Hydrogen peroxide activation with diones

Agent (A) for coloring and/or brightening of keratin fibers, preferably human hair, comprises an alkyl compound (I) (0.001-15 wt.%). Agent (A) for coloring and/or brightening of keratin fibers, preferably human hair, comprises an alkyl compound (I) of formula (A-C(=X)-B1-C(=Y1)-C1) (0.001-15 wt.%). X, Y1 : (=O) or (=N-R 1>); either A, C1 : 1-28C (preferably 1-6C) alkyl or 2-28C (preferably 2-6C) alkylene (both optionally substituted, preferably halogenated), preferably -CH 3, -CH 2CH 3, -(CH 2) 2CH 2, -CH(CH 3) 2, -(CH 2) 3CH 3, -CH(CH 3)CH 2CH 3, -CH 2CH(CH 3) 2, -C(CH 3) 3, -CF 3, -CCl 3, -CBr 3, -Cl 3, -CF 2CF 3 or -CCl 2CCl 3; or A+C1 : a ring; B1 : a chemical bond or -(CH 2) n; and n : 0-10 (preferably 0). An independent claim is included for a procedure for brightening of keratin fiber, preferably human hair comprising applying a pre-treating agent (M1) on the fiber, applying an agent (M2), where (M2) is applied before using a further agent (M3), washing (M2) after 5-30 minutes, and optionally applying a follow-up treating agent (M4) after the treatment and washing after an influential time of some minutes.