Synthesis of Tetrasubstituted Pyrazoles from Substituted Hydrazines and β-Keto Esters

Herein we report the synthesis of tetrasubstituted pyrazoles from simple hydrazines and β-keto esters under mild, basic conditions. This reaction enables the selective synthesis of pyrazolones, alkoxypyrazoles, and tetrasubstituted pyrazoles for a large variety of aromatic hydrazines and substituted β-keto esters with high yields and selectivities. This method permits access to highly complex pyrazole scaffolds with four orthogonal diversification groups.