| abstract |
Pyrazolo-(1,5-a)-pyrimidines have formula (I), in which the groups R?1, R?2 and R?3 represent independently from each other hydrogen or alkyl groups with 1 to 4 C-atoms or one of the groups R?1 and R?3 represents a carboxyl or hydroxyl group, and the other one, with R?2, represents hydrogen or alkyl groups with 1 to 4 C-atoms. These compounds and their salts are useful as couplers in oxidizing hair dyes containing usual developers for durably dying hair. The new couplers together with developers of the aromatic or heterocyclic amino compound type generate intensive oxidation colours in the range extending from ruddy brown to bluish violet tones. |