1,720,979 research outputs found
Candida Cylindracea Lipase Catalysed Hydrolysis of Methyl Aziridine 2-Carboxylates and 2,3-Dicarboxylates.
No full textN-substituted aziridine-2-carboxylates and 2,3-dicarboxylates have been resolved with good to excellent stereochemical purity by enzymatic hydrolysis catalyzed by lipase from Candida cylindracea
Enantioselective Lipase-Catalyzed Acetylation of beta-Lactams Precursors of Carbapenem Antibiotics
No full textThe Amano PS-lipase-catalyzed enantioselective acetylation in vinyl acetate of (±)-3-hydroxyethyl-β-lactams 3–6, useful precursors of carbapenem antibiotics, proceeds with high enantioselectivity (E > 98) to afford the corresponding acetates 3b–6b in optically pure form. The rate of acetylation is influenced by the relative stereochemistry of the C(3)–C(4) β-lactam carbon atoms, the trans isomers being transformed much faster than the cis ones. The stereochemical preference of the lipase-PS is for the (1'R,3R) enantiomers, as determined by chemical correlation. On the other hand, the lipase-PS-catalyzed hydrolysis of esters 3b,d in phosphate buffer proceeds with low selectivity and at a lower rate
Enzymatic Resolution of Chiral N-Alkyloxaziridine-3,3-dicarboxylic Esters
No full textPorcine pancreatic lipase provided enentioselective hydrolyses of chiral N-alkyloxaziridine3,3-dicarboxylic ester
Enantioselective Synthesis of (S)-(Ð)-5,5,5-Trifluoro-4-Hydroxy-2-Pentanone by Baker's Yeast Reduction.
No full textBaker's yeast reduces 1,1,1-trifluoro-2,4-pentanedione with high regio- and enantio-selectivity to give (S)-5,5,5-trifluoro-4-hydroxy-2-pentanone. The enantiomeric excess was determined by Mosher's method and the absolute configuration was established by correlation with ethyl (R)-(+)-4,4,4-trifluoro-3-hydroxybutanoate
Enzymatic Resolution of Chiral N-alkyl Oxaziridine and N-Chloro Aziridine Dicarboxylic Esters
No full textSubstituent Effect on the Absolute Stereochemistry of the Bakers' Yeast Asymmetric Reduction of Fluorine Containing beta-diketones
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Effetto del Bromuro di Allile e dell'Alcool Allilico nella Riduzione con Lievito di Composti Carbonilici alfa-Alogenati
No full textRegioselectivity of Ring-opening reactions of optically active N-Acetyl-2-Methoxycarbonyl aziridine
No full text(S)-(-)-N-acetyl-2-methoxycarbonylaziridine 1 undergoes easy ring-opening by Bronsted acids or nucleophiles in the presence of a Lewis acid catalyst. The regioselectivity is not always exclusive, affording optically active alpha- and beta-aminoacids
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