The invention relates to methods for the treatment of Alzheimer's disease, cerebral amyloid angiopathy, hereditary cerebral hemorrhage with amyloidosis, Dutch-type (HCHWA-D), multi-infarct dementia, dementia pugilistica and Down syndrome which comprise administering a therapeutically effective amount of a compound of formula I wherein R1, R2, R3, V, W, Y, and Z are as defined herein or a pharmaceutically active acid addition salt of such compounds. The invention also relates to a subgenus of such compounds and pharmaceutical compositions containing them, as well as methods for their manufacture.
