Process for Preparing Pyridyl-Substituted Pyrazoles

Process for preparing pyridyl-substituted pyrazole derivatives of the general formula (I)

• in which
• R1 is alkoxy, hydroxyl, aryloxy, alkylaryloxy, alkyl, cycloalkyl, halogen,
• R2 is hydroxyl, alkoxy, arylalkoxy, allylthio, chlorine, bromine, fluorine, iodine, O—(C═O)alkyl, O—(C═O)O-alkyl, OSO2alkyl, OSO2Ph, OSO2-haloalkyl, OSO2-aryl,
• characterized in that
• (A) acetyleneketones of the formula (II)
• in which
• R4 is a protecting group selected from (C1-C6)-alkyl, aryl, benzyl, tetrahydropyran, (C═O)-alkyl, (C═O)—Oalkyl, Si(alkyl)3,
• and X is halogen
• are reacted with hydrazinopyridines of the formula (III)
• in which
• R3 is halogen, CN, NO2, alkyl, cycloalkyl, haloalkyl, halocycloalkyl, alkoxy, haloalkoxy, alkylamino, dialkylamino, cycloalkylamino,
• to give 1-pyridyl-substituted dihydro-1H-pyrazoles of the formula (IV)
• in which X, R3, R4 are each as defined above,
• (B) the latter are optionally converted further, without preceding isolation, with elimination of water, to 1-pyridyl-substituted trihalomethylpyrazoles of the formula (V)
• in which X, R3, R4 are each as defined above,
• (C) these compounds of the general formula (V)
• are converted with addition of H2SO4, for example, to pyrazolecarboxylic acids of the formula (VI)
• in which R3, R4 are each as defined above,
• (D) the latter are converted, after detaching the protecting group R4, to hydroxymethylpyrazole acids of the formula (VII)
• in which R3 is as defined above, and
• (E) the latter are converted to compounds of the formula (I).