| Abstract
| - The enzyme (lipases and chymotrypsin)-catalyzed hydrolysis ofSchiff bases derived from racemicamino acid esters and aromatic aldehydes has been investigated.The reactions were successfullycarried out in different aqueous organic solvents at ambienttemperature, but the aqueousacetonitrile (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 theliberated aldehyde andunhydrolyzed d-ester (ee 40−98%) remained in thesolution. The range of substrates includedamino acids having different types of side chains. The addition ofan organic base (DABCO) intothe solution resulted in the racemization of the remainingd-ester and the additional hydrolysis ofthe substrate, thus leading to the effective asymmetric transformationof the initial ester. Upto87.5% of the initial racemate was converted into thel-enantiomer.
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