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