Compounds of Formula (I), ##STR00001## are provided where T is CHO, CON, or C(OH)R.sub.1R.sub.2; R.sub.1 and R.sub.2 are hydrogen, optionally substituted lower alkyl, CF.sub.3, optionally substituted alkenyl, or optionally substituted alkynyl; R.sub.3 is hydrogen or optionally substituted lower alkyl; R.sub.4 is (CF.sub.3).sub.nalkyl, (CF.sub.3).sub.n(substitutedalkyl), (CF.sub.3).sub.nalkylphenyl, (CF.sub.3).sub.nalkyl(substitutedphenyl), or (F).sub.ncycloalkyl; n=1-3; R.sub.5 is hydrogen, halogen, CF.sub.3, diene fused to Y when Y.dbd.C, or substituted diene fused to Y when Y.dbd.C; W, Y and Z are C, CR.sub.6 or N where at least one of W, Y or Z are C; R.sub.6 is hydrogen, halogen, or optionally substituted lower alkyl; X is O, S, SO.sub.2, or NR.sub.7; R.sub.7 is hydrogen, optionally substituted lower alkyl, optionally substituted benzyl, or optionally substituted phenyl; and R.sub.8 is lower alkyl, CF.sub.3, or optionally substituted phenyl. Methods of preparing and using these compounds for inhibiting beta amyloid production and for treatment of Alzheimer's Disease and Down's syndrome are also described.