Dual inhibitors for the treatment of alzheimer's disease

A compound of formula I, a stereoisomer or a mixture of stereoisomers thereof, or a pharmaceutically acceptable salt of any of them,

• wherein:
• R1 and R2 are each one a radical independently selected from the group consisting of H and (C1-C3)-alkyl;
• X is a biradical selected from the group consisting of a biradical of a linear methylene chain of formula —[CH2]n— with n=0, 1 or 2, and a biradical from a branched saturated (C2-C4)-alkylene chain;
• and
• A is either a C-radical from a non-aromatic polycyclic 6- to 15-membered carbocyclic ring system, or a C-radical from a non-aromatic polycyclic 6- to 15-membered heterocyclic ring system having one or two heteroatoms in the ring, the heteroatoms being independently selected from O, S and N;
• wherein the C-radicals are unsubstituted or the C-radicals have one or more of their H atoms substituted by one or more substituents that are attached to any of the possible substitution positions, the substituents being independently selected from the group consisting of (C1-C4)-alkyl, O[(C1-C4)-alkyl], OH, F, Cl, Br, and I;
• on the proviso that A does not have any one of the three accompanying unsubstituted formulas, nor any of the possible substituted formulas derived thereof, and
• on the proviso that the compound of formula I does not have the accompanying formula Ib