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High Enantiomeric Purity (high + enantiomeric_purity)
Selected AbstractsAn Asymmetric Catalytic Darzens Reaction between Diazoacetamides and Aldehydes Generates cis -Glycidic Amides with High Enantiomeric Purity,ANGEWANDTE CHEMIE, Issue 35 2009Wei-Jun Liu Dr. Titanverstärkt: Die Titelreaktion wurde durch einen chiralen Titankomplex katalysiert, der in,situ aus käuflichem Ti(OiPr)4 und (R)-Binol gebildet wurde, und lieferte mit ausgezeichneter Enantiomerenreinheit cis -Glycidamide (siehe Schema). Mit dieser neuen Methode wurden chirale Bausteine für die Synthese der Seitenketten von Taxol und (,)-Bestatin hergestellt. [source] ChemInform Abstract: Efficient Syntheses of Fluorinated Aryl Alcohols of High Enantiomeric Purity via Boronic Esters.CHEMINFORM, Issue 12 2001Rajendra P. Singh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Semipreparative chiral supercritical fluid chromatography in the fractionation of lansoprazole and two related antiulcer drugs enantiomersJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2008Laura Toribio Abstract The semipreparative chiral separation of lansoprazole and two related compounds (pantoprazole and rabeprazole) using supercritical fluid chromatography (SFC) is presented in this work. Different loads were evaluated in order to obtain high enantiomeric purities and production rates. The volumes injected were 1, 2 and 4 mL. The concentrations of the racemic mixtures were 3 and 6 g/L for lansoprazole and 1.5 g/L for pantoprazole and rabeprazole. In all the cases, the recoveries, for a purity higher than 99.9%, were better for the second eluted enantiomer than for the first one. This fact conditioned the production rate of the first eluted enantiomer that, considering a fixed purity, was always lower than that obtained for the other one. In the case of lansoprazole it was possible to obtain 0.025 and 0.090 mg/min of the first and second eluted enantiomer, respectively, with an enantiomeric purity of 99.9%. For rabeprazole enantiomers 0.037 and 0.062 mg/min, and in the case of pantoprazole the results were better (0.062 and 0.122 mg/min) due to the higher resolution. [source] Catalytic Asymmetric Synthesis of Branched Chiral Allylic Phenyl Ethers from (E)-Allylic AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Angela Abstract The first di-,-amidate dipalladium complexes and a new di-,-carboxylate dipalladium complex of the COP (cobalt oxazoline palladacycle) palladium(II) catalyst family are reported and characterized crystallographically. The di-,-amidate complex 3 and its enantiomer (ent - 3) are the first asymmetric catalysts that allow commercially available, or readily accessible, (E)-2-alken-1-ols to be transformed to enantioenriched branched allylic aryl ethers upon reaction of their trichloroacetimidate derivatives with phenols. The 3-aryloxy-1-alkene products are formed in high enantiomeric purity (typically 90,98% ee) and useful yields (61,88%). [source] One-Pot, Regioselective Synthesis of Substituted Arylglycines for Kinetic Resolution by Penicillin G AcylaseADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Peter Grundmann Abstract Amido-alkylation of electron-rich arenes with phenylacetamide and glyoxylic acid offers an inexpensive route to a large variety of N -phenylacetylated arylglycines that are suited for immediate enzymatic resolution by penicillin G acylase. When performed under mild conditions at 5,°C in acetic acid/HCl, this simple one-pot operation resulted in the formation of single regioisomers only (,98%). Subsequent kinetic resolution of the amino acid derivatives by penicillin G acylase at pH,8.0 occurred generally with E values>100 and thus furnished free (S)-configurated arylglycines with high enantiomeric purity. The corresponding enantiopure (R)-substrates, easily separable by a phase-selective extraction process, provided the corresponding (R)-enantiomers upon conventional hydrolysis. This one-pot, two-step procedure for arylglycine synthesis, resolution and work-up requires a minimum of equipment and grants rapid access to both enantiopure (S)- and (R)-antipodes of non-natural ,-amino acids in small- to large-scale quantities. [source] | ||||||||||