Piperidine compounds and their preparation and use

Abstract From the Canadian patent

New piperidine compounds having the formula (see formula I), wherein, at least one of R3 R4, and R5 are (see formula II) or (see formula III) and the other independently are H, C1-6-alkyl wherein R' is H, C1-8-alkyl, phenyl, thienyl cyclopropyl, or C1-3-alkoxymethyl ; and R1 and R6 independently are H or C1-6-alkyl and wherein, (see formula IV) is (see formula V) or (see formula VI) ; 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.