Compounds of the formula I
wherein the groups A, R1, R2 and R3 are as defined in the specification, exhibit valuable pharmacological properties, especially as antifibrotic agents. They are prepared by methods known per se.
式 I 的化合物(其中基团 A、R1、R2 和 R3 如说明书中所定义)具有重要的药理特性,特别是作为抗纤维化剂。 它们是通过本身已知的方法制备的。