The present invention relates to a compound of formulawhereinHetAr is a five or six membered hetaryl group, containing one, two or three heteroatoms, selected from N, O or S；R1 is hydrogen, lower alkyl, lower alkyl substituted by halogen, halogen, or lower alkoxy；R2 is lower alkyl substituted by halogen, —；CH2—；C3-6-cycloalkyl, substituted by one or two substituents, selected from lower alkyl substituted by halogen or halogen, or is lower alkenyl substituted by halogen；R3 is hydrogen, lower alkyl substituted by halogen, lower alkyl, halogen, C3-6-cycloalkyl or lower alkyl substituted by hydroxy；n is 1 or 2； for n=2, R1 can be independent to each other；Y is CH or N；or to a pharmaceutically active acid addition salt thereof, to a racemic mixture or its corresponding enantiomer and/or optical isomer and/or stereoisomer thereof. The compounds may be used for the treatment of Alzheimer's disease, cerebral amyloid angiopathy, hereditary cerebral hemorrhage with amyloidosis, Dutch-type (HCHWA-D), multi-infarct dementia, dementia pugilistica or Down syndrome.
