- L-Methionine related 1-amino acids by acylase cleavage of their corresponding N-acetyl-DL-derivatives
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Acylase I from Aspergillus oryzae is an even more useful enzyme than suggested so far. Besides standard amino acids such as L-Met, L-Val and L-Phe, a number of additional sulfur- and selenium-containing amino acids can be obtained at useful reaction rates and in very high enantiomeric purity by kinetic resolution of the respective N-acetyl-DL-amino acids.
- Bommarius, Andreas S.,Drauz, Karlheinz,Guenther, Kurt,Knaup, Guenter,Schwarm, Michael
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p. 3197 - 3200
(2007/10/03)
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- Synthesis and application of (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran as ligand for asymmetric hydrogenation of acrylic acids
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A new, chiral bisphosphine, (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran (4), is synthesized in three steps from (R,R)-tartaric acid esters. With rhodium(I) complexes of 4 enantiomeric excesses of 54 to 97% are obtained on catalytic hydrogenation of 2-(acetylamino)acrylic acid, 2-(acetylamino)cinnamic acids and itaconic acid. The applied substrate/catalyst ratios were between 250:1 and 11,000:1.
- Terfort
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p. 951 - 953
(2007/10/02)
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- Kinetic Resolution of Unnatural and Rarely Occuring Amino Acids: Enantioselective Hydrolysis of N-Acyl Amino Acids Catalyzed by Acylase I
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Acylase I (aminoacylase; N-acylamino-acid amidohydrolase, EC 3.5.1.14, from porcine kidney and the fungus Aspergillus) is broadly applicable enzymatic catalyst for the kinetic resolution of unnatural and rarely occuring α-amino acids.Its enantioselectivity for the hydrolysis of N-acyl L-α-amino acids is nearly absolute, yet it accepts substrates having a wide range of structure and functionality.This paper reports the initial rates of enzyme-catalyzed hydrolysis of over 50 N-acyl amino acids and analogues, the stabilities of the enzymes in aqueous and aqueous/organic solutions, and the effects of different acyl groups and metal ions on the rates of enzymatic hydrolysis.Eleven α-amino and α-methyl α-amino acids were resolved on a 2-29-g scale.Crude L- and D-amino acid products had generally >90percent ee.The utility of resolved amino acids as chiral synthons was illustrated by the preparation of (R)- and (S)-1-butene oxide and the diastereoselective (cis:trans, 7-8:1) iodolactonization of three 2-amino-4-alkenoic acid derivatives.
- Chenault, H. Keith,Dahmer, Juergen,Whitesides, George M.
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p. 6354 - 6364
(2007/10/02)
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- ASYMMETRISCHE KATALYSEN. XXX. ENANTIOSELEKTIVE HYDRIERUNG VON CROTONSAEUREDERIVATEN MIT RHODIUM-PHOSPHIN-KATALYSATOREN
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The Z- and E-isomers of the α-N-benzoylamino-2-butenoic acid methyl ester, the E/Z mixtures of α-N-benzoylamino-2-butenoic acid, and the Z-form of α-N-acetylamino-2-butenoic acid were hydrogenated enantioselectively.The hydrogenation products are derivatives of α-aminobutyric acid, which can be reduced to aminobutanol, the optically active component of the antituberculosis drug (+)-ethambutol.In situ catalysts consisting of 2 and the optically active phosphine ligands (+)- and (-)-Norphos, (+)-Prophos, (-)-Chiraphos, (-)-BPPFA, (-)-Diop, and (+)- and (-)-CpMn(CO)2diop were used.The best results were obtained with the substrate (Z)-α-acetylamino-2-butenoic acid and the catalyst 2/(-)-Norphos with 91.5percent e.e.
- Brunner, Henri,Knott, Alfons,Kunz, Manfred,Thalhammer, Elisabeth
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- ENANTIOSELECTIVE HYDROLYSIS BY BAKER'S YEAST
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Optically active N-acetylamino acid esters were obtained by enantioselective hydrolysis of their racemates using fermenting baker's yeast.
- Glaenzer, B.I.,Faber, K.,Griengl, H.
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p. 4293 - 4294
(2007/10/02)
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