An agent for oxidatively changing the colour of keratinic fibres, especially human hair, comprises at least one p-phenylenediamine oxidation dye precursor of formula (I) and/or a physiologically acceptable salt thereof in a cosmetic carrier Z may be a heterocyclic ring selected from a pyrrolidine, piperidine, morpholine, pyrrole, pyrazole, imidazole, piperazine, thiazine, or pyrroline moiety, preferably pyrrolidine. Alternatively, Z may be a carbocyclic ring chosen from phenyl, cyclohexyl, or cyclopentyl. Typically, R1 is methyl or hydrogen and R2, R3, and R4 are hydrogen. The oxidation dye precursor (I) may be present in an amount of 0.001-5.0 wt.%. The agent may also contain hydrogen peroxide as an oxidising agent. Compounds of formula (I) per se are also claimed.
