Synthesis of Pyrimido[1,2-a]benzimidazol-4(10H)-one Derivatives and Evaluation of their Interactions with DNA

The synthesis of new derivatives of the planar tricyclic pyrimido[1,2-a]benzimidazole system featuring protonable side chains in the 3 and/or 10 positions is described. The reported literature procedures for the preparation of the intermediate 3-ethoxycarbonylpyrimido[1,2-a]benzimidazol-4(10H)-one 15, starting from 2-aminobenzimidazole 18 and diethyl ethoxymethylenemalonate, were revised. The interaction with DNA, the intrinsic binding constants, and the antiproliferative activity of a number of compounds (1-8, 10, 11) were preliminarly investigated.