| abstract |
The present invention provides a compound which has an effect of inhibiting amyloid beta production, especially an effect of inhibiting BACE1, and which is useful as a therapeutic or prophylactic agent for diseases induced by production, secretion and/or deposition of amyloid beta proteins. A compound of the formula (I):wherein X is -C(R 3a )(R 3b )-, -C(R 3a )(R 3b )-C(R 3c )(R 3d )- or -C(R 3a )=C(R 3c )-, R 1 is substituted or unsubstituted alkyl or the like,R 2a , R 2b , R 3a , R 3b , R 3c and R 3d are each independently hydrogen, halogen or the like, R 4 is hydrogen or halogen,Ring B is substituted or unsubstituted carbocycle or a substituted or unsubstituted heterocycle, or a pharmaceutically acceptable salt thereof. |