The synthesis of new pyrido[1,2-a]- and pyridazino[1,6-a]benzimidazolium salts by basic condensation of 1,3-disubstituted 2-alkylbenzimidazolium salts and 1,2-diketones and subsequent chemical transformations is described. The DNA-binding properties were examined by UV-vis spectroscopy, viscosimetric determinations, and molecular modeling techniques. The presence of a flat polycyclic hydrocarbon moiety such as a naphthalene-1,8-diyl or a biphenyl-o,o'-diyl, fused to the cationic heterocycle, appears to enhance the interaction with DNA. Variation of the substituents on the indole-like N will allow us to build up a new series of bis-salts with bis-intercalating properties.

A simple and efficient method for the cleavage of tertbutoxycarbonyl amides and amines is described, which takes place on silica gel under microwave irradiation.

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