One-Pot Synthesis of Some New Semicarbazone, Thiosemicarbazone, and Hydrazone Derivatives of 1-Phenyl-3-Arylpyrazole-4-Carboxaldehyde from Acetophenone Phenylhydrazones Using Vilsmeier–Haack Reagent

Abstract

Semicarbazone derivatives 3 of 1,3-diphenylpyrazole-4-carboxaldehyde have been synthesized in high yields through a one-pot procedure involving acetophenone phenylhydrazones 1 subjected to Vilsmeier double formylation and workup under new conditions (i.e., treatment with semicarbazide followed by sodium bicarbonate). This method is even suitable for preparing other derivatives (i.e., thiosemicarbazones 4 and hydrazones 5) in high yields.

Keywords:

• Acetophenone
• 1,3-diphenylpyrazole-4-carboxaldehyde
• phenylhydrazones
• semicarbazones
• thiosemicarbazones
• Vilsmeier–Haack reaction

ACKNOWLEDGMENTS

We are thankful to Council of Scientific and Industrial Research, New Delhi, for the award of a junior research fellowship to Pooja Ranjan and Defense Research Development Organization (ERIP/ER/0103294/M/01), New Delhi, for the award of a senior research fellowship to Kamaljeet Pannu to carry out this work.

Notes

^a Yields of the isolated products 2 and 3 with regard to 1.