Regioselective Synthesis of 1,3,5-Tri- and 1,3,4,5-Tetrasubstituted Pyrazoles from <i>N</i>-Arylhydrazones and Nitroolefins
作者:Xiaohu Deng、Neelakandha S. Mani
DOI:10.1021/jo7026195
日期:2008.3.1
[GRAPHICS]Two general protocols are developed for the regioselective synthesis of 1,3,5-tri- and 1,3,4,5-tetrasubstituted pyrazoles by the reaction of electron-deficient N-arylhydrazones with nitroolefins. Studies on the stereochemistry of the key pyrazolidine intermediate suggest a stepwise cycloaddition mechanism.