Process for the preparation of a diasteromerically enriched phenylglycine amide derivative in which an enantiomerically enriched phenylglycine amide is converted into the corresponding Schiff base with the aid of compound R2—C(O)—R3, and the Schiff base obtained is subsequently converted into the diastereomerically enriched phenyglycine amide derivative with the aid of a cyanide source, a reducing agent or an allyl organometallic compound. The phenylglycine amide derivatives obtained are interesting starting materials for the preparation of for example enantiomerically enriched &agr;- and or &bgr;-amino acids and derivatives thereof, such as amides and esters, and amines.