Synthesis and intercalation ability of new pyrido[1,2-a]benzimidazoles

Reductive intramolecular cyclization of N-(2-NO2-4-R-phenyl)pyridinium chlorides has been used to synthesize tricyclic condensed imidazole derivatives with a nodal nitrogen atom, pyrido[1,2-a]benzimidazoles. Ways of further modification of these compounds by means of nitration and reduction reactions are outlined. It is established that all obtained pyrido[1,2-a]benzimidazoles possess intercalation activity, i.e., are capable of producing undercondensation of chromosomes by inserting between pairs of DNA nitrogenous bases. The most active compound, 7-NH2-pyrido[1,2-a]benzimidazole, at a concentration of 1 mg/mL increases the length of L. grandiflorum chromosomes by 2.23 times compared with a control and provides a greater delay of condensation in experiments with 9-NH2-acridine.