Insertion of aryl monoamines into the isoquinoline-5,8-quinone core, to produce arylaminoisoquinolinequinones, strongly enhanced the cytotoxic activity of the scaffold. As a contribution to build new potential cytotoxic members of this series the behavior of aryl diamines to act as mono and/or bis nucleophiles against isoquinoline-5,8-quinones was evaluated. The experiments performed with the aryl diamines: p-phenylenediamine, benzidine and dapsone, and a number of isoquinolinequinones, with or without the presence of a Lewis catalyst, indicated that monoamination, is the preferred reaction to yield the respectives arylaminoisoquinolinequinones. The structures of the new products were established and their voltammetric properties were evaluated. Screening of the aminoquinones on a panel of three cancer cells showed moderate to high antiproliferative activities. Among the members of the series, eight compound stand out for their high potencies and selective index on the tested cancer cell lines, compared to those of the etoposide and taxol cancer drugs.