Synthesis and Cytotoxic Activity of Pyranocarbazole Analogues of Ellipticine and Acronycine

Various 2,2,5,11-tetramethyl- and 2,2,5,6,11-pentamethyl-2,6-dihydropyrano[3,2-b]carbazole derivatives were synthesized by condensation of 3-methyIbut-2-enal or 3-chloro-3-methylbut-1-yne with an appropriate hydroxycarbazole. These compounds associate the tricyclic system responsible for the intercalating properties of ellipticine related drugs, with the dimethylpyran pharmacophore of acronycine derivatives. The study of the biological properties of the new pyrano[3,2-b]carbazole derivatives was carried out in vitro on L1210 murine leukaemia cell line. The three (±)-cis-diol diesters 15, 16, and 18 were the most active compounds.