Method for producing N-substituted 3-hydroxypyrazoles

摘要

A process for preparing N-substituted 3-hydroxypyrazoles of the formula I, wherein, R1 is unsubstituted or substituted C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C10 cycloalkyl, aryl selected from phenyl and naphthyl, heteroaryl selected from furyl, thienyl, pyrrolyl, isoxazolyl, isothiazolyl, pyrazolyl, oxazolyl, imidazolyl, pyridyl, pyridazinyl, pyrimidinyl and triazinyl, R2 and R3 are hydrogen, cyano, halogen and unsubstituted or substituted C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C10 cycloalkyl, unsubstituted or substituted aryl selected from phenyl and naphthyl, heteroaryl selected from furyl, thienyl, pyrrolyl, isoxazolyl, isothiazolyl, pyrazolyl, oxazolyl, imidazolyl, pyridyl, pyridazinyl, pyrimidinyl and triazinyl, where the substituents R1, R2 and R3 are inert under the reaction conditions, by oxidizing a pyrazolidin-3-one of the formula II which comprises carrying out the reaction of the water-soluble compounds of the formula II in water in the presence of a base using oxygen as oxidizing agent.