New piperidine compounds having the formula ##STR1## wherein at least one of R.sup.3, R.sup.4, and R.sup.5 are ##STR2## and the other independently are H, C.sub.1-6 -alkyl, wherein R' is H, C.sub.1-8 -alkyl, phenyl, thienyl, cyclopropyl, or C.sub.1-3 -alkoxymethyl; and R.sup.1 and R.sup.6 independently are H or C.sub.1-6 -alkyl, and wherein ##STR3## and salts thereof with pharmaceutically-acceptable acids. The new compounds are useful in improving the cognitive functions of the forebrain and hippocampus of mammals, and are therefore useful in the treatment of Alzheimer's disease.
                            新的
哌啶化合物具有以下式子:##STR1## 其中R.sup.3、R.sup.4和R.sup.5中至少有一个为##STR2## 另外两个独立地为H、C.sub.1-6-烷基,其中R'为H、C.sub.1-8-烷基、苯基、
噻吩基、环丙基或C.sub.1-3-烷氧甲基;而R.sup.1和R.sup.6独立地为H或C.sub.1-6-烷基,其中##STR3##,以及与药学上可接受的酸形成的盐。这些新化合物有助于改善哺乳动物的前脑和海马的认知功能,因此对于治疗阿尔茨海默病有用。