Three bisannulation strategies have been used to rapidly construct pentacyclic benzo‐fused pyrrolo[4,3,2‐mn]acridines, similar to several biologically active natural products. The key steps involve Michael substitution of 2,3‐dichloro‐1,4‐naphthoquinone with o‐nitrophenylacetic acid derivatives, followed by domino amino‐Michael substitutions/cyclisations. The most efficient of these syntheses provided a model compound (1) including the ABCD ring‐system of alpkinidine, in just three steps and 55 % overall yield.

Twenty-two derivatives belonging to the cis-1,2-diacyloxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[a]pyrano[3,2-h]acridin-7-one series were synthesized in nine steps starting from 3,5-dimethoxyacetanilide (5) and 2-methoxy-1-naphthalenecarboxylic acid (7). Most of them exhibited submicromolar cytotoxicity when tested against murine leukemia (L1210) and human epidermoid carcinoma (KB-3-1) cell lines. The cytotoxic activity correlated strongly with the ability of the compounds to form covalent adducts with purified DNA. Among the most active compounds, 25, with IC50 values of 0.7 and 0.15 microM against L1210 and KB-3-1, respectively, was selected for evaluation in vivo against Colon 38 adenocarcinoma implanted in mice. This compound was active at 3 mg/kg i.v. (day 12 and 24) with 3/7 tumor free mice by day 80.

An efficient strategy for the control of the chemoselectivity in Dieckmann ring closures leading to tetramic acids derived from serine and α-methyl serine is reported, and this provides pathways to diversely substituted systems from a common starting material.