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Enantioselective Resolution (enantioselective + resolution)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

ChemInform Abstract: Humicola lanuginosa Lipase Catalyzed Enantioselective Resolution of ,-Hydroxy Sulfides: Versatile Synthons for Enantiopure ,-Hydroxy Sulfoxides.

CHEMINFORM, Issue 14 2002
Satwinder 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]

Enantioselective Recognition of Aspartic Acids by Chiral Ligand Exchange Potentiometry

ELECTROANALYSIS, Issue 11 2004
Yanxiu Zhou
Abstract Enantioselective resolution is realized by combining potentiometry with ligand exchange (CE) in a new method called chiral ligand exchange potentiometry (CLEP). A chiral selector, N -carbobenzoxy- L -aspartic acid (N-CBZ-L-Asp), preferentially recognizes D -aspartic acid (D-Asp) and undergoes ligand exchange with the enantiomeric labile coordination complexes of [Cu(II)(D-Asp)2] or [Cu(II)(L-Asp)2] to form a diastereoisomeric complex [(D-Asp)Cu(II)(N-CBZ-L-Asp)] (a) or [(L-Asp)Cu(II)(N-CBZ-L-Asp)] (b). Considerable stereoselectivity occurs in the formation of these diastereoisomeric complexes, and their net charges were ,2 (a) and 0 (b), respectively, resulting in different Nernst factor (electrode slope), thus enabling chiral D-Asp to be distinguished by potentiometry without any pre- or postseparation processes. [source]

Chemo-Enzymatic Synthesis of All Isomers of 2-Methylbutane-1,2,3,4-tetraol , Important Contributors to Atmospheric Aerosols

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2007
Anders Riise Moen
Abstract By a combination of stereospecific osmium catalyzed oxidation of dimethyl citraconate and lipase catalysed enantioselective resolution of the formed dimethyl (2R*,3S*)-2,3-dihydroxy-2-methylbutanedioate, followed by reduction, (2R,3S)- and (2S,3R)-2-methylbutane-1,2,3,4-tetraol were isolated. Similar reactions starting with dimethyl mesaconate gave the isomers, (2R,3R)- and (2S,3S)-2-methylbutane-1,2,3,4-tetraol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Stereoselectivity of Pseudomonas cepacia lipase toward secondary alcohols: A quantitative model

PROTEIN SCIENCE, Issue 6 2000
Tanja Schulz
Abstract The lipase from Pseudomonas cepacia represents a widely applied catalyst for highly enantioselective resolution of chiral secondary alcohols. While its stereopreference is determined predominantly by the substrate structure, stereoselectivity depends on atomic details of interactions between substrate and lipase. Thirty secondary alcohols with published E values using P. cepacia lipase in hydrolysis or esterification reactions were selected, and models of their octanoic acid esters were docked to the open conformation of P. cepacia lipase. The two enantiomers of 27 substrates bound preferentially in either of two binding modes: the fast-reacting enantiomer in a productive mode and the slow-reacting enantiomer in a nonproductive mode. Nonproductive mode of fast-reacting enantiomers was prohibited by repulsive interactions. For the slow-reacting enantiomers in the productive binding mode, the substrate pushes the active site histidine away from its proper orientation, and the distance d(HN, , Oalc) between the histidine side chain and the alcohol oxygen increases. d(HN, , Oalc) was correlated to experimentally observed enantioselectivity: in substrates for which P. cepacia lipase has high enantioselectivity (E > 100), d(HN, , Oalc) is>2.2 Å for slow-reacting enantiomers, thus preventing efficient catalysis of this enantiomer. In substrates of low enantioselectivity (E < 20), the distance d(HN, , Oalc) is less than 2.0 Å, and slow- and fast-reacting enantiomers are catalyzed at similar rates. For substrates of medium enantioselectivity (20 < E< 100), d(HN, , Oalc) is around 2.1 Å. This simple model can be applied to predict enantioselectivity of P. cepacia lipase toward a broad range of secondary alcohols. [source]