abstract |
A compound represented by general formula (I), wherein R1 and R2 are the same or different and each represents C1-4 alkyl; and R3 represents C1-7 alkoxy optionally substituted by hydroxy, halogeno, cyano, C1-4 alkoxy, amino or acylamino; provided that R1 and R2 do not represent methyl at the same time. The compound is useful as a medicine. |