This invention relates to compounds of formula (I): 1 wherein: A is C(O) or CH(OH); R.sup.1 is 2 R.sup.2 is H, C.sub.1-6alkyl, C.sub.3-6cycloalkyl-C.sub.0-6alkyl, Ar-C.sub.0-6alkyl, Het-C.sub.0-6alkyl, R.sup.5C(O)--, R.sup.5C(S)--, R.sup.5S0.sub.2--, R.sup.5OC(O)--, R.sup.5R'NC(O)--, R.sup.5R'NC(S)--, adamantyl-C(O)--, or 3 R" is H, C.sub.1-6alkyl, Ar-C.sub.0-6alkyl, or Het-C.sub.0-6alkyl; R'" is H, C.sub.1-6alkyl, C.sub.3-6cycloalkyl-C.sub.0-6alkyl, Ar-C.sub.0-6alkyl, or Het-C.sub.0-6alkyl;