- Chemoenzymatic approaches to the dynamic kinetic asymmetric synthesis of aromatic amino acids
-
Enzymatic approaches for the production of amino acids by nitrilases are described. Dynamic kinetic asymmetric synthesis conditions were established for the aromatic aminonitriles, phenylglycinonitrile and 4- fluorophenylglycinonitrile, at high pH to produce the corresponding amino acid products in high enantiomeric excess. N-Acylation of aromatic aminonitriles led to spontaneous racemization at pH 8, allowing preferential enzymatic hydrolysis of the (R)-enantiomer to afford the product N-acylamino acids in up to 99% enantiomeric excess (ee).
- Chaplin, Jennifer A.,Levin, Michael D.,Morgan, Brian,Farid, Nancy,Li, Jen,Zhu, Zuolin,McQuaid, Jeff,Nicholson, Lawrence W.,Rand, Cynthia A.,Burk, Mark J.
-
p. 2793 - 2796
(2007/10/03)
-
- Efficient chemoenzymatic synthesis of enantiomerically pure α-amino acids
-
A general two-step chemoenzymatic synthesis for enantiomerically pure natural and nonnatural α-amino acids is presented. In the first step of the sequence, the ubiquitous educts aldehyde, amide and carbon monoxide react by palladium-catalyzed amidocarbonylation to afford the racemic N-acyl amino acids in excellent yields. In the second step, enzymatic enantioselective hydrolysis yields the free optically pure a-amino acid and the other enantiomer as the N-acyl derivative, both in optical purities of 85-99.5% ee. The advantage of the chemoenzymatic process compared to other amino acid synthesis are demonstrated by the preparation of various functionalized (-OR, -Cl, -F, -SR) α-amino acids on a 10-g scale.
- Beller, Matthias,Eckert, Markus,Geissler, Holger,Napierski, Bernd,Rebenstock, Heinz-Peter,Holla, E. Wolfgang
-
p. 935 - 941
(2007/10/03)
-
- HOMOCHIRAL HETEROORGANIC ANALOGS OF NATURAL COMPOUNDS. I. PREPARATIVE BIOCATALYTIC METHOD OF OBTAINING FLUORINE-CONTAINING L- AND D-PHENYLGLYCINES
-
A biocatalytic method of obtaining homochiral o- and p-fluorine-substituted phenylglycines by enantiomeric hydrolysis from N-phenylacetyl or N-acetyl derivatives under the action of Escherichia coli penicillin acylase or Streptoverticillium olivoreticuli aminoacylase is proposed.The L form of the amino acid and the unhydrolyzed D-enantiomer of the initial derivative are separated by extraction and chromatographic methods.The acid hydrolysis of the D-enantiomers of N-phenylacetyl derivatives of fluorine-substituted phenylglycines leads to partial (about 15percent) racemization.With a substantially higher (by two orders of magnitude) concentration of enzyme and an increase in the reaction time it is possible to use penicillinase as a catalyst for the hydrolysis of the D-enantiomer of the N-phenylacetyl derivative not accompanied by any appreciable racemization whatever.
- Soloshonok, V. A.,Galaev, I. Yu.,Shvyadas, V. K.,Kozlova, E. V.,Kotik, N. V.,et al.
-
p. 228 - 232
(2007/10/02)
-