Enzymatic synthesis of ω-carboxy-β-hydroxy-( l)-α-amino acids

Abstract

Commercially available ω-carboxy-aldehydes and glycine have been subjected to the catalytic action of an l-threonine aldolase from Escherichia coli to give the corresponding β-hydroxy-α-( l)-amino acids as a mixture of erythro/ threo epimers. Specifically, the reaction with glyoxylic acid ( 2) gave the epimeric β-hydroxy-( l)-aspartates ( t, e)-9 that could be isolated by ion-exchange chromatography in 67% yield. Following esterification and N-Boc protection, the two epimers could be isolated as pure compounds. Similarly, the aldolase-catalyzed addition of glycine to succinic semialdehyde ( 4) gave the expected mixture of β-hydroxy- l-α-aminoadipic acids ( t)-12 and ( e)-12 in 34% yield.