Compositions for dyeing keratin fibers comprise (a) at least one keratin dyeing compound selected from aromatic systems which comprise at least one boronic acid or boronic ester moiety and which are capable of forming upon oxidation a nucleophile or an electrophile, (b) at least one additional keratin dyeing compound selected from the group consisting of auxiliary developers and auxiliary couplers, and (c) a cosmetically suitable medium. Methods for oxidatively dyeing keratin fibers comprise the steps of applying such compositions in the presence of an oxidizing agent and rinsing the hair. A hair coloring product in kit form comprises a first separately packaged container comprising a composition as described above and a second separately packaged container comprising an oxidizing agent.