HIV inhibitory compounds of formula: ##STR00001## salts and stereoisomers thereof, wherein R.sup.1 and R.sup.2 are hydrogen or optionally substituted C.sub.1-10alkyl; R.sup.3 is ##STR00002## n is 1, 2 or 3; R.sup.3a is nitro, cyano, amino, halo, hydroxy, C.sub.1-4alkyloxy, hydroxycarbonyl, aminocarbonyl, C .sub.1-4alkyloxycarbonyl, mono- or di(C.sub.1-4alkyl)aminocarbonyl, C.sub.1-4alkylcarbonyl, methanimidamidyl, mono- or di(C.sub.1-4alkyl)methanimidamidyl, N-hydroxy-methanimidamidyl or Het; or R.sup.3 is a monocyclic or bicyclic aromatic heterocyclic ring system, wherein one, two, three or four ring members are nitrogen, oxygen and sulfur, and wherein the remaining ring members are carbon atoms; and wherein each of said heterocyclic ring systems may optionally be substituted; X is --NR.sup.7--, --O-- or --S--; pharmaceutical compositions containing these compounds, methods for preparing these compounds and compositions.