A process for preparing a compound of formula (I) or a tautomeric form thereof or a pharmaceutically acceptable salt thereof, wherein: A.sup.1 represents a substituted or unsubstituted aromatic heterocyclyl group; R.sup.1 represents a hydrogen atom, an alkyl group, an acyl group, an aralkyl group, wherein the aryl moiety may be substituted or unsubstituted, or a substituted or unsubstituted aryl group; A.sup.2 represents a benzene ring having in total up to five substituents; and n represents an integer in the range of from 2 to 6, which process comprises catalytically reducing a compound of formula (II): wherein A.sup.1, R.sup.1, A.sup.2 and n are as defined in relation to formula (I), characterized in that the reduction reaction is carried out using a hydrogen pressure above 20 psi; and thereafter if required forming a pharmaceutically acceptable salt and/or a pharmaceutically acceptable solvate of the compound of formula (I). ##STR00001##