A compound of Formula (I), or a pharmaceutically acceptable salt thereof, is provided that has been shown to be useful for treating a PRC2-mediated disease or disorder: wherein R1, R2, R3, R4, R5, and n are as defined herein.本發明提供式(I)化合物或其醫藥上可接受之鹽,已顯示其可用於治療PRC2介導之疾病或病症:其中R1、R2、R3、R4、R5及n係如本文所定義。