ASYMMETRIC HYDROGENATION OF SCHIFF BASE PREPARED FROM alpha -KETO ESTER WITH ALIPHATIC AMINO ACID ESTER.

Article abstract of DOI:10.1246/bcsj.57.1367

Catalytic hydrogenation of Schiff bases prepared from alpha -keto esters with amino acid esters was carried out under various conditions. A significant substituent effect of the alkyl group of the ester moiety of amino acid on the stereoselectivity was observed in the hydrogenation of the Schiff bases prepared from methyl pyruvate with (S)-alanine ester. Higher asymmetric yields were obtained as the ester residue of amino acid ester became bulkier. A clear temperature effect on the asymmetric hydrogenation was also observed. These results could be explained by the chelation mechanism.