149207-93-2Relevant academic research and scientific papers
Schiff bases of amino acid esters as new substrates for the enantioselective enzymatic hydrolysis and accompanied asymmetric transformations in aqueous organic solvents
Parmar, Virinder S.,Singh, Amarjit,Bisht, Kirpal S.,Kumar, Naresh,Belokon,Kochetkov,Ikonnikov,Orlova,Tararov,Saveleva
, p. 1223 - 1226 (2007/10/03)
The enzyme (lipases and chymotrypsin)-catalyzed hydrolysis of Schiff bases derived from racemic amino acid esters and aromatic aldehydes has been investigated. The reactions were successfully carried out in different aqueous organic solvents at ambient temperature, but the aqueous acetonitrile (5.4% water content by volume) was the solvent of choice. The L-amino acid (ee 98%) precipitated out from the solution as the reaction progressed, and the liberated aldehyde and unhydrolyzed D-ester (ee 40-98%) remained in the solution. The range of substrates included amino acids having different types of side chains. The addition of an organic base (DABCO) into the solution resulted in the racemization of the remaining D-ester and the additional hydrolysis of the substrate, thus leading to the effective asymmetric transformation of the initial ester. Upto 87.5% of the initial racemate was converted into the L-enantiomer.
Chemo-Enzymic Synthesis of Optically Active α,α-Disubstituted α-Amino Acids
Liu, Weiguo,Ray, Paul,Benezra, Steven A.
, p. 553 - 560 (2007/10/02)
A series of α,α-disubstituted α-amino esters was chemically synthesized and then resolved through enantioselective hydrolysis catalysed by a new enzyme isolated from crude Humicola langinosa lipase.This enzyme only accepts free amino esters as substrates with neither lipase activity toward olive oil nor esterase activity toward o-nitrophenyl butyrate.It is unique in that it successfully catalyses the resolution of amino esters with two large α-alkyl groups including aliphatic, aromatic and cyclic amino esters.Examples of resolutions where the alkyl groups differ in size by as little as a single carbon atom have been demonstrated.For determination of absolute configuration, some of the optically active α,α-disubstituted amino acids were also prepared through Schoellkopf's asymmetric synthesis and the structures were verified by X-ray crystallography.A model depicting the substrate binding site of the enzyme is proposed.
