Embodiment 18: A process for the manufacture of a compound of formula (I) in free form or in pharmaceutically acceptable salt form according to embodiments 14 to 17 in which compound (Ilia) is obtained by the stereoselective reduction of a compound of formula (IVa- 2) in free form or in pharmaceutically acceptable salt form (IVa-2) in which Ra and R are protecting groups and LG is a leaving group.