| abstract |
The compounds of the formula ##STR1## in which one of the groups R 1 , R 2 and R 3 represents hydrogen, C 1 - 8 -alkyl, C 3 - 6 -cycloalkyl, phenyl optionally substituted by halogeno, C 1 - 4 -alkyl, C 1 - 4 -alkoxy and/or trifluoromethyl, or C 7 - 10 -phenylalkyl optionally substituted in the phenyl moiety by halogeno, C 1 - 4 -alkyl, C 1 - 4 -alkoxy and/or trifluormethyl, and the other two are hydrogen, or salts thereof. n These compounds have valuable pharmaceutical properties. |