Process for the preparation of propionic acid derivatives

A process for the preparation of a compound of formula (I)

• or a salt thereof, wherein a compound of formula (II)
• or a salt thereof is hydrogenated
• (e) in the presence of a catalyst comprising iridium;
• or
• (f) in the presence of a catalyst comprising ruthenium and a compound of:
• formula (IV),
• formula (V),
• formula (VI),
• or formula (VII),
• wherein
• R3 is alkyl, cycloalkyl or aryl;
• R4 is cycloalkyl, aryl or heteroaryl;
• R5 is cycloalkyl or aryl;
• R6 is cycloalkyl or aryl;
• R7 is cycloalkyl or aryl;
• R8 is cycloalkyl or aryl;
• and
• R9 is cycloalkyl or aryl.