The present invention is concerned with compounds of formula ##STR1## the N-oxides, the pharmaceutically acceptable addition salts and the stereochemically isomeric forms thereof, wherein R.sup.1 is hydrogen, hydroxy, C.sub.1-6 alkyl or aryl; R.sup.2 is hydrogen; optionally substituted C.sub.1-12 alkyl; C.sub.3-7 cycloalkyl; C.sub.2-8 alkenyl, optionally substituted pyrrolidinyl or aryl; R.sup.3 is hydrogen, optionally substituted C.sub.1-6 alkyl or aryl; Het is an optionally substituted unsaturated heterocycle selected from imidazolyl, triazolyl, tetrazolyl and pyridinyl; ##STR2## is an optionally substituted unsaturated mono- or bicyclic heterocycle; and aryl is optionally substituted phenyl. The present invention also relates to processes for their preparation and compositions comprising said new compounds, as well as their use as a medicine.