| abstract |
A compound represented by the formula [I]: or a pharmacologically acceptable salt or ester thereof, wherein Ring A represents a five-membered aromatic heterocyclic group or the like fused with a non-aromatic ring group, which may be substituted, Ring B represents a phenyl group or the like which may be substituted, X1 represents a single bond or the like, R1 and R2 each represent a C1-6 alkyl group or the like, m represents an integer of 0 to 3, and n represents an integer of 0 to 2, is effective as a therapeutic agent for a disease caused by Aβ. |