Synthesis of non proteinogenic dipeptides by asymmetric hydrogenation

N-Boc protected non-proteinogenic dipeptides with D,L- and L,L-configuration were prepared by catalytic asymmetric hydrogenation of the corresponding dehydrophenylalanyl-(L)-phenylalanine derivatives. The configuration of the new stereogenic centre depends first of all on the catalyst configuration and is less influenced by the substrate configuration. Diastereomeric excesses in the range of 80-96% de could be increased up to 99% by recrystallization. Analytical data of selected new compounds are given.