| abstract |
Compounds of the formula (I) and their salts with inorganic and organic acids, <IMAGE> (I) in which R1 is a hydrogen atom or a trimethylsilyl group, R2, R3, R4, and R5 are, independently of each other, a hydrogen atom, a (C1-C4) alkyl group, a hydroxy-(C2-C3) alkyl group, an alkoxy-(C2-C3) group, an amino-(C2-C3) group, or a 2,3-dihydroxypropyl group, and in which R1, R2, R3, R4 and R5 are not simultaneously hydrogen atoms, and processes for their preparation and use as hair-coloring agents. |