Abstract
Asymmetric synthesis of optically active amines (15) by catalytic hydrogenation and chemical transamination of the schiff bases (10) of (S)-α-amino acid esters (8) with ketones (9) was achieved. The effects of solvents and the ester moiety of chiral reagents on the asymmetric induction were examined, and (S)-(+)-2-amino-3-phenylpropane (15a) was prepared from (S)-valine tert-butyl ester and phenylacetone in 63% yield and 87% optical yield. The possible steric course of the asymmetric hydrogenation is discussed. The reduction of the Schiff bases (10) with sodium borohydride is also described.
