Pyrazole-3/5-carboxylic acids from 3/5-trifluoromethyl NH-pyrazoles

We report here the transformation of 3/5-trifluoromethylpyrazoles derivative into the corresponding NH-pyrazole-3/5-carboxylic acids. Moreover, from 4- or 5-iodinated-3/5-trifluoromethylpyrazoles building blocks and the use of Suzuki-Miyaura or Negishi reactions followed by the trifluoromethyl hydrolysis, we illustrate short and original accesses to many series of NH-pyrazole-3/5-carboxylic acids otherwise difficult to prepare.