According to one general process, (A), compounds of formula (I) may be prepared from a compound of formula (II) ##STR11## wherein Ar, X, Y, m and n are as defined in relation to formula (I), by reaction with a compound of the formula (III) ##STR12## wherein R and Z are as defined in relation to formula (I) and LG represents a leaving group such as a halogen atom or an alkyl- or aryl-sulphonyloxy g