Synthesis of 3-Cyanopyrazoles from 3-Trifluoromethyl-pyrazoles via Direct Ammonolysis Reaction
摘要:
A simple and green method to prepare 3-cyanopyrazoles in aqueous ammonia from easy-obtained 3-trifluoromethyl-pyrazoles was explored. Most substrates got acceptable yields. The hydrogen position of Nl-H on cyanopyrazoles was assigned by X-ray crystal structure analysis.
Pyrazole-3/5-carboxylic acids from 3/5-trifluoromethyl NH-pyrazoles
作者:Mikhail S. Ermolenko、Sandrine Guillou、Yves L. Janin
DOI:10.1016/j.tet.2012.10.034
日期:2013.1
transformation of 3/5-trifluoromethylpyrazoles derivative into the corresponding NH-pyrazole-3/5-carboxylic acids. Moreover, from 4- or 5-iodinated-3/5-trifluoromethylpyrazoles buildingblocks 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.
Use of a Traceless Activating and Directing Group for the Construction of Trifluoromethylpyrazoles: One-Pot Transformation of Nitroolefins and Trifluorodiazoethane
作者:Zhen Chen、Yan Zheng、Jun-An Ma
DOI:10.1002/anie.201700955
日期:2017.4.10
We disclose an efficient one‐pot transformation of trifluorodiazoethane and higher perfluorinated homologues with various nitroolefins. This method takes advantage of the nitro group as a traceless activating and directing group (TADG) that is released in the aromatization step to produce 4‐substituted 3‐perfluoroalkyl pyrazoles with complete regioselectivity. The potential of this method is further
Simple preparations of 4 and 5-iodinated pyrazoles as useful building blocks
作者:Sandrine Guillou、Frédéric J. Bonhomme、Mikhail S. Ermolenko、Yves L. Janin
DOI:10.1016/j.tet.2011.09.029
日期:2011.11
The pyrazole nucleus has recently become a recurrent scaffold in the research fields of CropScience and oncology. We report here the preparation of an array of 4- and 5-iodinated pyrazole derivatives, such as 4-iodo-3-trifluoromethylpyrazole or ethyl 5-iodo-4-carboxy-3-trifluoromethylpyrazoles. This work provide access to many new pyrazole derivative, including 11 original out of 16 iodinated building