The invention provides a further process for the preparation of compounds of the formula (II) wherein R3 is other than an amino group and X is a group of the sub-formula (b) or (c), which process comprises the reaction of a compound of the formula (VII): ##STR9## wherein R3 * is a group R3 as defined in relation to formula (II) except an amino group, with a compound of the formula (VIII) or (IX):