novel chiral pyridoxamines 3a–g containing a sidechain has been developed. The pyridoxamines displayed catalytic activity and promising enantioselectivity in biomimetic asymmetric transamination of α-keto acids, to give various α-amino acids in 47–90% yields with up to 87% ee’s under very mild conditions. An interesting effect of the sidechain on enantioselectivity was observed in the reaction.
A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine and (S)-alpha,alpha-diarylprolinols. The pyridoxals exhibited good catalytic activity in an asymmetric transamination of alpha-keto acids with 2,2-diphenylglycine (7f) as the amine source to give various alpha-amino acids in 29-85% yields with 53-80% ee's. The current asymmetric transamination has successfully mimicked a complete biological transamination process characterized by two half-transaminations, a small chiral pyridoxal molecule acting as the catalyst, and enantioselective control.
Staudinger; Reber, Helvetica Chimica Acta, 1921, vol. 4, p. 10,21