Ring Monofluorinated Hydroxypyrazoles

Article abstract of DOI:10.1246/bcsj.54.3221

3-Alkyl(or aryl)-4-fluoro-5-hydroxypyrazoles and their 1-methyl derivatives were prepared by the reaction of methyl α-fluoro-β-alkyl(or aryl)-β-keto esters with hydrazine hydrate or methylhydrazine in ethanol.The reaction of arylhydrazines with α-fluoro-β-keto esters gave only hydrazones which could not be cyclized to pyrazoles.