The invention relates to compounds of formula (I) wherein Ar1 is pyridyl or phenyl, substituted by hydroxy, lower alkyl, halogen, amino, nitro, benzyloxy or lower alkoxy-lower alkoxy, or is the group (a) wherein Z1 is a five membered heterocyclic ring, which contains one or two heteroatoms, selected from N or O; R1 is hydrogen, hydroxy or an oxo group; Ar2 is pyridyl or phenyl, optionally substituted by hydroxy, lower alkyl, halogen, amino, nitro, benzyloxy or lower alkoxy-lower alkoxy, or is the group (b) wherein Z2 is a five or six membered ring, which optionally contains one or two heteroatoms, selected from N or O; and Q is -S-, -S(O)- or -S(O)¿2?-; X is a bond, -CH(OH)- or -(CH2)n-; A is a bond or -(CHR)m-; R is hydrogen, halogen or hydroxy, independently from each other if m is 2 or 3; Y is -(CR2)m-, -O-, -C=C-, -C C-, piperidin-1-yl, pyrrolidin-1yl or C4-C6-cycloalkyl, which rings are optionally substituted by hydroxy; B is a bond, -O- or -(CHR)m; n is 1 or 2; and m is 1 to 3 and pharmaceutically acceptable acid addition salts thereof with the exception of compounds, wherein A and B are simultaneously a bond and Y is -CHR-. The compounds may be used in the treatment of neurodegenerative diseases.