abstract |
Disclosed is a compound represented by the formula (I): (wherein Ar1 represents imidazolyl optionally substituted by one to three substituents; Ar2 represents a pyridinyl, pyrimidinyl, or phenyl group optionally substituted by one to three substituents; X1 represents (1) -Ca"C- or (2) an optionally substituted double bond, etc.; and R1 and R2 each represents optionally substituted C1-6 alkyl, C3-8 cycloalkyl, etc.) or a pharmacologically acceptable salt of the compound; and a use of the compound or salt as a medicine for the treatment/prophylaxis of a disease resulting from amyloid betas, wherein the disease is selected from Alzheimer's disease, senile dementia, Down syndrome or amyloidosis. |