RING-D MODIFICATIONS OF ELLIPTICINE .2. CHLORINATION OF ELLIPTICINE VIA ITS N-OXIDE AND SYNTHESIS AND SELECTIVE ACETYLATION OF 5,6,11-TRIMETHYL-5H-BENZO[B]CARBAZOLE

The N-oxide of ellipticine can be used for the introduction of a chlorine atom at carbon-3 of the ellipticine nucleus. According to modelstudies with 5,8-dimethylisoquinoline-N-oxide the reaction is guided both by steric hindrance and by nitrogen-6 of the ellipticine system. Attempted nucleophilic substitution reactions of 3-chloro-ellipticines failed. The high cytostatic activity observed for 9-acetylellipticine stimulated us to prepare the corresponding deaza analogue. This compound was synthesized in 2 steps starting from 1-methylindole. Regioselective acetylation at C-2 was accomplished using acetic anhydride and ZnCl2 as a catalyst. Under a variety of other conditions the 2,9-diacetylproduct was formed and no 9-monoacetylated compound could be isolated. Just as the parent compound, the acetylated deazaellipticines showed only very low cytostatic activity.