Disclosed are compounds of formula I: ##STR00001## wherein X is a carbonyl, sulfonyl, methylene, or methylene substituted with optionally substituted phenyl; Z is nitrogen or CH; Ar.sub.1 and Ar.sub.2 independently represent aryl groups; and Y is hydrogen; or Y and R.sub.1 or R.sub.2 together represent CH.sub.2; CH.sub.2CH.sub.2; CH.sub.2O; CH.sub.2S forming a five or six membered ring and such ring may be optionally substituted with loweralkyl or phenyl; or the pharmaceutically acceptable salts thereof, useful in the treatment of neoplastic diseases, and bacterial or fungal infections, and in preventing or decreasing the production of abnormally phosphorylated paired helical filament (PHF) epitopes associated with Alzheimer's Disease and, therefore, useful for treating Alzheimer's Disease.