The invention is concerned with the compounds having the formula ##STR1## the pharmaceutically acceptable addition salts and the stereochemically isomeric forms thereof, wherein X is O or S; Y is CH or N; R.sup.1, R.sup.2 and R.sup.3 each independently are hydrogen or C.sub.1-4 alkyl; R.sup.4 and R.sup.5 each independently are hydrogen, halo, C.sub.1-4 alkyl, C.sub.1-4 alkyloxy, hydroxy, trifluoromethyl, trifluoromethyloxy or difluoromethyloxy; R.sup.6 is C.sub.1-4 alkyl; C.sub.1-4 alkyl substituted with arylcyclohexyl; aryl or arylcarbonyl; wherein aryl is phenyl optionally substituted with one or two substituents selected from halo and C.sub.1-4 alkyl;Z is C.dbd.O or CHOH; and ##STR2## is a radical of formula ##STR3## Compositions comprising said compounds, processes for preparing the same and the use of these compounds as a medicine.