Novel Process and Intermediates. A process for preparing a compound of formula (I) where R.sup.4 and R.sup.5 are as defined in the specification; and R.sup.6 is hydrogen or a protecting group, which process comprises cyclisation of a compound of formula (II) where R.sup.4 and R.sup.5 and R.sup.6 are as defined in relation to formula (I), and R.sup.7 is nitrogen protecting group, and removing the group R.sup.7, and thereafter if desired, removing any protecting group R.sup.6. Novel intermediates and the use of these in the formation of pharmaceutical compounds is also described and claimed ##STR00001##