(S)-o-N-(N-benzylprolyl)aminobenzaldehyde and (S)-o-N-(N-benzylprolyl)aminoacetophenone as reagents for asymmetric synthesis of threonine

Abstract

Chiral aldehydes and ketones, derivatives of proline and piperidine-2-carboxylic acid have been synthesized and their Schiff bases with glycine form copper complexes which were hydroxyethylated with acetaldehyde; decomposition of the complexes obtained gave threonine with an optical purity of up to 97–100% and with threo/allo ratios of up to 19 : 1, and the chiral reagents can be recovered and reused with no loss of optical purity of the threonine.