Compounds represented by formula 1: ##STR00001## wherein R.sup.1 is H, halogen, (C.sub.1-4)alkyl, O(C.sub.1-4)alkyl, and haloalkyl; R.sup.2 is H or methyl; R.sup.3 is H or (C.sub.1-4)alkyl; R.sup.4 is H or (C.sub.1-4)alkyl; R.sup.5 is (C.sub.1-4)alkyl, (C.sub.1-4)alkyl(C.sub.3-7)cyclo-alkyl or (C.sub.3-7)cycloalkyl; and W is a fused phenyl-5 or 6-membered heterocycle having one or two heteroatoms selected from N or S; or W is phenyl, 1,1'-biphenyl, 2,3-dihydro-1H-indene, 1,2,3,4-tetrahydronaphthyl, or naphthyl; said W being optionally substituted with (C.sub.1-4)alkyl, which in turn can be optionally substituted with a carboxy or (C.sub.1-4)alkoxycarbonyl, or a salt or ester thereof. The compounds have inhibitory activity against Wild Type, single and double mutant strains of HIV.