3-Methyl-2-((2S) -2- (4- (3-methyl-1,2,4-oxadiazol-5-yl) phenyl) morpholino) -6- as a tau protein kinase inhibitor (Pyrimidin-4-yl) pyrimidin-4 (3H) -one
A compound represented by the formula (I) or a pharmaceutically acceptable salt thereof: which is used for preventive and/or therapeutic treatment of a disease caused by abnormal activity of tau protein kinase 1 such as a neurodegenerative diseases (e.g. Alzheimer disease).