Abstract: The present invention relates to compound of general formula (1) wherein R1 represents C6-C10 aryl comprising one or two fused rings, wherein from 2 to 5 carbon atoms may be replaced with a heteroatom selected from O, S and NR6, and eventually substituted with from 5 to 11 substituents selected from R6, halo, CN, NO2, CF3, OCF3, COOR6, OCOR6, SO2NR6R7, CONR6R7, NR6R7, NR6COR7, (CH2)p—NR6R7, (CH2)p—OR6 and (CH2)pSR6, as well as, if appropriate, their pharmaceutically acceptable salts and/or isomers, tautomers, solvates or isotopic variations thereof. The compounds are useful for the treatment of cancers.