| abstract |
Provided is a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a method of treating Duchenne muscular dystrophy: [Chemical 1] (Wherein three of A 1, A 2, A 3 and A 4 represents CH, A 1, A 2, one of A 3 and A 4 represent CR 1; R 1 is Represents SO 2 R 2 or NHCOR 2 , R 2 represents C 1 -C 6 alkyl optionally substituted by one or more halogen, hydroxyl or alkoxy groups; R 9 represents C 6 -C 10 aryl .). [Selection figure] None |