Construction of Substituted N-Phenylpyrazoles via a Catalyst- Free and Additive-Free Intermolecular Cyclization Process

A simple and practical protocol for the construction of substituted N-phenylpyrazoles from phenylhydrazine and pentane-2,4-dione under catalyst-free and additive-free conditions was demonstrated.The catalyst-free and additive-free process has advantages of operational simplicity,good functional group tolerance,step economy,scaled-up synthesis and high yields,which render this strategy to be more useful in the synthesis of pyrazole drugs,biologically active molecules and pesticides.