Compounds of the general formula (I): ##STR00001## wherein m, n, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as described in the specification. Further included are pharmaceutical compositions comprising the compounds, processes for their preparation, as well as the use of the compounds for the preparation of a medicament for the treatment of 5-HT.sub.2A receptor-related disorders or medical conditions.