Condensed heterocyclic systems with a quaternary nitrogen atom. III. Synthesis of benzimidazo[3,2-b]isoquinolinium perchlorates

Isochromylium cations containing easily detached groupings (NHCOR, NH2, OCH3) in the 3 position react readily with o-phenylenediamine. The reaction is accompanied by opening of the benzopyrylium ring and condensation of the resulting compound at one or two amino groups of o-phenylenediamine. Benzimidazo[3,2-b]isoquinolinium salts were synthesized alternatively by acylation of 2-(3,4-dimethoxybenzyl)benzimidazole. The tautomerism of the synthesized N-(2-aminoaryl)isoquinolinium perchlorates was investigated.