| abstract |
Subject of the present invention are compounds of general formula (I), wherein A is oxygen or sulfur; X is oxygen or sulfur; R1 and R2 are independently hydrogen or an alkyl group with from 1 to 6 carbon atoms; R is selected from alkyl, cycloalkyl, alkylsulphinyl, alkylsulphonyl, hydroxyalkyl, napthtyl, phenyl group which can be unsubsituted or substituted; or R is a 5- or 6-membered heterocycle containing from 1 to 3 heteroatoms selected from oxygen, sulfur and nitrogen, which can be optionally benzocondensed, the pure steroisomers or mixtures thereof as well as salts thereof with pharmaceutically acceptable acids or bases, for the use as medicaments, in particular as antitumor agents. |