abstract |
N-substituted 3-hydroxypyrazoles of the formula I ##STR1## where R 1 is unsubstituted or substituted alkyl, aryl or heteroaryl and R 2 , R 3 is hydrogen, cyano, halogen or unsubstituted or substituted alkyl, aryl or heteroaryl, are prepared by oxidation of a corresponding pyrazolidin-3-one with atmospheric oxygen in the presence of a metal salt in an essentially pH-neutral medium. |