker, Stefan Berger, Klaus BurgerAbstract:Starting from (S)-aspartic, (S)-malic, (S)-citramalic and (S,R)-Thiomalic Acid, new types of 4,4-difluoro-substituted a-ami- no-, a-hydroxy- and a-mercaptopentanoic Acids have been synthe- sized, applying hexafluoroacetone as protecting and activating reagent. The new partially fluorinated a-functionalized carboxylic Acids represent interesting monomers for peptide and depsipeptide modification and for rational design and elucidation of secondary structure.
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N- and O-Glycosylation of Isoserine and Isocysteine
2004Co-Authors: Jan Spengler, Lothar Hennig, O Albericio, Klaus BurgerAbstract:Summary. Starting from HFA-protected malic and Thiomalic Acid a series of O- and N-glycoconjugates suitable for peptide and depsipeptide modification has been synthesized
Alka Jain - One of the best experts on this subject based on the ideXlab platform.
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Grafting of polyacrylamide on to guar gum with the redox system potassium bromate/Thiomalic Acid
Polymer International, 1993Co-Authors: U. D. N. Bajpai, Alka JainAbstract:The kinetics of graft copolymerization of polyacrylamide on to a natural polysaccharide guar gum have been studied in aqueous medium at 35 ± 0.2°C. Chemical initiation, using a water-soluble redox system, potassium bromate/Thiomalic Acid, was used. This redox pair works in the presence of oxygen and thus makes the whole system cost-effective. A plausible mechanism of graft copolymerization has been suggested on the basis of the experimental results obtained by varying the parameters.
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grafting of polyacrylamide on to guar gum with the redox system potassium bromate Thiomalic Acid
Polymer International, 1993Co-Authors: U. D. N. Bajpai, Alka JainAbstract:The kinetics of graft copolymerization of polyacrylamide on to a natural polysaccharide guar gum have been studied in aqueous medium at 35 ± 0.2°C. Chemical initiation, using a water-soluble redox system, potassium bromate/Thiomalic Acid, was used. This redox pair works in the presence of oxygen and thus makes the whole system cost-effective. A plausible mechanism of graft copolymerization has been suggested on the basis of the experimental results obtained by varying the parameters.
U. D. N. Bajpai - One of the best experts on this subject based on the ideXlab platform.
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Grafting of polyacrylamide on to guar gum with the redox system potassium bromate/Thiomalic Acid
Polymer International, 1993Co-Authors: U. D. N. Bajpai, Alka JainAbstract:The kinetics of graft copolymerization of polyacrylamide on to a natural polysaccharide guar gum have been studied in aqueous medium at 35 ± 0.2°C. Chemical initiation, using a water-soluble redox system, potassium bromate/Thiomalic Acid, was used. This redox pair works in the presence of oxygen and thus makes the whole system cost-effective. A plausible mechanism of graft copolymerization has been suggested on the basis of the experimental results obtained by varying the parameters.
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grafting of polyacrylamide on to guar gum with the redox system potassium bromate Thiomalic Acid
Polymer International, 1993Co-Authors: U. D. N. Bajpai, Alka JainAbstract:The kinetics of graft copolymerization of polyacrylamide on to a natural polysaccharide guar gum have been studied in aqueous medium at 35 ± 0.2°C. Chemical initiation, using a water-soluble redox system, potassium bromate/Thiomalic Acid, was used. This redox pair works in the presence of oxygen and thus makes the whole system cost-effective. A plausible mechanism of graft copolymerization has been suggested on the basis of the experimental results obtained by varying the parameters.
Raul Pires - One of the best experts on this subject based on the ideXlab platform.
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New building blocks for peptide and depsipeptide synthesis: hexafluoroacetone protected l-homoisoserine and d,l-homoisocysteine derivatives ☆
Tetrahedron Letters, 2003Co-Authors: Gabor Radics, Raul Pires, Beate Koksch, Salah M. El-kousy, Klaus BurgerAbstract:Abstract Efficient syntheses of l -homoisoserine and d , l -homoisocysteine derivatives starting from l -malic and d , l -Thiomalic Acid using hexafluoroacetone as protecting and activating agent are described. The new compounds are interesting building blocks for the preparation of non-natural peptides and depsipeptides as well as for the construction of new GABA derivatives.
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Synthesis of DL-isocysteine and some derivatives from Thiomalic Acid
Tetrahedron Letters, 1996Co-Authors: Raul Pires, Klaus BurgerAbstract:Abstract Thiomalic Acid is transformed into isocysteine using hexafluoroacetone as protecting and activating agent. The urethanes 5, 6 , 7 obtained represent N-protected, carboxylic group activated derivatives of isocysteine and are perfectly suited for further derivatizations.
Yoshiaki Kinjo - One of the best experts on this subject based on the ideXlab platform.
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Complexation of Thiomalic Acid with mercury (II) and lead (II) under physiological conditions.
Journal of inorganic biochemistry, 1991Co-Authors: Masunobu Maeda, Kohji Okada, Kazuhiro Wakabayashi, Kohji Honda, Kaname Ito, Yoshiaki KinjoAbstract:The complex formation of Thiomalic Acid (H3L) with Hg(II) and Pb(II) was investigated under physiological conditions of 37°C and 0.15 mol dm−3 NaCl by potentiometric titrations using glass electrodes. From the analysis of the emf data in the two systems by use of computer program miquv it was concluded that the species formed in the two systems are [HgH4L2], [HgH3L]−, [HgH2L2]2−, [HgHL2]3−, [HgHL], [HgL]−, [HgL2]4−, [Hg(OH)L]2−, [Hg(OH)L2]5−, [PbH2L2]2−, [PbH2L]+, [PbHL2]3−, [PbHL], [PbL]−, [Pb(OH)L]2−, and [Pb(OH)2L]3−. The hydrolytic reactions of Hg(II), data omn which were used in the analysis of the above system, were also studied by separate potentiometric titrations. Measurements of 13C NMR spectra of [HgL2]4− and [PbL]− and [PbHL2]3− in D2O solutions suggested that the ligand coordinates with both the metal ions through the sulfhydryl group and one of the two carboxylate groups in such a way that the five-membered chelate ring is formed within the complexes.