2-(叔丁基二甲基硅杂氧基)环己酮 、 Bredereck 试剂 以to give crude title compound (85 mg) as a brown oil which的产率得到2-(tert-butyldimethylsilanyloxy)-6-[1-dimethylaminometh-(E)-ylidene]cyclohexanone
The invention relates to compounds of formula
wherein R1, R2, R3, R4, X and Y are as defined herein and to pharmaceutically active acid addition salts thereof. The compounds can 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.