or crystallisation thereafter if desirable removing the r3 group of the resulting s enantiomer according to general formula tv with a suitable reagent such as an acid or base and if desirable deprotecting the q group of the resulting s enantiomer according to general formula iv with a deprotecting agent optionally a free carboxylic acid function may in the end be protected with the group r p the present invention further relates to a process for the preparation of the s enantiomer of a compound of the general formula vii wherein q is a protecting group or h r2 is oh or the group or p wherein r p is a protecting group and one or more of the hydrogen atoms of the phenyl group are optionally substituted by the equivalent number of halogen atoms comprising separating the enantiomers by chiral chromatography and thereafter if desirable deprotecting the q group of the resulting compound with a deprotecting agent and optionally protecting a free carboxylic acid function with the group r p the present invention further relates to a process for the preparation of a compound of the general formula viii wherein q is a protecting group or h a is oh a chiral auxiliary group or the group or p wherein r p is a protecting group and one or more of the hydrogen atoms of the phenyl group are optionally substituted by the equivalent number of halogen atoms comprising reducing a compound according to the general formula vi wherein q is a protecting group or h and a is oh a chiral auxiliary group or the group or p wherein r p is a protecting group and one or more of the hydrogen.