Synthesis and Cytotoxic Activity of Dimeric Analogs of Acronycine in the Benzo[b]pyrano[3,2-h]acridin-7-one Series

Abstract

Coupling of 6-hydroxy-3,3-14-trimethyl-3,14-dihydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one (6) with α,ω-diiodoalkanes of varying length under alkaline conditions gave dimers 7—10. Halogenated ethers 11—14, cyclization products 15—17, and compounds 18—22 were also isolated in small yield from the reaction mixtures. Compounds 7—10 were more potent than acronycine and benzo[b]acronycine in inhibiting L1210 cell proliferation. The length of the alkyl ether linkage between the two benzopyranoacridone units had a dramatic influence on the cytotoxic activity. Compound 9 (n=5) was the most active, with an IC₅₀ value against L1210 cells within the same range of magnitude as diacetate 5, currently under clinical development.