Patent No. 594776 Disclosed is a compound of formula I, such as 8-[2-chloro-5-(5-trifluoromethylpyridine-2-yl)phenyl]-2-[6-methoxy-5-(4-methyl-1H-imidazol-1-yl)pyridin-2-yl]-5,6,7,8-tetrahydro[1,2,4]triazolo[1,5-a] pyridine, which is useful for treating Alzheimer's disease, dementia, Down's syndrome and amyloidosis.