Schiff s bases preparation

Studies on the transamination reaction between f-butyl esters of optically active amino acids and methyl pyruvate were carried out, as shown in Scheme 7. The resulting iminodicarboxylic acid (16) was partially hydrolyzed and then oxidized with f-butyl hypochlorite to form alanine. The oxidation is a generally applicable one, and the optical purity of alanine is high (50-70%). Similar asymmetric transamination between an (S)-amino acid and ketones was carried out. Catalytic hydrogenation of the Schiff s bases prepared from a-keto acid esters and amino acid esters was carried out, and a substituent and temperature effect observed (de 40-70%). ... 

In buffered aqueous ethanolic and dimethylformamide solutions Schiff s bases (prepared from aniline and salicylaldehyde or o-tosyl-aminobenzaldehyde derivatives) with an intramolecular hydrogen bond give two one-electron waves. In aqueous ethanolic solution both waves are shifted towards negative potentials with increase in the pH value, which indicates that electron transfer is preceded by protonation. 

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