The present invention is concerned among others with compounds of formula (1), the N-oxides, the pharmaceutically acceptable addition salts, the quaternary amines and stereochemically isomeric forms thereof, wherein Q is halo, C.sub.1-6 alkyl or C.sub.2-6 alkenyl; X is (a-2) with q and r being O and Z being O, S or SO; R.sub.1 is aryl; R.sub.2 is selected from formyl; C.sub.1-6alkyloxycarbonylalkyl; Het.sup.2; Het.sup.2C.sub.1-6alkyl, C.sub.1-6alkylthio; C.sub.1-6alkyl optionally substituted with one or two substituents each independently selected from hydroxy, and halo; R.sub.3 is selected from formyl; C.sub.1-6alkyl optionally substituted with one or two C.sub.1-6alkyloxy; R.sub.4 is hydrogen, with HTV inhibiting properties ##STR00001##