Synthesis and 13C NMR of (trifluoromethyl)hydroxypyrazoles

Abstract Reaction of ethyl 4,4,4‐trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5‐hydroxy‐3‐(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3‐hydroxy‐5‐(trifluoromethyl)pyrazole 4 . The structure assignments are established based on 13 C nmr spectra. Compound 1 was converted to 5‐chloro‐3‐(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps.