Abstract: Compounds represented by the formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are lower alkyl, R.sub.4 is lower alkoxy, R.sub.6 and R.sub.8 are methyl or trifluoro methyl, R.sub.9 is formyl, hydroxymethyl, alkoxymethyl, alkanoyloxymethyl, carboxyl, alkoxycarbonyl, lower alkenoxycarbonyl, lower alkynoxycarbonyl, carbamoyl, mono(lower alkyl)-carbamoyl, di(lower alkyl)carbamoyl or N-heterocyclylcarbonyl, R.sub.5, R.sub.7, R.sub.10, R.sub.11 R.sub.12 and R.sub.13 are hydrogen or fluorine with the proviso that at least one of R.sub.5, R.sub.7, R.sub.10, R.sub.11, R.sub.12 or R.sub.13 is fluorine or at least one of R.sub.6 or R.sub.8 is trifluoro methyl,or pharmaceutically acceptable salts thereof useful as antitumor agents are disclosed.